summaryrefslogtreecommitdiff
path: root/layout/base/nsCSSRendering.cpp
blob: 74d0cabc6dbd5c9256dbb87c0b60227fb0e3d060 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
2799
2800
2801
2802
2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
2816
2817
2818
2819
2820
2821
2822
2823
2824
2825
2826
2827
2828
2829
2830
2831
2832
2833
2834
2835
2836
2837
2838
2839
2840
2841
2842
2843
2844
2845
2846
2847
2848
2849
2850
2851
2852
2853
2854
2855
2856
2857
2858
2859
2860
2861
2862
2863
2864
2865
2866
2867
2868
2869
2870
2871
2872
2873
2874
2875
2876
2877
2878
2879
2880
2881
2882
2883
2884
2885
2886
2887
2888
2889
2890
2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901
2902
2903
2904
2905
2906
2907
2908
2909
2910
2911
2912
2913
2914
2915
2916
2917
2918
2919
2920
2921
2922
2923
2924
2925
2926
2927
2928
2929
2930
2931
2932
2933
2934
2935
2936
2937
2938
2939
2940
2941
2942
2943
2944
2945
2946
2947
2948
2949
2950
2951
2952
2953
2954
2955
2956
2957
2958
2959
2960
2961
2962
2963
2964
2965
2966
2967
2968
2969
2970
2971
2972
2973
2974
2975
2976
2977
2978
2979
2980
2981
2982
2983
2984
2985
2986
2987
2988
2989
2990
2991
2992
2993
2994
2995
2996
2997
2998
2999
3000
3001
3002
3003
3004
3005
3006
3007
3008
3009
3010
3011
3012
3013
3014
3015
3016
3017
3018
3019
3020
3021
3022
3023
3024
3025
3026
3027
3028
3029
3030
3031
3032
3033
3034
3035
3036
3037
3038
3039
3040
3041
3042
3043
3044
3045
3046
3047
3048
3049
3050
3051
3052
3053
3054
3055
3056
3057
3058
3059
3060
3061
3062
3063
3064
3065
3066
3067
3068
3069
3070
3071
3072
3073
3074
3075
3076
3077
3078
3079
3080
3081
3082
3083
3084
3085
3086
3087
3088
3089
3090
3091
3092
3093
3094
3095
3096
3097
3098
3099
3100
3101
3102
3103
3104
3105
3106
3107
3108
3109
3110
3111
3112
3113
3114
3115
3116
3117
3118
3119
3120
3121
3122
3123
3124
3125
3126
3127
3128
3129
3130
3131
3132
3133
3134
3135
3136
3137
3138
3139
3140
3141
3142
3143
3144
3145
3146
3147
3148
3149
3150
3151
3152
3153
3154
3155
3156
3157
3158
3159
3160
3161
3162
3163
3164
3165
3166
3167
3168
3169
3170
3171
3172
3173
3174
3175
3176
3177
3178
3179
3180
3181
3182
3183
3184
3185
3186
3187
3188
3189
3190
3191
3192
3193
3194
3195
3196
3197
3198
3199
3200
3201
3202
3203
3204
3205
3206
3207
3208
3209
3210
3211
3212
3213
3214
3215
3216
3217
3218
3219
3220
3221
3222
3223
3224
3225
3226
3227
3228
3229
3230
3231
3232
3233
3234
3235
3236
3237
3238
3239
3240
3241
3242
3243
3244
3245
3246
3247
3248
3249
3250
3251
3252
3253
3254
3255
3256
3257
3258
3259
3260
3261
3262
3263
3264
3265
3266
3267
3268
3269
3270
3271
3272
3273
3274
3275
3276
3277
3278
3279
3280
3281
3282
3283
3284
3285
3286
3287
3288
3289
3290
3291
3292
3293
3294
3295
3296
3297
3298
3299
3300
3301
3302
3303
3304
3305
3306
3307
3308
3309
3310
3311
3312
3313
3314
3315
3316
3317
3318
3319
3320
3321
3322
3323
3324
3325
3326
3327
3328
3329
3330
3331
3332
3333
3334
3335
3336
3337
3338
3339
3340
3341
3342
3343
3344
3345
3346
3347
3348
3349
3350
3351
3352
3353
3354
3355
3356
3357
3358
3359
3360
3361
3362
3363
3364
3365
3366
3367
3368
3369
3370
3371
3372
3373
3374
3375
3376
3377
3378
3379
3380
3381
3382
3383
3384
3385
3386
3387
3388
3389
3390
3391
3392
3393
3394
3395
3396
3397
3398
3399
3400
3401
3402
3403
3404
3405
3406
3407
3408
3409
3410
3411
3412
3413
3414
3415
3416
3417
3418
3419
3420
3421
3422
3423
3424
3425
3426
3427
3428
3429
3430
3431
3432
3433
3434
3435
3436
3437
3438
3439
3440
3441
3442
3443
3444
3445
3446
3447
3448
3449
3450
3451
3452
3453
3454
3455
3456
3457
3458
3459
3460
3461
3462
3463
3464
3465
3466
3467
3468
3469
3470
3471
3472
3473
3474
3475
3476
3477
3478
3479
3480
3481
3482
3483
3484
3485
3486
3487
3488
3489
3490
3491
3492
3493
3494
3495
3496
3497
3498
3499
3500
3501
3502
3503
3504
3505
3506
3507
3508
3509
3510
3511
3512
3513
3514
3515
3516
3517
3518
3519
3520
3521
3522
3523
3524
3525
3526
3527
3528
3529
3530
3531
3532
3533
3534
3535
3536
3537
3538
3539
3540
3541
3542
3543
3544
3545
3546
3547
3548
3549
3550
3551
3552
3553
3554
3555
3556
3557
3558
3559
3560
3561
3562
3563
3564
3565
3566
3567
3568
3569
3570
3571
3572
3573
3574
3575
3576
3577
3578
3579
3580
3581
3582
3583
3584
3585
3586
3587
3588
3589
3590
3591
3592
3593
3594
3595
3596
3597
3598
3599
3600
3601
3602
3603
3604
3605
3606
3607
3608
3609
3610
3611
3612
3613
3614
3615
3616
3617
3618
3619
3620
3621
3622
3623
3624
3625
3626
3627
3628
3629
3630
3631
3632
3633
3634
3635
3636
3637
3638
3639
3640
3641
3642
3643
3644
3645
3646
3647
3648
3649
3650
3651
3652
3653
3654
3655
3656
3657
3658
3659
3660
3661
3662
3663
3664
3665
3666
3667
3668
3669
3670
3671
3672
3673
3674
3675
3676
3677
3678
3679
3680
3681
3682
3683
3684
3685
3686
3687
3688
3689
3690
3691
3692
3693
3694
3695
3696
3697
3698
3699
3700
3701
3702
3703
3704
3705
3706
3707
3708
3709
3710
3711
3712
3713
3714
3715
3716
3717
3718
3719
3720
3721
3722
3723
3724
3725
3726
3727
3728
3729
3730
3731
3732
3733
3734
3735
3736
3737
3738
3739
3740
3741
3742
3743
3744
3745
3746
3747
3748
3749
3750
3751
3752
3753
3754
3755
3756
3757
3758
3759
3760
3761
3762
3763
3764
3765
3766
3767
3768
3769
3770
3771
3772
3773
3774
3775
3776
3777
3778
3779
3780
3781
3782
3783
3784
3785
3786
3787
3788
3789
3790
3791
3792
3793
3794
3795
3796
3797
3798
3799
3800
3801
3802
3803
3804
3805
3806
3807
3808
3809
3810
3811
3812
3813
3814
3815
3816
3817
3818
3819
3820
3821
3822
3823
3824
3825
3826
3827
3828
3829
3830
3831
3832
3833
3834
3835
3836
3837
3838
3839
3840
3841
3842
3843
3844
3845
3846
3847
3848
3849
3850
3851
3852
3853
3854
3855
3856
3857
3858
3859
3860
3861
3862
3863
3864
3865
3866
3867
3868
3869
3870
3871
3872
3873
3874
3875
3876
3877
3878
3879
3880
3881
3882
3883
3884
3885
3886
3887
3888
3889
3890
3891
3892
3893
3894
3895
3896
3897
3898
3899
3900
3901
3902
3903
3904
3905
3906
3907
3908
3909
3910
3911
3912
3913
3914
3915
3916
3917
3918
3919
3920
3921
3922
3923
3924
3925
3926
3927
3928
3929
3930
3931
3932
3933
3934
3935
3936
3937
3938
3939
3940
3941
3942
3943
3944
3945
3946
3947
3948
3949
3950
3951
3952
3953
3954
3955
3956
3957
3958
3959
3960
3961
3962
3963
3964
3965
3966
3967
3968
3969
3970
3971
3972
3973
3974
3975
3976
3977
3978
3979
3980
3981
3982
3983
3984
3985
3986
3987
3988
3989
3990
3991
3992
3993
3994
3995
3996
3997
3998
3999
4000
4001
4002
4003
4004
4005
4006
4007
4008
4009
4010
4011
4012
4013
4014
4015
4016
4017
4018
4019
4020
4021
4022
4023
4024
4025
4026
4027
4028
4029
4030
4031
4032
4033
4034
4035
4036
4037
4038
4039
4040
4041
4042
4043
4044
4045
4046
4047
4048
4049
4050
4051
4052
4053
4054
4055
4056
4057
4058
4059
4060
4061
4062
4063
4064
4065
4066
4067
4068
4069
4070
4071
4072
4073
4074
4075
4076
4077
4078
4079
4080
4081
4082
4083
4084
4085
4086
4087
4088
4089
4090
4091
4092
4093
4094
4095
4096
4097
4098
4099
4100
4101
4102
4103
4104
4105
4106
4107
4108
4109
4110
4111
4112
4113
4114
4115
4116
4117
4118
4119
4120
4121
4122
4123
4124
4125
4126
4127
4128
4129
4130
4131
4132
4133
4134
4135
4136
4137
4138
4139
4140
4141
4142
4143
4144
4145
4146
4147
4148
4149
4150
4151
4152
4153
4154
4155
4156
4157
4158
4159
4160
4161
4162
4163
4164
4165
4166
4167
4168
4169
4170
4171
4172
4173
4174
4175
4176
4177
4178
4179
4180
4181
4182
4183
4184
4185
4186
4187
4188
4189
4190
4191
4192
4193
4194
4195
4196
4197
4198
4199
4200
4201
4202
4203
4204
4205
4206
4207
4208
4209
4210
4211
4212
4213
4214
4215
4216
4217
4218
4219
4220
4221
4222
4223
4224
4225
4226
4227
4228
4229
4230
4231
4232
4233
4234
4235
4236
4237
4238
4239
4240
4241
4242
4243
4244
4245
4246
4247
4248
4249
4250
4251
4252
4253
4254
4255
4256
4257
4258
4259
4260
4261
4262
4263
4264
4265
4266
4267
4268
4269
4270
4271
4272
4273
4274
4275
4276
4277
4278
4279
4280
4281
4282
4283
4284
4285
4286
4287
4288
4289
4290
4291
4292
4293
4294
4295
4296
4297
4298
4299
4300
4301
4302
4303
4304
4305
4306
4307
4308
4309
4310
4311
4312
4313
4314
4315
4316
4317
4318
4319
4320
4321
4322
4323
4324
4325
4326
4327
4328
4329
4330
4331
4332
4333
4334
4335
4336
4337
4338
4339
4340
4341
4342
4343
4344
4345
4346
4347
4348
4349
4350
4351
4352
4353
4354
4355
4356
4357
4358
4359
4360
4361
4362
4363
4364
4365
4366
4367
4368
4369
4370
4371
4372
4373
4374
4375
4376
4377
4378
4379
4380
4381
4382
4383
4384
4385
4386
4387
4388
4389
4390
4391
4392
4393
4394
4395
4396
4397
4398
4399
4400
4401
4402
4403
4404
4405
4406
4407
4408
4409
4410
4411
4412
4413
4414
4415
4416
4417
4418
4419
4420
4421
4422
4423
4424
4425
4426
4427
4428
4429
4430
4431
4432
4433
4434
4435
4436
4437
4438
4439
4440
4441
4442
4443
4444
4445
4446
4447
4448
4449
4450
4451
4452
4453
4454
4455
4456
4457
4458
4459
4460
4461
4462
4463
4464
4465
4466
4467
4468
4469
4470
4471
4472
4473
4474
4475
4476
4477
4478
4479
4480
4481
4482
4483
4484
4485
4486
4487
4488
4489
4490
4491
4492
4493
4494
4495
4496
4497
4498
4499
4500
4501
4502
4503
4504
4505
4506
4507
4508
4509
4510
4511
4512
4513
4514
4515
4516
4517
4518
4519
4520
4521
4522
4523
4524
4525
4526
4527
4528
4529
4530
4531
4532
4533
4534
4535
4536
4537
4538
4539
4540
4541
4542
4543
4544
4545
4546
4547
4548
4549
4550
4551
4552
4553
4554
4555
4556
4557
4558
4559
4560
4561
4562
4563
4564
4565
4566
4567
4568
4569
4570
4571
4572
4573
4574
4575
4576
4577
4578
4579
4580
4581
4582
4583
4584
4585
4586
4587
4588
4589
4590
4591
4592
4593
4594
4595
4596
4597
4598
4599
4600
4601
4602
4603
4604
4605
4606
4607
4608
4609
4610
4611
4612
4613
4614
4615
4616
4617
4618
4619
4620
4621
4622
4623
4624
4625
4626
4627
4628
4629
4630
4631
4632
4633
4634
4635
4636
4637
4638
4639
4640
4641
4642
4643
4644
4645
4646
4647
4648
4649
4650
4651
4652
4653
4654
4655
4656
4657
4658
4659
4660
4661
4662
4663
4664
4665
4666
4667
4668
4669
4670
4671
4672
4673
4674
4675
4676
4677
4678
4679
4680
4681
4682
4683
4684
4685
4686
4687
4688
4689
4690
4691
4692
4693
4694
4695
4696
4697
4698
4699
4700
4701
4702
4703
4704
4705
4706
4707
4708
4709
4710
4711
4712
4713
4714
4715
4716
4717
4718
4719
4720
4721
4722
4723
4724
4725
4726
4727
4728
4729
4730
4731
4732
4733
4734
4735
4736
4737
4738
4739
4740
4741
4742
4743
4744
4745
4746
4747
4748
4749
4750
4751
4752
4753
4754
4755
4756
4757
4758
4759
4760
4761
4762
4763
4764
4765
4766
4767
4768
4769
4770
4771
4772
4773
4774
4775
4776
4777
4778
4779
4780
4781
4782
4783
4784
4785
4786
4787
4788
4789
4790
4791
4792
4793
4794
4795
4796
4797
4798
4799
4800
4801
4802
4803
4804
4805
4806
4807
4808
4809
4810
4811
4812
4813
4814
4815
4816
4817
4818
4819
4820
4821
4822
4823
4824
4825
4826
4827
4828
4829
4830
4831
4832
4833
4834
4835
4836
4837
4838
4839
4840
4841
4842
4843
4844
4845
4846
4847
4848
4849
4850
4851
4852
4853
4854
4855
4856
4857
4858
4859
4860
4861
4862
4863
4864
4865
4866
4867
4868
4869
4870
4871
4872
4873
4874
4875
4876
4877
4878
4879
4880
4881
4882
4883
4884
4885
4886
4887
4888
4889
4890
4891
4892
4893
4894
4895
4896
4897
4898
4899
4900
4901
4902
4903
4904
4905
4906
4907
4908
4909
4910
4911
4912
4913
4914
4915
4916
4917
4918
4919
4920
4921
4922
4923
4924
4925
4926
4927
4928
4929
4930
4931
4932
4933
4934
4935
4936
4937
4938
4939
4940
4941
4942
4943
4944
4945
4946
4947
4948
4949
4950
4951
4952
4953
4954
4955
4956
4957
4958
4959
4960
4961
4962
4963
4964
4965
4966
4967
4968
4969
4970
4971
4972
4973
4974
4975
4976
4977
4978
4979
4980
4981
4982
4983
4984
4985
4986
4987
4988
4989
4990
4991
4992
4993
4994
4995
4996
4997
4998
4999
5000
5001
5002
5003
5004
5005
5006
5007
5008
5009
5010
5011
5012
5013
5014
5015
5016
5017
5018
5019
5020
5021
5022
5023
5024
5025
5026
5027
5028
5029
5030
5031
5032
5033
5034
5035
5036
5037
5038
5039
5040
5041
5042
5043
5044
5045
5046
5047
5048
5049
5050
5051
5052
5053
5054
5055
5056
5057
5058
5059
5060
5061
5062
5063
5064
5065
5066
5067
5068
5069
5070
5071
5072
5073
5074
5075
5076
5077
5078
5079
5080
5081
5082
5083
5084
5085
5086
5087
5088
5089
5090
5091
5092
5093
5094
5095
5096
5097
5098
5099
5100
5101
5102
5103
5104
5105
5106
5107
5108
5109
5110
5111
5112
5113
5114
5115
5116
5117
5118
5119
5120
5121
5122
5123
5124
5125
5126
5127
5128
5129
5130
5131
5132
5133
5134
5135
5136
5137
5138
5139
5140
5141
5142
5143
5144
5145
5146
5147
5148
5149
5150
5151
5152
5153
5154
5155
5156
5157
5158
5159
5160
5161
5162
5163
5164
5165
5166
5167
5168
5169
5170
5171
5172
5173
5174
5175
5176
5177
5178
5179
5180
5181
5182
5183
5184
5185
5186
5187
5188
5189
5190
5191
5192
5193
5194
5195
5196
5197
5198
5199
5200
5201
5202
5203
5204
5205
5206
5207
5208
5209
5210
5211
5212
5213
5214
5215
5216
5217
5218
5219
5220
5221
5222
5223
5224
5225
5226
5227
5228
5229
5230
5231
5232
5233
5234
5235
5236
5237
5238
5239
5240
5241
5242
5243
5244
5245
5246
5247
5248
5249
5250
5251
5252
5253
5254
5255
5256
5257
5258
5259
5260
5261
5262
5263
5264
5265
5266
5267
5268
5269
5270
5271
5272
5273
5274
5275
5276
5277
5278
5279
5280
5281
5282
5283
5284
5285
5286
5287
5288
5289
5290
5291
5292
5293
5294
5295
5296
5297
5298
5299
5300
5301
5302
5303
5304
5305
5306
5307
5308
5309
5310
5311
5312
5313
5314
5315
5316
5317
5318
5319
5320
5321
5322
5323
5324
5325
5326
5327
5328
5329
5330
5331
5332
5333
5334
5335
5336
5337
5338
5339
5340
5341
5342
5343
5344
5345
5346
5347
5348
5349
5350
5351
5352
5353
5354
5355
5356
5357
5358
5359
5360
5361
5362
5363
5364
5365
5366
5367
5368
5369
5370
5371
5372
5373
5374
5375
5376
5377
5378
5379
5380
5381
5382
5383
5384
5385
5386
5387
5388
5389
5390
5391
5392
5393
5394
5395
5396
5397
5398
5399
5400
5401
5402
5403
5404
5405
5406
5407
5408
5409
5410
5411
5412
5413
5414
5415
5416
5417
5418
5419
5420
5421
5422
5423
5424
5425
5426
5427
5428
5429
5430
5431
5432
5433
5434
5435
5436
5437
5438
5439
5440
5441
5442
5443
5444
5445
5446
5447
5448
5449
5450
5451
5452
5453
5454
5455
5456
5457
5458
5459
5460
5461
5462
5463
5464
5465
5466
5467
5468
5469
5470
5471
5472
5473
5474
5475
5476
5477
5478
5479
5480
5481
5482
5483
5484
5485
5486
5487
5488
5489
5490
5491
5492
5493
5494
5495
5496
5497
5498
5499
5500
5501
5502
5503
5504
5505
5506
5507
5508
5509
5510
5511
5512
5513
5514
5515
5516
5517
5518
5519
5520
5521
5522
5523
5524
5525
5526
5527
5528
5529
5530
5531
5532
5533
5534
5535
5536
5537
5538
5539
5540
5541
5542
5543
5544
5545
5546
5547
5548
5549
5550
5551
5552
5553
5554
5555
5556
5557
5558
5559
5560
5561
5562
5563
5564
5565
5566
5567
5568
5569
5570
5571
5572
5573
5574
5575
5576
5577
5578
5579
5580
5581
5582
5583
5584
5585
5586
5587
5588
5589
5590
5591
5592
5593
5594
5595
5596
5597
5598
5599
5600
5601
5602
5603
5604
5605
5606
5607
5608
5609
5610
5611
5612
5613
5614
5615
5616
5617
5618
5619
5620
5621
5622
5623
5624
5625
5626
5627
5628
5629
5630
5631
5632
5633
5634
5635
5636
5637
5638
5639
5640
5641
5642
5643
5644
5645
5646
5647
5648
5649
5650
5651
5652
5653
5654
5655
5656
5657
5658
5659
5660
5661
5662
5663
5664
5665
5666
5667
5668
5669
5670
5671
5672
5673
5674
5675
5676
5677
5678
5679
5680
5681
5682
5683
5684
5685
5686
5687
5688
5689
5690
5691
5692
5693
5694
5695
5696
5697
5698
5699
5700
5701
5702
5703
5704
5705
5706
5707
5708
5709
5710
5711
5712
5713
5714
5715
5716
5717
5718
5719
5720
5721
5722
5723
5724
5725
5726
5727
5728
5729
5730
5731
5732
5733
5734
5735
5736
5737
5738
5739
5740
5741
5742
5743
5744
5745
5746
5747
5748
5749
5750
5751
5752
5753
5754
5755
5756
5757
5758
5759
5760
5761
5762
5763
5764
5765
5766
5767
5768
5769
5770
5771
5772
5773
5774
5775
5776
5777
5778
5779
5780
5781
5782
5783
5784
5785
5786
5787
5788
5789
5790
5791
5792
5793
5794
5795
5796
5797
5798
5799
5800
5801
5802
5803
5804
5805
5806
5807
5808
5809
5810
5811
5812
5813
5814
5815
5816
5817
5818
5819
5820
5821
5822
5823
5824
5825
5826
5827
5828
5829
5830
5831
5832
5833
5834
5835
5836
5837
5838
5839
5840
5841
5842
5843
5844
5845
5846
5847
5848
5849
5850
5851
5852
5853
5854
5855
5856
5857
5858
5859
5860
5861
5862
5863
5864
5865
5866
5867
5868
5869
5870
5871
5872
5873
5874
5875
5876
5877
5878
5879
5880
5881
5882
5883
5884
5885
5886
5887
5888
5889
5890
5891
5892
5893
5894
5895
5896
5897
5898
5899
5900
5901
5902
5903
5904
5905
5906
5907
5908
5909
5910
5911
5912
5913
5914
5915
5916
5917
5918
5919
5920
5921
5922
5923
5924
5925
5926
5927
5928
5929
5930
5931
5932
5933
5934
5935
5936
5937
5938
5939
5940
5941
5942
5943
5944
5945
5946
5947
5948
5949
5950
5951
5952
5953
5954
5955
5956
5957
5958
5959
5960
5961
5962
5963
5964
5965
5966
5967
5968
5969
5970
5971
5972
5973
5974
5975
5976
5977
5978
5979
5980
5981
5982
5983
5984
5985
5986
5987
5988
5989
5990
5991
5992
5993
5994
5995
5996
5997
5998
5999
6000
6001
6002
6003
6004
6005
6006
6007
6008
6009
6010
6011
6012
6013
6014
6015
6016
6017
6018
6019
6020
6021
6022
6023
6024
6025
6026
6027
6028
6029
6030
6031
6032
6033
6034
6035
6036
6037
6038
6039
6040
6041
6042
6043
6044
6045
6046
6047
6048
6049
6050
6051
6052
6053
6054
6055
6056
6057
6058
6059
6060
6061
6062
6063
6064
6065
6066
6067
6068
6069
6070
6071
6072
6073
6074
6075
6076
6077
6078
6079
6080
6081
6082
6083
6084
6085
6086
6087
6088
6089
6090
6091
6092
6093
6094
6095
6096
6097
6098
6099
6100
6101
6102
6103
6104
6105
6106
6107
6108
6109
6110
6111
6112
6113
6114
6115
6116
6117
6118
6119
6120
6121
6122
6123
6124
6125
6126
6127
6128
6129
6130
6131
6132
6133
6134
6135
6136
6137
6138
6139
6140
6141
6142
6143
6144
6145
6146
6147
6148
6149
6150
6151
6152
6153
6154
6155
6156
6157
6158
6159
6160
6161
6162
6163
6164
6165
6166
6167
6168
6169
6170
6171
6172
6173
6174
6175
6176
6177
6178
6179
6180
6181
6182
6183
6184
6185
6186
6187
6188
6189
6190
6191
6192
6193
6194
6195
6196
6197
6198
6199
6200
6201
6202
6203
6204
6205
6206
6207
6208
6209
6210
6211
6212
6213
6214
6215
6216
6217
6218
6219
6220
6221
6222
6223
6224
6225
6226
6227
6228
6229
6230
6231
6232
6233
6234
6235
6236
6237
6238
6239
6240
6241
6242
6243
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/* utility functions for drawing borders and backgrounds */

#include <ctime>

#include "gfx2DGlue.h"
#include "mozilla/ArrayUtils.h"
#include "mozilla/DebugOnly.h"
#include "mozilla/gfx/2D.h"
#include "mozilla/gfx/Helpers.h"
#include "mozilla/gfx/PathHelpers.h"
#include "mozilla/HashFunctions.h"
#include "mozilla/MathAlgorithms.h"

#include "BorderConsts.h"
#include "nsISVGChildFrame.h"
#include "nsStyleConsts.h"
#include "nsPresContext.h"
#include "nsIFrame.h"
#include "nsPoint.h"
#include "nsRect.h"
#include "nsIPresShell.h"
#include "nsFrameManager.h"
#include "nsStyleContext.h"
#include "nsGkAtoms.h"
#include "nsCSSAnonBoxes.h"
#include "nsIContent.h"
#include "nsIDocumentInlines.h"
#include "nsIScrollableFrame.h"
#include "imgIRequest.h"
#include "imgIContainer.h"
#include "ImageOps.h"
#include "nsCSSRendering.h"
#include "nsCSSColorUtils.h"
#include "nsITheme.h"
#include "nsThemeConstants.h"
#include "nsLayoutUtils.h"
#include "nsBlockFrame.h"
#include "gfxContext.h"
#include "nsRenderingContext.h"
#include "nsStyleStructInlines.h"
#include "nsCSSFrameConstructor.h"
#include "nsCSSProps.h"
#include "nsContentUtils.h"
#include "nsSVGEffects.h"
#include "nsSVGIntegrationUtils.h"
#include "gfxDrawable.h"
#include "GeckoProfiler.h"
#include "nsCSSRenderingBorders.h"
#include "mozilla/css/ImageLoader.h"
#include "ImageContainer.h"
#include "gfxUtils.h"
#include "gfxGradientCache.h"
#include "nsInlineFrame.h"
#include "nsRubyTextContainerFrame.h"
#include <algorithm>

using namespace mozilla;
using namespace mozilla::css;
using namespace mozilla::gfx;
using namespace mozilla::image;
using mozilla::CSSSizeOrRatio;

static int gFrameTreeLockCount = 0;

// To avoid storing this data on nsInlineFrame (bloat) and to avoid
// recalculating this for each frame in a continuation (perf), hold
// a cache of various coordinate information that we need in order
// to paint inline backgrounds.
struct InlineBackgroundData
{
  InlineBackgroundData()
      : mFrame(nullptr), mLineContainer(nullptr)
  {
  }

  ~InlineBackgroundData()
  {
  }

  void Reset()
  {
    mBoundingBox.SetRect(0,0,0,0);
    mContinuationPoint = mLineContinuationPoint = mUnbrokenMeasure = 0;
    mFrame = mLineContainer = nullptr;
    mPIStartBorderData.Reset();
  }

  /**
   * Return a continuous rect for (an inline) aFrame relative to the
   * continuation that draws the left-most part of the background.
   * This is used when painting backgrounds.
   */
  nsRect GetContinuousRect(nsIFrame* aFrame)
  {
    MOZ_ASSERT(static_cast<nsInlineFrame*>(do_QueryFrame(aFrame)));

    SetFrame(aFrame);

    nscoord pos; // an x coordinate if writing-mode is horizontal;
                 // y coordinate if vertical
    if (mBidiEnabled) {
      pos = mLineContinuationPoint;

      // Scan continuations on the same line as aFrame and accumulate the widths
      // of frames that are to the left (if this is an LTR block) or right
      // (if it's RTL) of the current one.
      bool isRtlBlock = (mLineContainer->StyleVisibility()->mDirection ==
                           NS_STYLE_DIRECTION_RTL);
      nscoord curOffset = mVertical ? aFrame->GetOffsetTo(mLineContainer).y
                                    : aFrame->GetOffsetTo(mLineContainer).x;

      // If the continuation is fluid we know inlineFrame is not on the same line.
      // If it's not fluid, we need to test further to be sure.
      nsIFrame* inlineFrame = aFrame->GetPrevContinuation();
      while (inlineFrame && !inlineFrame->GetNextInFlow() &&
             AreOnSameLine(aFrame, inlineFrame)) {
        nscoord frameOffset = mVertical
          ? inlineFrame->GetOffsetTo(mLineContainer).y
          : inlineFrame->GetOffsetTo(mLineContainer).x;
        if (isRtlBlock == (frameOffset >= curOffset)) {
          pos += mVertical
               ? inlineFrame->GetSize().height
               : inlineFrame->GetSize().width;
        }
        inlineFrame = inlineFrame->GetPrevContinuation();
      }

      inlineFrame = aFrame->GetNextContinuation();
      while (inlineFrame && !inlineFrame->GetPrevInFlow() &&
             AreOnSameLine(aFrame, inlineFrame)) {
        nscoord frameOffset = mVertical
          ? inlineFrame->GetOffsetTo(mLineContainer).y
          : inlineFrame->GetOffsetTo(mLineContainer).x;
        if (isRtlBlock == (frameOffset >= curOffset)) {
          pos += mVertical
                 ? inlineFrame->GetSize().height
                 : inlineFrame->GetSize().width;
        }
        inlineFrame = inlineFrame->GetNextContinuation();
      }
      if (isRtlBlock) {
        // aFrame itself is also to the right of its left edge, so add its width.
        pos += mVertical ? aFrame->GetSize().height : aFrame->GetSize().width;
        // pos is now the distance from the left [top] edge of aFrame to the right [bottom] edge
        // of the unbroken content. Change it to indicate the distance from the
        // left [top] edge of the unbroken content to the left [top] edge of aFrame.
        pos = mUnbrokenMeasure - pos;
      }
    } else {
      pos = mContinuationPoint;
    }

    // Assume background-origin: border and return a rect with offsets
    // relative to (0,0).  If we have a different background-origin,
    // then our rect should be deflated appropriately by our caller.
    return mVertical
      ? nsRect(0, -pos, mFrame->GetSize().width, mUnbrokenMeasure)
      : nsRect(-pos, 0, mUnbrokenMeasure, mFrame->GetSize().height);
  }

  /**
   * Return a continuous rect for (an inline) aFrame relative to the
   * continuation that should draw the left[top]-border.  This is used when painting
   * borders and clipping backgrounds.  This may NOT be the same continuous rect
   * as for drawing backgrounds; the continuation with the left[top]-border might be
   * somewhere in the middle of that rect (e.g. BIDI), in those cases we need
   * the reverse background order starting at the left[top]-border continuation.
   */
  nsRect GetBorderContinuousRect(nsIFrame* aFrame, nsRect aBorderArea)
  {
    // Calling GetContinuousRect(aFrame) here may lead to Reset/Init which
    // resets our mPIStartBorderData so we save it ...
    PhysicalInlineStartBorderData saved(mPIStartBorderData);
    nsRect joinedBorderArea = GetContinuousRect(aFrame);
    if (!saved.mIsValid || saved.mFrame != mPIStartBorderData.mFrame) {
      if (aFrame == mPIStartBorderData.mFrame) {
        if (mVertical) {
          mPIStartBorderData.SetCoord(joinedBorderArea.y);
        } else {
          mPIStartBorderData.SetCoord(joinedBorderArea.x);
        }
      } else if (mPIStartBorderData.mFrame) {
        if (mVertical) {
          mPIStartBorderData.SetCoord(GetContinuousRect(mPIStartBorderData.mFrame).y);
        } else {
          mPIStartBorderData.SetCoord(GetContinuousRect(mPIStartBorderData.mFrame).x);
        }
      }
    } else {
      // ... and restore it when possible.
      mPIStartBorderData.mCoord = saved.mCoord;
    }
    if (mVertical) {
      if (joinedBorderArea.y > mPIStartBorderData.mCoord) {
        joinedBorderArea.y =
          -(mUnbrokenMeasure + joinedBorderArea.y - aBorderArea.height);
      } else {
        joinedBorderArea.y -= mPIStartBorderData.mCoord;
      }
    } else {
      if (joinedBorderArea.x > mPIStartBorderData.mCoord) {
        joinedBorderArea.x =
          -(mUnbrokenMeasure + joinedBorderArea.x - aBorderArea.width);
      } else {
        joinedBorderArea.x -= mPIStartBorderData.mCoord;
      }
    }
    return joinedBorderArea;
  }

  nsRect GetBoundingRect(nsIFrame* aFrame)
  {
    SetFrame(aFrame);

    // Move the offsets relative to (0,0) which puts the bounding box into
    // our coordinate system rather than our parent's.  We do this by
    // moving it the back distance from us to the bounding box.
    // This also assumes background-origin: border, so our caller will
    // need to deflate us if needed.
    nsRect boundingBox(mBoundingBox);
    nsPoint point = mFrame->GetPosition();
    boundingBox.MoveBy(-point.x, -point.y);

    return boundingBox;
  }

protected:
  // This is a coordinate on the inline axis, but is not a true logical inline-
  // coord because it is always measured from left to right (if horizontal) or
  // from top to bottom (if vertical), ignoring any bidi RTL directionality.
  // We'll call this "physical inline start", or PIStart for short.
  struct PhysicalInlineStartBorderData {
    nsIFrame* mFrame;   // the continuation that may have a left-border
    nscoord   mCoord;   // cached GetContinuousRect(mFrame).x or .y
    bool      mIsValid; // true if mCoord is valid
    void Reset() { mFrame = nullptr; mIsValid = false; }
    void SetCoord(nscoord aCoord) { mCoord = aCoord; mIsValid = true; }
  };

  nsIFrame*      mFrame;
  nsIFrame*      mLineContainer;
  nsRect         mBoundingBox;
  nscoord        mContinuationPoint;
  nscoord        mUnbrokenMeasure;
  nscoord        mLineContinuationPoint;
  PhysicalInlineStartBorderData mPIStartBorderData;
  bool           mBidiEnabled;
  bool           mVertical;

  void SetFrame(nsIFrame* aFrame)
  {
    NS_PRECONDITION(aFrame, "Need a frame");
    NS_ASSERTION(gFrameTreeLockCount > 0,
                 "Can't call this when frame tree is not locked");

    if (aFrame == mFrame) {
      return;
    }

    nsIFrame *prevContinuation = GetPrevContinuation(aFrame);

    if (!prevContinuation || mFrame != prevContinuation) {
      // Ok, we've got the wrong frame.  We have to start from scratch.
      Reset();
      Init(aFrame);
      return;
    }

    // Get our last frame's size and add its width to our continuation
    // point before we cache the new frame.
    mContinuationPoint += mVertical ? mFrame->GetSize().height
                                    : mFrame->GetSize().width;

    // If this a new line, update mLineContinuationPoint.
    if (mBidiEnabled &&
        (aFrame->GetPrevInFlow() || !AreOnSameLine(mFrame, aFrame))) {
       mLineContinuationPoint = mContinuationPoint;
    }

    mFrame = aFrame;
  }

  nsIFrame* GetPrevContinuation(nsIFrame* aFrame)
  {
    nsIFrame* prevCont = aFrame->GetPrevContinuation();
    if (!prevCont &&
        (aFrame->GetStateBits() & NS_FRAME_PART_OF_IBSPLIT)) {
      nsIFrame* block =
        aFrame->GetProperty(nsIFrame::IBSplitPrevSibling());
      if (block) {
        // The {ib} properties are only stored on first continuations
        NS_ASSERTION(!block->GetPrevContinuation(),
                     "Incorrect value for IBSplitPrevSibling");
        prevCont =
          block->GetProperty(nsIFrame::IBSplitPrevSibling());
        NS_ASSERTION(prevCont, "How did that happen?");
      }
    }
    return prevCont;
  }

  nsIFrame* GetNextContinuation(nsIFrame* aFrame)
  {
    nsIFrame* nextCont = aFrame->GetNextContinuation();
    if (!nextCont &&
        (aFrame->GetStateBits() & NS_FRAME_PART_OF_IBSPLIT)) {
      // The {ib} properties are only stored on first continuations
      aFrame = aFrame->FirstContinuation();
      nsIFrame* block = aFrame->GetProperty(nsIFrame::IBSplitSibling());
      if (block) {
        nextCont = block->GetProperty(nsIFrame::IBSplitSibling());
        NS_ASSERTION(nextCont, "How did that happen?");
      }
    }
    return nextCont;
  }

  void Init(nsIFrame* aFrame)
  {
    mPIStartBorderData.Reset();
    mBidiEnabled = aFrame->PresContext()->BidiEnabled();
    if (mBidiEnabled) {
      // Find the line container frame
      mLineContainer = aFrame;
      while (mLineContainer &&
             mLineContainer->IsFrameOfType(nsIFrame::eLineParticipant)) {
        mLineContainer = mLineContainer->GetParent();
      }

      MOZ_ASSERT(mLineContainer, "Cannot find line containing frame.");
      MOZ_ASSERT(mLineContainer != aFrame, "line container frame "
                 "should be an ancestor of the target frame.");
    }

    mVertical = aFrame->GetWritingMode().IsVertical();

    // Start with the previous flow frame as our continuation point
    // is the total of the widths of the previous frames.
    nsIFrame* inlineFrame = GetPrevContinuation(aFrame);
    while (inlineFrame) {
      if (!mPIStartBorderData.mFrame &&
          !(mVertical ? inlineFrame->GetSkipSides().Top()
                      : inlineFrame->GetSkipSides().Left())) {
        mPIStartBorderData.mFrame = inlineFrame;
      }
      nsRect rect = inlineFrame->GetRect();
      mContinuationPoint += mVertical ? rect.height : rect.width;
      if (mBidiEnabled && !AreOnSameLine(aFrame, inlineFrame)) {
        mLineContinuationPoint += mVertical ? rect.height : rect.width;
      }
      mUnbrokenMeasure += mVertical ? rect.height : rect.width;
      mBoundingBox.UnionRect(mBoundingBox, rect);
      inlineFrame = GetPrevContinuation(inlineFrame);
    }

    // Next add this frame and subsequent frames to the bounding box and
    // unbroken width.
    inlineFrame = aFrame;
    while (inlineFrame) {
      if (!mPIStartBorderData.mFrame &&
          !(mVertical ? inlineFrame->GetSkipSides().Top()
                      : inlineFrame->GetSkipSides().Left())) {
        mPIStartBorderData.mFrame = inlineFrame;
      }
      nsRect rect = inlineFrame->GetRect();
      mUnbrokenMeasure += mVertical ? rect.height : rect.width;
      mBoundingBox.UnionRect(mBoundingBox, rect);
      inlineFrame = GetNextContinuation(inlineFrame);
    }

    mFrame = aFrame;
  }

  bool AreOnSameLine(nsIFrame* aFrame1, nsIFrame* aFrame2) {
    if (nsBlockFrame* blockFrame = do_QueryFrame(mLineContainer)) {
      bool isValid1, isValid2;
      nsBlockInFlowLineIterator it1(blockFrame, aFrame1, &isValid1);
      nsBlockInFlowLineIterator it2(blockFrame, aFrame2, &isValid2);
      return isValid1 && isValid2 &&
        // Make sure aFrame1 and aFrame2 are in the same continuation of
        // blockFrame.
        it1.GetContainer() == it2.GetContainer() &&
        // And on the same line in it
        it1.GetLine() == it2.GetLine();
    }
    if (nsRubyTextContainerFrame* rtcFrame = do_QueryFrame(mLineContainer)) {
      nsBlockFrame* block = nsLayoutUtils::FindNearestBlockAncestor(rtcFrame);
      // Ruby text container can only hold one line of text, so if they
      // are in the same continuation, they are in the same line. Since
      // ruby text containers are bidi isolate, they are never split for
      // bidi reordering, which means being in different continuation
      // indicates being in different lines.
      for (nsIFrame* frame = rtcFrame->FirstContinuation();
           frame; frame = frame->GetNextContinuation()) {
        bool isDescendant1 =
          nsLayoutUtils::IsProperAncestorFrame(frame, aFrame1, block);
        bool isDescendant2 =
          nsLayoutUtils::IsProperAncestorFrame(frame, aFrame2, block);
        if (isDescendant1 && isDescendant2) {
          return true;
        }
        if (isDescendant1 || isDescendant2) {
          return false;
        }
      }
      MOZ_ASSERT_UNREACHABLE("None of the frames is a descendant of this rtc?");
    }
    MOZ_ASSERT_UNREACHABLE("Do we have any other type of line container?");
    return false;
  }
};

// A resolved color stop, with a specific position along the gradient line and
// a color.
struct ColorStop {
  ColorStop(): mPosition(0), mIsMidpoint(false) {}
  ColorStop(double aPosition, bool aIsMidPoint, const Color& aColor) :
    mPosition(aPosition), mIsMidpoint(aIsMidPoint), mColor(aColor) {}
  double mPosition; // along the gradient line; 0=start, 1=end
  bool mIsMidpoint;
  Color mColor;
};

/* Local functions */
static DrawResult DrawBorderImage(nsPresContext* aPresContext,
                                  nsRenderingContext& aRenderingContext,
                                  nsIFrame* aForFrame,
                                  const nsRect& aBorderArea,
                                  const nsStyleBorder& aStyleBorder,
                                  const nsRect& aDirtyRect,
                                  Sides aSkipSides,
                                  PaintBorderFlags aFlags);

static nscolor MakeBevelColor(mozilla::css::Side whichSide, uint8_t style,
                              nscolor aBackgroundColor,
                              nscolor aBorderColor);

static InlineBackgroundData* gInlineBGData = nullptr;

// Initialize any static variables used by nsCSSRendering.
void nsCSSRendering::Init()
{
  NS_ASSERTION(!gInlineBGData, "Init called twice");
  gInlineBGData = new InlineBackgroundData();
}

// Clean up any global variables used by nsCSSRendering.
void nsCSSRendering::Shutdown()
{
  delete gInlineBGData;
  gInlineBGData = nullptr;
}

/**
 * Make a bevel color
 */
static nscolor
MakeBevelColor(mozilla::css::Side whichSide, uint8_t style,
               nscolor aBackgroundColor, nscolor aBorderColor)
{

  nscolor colors[2];
  nscolor theColor;

  // Given a background color and a border color
  // calculate the color used for the shading
  NS_GetSpecial3DColors(colors, aBackgroundColor, aBorderColor);

  if ((style == NS_STYLE_BORDER_STYLE_OUTSET) ||
      (style == NS_STYLE_BORDER_STYLE_RIDGE)) {
    // Flip colors for these two border styles
    switch (whichSide) {
    case NS_SIDE_BOTTOM: whichSide = NS_SIDE_TOP;    break;
    case NS_SIDE_RIGHT:  whichSide = NS_SIDE_LEFT;   break;
    case NS_SIDE_TOP:    whichSide = NS_SIDE_BOTTOM; break;
    case NS_SIDE_LEFT:   whichSide = NS_SIDE_RIGHT;  break;
    }
  }

  switch (whichSide) {
  case NS_SIDE_BOTTOM:
    theColor = colors[1];
    break;
  case NS_SIDE_RIGHT:
    theColor = colors[1];
    break;
  case NS_SIDE_TOP:
    theColor = colors[0];
    break;
  case NS_SIDE_LEFT:
  default:
    theColor = colors[0];
    break;
  }
  return theColor;
}

static bool
GetRadii(nsIFrame* aForFrame, const nsStyleBorder& aBorder,
         const nsRect& aOrigBorderArea, const nsRect& aBorderArea,
         nscoord aRadii[8])
{
  bool haveRoundedCorners;
  nsSize sz = aBorderArea.Size();
  nsSize frameSize = aForFrame->GetSize();
  if (&aBorder == aForFrame->StyleBorder() &&
      frameSize == aOrigBorderArea.Size()) {
    haveRoundedCorners = aForFrame->GetBorderRadii(sz, sz, Sides(), aRadii);
   } else {
    haveRoundedCorners =
      nsIFrame::ComputeBorderRadii(aBorder.mBorderRadius, frameSize, sz, Sides(), aRadii);
  }

  return haveRoundedCorners;
}

static bool
GetRadii(nsIFrame* aForFrame, const nsStyleBorder& aBorder,
         const nsRect& aOrigBorderArea, const nsRect& aBorderArea,
         RectCornerRadii* aBgRadii)
{
  nscoord radii[8];
  bool haveRoundedCorners = GetRadii(aForFrame, aBorder, aOrigBorderArea, aBorderArea, radii);

  if (haveRoundedCorners) {
    auto d2a = aForFrame->PresContext()->AppUnitsPerDevPixel();
    nsCSSRendering::ComputePixelRadii(radii, d2a, aBgRadii);
  }
  return haveRoundedCorners;
}

static nsRect
JoinBoxesForVerticalSlice(nsIFrame* aFrame, const nsRect& aBorderArea)
{
  // Inflate vertically as if our continuations were laid out vertically
  // adjacent. Note that we don't touch the width.
  nsRect borderArea = aBorderArea;
  nscoord h = 0;
  nsIFrame* f = aFrame->GetNextContinuation();
  for (; f; f = f->GetNextContinuation()) {
    MOZ_ASSERT(!(f->GetStateBits() & NS_FRAME_PART_OF_IBSPLIT),
               "anonymous ib-split block shouldn't have border/background");
    h += f->GetRect().height;
  }
  borderArea.height += h;
  h = 0;
  f = aFrame->GetPrevContinuation();
  for (; f; f = f->GetPrevContinuation()) {
    MOZ_ASSERT(!(f->GetStateBits() & NS_FRAME_PART_OF_IBSPLIT),
               "anonymous ib-split block shouldn't have border/background");
    h += f->GetRect().height;
  }
  borderArea.y -= h;
  borderArea.height += h;
  return borderArea;
}

/**
 * Inflate aBorderArea which is relative to aFrame's origin to calculate
 * a hypothetical non-split frame area for all the continuations.
 * See "Joining Boxes for 'slice'" in
 * http://dev.w3.org/csswg/css-break/#break-decoration
 */
enum InlineBoxOrder { eForBorder, eForBackground };
static nsRect
JoinBoxesForSlice(nsIFrame* aFrame, const nsRect& aBorderArea,
                  InlineBoxOrder aOrder)
{
  if (static_cast<nsInlineFrame*>(do_QueryFrame(aFrame))) {
    return (aOrder == eForBorder
            ? gInlineBGData->GetBorderContinuousRect(aFrame, aBorderArea)
            : gInlineBGData->GetContinuousRect(aFrame)) +
      aBorderArea.TopLeft();
  }
  return JoinBoxesForVerticalSlice(aFrame, aBorderArea);
}

static bool
IsBoxDecorationSlice(const nsStyleBorder& aStyleBorder)
{
  return aStyleBorder.mBoxDecorationBreak == StyleBoxDecorationBreak::Slice;
}

static nsRect
BoxDecorationRectForBorder(nsIFrame* aFrame, const nsRect& aBorderArea,
                           Sides aSkipSides,
                           const nsStyleBorder* aStyleBorder = nullptr)
{
  if (!aStyleBorder) {
    aStyleBorder = aFrame->StyleBorder();
  }
  // If aSkipSides.IsEmpty() then there are no continuations, or it's
  // a ::first-letter that wants all border sides on the first continuation.
  return ::IsBoxDecorationSlice(*aStyleBorder) && !aSkipSides.IsEmpty()
           ? ::JoinBoxesForSlice(aFrame, aBorderArea, eForBorder)
           : aBorderArea;
}

static nsRect
BoxDecorationRectForBackground(nsIFrame* aFrame, const nsRect& aBorderArea,
                               Sides aSkipSides,
                               const nsStyleBorder* aStyleBorder = nullptr)
{
  if (!aStyleBorder) {
    aStyleBorder = aFrame->StyleBorder();
  }
  // If aSkipSides.IsEmpty() then there are no continuations, or it's
  // a ::first-letter that wants all border sides on the first continuation.
  return ::IsBoxDecorationSlice(*aStyleBorder) && !aSkipSides.IsEmpty()
           ? ::JoinBoxesForSlice(aFrame, aBorderArea, eForBackground)
           : aBorderArea;
}

//----------------------------------------------------------------------
// Thebes Border Rendering Code Start

/*
 * Compute the float-pixel radii that should be used for drawing
 * this border/outline, given the various input bits.
 */
/* static */ void
nsCSSRendering::ComputePixelRadii(const nscoord *aAppUnitsRadii,
                                  nscoord aAppUnitsPerPixel,
                                  RectCornerRadii *oBorderRadii)
{
  Float radii[8];
  NS_FOR_CSS_HALF_CORNERS(corner)
    radii[corner] = Float(aAppUnitsRadii[corner]) / aAppUnitsPerPixel;

  (*oBorderRadii)[C_TL] = Size(radii[NS_CORNER_TOP_LEFT_X],
                               radii[NS_CORNER_TOP_LEFT_Y]);
  (*oBorderRadii)[C_TR] = Size(radii[NS_CORNER_TOP_RIGHT_X],
                               radii[NS_CORNER_TOP_RIGHT_Y]);
  (*oBorderRadii)[C_BR] = Size(radii[NS_CORNER_BOTTOM_RIGHT_X],
                               radii[NS_CORNER_BOTTOM_RIGHT_Y]);
  (*oBorderRadii)[C_BL] = Size(radii[NS_CORNER_BOTTOM_LEFT_X],
                               radii[NS_CORNER_BOTTOM_LEFT_Y]);
}

DrawResult
nsCSSRendering::PaintBorder(nsPresContext* aPresContext,
                            nsRenderingContext& aRenderingContext,
                            nsIFrame* aForFrame,
                            const nsRect& aDirtyRect,
                            const nsRect& aBorderArea,
                            nsStyleContext* aStyleContext,
                            PaintBorderFlags aFlags,
                            Sides aSkipSides)
{
  PROFILER_LABEL("nsCSSRendering", "PaintBorder",
    js::ProfileEntry::Category::GRAPHICS);

  nsStyleContext *styleIfVisited = aStyleContext->GetStyleIfVisited();
  const nsStyleBorder *styleBorder = aStyleContext->StyleBorder();
  // Don't check RelevantLinkVisited here, since we want to take the
  // same amount of time whether or not it's true.
  if (!styleIfVisited) {
    return PaintBorderWithStyleBorder(aPresContext, aRenderingContext, aForFrame,
                                      aDirtyRect, aBorderArea, *styleBorder,
                                      aStyleContext, aFlags, aSkipSides);
  }

  nsStyleBorder newStyleBorder(*styleBorder);

  NS_FOR_CSS_SIDES(side) {
    nscolor color = aStyleContext->GetVisitedDependentColor(
      nsCSSProps::SubpropertyEntryFor(eCSSProperty_border_color)[side]);
    newStyleBorder.mBorderColor[side] = StyleComplexColor::FromColor(color);
  }
  DrawResult result =
    PaintBorderWithStyleBorder(aPresContext, aRenderingContext, aForFrame,
                               aDirtyRect, aBorderArea, newStyleBorder,
                               aStyleContext, aFlags, aSkipSides);

  return result;
}

DrawResult
nsCSSRendering::PaintBorderWithStyleBorder(nsPresContext* aPresContext,
                                           nsRenderingContext& aRenderingContext,
                                           nsIFrame* aForFrame,
                                           const nsRect& aDirtyRect,
                                           const nsRect& aBorderArea,
                                           const nsStyleBorder& aStyleBorder,
                                           nsStyleContext* aStyleContext,
                                           PaintBorderFlags aFlags,
                                           Sides aSkipSides)
{
  DrawTarget& aDrawTarget = *aRenderingContext.GetDrawTarget();

  PrintAsStringNewline("++ PaintBorder");

  // Check to see if we have an appearance defined.  If so, we let the theme
  // renderer draw the border.  DO not get the data from aForFrame, since the passed in style context
  // may be different!  Always use |aStyleContext|!
  const nsStyleDisplay* displayData = aStyleContext->StyleDisplay();
  if (displayData->mAppearance) {
    nsITheme *theme = aPresContext->GetTheme();
    if (theme &&
        theme->ThemeSupportsWidget(aPresContext, aForFrame,
                                   displayData->mAppearance)) {
      return DrawResult::SUCCESS; // Let the theme handle it.
    }
  }

  if (aStyleBorder.IsBorderImageLoaded()) {
    return DrawBorderImage(aPresContext, aRenderingContext, aForFrame,
                           aBorderArea, aStyleBorder, aDirtyRect,
                           aSkipSides, aFlags);
  }

  DrawResult result = DrawResult::SUCCESS;

  // If we had a border-image, but it wasn't loaded, then we should return
  // DrawResult::NOT_READY; we'll want to try again if we do a paint with sync
  // decoding enabled.
  if (aStyleBorder.mBorderImageSource.GetType() != eStyleImageType_Null) {
    result = DrawResult::NOT_READY;
  }

  // Get our style context's color struct.
  const nsStyleColor* ourColor = aStyleContext->StyleColor();

  // In NavQuirks mode we want to use the parent's context as a starting point
  // for determining the background color.
  bool quirks = aPresContext->CompatibilityMode() == eCompatibility_NavQuirks;
  nsIFrame* bgFrame = FindNonTransparentBackgroundFrame(aForFrame, quirks);
  nsStyleContext* bgContext = bgFrame->StyleContext();
  nscolor bgColor =
    bgContext->GetVisitedDependentColor(eCSSProperty_background_color);

  nsMargin border = aStyleBorder.GetComputedBorder();
  if (0 == border.left && 0 == border.right &&
      0 == border.top  && 0 == border.bottom) {
    // Empty border area
    return result;
  }

  // Compute the outermost boundary of the area that might be painted.
  // Same coordinate space as aBorderArea & aBGClipRect.
  nsRect joinedBorderArea =
    ::BoxDecorationRectForBorder(aForFrame, aBorderArea, aSkipSides, &aStyleBorder);
  RectCornerRadii bgRadii;
  ::GetRadii(aForFrame, aStyleBorder, aBorderArea, joinedBorderArea, &bgRadii);

  PrintAsFormatString(" joinedBorderArea: %d %d %d %d\n", joinedBorderArea.x, joinedBorderArea.y,
     joinedBorderArea.width, joinedBorderArea.height);

  // start drawing
  bool needToPopClip = false;

  if (::IsBoxDecorationSlice(aStyleBorder)) {
    if (joinedBorderArea.IsEqualEdges(aBorderArea)) {
      // No need for a clip, just skip the sides we don't want.
      border.ApplySkipSides(aSkipSides);
    } else {
      // We're drawing borders around the joined continuation boxes so we need
      // to clip that to the slice that we want for this frame.
      aDrawTarget.PushClipRect(
        NSRectToSnappedRect(aBorderArea,
                            aForFrame->PresContext()->AppUnitsPerDevPixel(),
                            aDrawTarget));
      needToPopClip = true;
    }
  } else {
    MOZ_ASSERT(joinedBorderArea.IsEqualEdges(aBorderArea),
               "Should use aBorderArea for box-decoration-break:clone");
    MOZ_ASSERT(aForFrame->GetSkipSides().IsEmpty() ||
               IS_TRUE_OVERFLOW_CONTAINER(aForFrame),
               "Should not skip sides for box-decoration-break:clone except "
               "::first-letter/line continuations or other frame types that "
               "don't have borders but those shouldn't reach this point. "
               "Overflow containers do reach this point though.");
    border.ApplySkipSides(aSkipSides);
  }

  // Convert to dev pixels.
  nscoord twipsPerPixel = aPresContext->DevPixelsToAppUnits(1);
  Rect joinedBorderAreaPx = NSRectToRect(joinedBorderArea, twipsPerPixel);
  Float borderWidths[4] = { Float(border.top / twipsPerPixel),
                            Float(border.right / twipsPerPixel),
                            Float(border.bottom / twipsPerPixel),
                            Float(border.left / twipsPerPixel) };
  Rect dirtyRect = NSRectToRect(aDirtyRect, twipsPerPixel);

  uint8_t borderStyles[4];
  nscolor borderColors[4];
  nsBorderColors *compositeColors[4];

  // pull out styles, colors, composite colors
  NS_FOR_CSS_SIDES (i) {
    borderStyles[i] = aStyleBorder.GetBorderStyle(i);
    borderColors[i] = ourColor->CalcComplexColor(aStyleBorder.mBorderColor[i]);
    aStyleBorder.GetCompositeColors(i, &compositeColors[i]);
  }

  PrintAsFormatString(" borderStyles: %d %d %d %d\n", borderStyles[0], borderStyles[1], borderStyles[2], borderStyles[3]);
  //PrintAsFormatString ("bgRadii: %f %f %f %f\n", bgRadii[0], bgRadii[1], bgRadii[2], bgRadii[3]);

#if 0
  // this will draw a transparent red backround underneath the border area
  ColorPattern color(ToDeviceColor(Color(1.f, 0.f, 0.f, 0.5f)));
  aDrawTarget.FillRect(joinedBorderAreaPx, color);
#endif

  nsIDocument* document = nullptr;
  nsIContent* content = aForFrame->GetContent();
  if (content) {
    document = content->OwnerDoc();
  }

  nsCSSBorderRenderer br(aPresContext,
                         document,
                         &aDrawTarget,
                         dirtyRect,
                         joinedBorderAreaPx,
                         borderStyles,
                         borderWidths,
                         bgRadii,
                         borderColors,
                         compositeColors,
                         bgColor);
  br.DrawBorders();

  if (needToPopClip) {
    aDrawTarget.PopClip();
  }

  PrintAsStringNewline();

  return result;
}

static nsRect
GetOutlineInnerRect(nsIFrame* aFrame)
{
  nsRect* savedOutlineInnerRect =
    aFrame->GetProperty(nsIFrame::OutlineInnerRectProperty());
  if (savedOutlineInnerRect)
    return *savedOutlineInnerRect;
  NS_NOTREACHED("we should have saved a frame property");
  return nsRect(nsPoint(0, 0), aFrame->GetSize());
}

void
nsCSSRendering::PaintOutline(nsPresContext* aPresContext,
                             nsRenderingContext& aRenderingContext,
                             nsIFrame* aForFrame,
                             const nsRect& aDirtyRect,
                             const nsRect& aBorderArea,
                             nsStyleContext* aStyleContext)
{
  nscoord             twipsRadii[8];

  // Get our style context's color struct.
  const nsStyleOutline* ourOutline = aStyleContext->StyleOutline();
  MOZ_ASSERT(ourOutline != NS_STYLE_BORDER_STYLE_NONE,
             "shouldn't have created nsDisplayOutline item");

  uint8_t outlineStyle = ourOutline->mOutlineStyle;
  nscoord width = ourOutline->GetOutlineWidth();

  if (width == 0 && outlineStyle != NS_STYLE_BORDER_STYLE_AUTO) {
    // Empty outline
    return;
  }

  nsIFrame* bgFrame = nsCSSRendering::FindNonTransparentBackgroundFrame
    (aForFrame, false);
  nsStyleContext* bgContext = bgFrame->StyleContext();
  nscolor bgColor =
    bgContext->GetVisitedDependentColor(eCSSProperty_background_color);

  nsRect innerRect;
  if (aStyleContext->GetPseudoType() == CSSPseudoElementType::XULTree) {
    innerRect = aBorderArea;
  } else {
    innerRect = GetOutlineInnerRect(aForFrame) + aBorderArea.TopLeft();
  }
  nscoord offset = ourOutline->mOutlineOffset;
  innerRect.Inflate(offset, offset);
  // If the dirty rect is completely inside the border area (e.g., only the
  // content is being painted), then we can skip out now
  // XXX this isn't exactly true for rounded borders, where the inside curves may
  // encroach into the content area.  A safer calculation would be to
  // shorten insideRect by the radius one each side before performing this test.
  if (innerRect.Contains(aDirtyRect))
    return;

  nsRect outerRect = innerRect;
  outerRect.Inflate(width, width);

  // get the radius for our outline
  nsIFrame::ComputeBorderRadii(ourOutline->mOutlineRadius, aBorderArea.Size(),
                               outerRect.Size(), Sides(), twipsRadii);

  // Get our conversion values
  nscoord twipsPerPixel = aPresContext->DevPixelsToAppUnits(1);

  // get the outer rectangles
  Rect oRect(NSRectToRect(outerRect, twipsPerPixel));

  // convert the radii
  nsMargin outlineMargin(width, width, width, width);
  RectCornerRadii outlineRadii;
  ComputePixelRadii(twipsRadii, twipsPerPixel, &outlineRadii);

  if (outlineStyle == NS_STYLE_BORDER_STYLE_AUTO) {
    if (nsLayoutUtils::IsOutlineStyleAutoEnabled()) {
      nsITheme* theme = aPresContext->GetTheme();
      if (theme && theme->ThemeSupportsWidget(aPresContext, aForFrame,
                                              NS_THEME_FOCUS_OUTLINE)) {
        theme->DrawWidgetBackground(&aRenderingContext, aForFrame,
                                    NS_THEME_FOCUS_OUTLINE, innerRect,
                                    aDirtyRect);
        return;
      }
    }
    if (width == 0) {
      return; // empty outline
    }
    // http://dev.w3.org/csswg/css-ui/#outline
    // "User agents may treat 'auto' as 'solid'."
    outlineStyle = NS_STYLE_BORDER_STYLE_SOLID;
  }

  uint8_t outlineStyles[4] = { outlineStyle, outlineStyle,
                               outlineStyle, outlineStyle };

  // This handles treating the initial color as 'currentColor'; if we
  // ever want 'invert' back we'll need to do a bit of work here too.
  nscolor outlineColor =
    aStyleContext->GetVisitedDependentColor(eCSSProperty_outline_color);
  nscolor outlineColors[4] = { outlineColor,
                               outlineColor,
                               outlineColor,
                               outlineColor };

  // convert the border widths
  Float outlineWidths[4] = { Float(width / twipsPerPixel),
                             Float(width / twipsPerPixel),
                             Float(width / twipsPerPixel),
                             Float(width / twipsPerPixel) };
  Rect dirtyRect = NSRectToRect(aDirtyRect, twipsPerPixel);

  nsIDocument* document = nullptr;
  nsIContent* content = aForFrame->GetContent();
  if (content) {
    document = content->OwnerDoc();
  }

  // start drawing

  nsCSSBorderRenderer br(aPresContext,
                         document,
                         aRenderingContext.GetDrawTarget(),
                         dirtyRect,
                         oRect,
                         outlineStyles,
                         outlineWidths,
                         outlineRadii,
                         outlineColors,
                         nullptr,
                         bgColor);
  br.DrawBorders();

  PrintAsStringNewline();
}

void
nsCSSRendering::PaintFocus(nsPresContext* aPresContext,
                           DrawTarget* aDrawTarget,
                           const nsRect& aFocusRect,
                           nscolor aColor)
{
  nscoord oneCSSPixel = nsPresContext::CSSPixelsToAppUnits(1);
  nscoord oneDevPixel = aPresContext->DevPixelsToAppUnits(1);

  Rect focusRect(NSRectToRect(aFocusRect, oneDevPixel));

  RectCornerRadii focusRadii;
  {
    nscoord twipsRadii[8] = { 0, 0, 0, 0, 0, 0, 0, 0 };
    ComputePixelRadii(twipsRadii, oneDevPixel, &focusRadii);
  }
  Float focusWidths[4] = { Float(oneCSSPixel / oneDevPixel),
                           Float(oneCSSPixel / oneDevPixel),
                           Float(oneCSSPixel / oneDevPixel),
                           Float(oneCSSPixel / oneDevPixel) };

  uint8_t focusStyles[4] = { NS_STYLE_BORDER_STYLE_DOTTED,
                             NS_STYLE_BORDER_STYLE_DOTTED,
                             NS_STYLE_BORDER_STYLE_DOTTED,
                             NS_STYLE_BORDER_STYLE_DOTTED };
  nscolor focusColors[4] = { aColor, aColor, aColor, aColor };

  // Because this renders a dotted border, the background color
  // should not be used.  Therefore, we provide a value that will
  // be blatantly wrong if it ever does get used.  (If this becomes
  // something that CSS can style, this function will then have access
  // to a style context and can use the same logic that PaintBorder
  // and PaintOutline do.)
  nsCSSBorderRenderer br(aPresContext,
                         nullptr,
                         aDrawTarget,
                         focusRect,
                         focusRect,
                         focusStyles,
                         focusWidths,
                         focusRadii,
                         focusColors,
                         nullptr,
                         NS_RGB(255, 0, 0));
  br.DrawBorders();

  PrintAsStringNewline();
}

// Thebes Border Rendering Code End
//----------------------------------------------------------------------


//----------------------------------------------------------------------

/**
 * Helper for ComputeObjectAnchorPoint; parameters are the same as for
 * that function, except they're for a single coordinate / a single size
 * dimension. (so, x/width vs. y/height)
 */
static void
ComputeObjectAnchorCoord(const Position::Coord& aCoord,
                         const nscoord aOriginBounds,
                         const nscoord aImageSize,
                         nscoord* aTopLeftCoord,
                         nscoord* aAnchorPointCoord)
{
  *aAnchorPointCoord = aCoord.mLength;
  *aTopLeftCoord = aCoord.mLength;

  if (aCoord.mHasPercent) {
    // Adjust aTopLeftCoord by the specified % of the extra space.
    nscoord extraSpace = aOriginBounds - aImageSize;
    *aTopLeftCoord += NSToCoordRound(aCoord.mPercent * extraSpace);

    // The anchor-point doesn't care about our image's size; just the size
    // of the region we're rendering into.
    *aAnchorPointCoord += NSToCoordRound(aCoord.mPercent * aOriginBounds);
  }
}

void
nsImageRenderer::ComputeObjectAnchorPoint(
  const Position& aPos,
  const nsSize& aOriginBounds,
  const nsSize& aImageSize,
  nsPoint* aTopLeft,
  nsPoint* aAnchorPoint)
{
  ComputeObjectAnchorCoord(aPos.mXPosition,
                           aOriginBounds.width, aImageSize.width,
                           &aTopLeft->x, &aAnchorPoint->x);

  ComputeObjectAnchorCoord(aPos.mYPosition,
                           aOriginBounds.height, aImageSize.height,
                           &aTopLeft->y, &aAnchorPoint->y);
}

nsIFrame*
nsCSSRendering::FindNonTransparentBackgroundFrame(nsIFrame* aFrame,
                                                  bool aStartAtParent /*= false*/)
{
  NS_ASSERTION(aFrame, "Cannot find NonTransparentBackgroundFrame in a null frame");

  nsIFrame* frame = nullptr;
  if (aStartAtParent) {
    frame = nsLayoutUtils::GetParentOrPlaceholderFor(aFrame);
  }
  if (!frame) {
    frame = aFrame;
  }

  while (frame) {
    // No need to call GetVisitedDependentColor because it always uses
    // this alpha component anyway.
    if (NS_GET_A(frame->StyleBackground()->mBackgroundColor) > 0)
      break;

    if (frame->IsThemed())
      break;

    nsIFrame* parent = nsLayoutUtils::GetParentOrPlaceholderFor(frame);
    if (!parent)
      break;

    frame = parent;
  }
  return frame;
}

// Returns true if aFrame is a canvas frame.
// We need to treat the viewport as canvas because, even though
// it does not actually paint a background, we need to get the right
// background style so we correctly detect transparent documents.
bool
nsCSSRendering::IsCanvasFrame(nsIFrame* aFrame)
{
  nsIAtom* frameType = aFrame->GetType();
  return frameType == nsGkAtoms::canvasFrame ||
         frameType == nsGkAtoms::rootFrame ||
         frameType == nsGkAtoms::pageContentFrame ||
         frameType == nsGkAtoms::viewportFrame;
}

nsIFrame*
nsCSSRendering::FindBackgroundStyleFrame(nsIFrame* aForFrame)
{
  const nsStyleBackground* result = aForFrame->StyleBackground();

  // Check if we need to do propagation from BODY rather than HTML.
  if (!result->IsTransparent()) {
    return aForFrame;
  }

  nsIContent* content = aForFrame->GetContent();
  // The root element content can't be null. We wouldn't know what
  // frame to create for aFrame.
  // Use |OwnerDoc| so it works during destruction.
  if (!content) {
    return aForFrame;
  }

  nsIDocument* document = content->OwnerDoc();

  dom::Element* bodyContent = document->GetBodyElement();
  // We need to null check the body node (bug 118829) since
  // there are cases, thanks to the fix for bug 5569, where we
  // will reflow a document with no body.  In particular, if a
  // SCRIPT element in the head blocks the parser and then has a
  // SCRIPT that does "document.location.href = 'foo'", then
  // nsParser::Terminate will call |DidBuildModel| methods
  // through to the content sink, which will call |StartLayout|
  // and thus |Initialize| on the pres shell.  See bug 119351
  // for the ugly details.
  if (!bodyContent) {
    return aForFrame;
  }

  nsIFrame *bodyFrame = bodyContent->GetPrimaryFrame();
  if (!bodyFrame) {
    return aForFrame;
  }

  return nsLayoutUtils::GetStyleFrame(bodyFrame);
}

/**
 * |FindBackground| finds the correct style data to use to paint the
 * background.  It is responsible for handling the following two
 * statements in section 14.2 of CSS2:
 *
 *   The background of the box generated by the root element covers the
 *   entire canvas.
 *
 *   For HTML documents, however, we recommend that authors specify the
 *   background for the BODY element rather than the HTML element. User
 *   agents should observe the following precedence rules to fill in the
 *   background: if the value of the 'background' property for the HTML
 *   element is different from 'transparent' then use it, else use the
 *   value of the 'background' property for the BODY element. If the
 *   resulting value is 'transparent', the rendering is undefined.
 *
 * Thus, in our implementation, it is responsible for ensuring that:
 *  + we paint the correct background on the |nsCanvasFrame|,
 *    |nsRootBoxFrame|, or |nsPageFrame|,
 *  + we don't paint the background on the root element, and
 *  + we don't paint the background on the BODY element in *some* cases,
 *    and for SGML-based HTML documents only.
 *
 * |FindBackground| returns true if a background should be painted, and
 * the resulting style context to use for the background information
 * will be filled in to |aBackground|.
 */
nsStyleContext*
nsCSSRendering::FindRootFrameBackground(nsIFrame* aForFrame)
{
  return FindBackgroundStyleFrame(aForFrame)->StyleContext();
}

inline bool
FindElementBackground(nsIFrame* aForFrame, nsIFrame* aRootElementFrame,
                      nsStyleContext** aBackgroundSC)
{
  if (aForFrame == aRootElementFrame) {
    // We must have propagated our background to the viewport or canvas. Abort.
    return false;
  }

  *aBackgroundSC = aForFrame->StyleContext();

  // Return true unless the frame is for a BODY element whose background
  // was propagated to the viewport.

  nsIContent* content = aForFrame->GetContent();
  if (!content || content->NodeInfo()->NameAtom() != nsGkAtoms::body)
    return true; // not frame for a "body" element
  // It could be a non-HTML "body" element but that's OK, we'd fail the
  // bodyContent check below

  if (aForFrame->StyleContext()->GetPseudo())
    return true; // A pseudo-element frame.

  // We should only look at the <html> background if we're in an HTML document
  nsIDocument* document = content->OwnerDoc();

  dom::Element* bodyContent = document->GetBodyElement();
  if (bodyContent != content)
    return true; // this wasn't the background that was propagated

  // This can be called even when there's no root element yet, during frame
  // construction, via nsLayoutUtils::FrameHasTransparency and
  // nsContainerFrame::SyncFrameViewProperties.
  if (!aRootElementFrame)
    return true;

  const nsStyleBackground* htmlBG = aRootElementFrame->StyleBackground();
  return !htmlBG->IsTransparent();
}

bool
nsCSSRendering::FindBackground(nsIFrame* aForFrame,
                               nsStyleContext** aBackgroundSC)
{
  nsIFrame* rootElementFrame =
    aForFrame->PresContext()->PresShell()->FrameConstructor()->GetRootElementStyleFrame();
  if (IsCanvasFrame(aForFrame)) {
    *aBackgroundSC = FindCanvasBackground(aForFrame, rootElementFrame);
    return true;
  } else {
    return FindElementBackground(aForFrame, rootElementFrame, aBackgroundSC);
  }
}

void
nsCSSRendering::BeginFrameTreesLocked()
{
  ++gFrameTreeLockCount;
}

void
nsCSSRendering::EndFrameTreesLocked()
{
  NS_ASSERTION(gFrameTreeLockCount > 0, "Unbalanced EndFrameTreeLocked");
  --gFrameTreeLockCount;
  if (gFrameTreeLockCount == 0) {
    gInlineBGData->Reset();
  }
}

void
nsCSSRendering::PaintBoxShadowOuter(nsPresContext* aPresContext,
                                    nsRenderingContext& aRenderingContext,
                                    nsIFrame* aForFrame,
                                    const nsRect& aFrameArea,
                                    const nsRect& aDirtyRect,
                                    float aOpacity)
{
  DrawTarget& aDrawTarget = *aRenderingContext.GetDrawTarget();
  nsCSSShadowArray* shadows = aForFrame->StyleEffects()->mBoxShadow;
  if (!shadows)
    return;

  bool hasBorderRadius;
  bool nativeTheme; // mutually exclusive with hasBorderRadius
  const nsStyleDisplay* styleDisplay = aForFrame->StyleDisplay();
  nsITheme::Transparency transparency;
  if (aForFrame->IsThemed(styleDisplay, &transparency)) {
    // We don't respect border-radius for native-themed widgets
    hasBorderRadius = false;
    // For opaque (rectangular) theme widgets we can take the generic
    // border-box path with border-radius disabled.
    nativeTheme = transparency != nsITheme::eOpaque;
  } else {
    nativeTheme = false;
    hasBorderRadius = true; // we'll update this below
  }

  nsRect frameRect = nativeTheme ?
    aForFrame->GetVisualOverflowRectRelativeToSelf() + aFrameArea.TopLeft() :
    aFrameArea;
  Sides skipSides = aForFrame->GetSkipSides();
  frameRect = ::BoxDecorationRectForBorder(aForFrame, frameRect, skipSides);

  // Get any border radius, since box-shadow must also have rounded corners if
  // the frame does.
  RectCornerRadii borderRadii;
  const nscoord twipsPerPixel = aPresContext->DevPixelsToAppUnits(1);
  if (hasBorderRadius) {
    nscoord twipsRadii[8];
    NS_ASSERTION(aFrameArea.Size() == aForFrame->VisualBorderRectRelativeToSelf().Size(),
                 "unexpected size");
    nsSize sz = frameRect.Size();
    hasBorderRadius = aForFrame->GetBorderRadii(sz, sz, Sides(), twipsRadii);
    if (hasBorderRadius) {
      ComputePixelRadii(twipsRadii, twipsPerPixel, &borderRadii);
    }
  }


  // We don't show anything that intersects with the frame we're blurring on. So tell the
  // blurrer not to do unnecessary work there.
  gfxRect skipGfxRect = ThebesRect(NSRectToRect(frameRect, twipsPerPixel));
  skipGfxRect.Round();
  bool useSkipGfxRect = true;
  if (nativeTheme) {
    // Optimize non-leaf native-themed frames by skipping computing pixels
    // in the padding-box. We assume the padding-box is going to be painted
    // opaquely for non-leaf frames.
    // XXX this may not be a safe assumption; we should make this go away
    // by optimizing box-shadow drawing more for the cases where we don't have a skip-rect.
    useSkipGfxRect = !aForFrame->IsLeaf();
    nsRect paddingRect =
      aForFrame->GetPaddingRect() - aForFrame->GetPosition() + aFrameArea.TopLeft();
    skipGfxRect = nsLayoutUtils::RectToGfxRect(paddingRect, twipsPerPixel);
  } else if (hasBorderRadius) {
    skipGfxRect.Deflate(gfxMargin(
        std::max(borderRadii[C_TL].height, borderRadii[C_TR].height), 0,
        std::max(borderRadii[C_BL].height, borderRadii[C_BR].height), 0));
  }

  gfxContext* renderContext = aRenderingContext.ThebesContext();

  for (uint32_t i = shadows->Length(); i > 0; --i) {
    nsCSSShadowItem* shadowItem = shadows->ShadowAt(i - 1);
    if (shadowItem->mInset)
      continue;

    nsRect shadowRect = frameRect;
    shadowRect.MoveBy(shadowItem->mXOffset, shadowItem->mYOffset);
    if (!nativeTheme) {
      shadowRect.Inflate(shadowItem->mSpread, shadowItem->mSpread);
    }

    // shadowRect won't include the blur, so make an extra rect here that includes the blur
    // for use in the even-odd rule below.
    nsRect shadowRectPlusBlur = shadowRect;
    nscoord blurRadius = shadowItem->mRadius;
    shadowRectPlusBlur.Inflate(
      nsContextBoxBlur::GetBlurRadiusMargin(blurRadius, twipsPerPixel));

    Rect shadowGfxRectPlusBlur =
      NSRectToRect(shadowRectPlusBlur, twipsPerPixel);
    shadowGfxRectPlusBlur.RoundOut();
    MaybeSnapToDevicePixels(shadowGfxRectPlusBlur, aDrawTarget, true);

    // Set the shadow color; if not specified, use the foreground color
    nscolor shadowColor;
    if (shadowItem->mHasColor)
      shadowColor = shadowItem->mColor;
    else
      shadowColor = aForFrame->StyleColor()->mColor;

    Color gfxShadowColor(Color::FromABGR(shadowColor));
    gfxShadowColor.a *= aOpacity;

    if (nativeTheme) {
      nsContextBoxBlur blurringArea;

      // When getting the widget shape from the native theme, we're going
      // to draw the widget into the shadow surface to create a mask.
      // We need to ensure that there actually *is* a shadow surface
      // and that we're not going to draw directly into renderContext.
      gfxContext* shadowContext =
        blurringArea.Init(shadowRect, shadowItem->mSpread,
                          blurRadius, twipsPerPixel, renderContext, aDirtyRect,
                          useSkipGfxRect ? &skipGfxRect : nullptr,
                          nsContextBoxBlur::FORCE_MASK);
      if (!shadowContext)
        continue;

      MOZ_ASSERT(shadowContext == blurringArea.GetContext());

      renderContext->Save();
      renderContext->SetColor(gfxShadowColor);

      // Draw the shape of the frame so it can be blurred. Recall how nsContextBoxBlur
      // doesn't make any temporary surfaces if blur is 0 and it just returns the original
      // surface? If we have no blur, we're painting this fill on the actual content surface
      // (renderContext == shadowContext) which is why we set up the color and clip
      // before doing this.

      // We don't clip the border-box from the shadow, nor any other box.
      // We assume that the native theme is going to paint over the shadow.

      // Draw the widget shape
      gfxContextMatrixAutoSaveRestore save(shadowContext);
      gfxPoint devPixelOffset =
        nsLayoutUtils::PointToGfxPoint(nsPoint(shadowItem->mXOffset,
                                               shadowItem->mYOffset),
                                       aPresContext->AppUnitsPerDevPixel());
      shadowContext->SetMatrix(
        shadowContext->CurrentMatrix().Translate(devPixelOffset));

      nsRect nativeRect = aDirtyRect;
      nativeRect.MoveBy(-nsPoint(shadowItem->mXOffset, shadowItem->mYOffset));
      nativeRect.IntersectRect(frameRect, nativeRect);
      nsRenderingContext wrapperCtx(shadowContext);
      aPresContext->GetTheme()->DrawWidgetBackground(&wrapperCtx, aForFrame,
          styleDisplay->mAppearance, aFrameArea, nativeRect);

      blurringArea.DoPaint();
      renderContext->Restore();
    } else {
      renderContext->Save();

      {
        Rect innerClipRect = NSRectToRect(frameRect, twipsPerPixel);
        if (!MaybeSnapToDevicePixels(innerClipRect, aDrawTarget, true)) {
          innerClipRect.Round();
        }

        // Clip out the interior of the frame's border edge so that the shadow
        // is only painted outside that area.
        RefPtr<PathBuilder> builder =
          aDrawTarget.CreatePathBuilder(FillRule::FILL_EVEN_ODD);
        AppendRectToPath(builder, shadowGfxRectPlusBlur);
        if (hasBorderRadius) {
          AppendRoundedRectToPath(builder, innerClipRect, borderRadii);
        } else {
          AppendRectToPath(builder, innerClipRect);
        }
        RefPtr<Path> path = builder->Finish();
        renderContext->Clip(path);
      }

      // Clip the shadow so that we only get the part that applies to aForFrame.
      nsRect fragmentClip = shadowRectPlusBlur;
      if (!skipSides.IsEmpty()) {
        if (skipSides.Left()) {
          nscoord xmost = fragmentClip.XMost();
          fragmentClip.x = aFrameArea.x;
          fragmentClip.width = xmost - fragmentClip.x;
        }
        if (skipSides.Right()) {
          nscoord xmost = fragmentClip.XMost();
          nscoord overflow = xmost - aFrameArea.XMost();
          if (overflow > 0) {
            fragmentClip.width -= overflow;
          }
        }
        if (skipSides.Top()) {
          nscoord ymost = fragmentClip.YMost();
          fragmentClip.y = aFrameArea.y;
          fragmentClip.height = ymost - fragmentClip.y;
        }
        if (skipSides.Bottom()) {
          nscoord ymost = fragmentClip.YMost();
          nscoord overflow = ymost - aFrameArea.YMost();
          if (overflow > 0) {
            fragmentClip.height -= overflow;
          }
        }
      }
      fragmentClip = fragmentClip.Intersect(aDirtyRect);
      renderContext->
        Clip(NSRectToSnappedRect(fragmentClip,
                                 aForFrame->PresContext()->AppUnitsPerDevPixel(),
                                 aDrawTarget));

      RectCornerRadii clipRectRadii;
      if (hasBorderRadius) {
        Float spreadDistance = shadowItem->mSpread / twipsPerPixel;

        Float borderSizes[4];

        borderSizes[NS_SIDE_LEFT] = spreadDistance;
        borderSizes[NS_SIDE_TOP] = spreadDistance;
        borderSizes[NS_SIDE_RIGHT] = spreadDistance;
        borderSizes[NS_SIDE_BOTTOM] = spreadDistance;

        nsCSSBorderRenderer::ComputeOuterRadii(borderRadii, borderSizes,
            &clipRectRadii);

      }
      nsContextBoxBlur::BlurRectangle(renderContext,
                                      shadowRect,
                                      twipsPerPixel,
                                      hasBorderRadius ? &clipRectRadii : nullptr,
                                      blurRadius,
                                      gfxShadowColor,
                                      aDirtyRect,
                                      skipGfxRect);
      renderContext->Restore();
    }

  }
}

void
nsCSSRendering::PaintBoxShadowInner(nsPresContext* aPresContext,
                                    nsRenderingContext& aRenderingContext,
                                    nsIFrame* aForFrame,
                                    const nsRect& aFrameArea)
{
  nsCSSShadowArray* shadows = aForFrame->StyleEffects()->mBoxShadow;
  if (!shadows)
    return;
  if (aForFrame->IsThemed() && aForFrame->GetContent() &&
      !nsContentUtils::IsChromeDoc(aForFrame->GetContent()->GetUncomposedDoc())) {
    // There's no way of getting hold of a shape corresponding to a
    // "padding-box" for native-themed widgets, so just don't draw
    // inner box-shadows for them. But we allow chrome to paint inner
    // box shadows since chrome can be aware of the platform theme.
    return;
  }

  NS_ASSERTION(aForFrame->GetType() == nsGkAtoms::fieldSetFrame ||
               aFrameArea.Size() == aForFrame->GetSize(), "unexpected size");

  Sides skipSides = aForFrame->GetSkipSides();
  nsRect frameRect =
    ::BoxDecorationRectForBorder(aForFrame, aFrameArea, skipSides);
  nsRect paddingRect = frameRect;
  nsMargin border = aForFrame->GetUsedBorder();
  paddingRect.Deflate(border);

  // Get any border radius, since box-shadow must also have rounded corners
  // if the frame does.
  nscoord twipsRadii[8];
  nsSize sz = frameRect.Size();
  bool hasBorderRadius = aForFrame->GetBorderRadii(sz, sz, Sides(), twipsRadii);
  const nscoord twipsPerPixel = aPresContext->DevPixelsToAppUnits(1);

  RectCornerRadii innerRadii;
  if (hasBorderRadius) {
    RectCornerRadii borderRadii;

    ComputePixelRadii(twipsRadii, twipsPerPixel, &borderRadii);
    Float borderSizes[4] = {
      Float(border.top / twipsPerPixel),
      Float(border.right / twipsPerPixel),
      Float(border.bottom / twipsPerPixel),
      Float(border.left / twipsPerPixel)
    };
    nsCSSBorderRenderer::ComputeInnerRadii(borderRadii, borderSizes,
                                           &innerRadii);
  }

  for (uint32_t i = shadows->Length(); i > 0; --i) {
    nsCSSShadowItem* shadowItem = shadows->ShadowAt(i - 1);
    if (!shadowItem->mInset)
      continue;

    // shadowPaintRect: the area to paint on the temp surface
    // shadowClipRect: the area on the temporary surface within shadowPaintRect
    //                 that we will NOT paint in
    nscoord blurRadius = shadowItem->mRadius;
    nsMargin blurMargin =
      nsContextBoxBlur::GetBlurRadiusMargin(blurRadius, twipsPerPixel);
    nsRect shadowPaintRect = paddingRect;
    shadowPaintRect.Inflate(blurMargin);

    Rect shadowPaintGfxRect = NSRectToRect(shadowPaintRect, twipsPerPixel);
    shadowPaintGfxRect.RoundOut();

    // Round the spread radius to device pixels (by truncation).
    // This mostly matches what we do for borders, except that we don't round
    // up values between zero and one device pixels to one device pixel.
    // This way of rounding is symmetric around zero, which makes sense for
    // the spread radius.
    int32_t spreadDistance = shadowItem->mSpread / twipsPerPixel;
    nscoord spreadDistanceAppUnits = aPresContext->DevPixelsToAppUnits(spreadDistance);

    nsRect shadowClipRect = paddingRect;
    shadowClipRect.MoveBy(shadowItem->mXOffset, shadowItem->mYOffset);
    shadowClipRect.Deflate(spreadDistanceAppUnits, spreadDistanceAppUnits);

    Rect shadowClipGfxRect = NSRectToRect(shadowClipRect, twipsPerPixel);
    shadowClipGfxRect.Round();

    RectCornerRadii clipRectRadii;
    if (hasBorderRadius) {
      // Calculate the radii the inner clipping rect will have
      Float borderSizes[4] = {0, 0, 0, 0};

      // See PaintBoxShadowOuter and bug 514670
      if (innerRadii[C_TL].width > 0 || innerRadii[C_BL].width > 0) {
        borderSizes[NS_SIDE_LEFT] = spreadDistance;
      }

      if (innerRadii[C_TL].height > 0 || innerRadii[C_TR].height > 0) {
        borderSizes[NS_SIDE_TOP] = spreadDistance;
      }

      if (innerRadii[C_TR].width > 0 || innerRadii[C_BR].width > 0) {
        borderSizes[NS_SIDE_RIGHT] = spreadDistance;
      }

      if (innerRadii[C_BL].height > 0 || innerRadii[C_BR].height > 0) {
        borderSizes[NS_SIDE_BOTTOM] = spreadDistance;
      }

      nsCSSBorderRenderer::ComputeInnerRadii(innerRadii, borderSizes,
                                             &clipRectRadii);
    }

    // Set the "skip rect" to the area within the frame that we don't paint in,
    // including after blurring.
    nsRect skipRect = shadowClipRect;
    skipRect.Deflate(blurMargin);
    gfxRect skipGfxRect = nsLayoutUtils::RectToGfxRect(skipRect, twipsPerPixel);
    if (hasBorderRadius) {
      skipGfxRect.Deflate(gfxMargin(
          std::max(clipRectRadii[C_TL].height, clipRectRadii[C_TR].height), 0,
          std::max(clipRectRadii[C_BL].height, clipRectRadii[C_BR].height), 0));
    }

    // When there's a blur radius, gfxAlphaBoxBlur leaves the skiprect area
    // unchanged. And by construction the gfxSkipRect is not touched by the
    // rendered shadow (even after blurring), so those pixels must be completely
    // transparent in the shadow, so drawing them changes nothing.
    gfxContext* renderContext = aRenderingContext.ThebesContext();
    DrawTarget* drawTarget = renderContext->GetDrawTarget();

    // Clip the context to the area of the frame's padding rect, so no part of the
    // shadow is painted outside. Also cut out anything beyond where the inset shadow
    // will be.
    Rect shadowGfxRect = NSRectToRect(paddingRect, twipsPerPixel);
    shadowGfxRect.Round();

    // Set the shadow color; if not specified, use the foreground color
    Color shadowColor = Color::FromABGR(shadowItem->mHasColor ?
                                          shadowItem->mColor :
                                          aForFrame->StyleColor()->mColor);

    renderContext->Save();

    // This clips the outside border radius.
    // clipRectRadii is the border radius inside the inset shadow.
    if (hasBorderRadius) {
      RefPtr<Path> roundedRect =
        MakePathForRoundedRect(*drawTarget, shadowGfxRect, innerRadii);
      renderContext->Clip(roundedRect);
    } else {
      renderContext->Clip(shadowGfxRect);
    }

    nsContextBoxBlur insetBoxBlur;
    gfxRect destRect = nsLayoutUtils::RectToGfxRect(shadowPaintRect, twipsPerPixel);
    Point shadowOffset(shadowItem->mXOffset / twipsPerPixel,
                       shadowItem->mYOffset / twipsPerPixel);

    insetBoxBlur.InsetBoxBlur(renderContext, ToRect(destRect),
                              shadowClipGfxRect, shadowColor,
                              blurRadius, spreadDistanceAppUnits,
                              twipsPerPixel, hasBorderRadius,
                              clipRectRadii, ToRect(skipGfxRect),
                              shadowOffset);
    renderContext->Restore();
  }
}

/* static */
nsCSSRendering::PaintBGParams
nsCSSRendering::PaintBGParams::ForAllLayers(nsPresContext& aPresCtx,
                                            nsRenderingContext& aRenderingCtx,
                                            const nsRect& aDirtyRect,
                                            const nsRect& aBorderArea,
                                            nsIFrame *aFrame,
                                            uint32_t aPaintFlags)
{
  MOZ_ASSERT(aFrame);

  PaintBGParams result(aPresCtx, aRenderingCtx, aDirtyRect, aBorderArea, aFrame,
    aPaintFlags, -1, CompositionOp::OP_OVER);

  return result;
}

/* static */
nsCSSRendering::PaintBGParams
nsCSSRendering::PaintBGParams::ForSingleLayer(nsPresContext& aPresCtx,
                                              nsRenderingContext& aRenderingCtx,
                                              const nsRect& aDirtyRect,
                                              const nsRect& aBorderArea,
                                              nsIFrame *aFrame,
                                              uint32_t aPaintFlags,
                                              int32_t aLayer,
                                              CompositionOp aCompositionOp)
{
  MOZ_ASSERT(aFrame && (aLayer != -1));

  PaintBGParams result(aPresCtx, aRenderingCtx, aDirtyRect, aBorderArea, aFrame,
    aPaintFlags, aLayer, aCompositionOp);

  return result;
}

DrawResult
nsCSSRendering::PaintBackground(const PaintBGParams& aParams)
{
  PROFILER_LABEL("nsCSSRendering", "PaintBackground",
    js::ProfileEntry::Category::GRAPHICS);

  NS_PRECONDITION(aParams.frame,
                  "Frame is expected to be provided to PaintBackground");

  nsStyleContext *sc;
  if (!FindBackground(aParams.frame, &sc)) {
    // We don't want to bail out if moz-appearance is set on a root
    // node. If it has a parent content node, bail because it's not
    // a root, otherwise keep going in order to let the theme stuff
    // draw the background. The canvas really should be drawing the
    // bg, but there's no way to hook that up via css.
    if (!aParams.frame->StyleDisplay()->mAppearance) {
      return DrawResult::SUCCESS;
    }

    nsIContent* content = aParams.frame->GetContent();
    if (!content || content->GetParent()) {
      return DrawResult::SUCCESS;
    }

    sc = aParams.frame->StyleContext();
  }

  return PaintBackgroundWithSC(aParams, sc, *aParams.frame->StyleBorder());
}

static bool
IsOpaqueBorderEdge(const nsStyleBorder& aBorder, mozilla::css::Side aSide)
{
  if (aBorder.GetComputedBorder().Side(aSide) == 0)
    return true;
  switch (aBorder.GetBorderStyle(aSide)) {
  case NS_STYLE_BORDER_STYLE_SOLID:
  case NS_STYLE_BORDER_STYLE_GROOVE:
  case NS_STYLE_BORDER_STYLE_RIDGE:
  case NS_STYLE_BORDER_STYLE_INSET:
  case NS_STYLE_BORDER_STYLE_OUTSET:
    break;
  default:
    return false;
  }

  // If we're using a border image, assume it's not fully opaque,
  // because we may not even have the image loaded at this point, and
  // even if we did, checking whether the relevant tile is fully
  // opaque would be too much work.
  if (aBorder.mBorderImageSource.GetType() != eStyleImageType_Null)
    return false;

  StyleComplexColor color = aBorder.mBorderColor[aSide];
  // We don't know the foreground color here, so if it's being used
  // we must assume it might be transparent.
  if (!color.IsNumericColor()) {
    return false;
  }
  return NS_GET_A(color.mColor) == 255;
}

/**
 * Returns true if all border edges are either missing or opaque.
 */
static bool
IsOpaqueBorder(const nsStyleBorder& aBorder)
{
  if (aBorder.mBorderColors)
    return false;
  NS_FOR_CSS_SIDES(i) {
    if (!IsOpaqueBorderEdge(aBorder, i))
      return false;
  }
  return true;
}

static inline void
SetupDirtyRects(const nsRect& aBGClipArea, const nsRect& aCallerDirtyRect,
                nscoord aAppUnitsPerPixel,
                /* OUT: */
                nsRect* aDirtyRect, gfxRect* aDirtyRectGfx)
{
  aDirtyRect->IntersectRect(aBGClipArea, aCallerDirtyRect);

  // Compute the Thebes equivalent of the dirtyRect.
  *aDirtyRectGfx = nsLayoutUtils::RectToGfxRect(*aDirtyRect, aAppUnitsPerPixel);
  NS_WARNING_ASSERTION(aDirtyRect->IsEmpty() || !aDirtyRectGfx->IsEmpty(),
                       "converted dirty rect should not be empty");
  MOZ_ASSERT(!aDirtyRect->IsEmpty() || aDirtyRectGfx->IsEmpty(),
             "second should be empty if first is");
}

static bool
IsSVGStyleGeometryBox(StyleGeometryBox aBox)
{
  return (aBox == StyleGeometryBox::Fill || aBox == StyleGeometryBox::Stroke ||
          aBox == StyleGeometryBox::View);
}

static bool
IsHTMLStyleGeometryBox(StyleGeometryBox aBox)
{
  return (aBox == StyleGeometryBox::Content ||
          aBox == StyleGeometryBox::Padding ||
          aBox == StyleGeometryBox::Border ||
          aBox == StyleGeometryBox::Margin);
}

static StyleGeometryBox
ComputeBoxValue(nsIFrame* aForFrame, StyleGeometryBox aBox)
{
  // Except <svg>, all svg elements are not associate with CSS layout box.
  if (aForFrame->IsFrameOfType(nsIFrame::eSVG) &&
      (aForFrame->GetType() != nsGkAtoms::svgOuterSVGFrame)) {
    // For SVG elements without associated CSS layout box, the values
    // content-box, padding-box, border-box and margin-box compute to fill-box.
    if (IsHTMLStyleGeometryBox(aBox)) {
      return StyleGeometryBox::Fill;
    }
  } else {
    // For elements with associated CSS layout box, the values fill-box,
    // stroke-box and view-box compute to the initial value of mask-clip.
    if (IsSVGStyleGeometryBox(aBox)) {
      return StyleGeometryBox::Border;
    }
  }

  return aBox;
}

/* static */ void
nsCSSRendering::GetImageLayerClip(const nsStyleImageLayers::Layer& aLayer,
                                  nsIFrame* aForFrame, const nsStyleBorder& aBorder,
                                  const nsRect& aBorderArea, const nsRect& aCallerDirtyRect,
                                  bool aWillPaintBorder, nscoord aAppUnitsPerPixel,
                                  /* out */ ImageLayerClipState* aClipState)
{
  StyleGeometryBox layerClip = ComputeBoxValue(aForFrame, aLayer.mClip);

  if (IsSVGStyleGeometryBox(layerClip)) {
    MOZ_ASSERT(aForFrame->IsFrameOfType(nsIFrame::eSVG) &&
               (aForFrame->GetType() != nsGkAtoms::svgOuterSVGFrame));

    aClipState->mHasAdditionalBGClipArea = false;
    aClipState->mCustomClip = false;

    // The coordinate space of clipArea is svg user space.
    nsRect clipArea =
      nsLayoutUtils::ComputeGeometryBox(aForFrame, layerClip);

    nsRect strokeBox = (layerClip == StyleGeometryBox::Stroke)
      ? clipArea
      : nsLayoutUtils::ComputeGeometryBox(aForFrame, StyleGeometryBox::Stroke);
    nsRect clipAreaRelativeToStrokeBox = clipArea - strokeBox.TopLeft();

    // aBorderArea is the stroke-box area in a coordinate space defined by
    // the caller. This coordinate space can be svg user space of aForFrame,
    // the space of aForFrame's reference-frame, or anything else.
    //
    // Which coordinate space chosen for aBorderArea is not matter. What
    // matter is to ensure returning aClipState->mBGClipArea in the consistent
    // coordiante space with aBorderArea. So we evaluate the position of clip
    // area base on the position of aBorderArea here.
    aClipState->mBGClipArea =
      clipAreaRelativeToStrokeBox + aBorderArea.TopLeft();

    SetupDirtyRects(aClipState->mBGClipArea, aCallerDirtyRect,
                    aAppUnitsPerPixel, &aClipState->mDirtyRect,
                    &aClipState->mDirtyRectGfx);
    return;
  }

  if (layerClip == StyleGeometryBox::NoClip) {
    aClipState->mBGClipArea = aCallerDirtyRect;
    aClipState->mHasAdditionalBGClipArea = false;
    aClipState->mCustomClip = false;

    SetupDirtyRects(aClipState->mBGClipArea, aCallerDirtyRect,
                    aAppUnitsPerPixel, &aClipState->mDirtyRect,
                    &aClipState->mDirtyRectGfx);
    return;
  }

  MOZ_ASSERT(!aForFrame->IsFrameOfType(nsIFrame::eSVG) ||
             aForFrame->GetType() == nsGkAtoms::svgOuterSVGFrame);

  // Compute the outermost boundary of the area that might be painted.
  // Same coordinate space as aBorderArea.
  Sides skipSides = aForFrame->GetSkipSides();
  nsRect clipBorderArea =
    ::BoxDecorationRectForBorder(aForFrame, aBorderArea, skipSides, &aBorder);

  bool haveRoundedCorners = false;
   nsIAtom* fType = aForFrame->GetType();
   if (fType != nsGkAtoms::tableColGroupFrame &&
       fType != nsGkAtoms::tableColFrame &&
       fType != nsGkAtoms::tableRowFrame &&
       fType != nsGkAtoms::tableRowGroupFrame) {
     haveRoundedCorners = GetRadii(aForFrame, aBorder, aBorderArea,
                                   clipBorderArea, aClipState->mRadii);
   }

  bool isSolidBorder =
      aWillPaintBorder && IsOpaqueBorder(aBorder);
  if (isSolidBorder && layerClip == StyleGeometryBox::Border) {
    // If we have rounded corners, we need to inflate the background
    // drawing area a bit to avoid seams between the border and
    // background.
    layerClip = haveRoundedCorners
                     ? StyleGeometryBox::MozAlmostPadding
                     : StyleGeometryBox::Padding;
  }

  aClipState->mBGClipArea = clipBorderArea;
  aClipState->mHasAdditionalBGClipArea = false;
  aClipState->mCustomClip = false;

  if (aForFrame->GetType() == nsGkAtoms::scrollFrame &&
      NS_STYLE_IMAGELAYER_ATTACHMENT_LOCAL == aLayer.mAttachment) {
    // As of this writing, this is still in discussion in the CSS Working Group
    // http://lists.w3.org/Archives/Public/www-style/2013Jul/0250.html

    // The rectangle for 'background-clip' scrolls with the content,
    // but the background is also clipped at a non-scrolling 'padding-box'
    // like the content. (See below.)
    // Therefore, only 'content-box' makes a difference here.
    if (layerClip == StyleGeometryBox::Content) {
      nsIScrollableFrame* scrollableFrame = do_QueryFrame(aForFrame);
      // Clip at a rectangle attached to the scrolled content.
      aClipState->mHasAdditionalBGClipArea = true;
      aClipState->mAdditionalBGClipArea = nsRect(
        aClipState->mBGClipArea.TopLeft()
          + scrollableFrame->GetScrolledFrame()->GetPosition()
          // For the dir=rtl case:
          + scrollableFrame->GetScrollRange().TopLeft(),
        scrollableFrame->GetScrolledRect().Size());
      nsMargin padding = aForFrame->GetUsedPadding();
      // padding-bottom is ignored on scrollable frames:
      // https://bugzilla.mozilla.org/show_bug.cgi?id=748518
      padding.bottom = 0;
      padding.ApplySkipSides(skipSides);
      aClipState->mAdditionalBGClipArea.Deflate(padding);
    }

    // Also clip at a non-scrolling, rounded-corner 'padding-box',
    // same as the scrolled content because of the 'overflow' property.
    layerClip = StyleGeometryBox::Padding;
  }

  // See the comment of StyleGeometryBox::Margin.
  // Hitting this assertion means we decide to turn on margin-box support for
  // positioned mask from CSS parser and style system. In this case, you
  // should *inflate* mBGClipArea by the margin returning from
  // aForFrame->GetUsedMargin() in the code chunk bellow.
  MOZ_ASSERT(layerClip != StyleGeometryBox::Margin,
             "StyleGeometryBox::Margin rendering is not supported yet.\n");

  if (layerClip != StyleGeometryBox::Border &&
      layerClip != StyleGeometryBox::Text) {
    nsMargin border = aForFrame->GetUsedBorder();
    if (layerClip == StyleGeometryBox::MozAlmostPadding) {
      // Reduce |border| by 1px (device pixels) on all sides, if
      // possible, so that we don't get antialiasing seams between the
      // {background|mask} and border.
      border.top = std::max(0, border.top - aAppUnitsPerPixel);
      border.right = std::max(0, border.right - aAppUnitsPerPixel);
      border.bottom = std::max(0, border.bottom - aAppUnitsPerPixel);
      border.left = std::max(0, border.left - aAppUnitsPerPixel);
    } else if (layerClip != StyleGeometryBox::Padding) {
      NS_ASSERTION(layerClip == StyleGeometryBox::Content,
                   "unexpected background-clip");
      border += aForFrame->GetUsedPadding();
    }
    border.ApplySkipSides(skipSides);
    aClipState->mBGClipArea.Deflate(border);

    if (haveRoundedCorners) {
      nsIFrame::InsetBorderRadii(aClipState->mRadii, border);
    }
  }

  if (haveRoundedCorners) {
    auto d2a = aForFrame->PresContext()->AppUnitsPerDevPixel();
    nsCSSRendering::ComputePixelRadii(aClipState->mRadii, d2a, &aClipState->mClippedRadii);
    aClipState->mHasRoundedCorners = true;
  } else {
    aClipState->mHasRoundedCorners = false;
  }


  if (!haveRoundedCorners && aClipState->mHasAdditionalBGClipArea) {
    // Do the intersection here to account for the fast path(?) below.
    aClipState->mBGClipArea =
      aClipState->mBGClipArea.Intersect(aClipState->mAdditionalBGClipArea);
    aClipState->mHasAdditionalBGClipArea = false;
  }

  SetupDirtyRects(aClipState->mBGClipArea, aCallerDirtyRect, aAppUnitsPerPixel,
                  &aClipState->mDirtyRect, &aClipState->mDirtyRectGfx);
}

static void
SetupImageLayerClip(nsCSSRendering::ImageLayerClipState& aClipState,
                    gfxContext *aCtx, nscoord aAppUnitsPerPixel,
                    gfxContextAutoSaveRestore* aAutoSR)
{
  if (aClipState.mDirtyRectGfx.IsEmpty()) {
    // Our caller won't draw anything under this condition, so no need
    // to set more up.
    return;
  }

  if (aClipState.mCustomClip) {
    // We don't support custom clips and rounded corners, arguably a bug, but
    // table painting seems to depend on it.
    return;
  }

  DrawTarget* drawTarget = aCtx->GetDrawTarget();

  // If we have rounded corners, clip all subsequent drawing to the
  // rounded rectangle defined by bgArea and bgRadii (we don't know
  // whether the rounded corners intrude on the dirtyRect or not).
  // Do not do this if we have a caller-provided clip rect --
  // as above with bgArea, arguably a bug, but table painting seems
  // to depend on it.

  if (aClipState.mHasAdditionalBGClipArea) {
    gfxRect bgAreaGfx = nsLayoutUtils::RectToGfxRect(
      aClipState.mAdditionalBGClipArea, aAppUnitsPerPixel);
    bgAreaGfx.Round();
    bgAreaGfx.Condition();

    aAutoSR->EnsureSaved(aCtx);
    aCtx->NewPath();
    aCtx->Rectangle(bgAreaGfx, true);
    aCtx->Clip();
  }

  if (aClipState.mHasRoundedCorners) {
    Rect bgAreaGfx = NSRectToRect(aClipState.mBGClipArea, aAppUnitsPerPixel);
    bgAreaGfx.Round();

    if (bgAreaGfx.IsEmpty()) {
      // I think it's become possible to hit this since
      // http://hg.mozilla.org/mozilla-central/rev/50e934e4979b landed.
      NS_WARNING("converted background area should not be empty");
      // Make our caller not do anything.
      aClipState.mDirtyRectGfx.SizeTo(gfxSize(0.0, 0.0));
      return;
    }

    aAutoSR->EnsureSaved(aCtx);

    RefPtr<Path> roundedRect =
      MakePathForRoundedRect(*drawTarget, bgAreaGfx, aClipState.mClippedRadii);
    aCtx->Clip(roundedRect);
  }
}

static void
DrawBackgroundColor(nsCSSRendering::ImageLayerClipState& aClipState,
                    gfxContext *aCtx, nscoord aAppUnitsPerPixel)
{
  if (aClipState.mDirtyRectGfx.IsEmpty()) {
    // Our caller won't draw anything under this condition, so no need
    // to set more up.
    return;
  }

  DrawTarget* drawTarget = aCtx->GetDrawTarget();

  // We don't support custom clips and rounded corners, arguably a bug, but
  // table painting seems to depend on it.
  if (!aClipState.mHasRoundedCorners || aClipState.mCustomClip) {
    aCtx->NewPath();
    aCtx->Rectangle(aClipState.mDirtyRectGfx, true);
    aCtx->Fill();
    return;
  }

  Rect bgAreaGfx = NSRectToRect(aClipState.mBGClipArea, aAppUnitsPerPixel);
  bgAreaGfx.Round();

  if (bgAreaGfx.IsEmpty()) {
    // I think it's become possible to hit this since
    // http://hg.mozilla.org/mozilla-central/rev/50e934e4979b landed.
    NS_WARNING("converted background area should not be empty");
    // Make our caller not do anything.
    aClipState.mDirtyRectGfx.SizeTo(gfxSize(0.0, 0.0));
    return;
  }

  aCtx->Save();
  gfxRect dirty = ThebesRect(bgAreaGfx).Intersect(aClipState.mDirtyRectGfx);

  aCtx->NewPath();
  aCtx->Rectangle(dirty, true);
  aCtx->Clip();

  if (aClipState.mHasAdditionalBGClipArea) {
    gfxRect bgAdditionalAreaGfx = nsLayoutUtils::RectToGfxRect(
      aClipState.mAdditionalBGClipArea, aAppUnitsPerPixel);
    bgAdditionalAreaGfx.Round();
    bgAdditionalAreaGfx.Condition();
    aCtx->NewPath();
    aCtx->Rectangle(bgAdditionalAreaGfx, true);
    aCtx->Clip();
  }

  RefPtr<Path> roundedRect =
    MakePathForRoundedRect(*drawTarget, bgAreaGfx, aClipState.mClippedRadii);
  aCtx->SetPath(roundedRect);
  aCtx->Fill();
  aCtx->Restore();
}

nscolor
nsCSSRendering::DetermineBackgroundColor(nsPresContext* aPresContext,
                                         nsStyleContext* aStyleContext,
                                         nsIFrame* aFrame,
                                         bool& aDrawBackgroundImage,
                                         bool& aDrawBackgroundColor)
{
  aDrawBackgroundImage = true;
  aDrawBackgroundColor = true;

  const nsStyleVisibility* visibility = aStyleContext->StyleVisibility();

  if (visibility->mColorAdjust != NS_STYLE_COLOR_ADJUST_EXACT &&
      aFrame->HonorPrintBackgroundSettings()) {
    aDrawBackgroundImage = aPresContext->GetBackgroundImageDraw();
    aDrawBackgroundColor = aPresContext->GetBackgroundColorDraw();
  }

  const nsStyleBackground *bg = aStyleContext->StyleBackground();
  nscolor bgColor;
  if (aDrawBackgroundColor) {
    bgColor =
      aStyleContext->GetVisitedDependentColor(eCSSProperty_background_color);
    if (NS_GET_A(bgColor) == 0) {
      aDrawBackgroundColor = false;
    }
  } else {
    // If GetBackgroundColorDraw() is false, we are still expected to
    // draw color in the background of any frame that's not completely
    // transparent, but we are expected to use white instead of whatever
    // color was specified.
    bgColor = NS_RGB(255, 255, 255);
    if (aDrawBackgroundImage || !bg->IsTransparent()) {
      aDrawBackgroundColor = true;
    } else {
      bgColor = NS_RGBA(0,0,0,0);
    }
  }

  // We can skip painting the background color if a background image is opaque.
  nsStyleImageLayers::Repeat repeat = bg->BottomLayer().mRepeat;
  bool xFullRepeat = repeat.mXRepeat == NS_STYLE_IMAGELAYER_REPEAT_REPEAT ||
                     repeat.mXRepeat == NS_STYLE_IMAGELAYER_REPEAT_ROUND;
  bool yFullRepeat = repeat.mYRepeat == NS_STYLE_IMAGELAYER_REPEAT_REPEAT ||
                     repeat.mYRepeat == NS_STYLE_IMAGELAYER_REPEAT_ROUND;
  if (aDrawBackgroundColor &&
      xFullRepeat && yFullRepeat &&
      bg->BottomLayer().mImage.IsOpaque() &&
      bg->BottomLayer().mBlendMode == NS_STYLE_BLEND_NORMAL) {
    aDrawBackgroundColor = false;
  }

  return bgColor;
}

static gfxFloat
ConvertGradientValueToPixels(const nsStyleCoord& aCoord,
                             gfxFloat aFillLength,
                             int32_t aAppUnitsPerPixel)
{
  switch (aCoord.GetUnit()) {
    case eStyleUnit_Percent:
      return aCoord.GetPercentValue() * aFillLength;
    case eStyleUnit_Coord:
      return NSAppUnitsToFloatPixels(aCoord.GetCoordValue(), aAppUnitsPerPixel);
    case eStyleUnit_Calc: {
      const nsStyleCoord::Calc *calc = aCoord.GetCalcValue();
      return calc->mPercent * aFillLength +
             NSAppUnitsToFloatPixels(calc->mLength, aAppUnitsPerPixel);
    }
    default:
      NS_WARNING("Unexpected coord unit");
      return 0;
  }
}

// Given a box with size aBoxSize and origin (0,0), and an angle aAngle,
// and a starting point for the gradient line aStart, find the endpoint of
// the gradient line --- the intersection of the gradient line with a line
// perpendicular to aAngle that passes through the farthest corner in the
// direction aAngle.
static gfxPoint
ComputeGradientLineEndFromAngle(const gfxPoint& aStart,
                                double aAngle,
                                const gfxSize& aBoxSize)
{
  double dx = cos(-aAngle);
  double dy = sin(-aAngle);
  gfxPoint farthestCorner(dx > 0 ? aBoxSize.width : 0,
                          dy > 0 ? aBoxSize.height : 0);
  gfxPoint delta = farthestCorner - aStart;
  double u = delta.x*dy - delta.y*dx;
  return farthestCorner + gfxPoint(-u*dy, u*dx);
}

// Compute the start and end points of the gradient line for a linear gradient.
static void
ComputeLinearGradientLine(nsPresContext* aPresContext,
                          nsStyleGradient* aGradient,
                          const gfxSize& aBoxSize,
                          gfxPoint* aLineStart,
                          gfxPoint* aLineEnd)
{
  if (aGradient->mBgPosX.GetUnit() == eStyleUnit_None) {
    double angle;
    if (aGradient->mAngle.IsAngleValue()) {
      angle = aGradient->mAngle.GetAngleValueInRadians();
      if (!aGradient->mLegacySyntax) {
        angle = M_PI_2 - angle;
      }
    } else {
      angle = -M_PI_2; // defaults to vertical gradient starting from top
    }
    gfxPoint center(aBoxSize.width/2, aBoxSize.height/2);
    *aLineEnd = ComputeGradientLineEndFromAngle(center, angle, aBoxSize);
    *aLineStart = gfxPoint(aBoxSize.width, aBoxSize.height) - *aLineEnd;
  } else if (!aGradient->mLegacySyntax) {
    float xSign = aGradient->mBgPosX.GetPercentValue() * 2 - 1;
    float ySign = 1 - aGradient->mBgPosY.GetPercentValue() * 2;
    double angle = atan2(ySign * aBoxSize.width, xSign * aBoxSize.height);
    gfxPoint center(aBoxSize.width/2, aBoxSize.height/2);
    *aLineEnd = ComputeGradientLineEndFromAngle(center, angle, aBoxSize);
    *aLineStart = gfxPoint(aBoxSize.width, aBoxSize.height) - *aLineEnd;
  } else {
    int32_t appUnitsPerPixel = aPresContext->AppUnitsPerDevPixel();
    *aLineStart = gfxPoint(
      ConvertGradientValueToPixels(aGradient->mBgPosX, aBoxSize.width,
                                   appUnitsPerPixel),
      ConvertGradientValueToPixels(aGradient->mBgPosY, aBoxSize.height,
                                   appUnitsPerPixel));
    if (aGradient->mAngle.IsAngleValue()) {
      MOZ_ASSERT(aGradient->mLegacySyntax);
      double angle = aGradient->mAngle.GetAngleValueInRadians();
      *aLineEnd = ComputeGradientLineEndFromAngle(*aLineStart, angle, aBoxSize);
    } else {
      // No angle, the line end is just the reflection of the start point
      // through the center of the box
      *aLineEnd = gfxPoint(aBoxSize.width, aBoxSize.height) - *aLineStart;
    }
  }
}

// Compute the start and end points of the gradient line for a radial gradient.
// Also returns the horizontal and vertical radii defining the circle or
// ellipse to use.
static void
ComputeRadialGradientLine(nsPresContext* aPresContext,
                          nsStyleGradient* aGradient,
                          const gfxSize& aBoxSize,
                          gfxPoint* aLineStart,
                          gfxPoint* aLineEnd,
                          double* aRadiusX,
                          double* aRadiusY)
{
  if (aGradient->mBgPosX.GetUnit() == eStyleUnit_None) {
    // Default line start point is the center of the box
    *aLineStart = gfxPoint(aBoxSize.width/2, aBoxSize.height/2);
  } else {
    int32_t appUnitsPerPixel = aPresContext->AppUnitsPerDevPixel();
    *aLineStart = gfxPoint(
      ConvertGradientValueToPixels(aGradient->mBgPosX, aBoxSize.width,
                                   appUnitsPerPixel),
      ConvertGradientValueToPixels(aGradient->mBgPosY, aBoxSize.height,
                                   appUnitsPerPixel));
  }

  // Compute gradient shape: the x and y radii of an ellipse.
  double radiusX, radiusY;
  double leftDistance = Abs(aLineStart->x);
  double rightDistance = Abs(aBoxSize.width - aLineStart->x);
  double topDistance = Abs(aLineStart->y);
  double bottomDistance = Abs(aBoxSize.height - aLineStart->y);
  switch (aGradient->mSize) {
  case NS_STYLE_GRADIENT_SIZE_CLOSEST_SIDE:
    radiusX = std::min(leftDistance, rightDistance);
    radiusY = std::min(topDistance, bottomDistance);
    if (aGradient->mShape == NS_STYLE_GRADIENT_SHAPE_CIRCULAR) {
      radiusX = radiusY = std::min(radiusX, radiusY);
    }
    break;
  case NS_STYLE_GRADIENT_SIZE_CLOSEST_CORNER: {
    // Compute x and y distances to nearest corner
    double offsetX = std::min(leftDistance, rightDistance);
    double offsetY = std::min(topDistance, bottomDistance);
    if (aGradient->mShape == NS_STYLE_GRADIENT_SHAPE_CIRCULAR) {
      radiusX = radiusY = NS_hypot(offsetX, offsetY);
    } else {
      // maintain aspect ratio
      radiusX = offsetX*M_SQRT2;
      radiusY = offsetY*M_SQRT2;
    }
    break;
  }
  case NS_STYLE_GRADIENT_SIZE_FARTHEST_SIDE:
    radiusX = std::max(leftDistance, rightDistance);
    radiusY = std::max(topDistance, bottomDistance);
    if (aGradient->mShape == NS_STYLE_GRADIENT_SHAPE_CIRCULAR) {
      radiusX = radiusY = std::max(radiusX, radiusY);
    }
    break;
  case NS_STYLE_GRADIENT_SIZE_FARTHEST_CORNER: {
    // Compute x and y distances to nearest corner
    double offsetX = std::max(leftDistance, rightDistance);
    double offsetY = std::max(topDistance, bottomDistance);
    if (aGradient->mShape == NS_STYLE_GRADIENT_SHAPE_CIRCULAR) {
      radiusX = radiusY = NS_hypot(offsetX, offsetY);
    } else {
      // maintain aspect ratio
      radiusX = offsetX*M_SQRT2;
      radiusY = offsetY*M_SQRT2;
    }
    break;
  }
  case NS_STYLE_GRADIENT_SIZE_EXPLICIT_SIZE: {
    int32_t appUnitsPerPixel = aPresContext->AppUnitsPerDevPixel();
    radiusX = ConvertGradientValueToPixels(aGradient->mRadiusX,
                                           aBoxSize.width, appUnitsPerPixel);
    radiusY = ConvertGradientValueToPixels(aGradient->mRadiusY,
                                           aBoxSize.height, appUnitsPerPixel);
    break;
  }
  default:
    radiusX = radiusY = 0;
    MOZ_ASSERT(false, "unknown radial gradient sizing method");
  }
  *aRadiusX = radiusX;
  *aRadiusY = radiusY;

  double angle;
  if (aGradient->mAngle.IsAngleValue()) {
    angle = aGradient->mAngle.GetAngleValueInRadians();
  } else {
    // Default angle is 0deg
    angle = 0.0;
  }

  // The gradient line end point is where the gradient line intersects
  // the ellipse.
  *aLineEnd = *aLineStart + gfxPoint(radiusX*cos(-angle), radiusY*sin(-angle));
}

// Returns aFrac*aC2 + (1 - aFrac)*C1. The interpolation is done
// in RGBA color space, which is what SVG gradients and cairo
// gradients expect.
static Color
InterpolateColor(const Color& aC1, const Color& aC2, float aFrac)
{
  double other = 1 - aFrac;
  return Color(aC2.r*aFrac + aC1.r*other,
               aC2.g*aFrac + aC1.g*other,
               aC2.b*aFrac + aC1.b*other,
               aC2.a*aFrac + aC1.a*other);
}

static nscoord
FindTileStart(nscoord aDirtyCoord, nscoord aTilePos, nscoord aTileDim)
{
  NS_ASSERTION(aTileDim > 0, "Non-positive tile dimension");
  double multiples = floor(double(aDirtyCoord - aTilePos)/aTileDim);
  return NSToCoordRound(multiples*aTileDim + aTilePos);
}

static gfxFloat
LinearGradientStopPositionForPoint(const gfxPoint& aGradientStart,
                                   const gfxPoint& aGradientEnd,
                                   const gfxPoint& aPoint)
{
  gfxPoint d = aGradientEnd - aGradientStart;
  gfxPoint p = aPoint - aGradientStart;
  /**
   * Compute a parameter t such that a line perpendicular to the
   * d vector, passing through aGradientStart + d*t, also
   * passes through aPoint.
   *
   * t is given by
   *   (p.x - d.x*t)*d.x + (p.y - d.y*t)*d.y = 0
   *
   * Solving for t we get
   *   numerator = d.x*p.x + d.y*p.y
   *   denominator = d.x^2 + d.y^2
   *   t = numerator/denominator
   *
   * In nsCSSRendering::PaintGradient we know the length of d
   * is not zero.
   */
  double numerator = d.x * p.x + d.y * p.y;
  double denominator = d.x * d.x + d.y * d.y;
  return numerator / denominator;
}

static bool
RectIsBeyondLinearGradientEdge(const gfxRect& aRect,
                               const gfxMatrix& aPatternMatrix,
                               const nsTArray<ColorStop>& aStops,
                               const gfxPoint& aGradientStart,
                               const gfxPoint& aGradientEnd,
                               Color* aOutEdgeColor)
{
  gfxFloat topLeft = LinearGradientStopPositionForPoint(
    aGradientStart, aGradientEnd, aPatternMatrix.Transform(aRect.TopLeft()));
  gfxFloat topRight = LinearGradientStopPositionForPoint(
    aGradientStart, aGradientEnd, aPatternMatrix.Transform(aRect.TopRight()));
  gfxFloat bottomLeft = LinearGradientStopPositionForPoint(
    aGradientStart, aGradientEnd, aPatternMatrix.Transform(aRect.BottomLeft()));
  gfxFloat bottomRight = LinearGradientStopPositionForPoint(
    aGradientStart, aGradientEnd, aPatternMatrix.Transform(aRect.BottomRight()));

  const ColorStop& firstStop = aStops[0];
  if (topLeft < firstStop.mPosition && topRight < firstStop.mPosition &&
      bottomLeft < firstStop.mPosition && bottomRight < firstStop.mPosition) {
    *aOutEdgeColor = firstStop.mColor;
    return true;
  }

  const ColorStop& lastStop = aStops.LastElement();
  if (topLeft >= lastStop.mPosition && topRight >= lastStop.mPosition &&
      bottomLeft >= lastStop.mPosition && bottomRight >= lastStop.mPosition) {
    *aOutEdgeColor = lastStop.mColor;
    return true;
  }

  return false;
}

static void ResolveMidpoints(nsTArray<ColorStop>& stops)
{
  for (size_t x = 1; x < stops.Length() - 1;) {
    if (!stops[x].mIsMidpoint) {
      x++;
      continue;
    }

    Color color1 = stops[x-1].mColor;
    Color color2 = stops[x+1].mColor;
    float offset1 = stops[x-1].mPosition;
    float offset2 = stops[x+1].mPosition;
    float offset = stops[x].mPosition;
    // check if everything coincides. If so, ignore the midpoint.
    if (offset - offset1 == offset2 - offset) {
      stops.RemoveElementAt(x);
      continue;
    }

    // Check if we coincide with the left colorstop.
    if (offset1 == offset) {
      // Morph the midpoint to a regular stop with the color of the next
      // color stop.
      stops[x].mColor = color2;
      stops[x].mIsMidpoint = false;
      continue;
    }

    // Check if we coincide with the right colorstop.
    if (offset2 == offset) {
      // Morph the midpoint to a regular stop with the color of the previous
      // color stop.
      stops[x].mColor = color1;
      stops[x].mIsMidpoint = false;
      continue;
    }

    float midpoint = (offset - offset1) / (offset2 - offset1);
    ColorStop newStops[9];
    if (midpoint > .5f) {
      for (size_t y = 0; y < 7; y++) {
        newStops[y].mPosition = offset1 + (offset - offset1) * (7 + y) / 13;
      }

      newStops[7].mPosition = offset + (offset2 - offset) / 3;
      newStops[8].mPosition = offset + (offset2 - offset) * 2 / 3;
    } else {
      newStops[0].mPosition = offset1 + (offset - offset1) / 3;
      newStops[1].mPosition = offset1 + (offset - offset1) * 2 / 3;

      for (size_t y = 0; y < 7; y++) {
        newStops[y+2].mPosition = offset + (offset2 - offset) * y / 13;
      }
    }
    // calculate colors

    for (size_t y = 0; y < 9; y++) {
      // Calculate the intermediate color stops per the formula of the CSS images
      // spec. http://dev.w3.org/csswg/css-images/#color-stop-syntax
      // 9 points were chosen since it is the minimum number of stops that always
      // give the smoothest appearace regardless of midpoint position and difference
      // in luminance of the end points.
      float relativeOffset = (newStops[y].mPosition - offset1) / (offset2 - offset1);
      float multiplier = powf(relativeOffset, logf(.5f) / logf(midpoint));

      gfx::Float red = color1.r + multiplier * (color2.r - color1.r);
      gfx::Float green = color1.g + multiplier * (color2.g - color1.g);
      gfx::Float blue = color1.b + multiplier * (color2.b - color1.b);
      gfx::Float alpha = color1.a + multiplier * (color2.a - color1.a);

      newStops[y].mColor = Color(red, green, blue, alpha);
    }

    stops.ReplaceElementsAt(x, 1, newStops, 9);
    x += 9;
  }
}

static ColorStop
InterpolateColorStop(const ColorStop& aFirst, const ColorStop& aSecond,
                     double aPosition, const Color& aDefault)
{
  MOZ_ASSERT(aFirst.mPosition <= aPosition);
  MOZ_ASSERT(aPosition <= aSecond.mPosition);

  double delta = aSecond.mPosition - aFirst.mPosition;

  if (delta < 1e-6) {
    return ColorStop(aPosition, false, aDefault);
  }

  return ColorStop(aPosition, false,
                   InterpolateColor(aFirst.mColor,
                                    aSecond.mColor,
                                    (aPosition - aFirst.mPosition) / delta));
}

// Clamp and extend the given ColorStop array in-place to fit exactly into the
// range [0, 1].
static void
ClampColorStops(nsTArray<ColorStop>& aStops)
{
  MOZ_ASSERT(aStops.Length() > 0);

  // If all stops are outside the range, then get rid of everything and replace
  // with a single colour.
  if (aStops.Length() < 2 || aStops[0].mPosition > 1 ||
      aStops.LastElement().mPosition < 0) {
    Color c = aStops[0].mPosition > 1 ? aStops[0].mColor : aStops.LastElement().mColor;
    aStops.Clear();
    aStops.AppendElement(ColorStop(0, false, c));
    return;
  }

  // Create the 0 and 1 points if they fall in the range of |aStops|, and discard
  // all stops outside the range [0, 1].
  // XXX: If we have stops positioned at 0 or 1, we only keep the innermost of
  // those stops. This should be fine for the current user(s) of this function.
  for (size_t i = aStops.Length() - 1; i > 0; i--) {
    if (aStops[i - 1].mPosition < 1 && aStops[i].mPosition >= 1) {
      // Add a point to position 1.
      aStops[i] = InterpolateColorStop(aStops[i - 1], aStops[i],
                                       /* aPosition = */ 1,
                                       aStops[i - 1].mColor);
      // Remove all the elements whose position is greater than 1.
      aStops.RemoveElementsAt(i + 1, aStops.Length() - (i + 1));
    }
    if (aStops[i - 1].mPosition <= 0 && aStops[i].mPosition > 0) {
      // Add a point to position 0.
      aStops[i - 1] = InterpolateColorStop(aStops[i - 1], aStops[i],
                                           /* aPosition = */ 0,
                                           aStops[i].mColor);
      // Remove all of the preceding stops -- they are all negative.
      aStops.RemoveElementsAt(0, i - 1);
      break;
    }
  }

  MOZ_ASSERT(aStops[0].mPosition >= -1e6);
  MOZ_ASSERT(aStops.LastElement().mPosition - 1 <= 1e6);

  // The end points won't exist yet if they don't fall in the original range of
  // |aStops|. Create them if needed.
  if (aStops[0].mPosition > 0) {
    aStops.InsertElementAt(0, ColorStop(0, false, aStops[0].mColor));
  }
  if (aStops.LastElement().mPosition < 1) {
    aStops.AppendElement(ColorStop(1, false, aStops.LastElement().mColor));
  }
}

void
nsCSSRendering::PaintGradient(nsPresContext* aPresContext,
                              nsRenderingContext& aRenderingContext,
                              nsStyleGradient* aGradient,
                              const nsRect& aDirtyRect,
                              const nsRect& aDest,
                              const nsRect& aFillArea,
                              const nsSize& aRepeatSize,
                              const CSSIntRect& aSrc,
                              const nsSize& aIntrinsicSize)
{
  PROFILER_LABEL("nsCSSRendering", "PaintGradient",
    js::ProfileEntry::Category::GRAPHICS);

  if (aDest.IsEmpty() || aFillArea.IsEmpty()) {
    return;
  }

  gfxContext *ctx = aRenderingContext.ThebesContext();
  nscoord appUnitsPerDevPixel = aPresContext->AppUnitsPerDevPixel();
  gfxSize srcSize = gfxSize(gfxFloat(aIntrinsicSize.width)/appUnitsPerDevPixel,
                            gfxFloat(aIntrinsicSize.height)/appUnitsPerDevPixel);

  bool cellContainsFill = aDest.Contains(aFillArea);

  // Compute "gradient line" start and end relative to the intrinsic size of
  // the gradient.
  gfxPoint lineStart, lineEnd;
  double radiusX = 0, radiusY = 0; // for radial gradients only
  if (aGradient->mShape == NS_STYLE_GRADIENT_SHAPE_LINEAR) {
    ComputeLinearGradientLine(aPresContext, aGradient, srcSize,
                              &lineStart, &lineEnd);
  } else {
    ComputeRadialGradientLine(aPresContext, aGradient, srcSize,
                              &lineStart, &lineEnd, &radiusX, &radiusY);
  }
  // Avoid sending Infs or Nans to downwind draw targets.
  if (!lineStart.IsFinite() || !lineEnd.IsFinite()) {
    lineStart = lineEnd = gfxPoint(0, 0);
  }
  gfxFloat lineLength = NS_hypot(lineEnd.x - lineStart.x,
                                  lineEnd.y - lineStart.y);

  MOZ_ASSERT(aGradient->mStops.Length() >= 2,
             "The parser should reject gradients with less than two stops");

  // Build color stop array and compute stop positions
  nsTArray<ColorStop> stops;
  // If there is a run of stops before stop i that did not have specified
  // positions, then this is the index of the first stop in that run, otherwise
  // it's -1.
  int32_t firstUnsetPosition = -1;
  for (uint32_t i = 0; i < aGradient->mStops.Length(); ++i) {
    const nsStyleGradientStop& stop = aGradient->mStops[i];
    double position;
    switch (stop.mLocation.GetUnit()) {
    case eStyleUnit_None:
      if (i == 0) {
        // First stop defaults to position 0.0
        position = 0.0;
      } else if (i == aGradient->mStops.Length() - 1) {
        // Last stop defaults to position 1.0
        position = 1.0;
      } else {
        // Other stops with no specified position get their position assigned
        // later by interpolation, see below.
        // Remeber where the run of stops with no specified position starts,
        // if it starts here.
        if (firstUnsetPosition < 0) {
          firstUnsetPosition = i;
        }
        stops.AppendElement(ColorStop(0, stop.mIsInterpolationHint,
                                      Color::FromABGR(stop.mColor)));
        continue;
      }
      break;
    case eStyleUnit_Percent:
      position = stop.mLocation.GetPercentValue();
      break;
    case eStyleUnit_Coord:
      position = lineLength < 1e-6 ? 0.0 :
          stop.mLocation.GetCoordValue() / appUnitsPerDevPixel / lineLength;
      break;
    case eStyleUnit_Calc:
      nsStyleCoord::Calc *calc;
      calc = stop.mLocation.GetCalcValue();
      position = calc->mPercent +
          ((lineLength < 1e-6) ? 0.0 :
          (NSAppUnitsToFloatPixels(calc->mLength, appUnitsPerDevPixel) / lineLength));
      break;
    default:
      MOZ_ASSERT(false, "Unknown stop position type");
    }

    if (i > 0) {
      // Prevent decreasing stop positions by advancing this position
      // to the previous stop position, if necessary
      position = std::max(position, stops[i - 1].mPosition);
    }
    stops.AppendElement(ColorStop(position, stop.mIsInterpolationHint,
                                  Color::FromABGR(stop.mColor)));
    if (firstUnsetPosition > 0) {
      // Interpolate positions for all stops that didn't have a specified position
      double p = stops[firstUnsetPosition - 1].mPosition;
      double d = (stops[i].mPosition - p)/(i - firstUnsetPosition + 1);
      for (uint32_t j = firstUnsetPosition; j < i; ++j) {
        p += d;
        stops[j].mPosition = p;
      }
      firstUnsetPosition = -1;
    }
  }

  // If a non-repeating linear gradient is axis-aligned and there are no gaps
  // between tiles, we can optimise away most of the work by converting to a
  // repeating linear gradient and filling the whole destination rect at once.
  bool forceRepeatToCoverTiles =
    aGradient->mShape == NS_STYLE_GRADIENT_SHAPE_LINEAR &&
    (lineStart.x == lineEnd.x) != (lineStart.y == lineEnd.y) &&
    aRepeatSize.width == aDest.width && aRepeatSize.height == aDest.height &&
    !aGradient->mRepeating && !aSrc.IsEmpty() && !cellContainsFill;

  gfxMatrix matrix;
  if (forceRepeatToCoverTiles) {
    // Length of the source rectangle along the gradient axis.
    double rectLen;
    // The position of the start of the rectangle along the gradient.
    double offset;

    // The gradient line is "backwards". Flip the line upside down to make
    // things easier, and then rotate the matrix to turn everything back the
    // right way up.
    if (lineStart.x > lineEnd.x || lineStart.y > lineEnd.y) {
      std::swap(lineStart, lineEnd);
      matrix.Scale(-1, -1);
    }

    // Fit the gradient line exactly into the source rect.
    // aSrc is relative to aIntrinsincSize.
    // srcRectDev will be relative to srcSize, so in the same coordinate space
    // as lineStart / lineEnd.
    gfxRect srcRectDev = nsLayoutUtils::RectToGfxRect(
      CSSPixel::ToAppUnits(aSrc), appUnitsPerDevPixel);
    if (lineStart.x != lineEnd.x) {
      rectLen = srcRectDev.width;
      offset = (srcRectDev.x - lineStart.x) / lineLength;
      lineStart.x = srcRectDev.x;
      lineEnd.x = srcRectDev.XMost();
    } else {
      rectLen = srcRectDev.height;
      offset = (srcRectDev.y - lineStart.y) / lineLength;
      lineStart.y = srcRectDev.y;
      lineEnd.y = srcRectDev.YMost();
    }

    // Adjust gradient stop positions for the new gradient line.
    double scale = lineLength / rectLen;
    for (size_t i = 0; i < stops.Length(); i++) {
      stops[i].mPosition = (stops[i].mPosition - offset) * fabs(scale);
    }

    // Clamp or extrapolate gradient stops to exactly [0, 1].
    ClampColorStops(stops);

    lineLength = rectLen;
  }

  // Special case for 'transparent'
  for (uint32_t i = 0; i < stops.Length(); ++i) {
    Color color = stops[i].mColor;
    if (color.r == 0 && color.g == 0 && color.b == 0 && color.a == 0) {
      // We have (0,0,0,0) as a color stop - this means 'transparent'.
      // In this case for the usually intended effect, we change the color
      // of the transparent stop to the color of the adjacent stop with
      // 0 opacity. If we are not on either edge, we add a stop on both
      // sides of the transparent point with the adjacent color value.
      // i.e.: c1 -> c1 (alpha 0) | c2 (alpha 0) -> c2
      // XXX: We should probably track the use of the transparent keyword
      // down from the CSS parsing level to here with a flag in mStops, if
      // rgba(0,0,0,0) ever is an intended thing (very much a corner case).
      if (i > 0) {
        // Change stop color to adjacent-previous (color->T)
        color = stops[i - 1].mColor;
        color.a = 0;
        stops[i].mColor = color;
        if (i < stops.Length() - 1) {
          // We're in the middle somewhere: insert stop adjacent-next (T->color)
          Color color2 = stops[i + 1].mColor;
          color2.a = 0;
          if (color != color2) {
            // Only insert an extra stop if c1 is different than c2 in c1->T->c2
            // Note: A transparent stop is never considered an interpolation hint
            stops.InsertElementAt(i + 1, ColorStop(stops[i].mPosition, false, color2));
            i++;
          }
        }
      } else if (i < stops.Length() - 1) {
        // Change stop color to adjacent-next (T->color)
        color = stops[i + 1].mColor;
        color.a = 0;
        stops[i].mColor = color;
      }
    }
  }

  // Eliminate negative-position stops if the gradient is radial.
  double firstStop = stops[0].mPosition;
  if (aGradient->mShape != NS_STYLE_GRADIENT_SHAPE_LINEAR && firstStop < 0.0) {
    if (aGradient->mRepeating) {
      // Choose an instance of the repeated pattern that gives us all positive
      // stop-offsets.
      double lastStop = stops[stops.Length() - 1].mPosition;
      double stopDelta = lastStop - firstStop;
      // If all the stops are in approximately the same place then logic below
      // will kick in that makes us draw just the last stop color, so don't
      // try to do anything in that case. We certainly need to avoid
      // dividing by zero.
      if (stopDelta >= 1e-6) {
        double instanceCount = ceil(-firstStop/stopDelta);
        // Advance stops by instanceCount multiples of the period of the
        // repeating gradient.
        double offset = instanceCount*stopDelta;
        for (uint32_t i = 0; i < stops.Length(); i++) {
          stops[i].mPosition += offset;
        }
      }
    } else {
      // Move negative-position stops to position 0.0. We may also need
      // to set the color of the stop to the color the gradient should have
      // at the center of the ellipse.
      for (uint32_t i = 0; i < stops.Length(); i++) {
        double pos = stops[i].mPosition;
        if (pos < 0.0) {
          stops[i].mPosition = 0.0;
          // If this is the last stop, we don't need to adjust the color,
          // it will fill the entire area.
          if (i < stops.Length() - 1) {
            double nextPos = stops[i + 1].mPosition;
            // If nextPos is approximately equal to pos, then we don't
            // need to adjust the color of this stop because it's
            // not going to be displayed.
            // If nextPos is negative, we don't need to adjust the color of
            // this stop since it's not going to be displayed because
            // nextPos will also be moved to 0.0.
            if (nextPos >= 0.0 && nextPos - pos >= 1e-6) {
              // Compute how far the new position 0.0 is along the interval
              // between pos and nextPos.
              // XXX Color interpolation (in cairo, too) should use the
              // CSS 'color-interpolation' property!
              float frac = float((0.0 - pos)/(nextPos - pos));
              stops[i].mColor =
                InterpolateColor(stops[i].mColor, stops[i + 1].mColor, frac);
            }
          }
        }
      }
    }
    firstStop = stops[0].mPosition;
    MOZ_ASSERT(firstStop >= 0.0, "Failed to fix stop offsets");
  }

  if (aGradient->mShape != NS_STYLE_GRADIENT_SHAPE_LINEAR && !aGradient->mRepeating) {
    // Direct2D can only handle a particular class of radial gradients because
    // of the way the it specifies gradients. Setting firstStop to 0, when we
    // can, will help us stay on the fast path. Currently we don't do this
    // for repeating gradients but we could by adjusting the stop collection
    // to start at 0
    firstStop = 0;
  }

  double lastStop = stops[stops.Length() - 1].mPosition;
  // Cairo gradients must have stop positions in the range [0, 1]. So,
  // stop positions will be normalized below by subtracting firstStop and then
  // multiplying by stopScale.
  double stopScale;
  double stopOrigin = firstStop;
  double stopEnd = lastStop;
  double stopDelta = lastStop - firstStop;
  bool zeroRadius = aGradient->mShape != NS_STYLE_GRADIENT_SHAPE_LINEAR &&
                      (radiusX < 1e-6 || radiusY < 1e-6);
  if (stopDelta < 1e-6 || lineLength < 1e-6 || zeroRadius) {
    // Stops are all at the same place. Map all stops to 0.0.
    // For repeating radial gradients, or for any radial gradients with
    // a zero radius, we need to fill with the last stop color, so just set
    // both radii to 0.
    if (aGradient->mRepeating || zeroRadius) {
      radiusX = radiusY = 0.0;
    }
    stopDelta = 0.0;
    lastStop = firstStop;
  }

  // Don't normalize non-repeating or degenerate gradients below 0..1
  // This keeps the gradient line as large as the box and doesn't
  // lets us avoiding having to get padding correct for stops
  // at 0 and 1
  if (!aGradient->mRepeating || stopDelta == 0.0) {
    stopOrigin = std::min(stopOrigin, 0.0);
    stopEnd = std::max(stopEnd, 1.0);
  }
  stopScale = 1.0/(stopEnd - stopOrigin);

  // Create the gradient pattern.
  RefPtr<gfxPattern> gradientPattern;
  gfxPoint gradientStart;
  gfxPoint gradientEnd;
  if (aGradient->mShape == NS_STYLE_GRADIENT_SHAPE_LINEAR) {
    // Compute the actual gradient line ends we need to pass to cairo after
    // stops have been normalized.
    gradientStart = lineStart + (lineEnd - lineStart)*stopOrigin;
    gradientEnd = lineStart + (lineEnd - lineStart)*stopEnd;
    gfxPoint gradientStopStart = lineStart + (lineEnd - lineStart)*firstStop;
    gfxPoint gradientStopEnd = lineStart + (lineEnd - lineStart)*lastStop;

    if (stopDelta == 0.0) {
      // Stops are all at the same place. For repeating gradients, this will
      // just paint the last stop color. We don't need to do anything.
      // For non-repeating gradients, this should render as two colors, one
      // on each "side" of the gradient line segment, which is a point. All
      // our stops will be at 0.0; we just need to set the direction vector
      // correctly.
      gradientEnd = gradientStart + (lineEnd - lineStart);
      gradientStopEnd = gradientStopStart + (lineEnd - lineStart);
    }

    gradientPattern = new gfxPattern(gradientStart.x, gradientStart.y,
                                      gradientEnd.x, gradientEnd.y);
  } else {
    NS_ASSERTION(firstStop >= 0.0,
                  "Negative stops not allowed for radial gradients");

    // To form an ellipse, we'll stretch a circle vertically, if necessary.
    // So our radii are based on radiusX.
    double innerRadius = radiusX*stopOrigin;
    double outerRadius = radiusX*stopEnd;
    if (stopDelta == 0.0) {
      // Stops are all at the same place.  See above (except we now have
      // the inside vs. outside of an ellipse).
      outerRadius = innerRadius + 1;
    }
    gradientPattern = new gfxPattern(lineStart.x, lineStart.y, innerRadius,
                                     lineStart.x, lineStart.y, outerRadius);
    if (radiusX != radiusY) {
      // Stretch the circles into ellipses vertically by setting a transform
      // in the pattern.
      // Recall that this is the transform from user space to pattern space.
      // So to stretch the ellipse by factor of P vertically, we scale
      // user coordinates by 1/P.
      matrix.Translate(lineStart);
      matrix.Scale(1.0, radiusX/radiusY);
      matrix.Translate(-lineStart);
    }
  }
  // Use a pattern transform to take account of source and dest rects
  matrix.Translate(gfxPoint(aPresContext->CSSPixelsToDevPixels(aSrc.x),
                            aPresContext->CSSPixelsToDevPixels(aSrc.y)));
  matrix.Scale(gfxFloat(aPresContext->CSSPixelsToAppUnits(aSrc.width))/aDest.width,
               gfxFloat(aPresContext->CSSPixelsToAppUnits(aSrc.height))/aDest.height);
  gradientPattern->SetMatrix(matrix);

  if (gradientPattern->CairoStatus())
    return;

  if (stopDelta == 0.0) {
    // Non-repeating gradient with all stops in same place -> just add
    // first stop and last stop, both at position 0.
    // Repeating gradient with all stops in the same place, or radial
    // gradient with radius of 0 -> just paint the last stop color.
    // We use firstStop offset to keep |stops| with same units (will later normalize to 0).
    Color firstColor(stops[0].mColor);
    Color lastColor(stops.LastElement().mColor);
    stops.Clear();

    if (!aGradient->mRepeating && !zeroRadius) {
      stops.AppendElement(ColorStop(firstStop, false, firstColor));
    }
    stops.AppendElement(ColorStop(firstStop, false, lastColor));
  }

  ResolveMidpoints(stops);

  bool isRepeat = aGradient->mRepeating || forceRepeatToCoverTiles;

  // Now set normalized color stops in pattern.
  // Offscreen gradient surface cache (not a tile):
  // On some backends (e.g. D2D), the GradientStops object holds an offscreen surface
  // which is a lookup table used to evaluate the gradient. This surface can use
  // much memory (ram and/or GPU ram) and can be expensive to create. So we cache it.
  // The cache key correlates 1:1 with the arguments for CreateGradientStops (also the implied backend type)
  // Note that GradientStop is a simple struct with a stop value (while GradientStops has the surface).
  nsTArray<gfx::GradientStop> rawStops(stops.Length());
  rawStops.SetLength(stops.Length());
  for(uint32_t i = 0; i < stops.Length(); i++) {
    rawStops[i].color = stops[i].mColor;
    rawStops[i].offset = stopScale * (stops[i].mPosition - stopOrigin);
  }
  RefPtr<mozilla::gfx::GradientStops> gs =
    gfxGradientCache::GetOrCreateGradientStops(ctx->GetDrawTarget(),
                                               rawStops,
                                               isRepeat ? gfx::ExtendMode::REPEAT : gfx::ExtendMode::CLAMP);
  gradientPattern->SetColorStops(gs);

  // Paint gradient tiles. This isn't terribly efficient, but doing it this
  // way is simple and sure to get pixel-snapping right. We could speed things
  // up by drawing tiles into temporary surfaces and copying those to the
  // destination, but after pixel-snapping tiles may not all be the same size.
  nsRect dirty;
  if (!dirty.IntersectRect(aDirtyRect, aFillArea))
    return;

  gfxRect areaToFill =
    nsLayoutUtils::RectToGfxRect(aFillArea, appUnitsPerDevPixel);
  gfxRect dirtyAreaToFill = nsLayoutUtils::RectToGfxRect(dirty, appUnitsPerDevPixel);
  dirtyAreaToFill.RoundOut();

  gfxMatrix ctm = ctx->CurrentMatrix();
  bool isCTMPreservingAxisAlignedRectangles = ctm.PreservesAxisAlignedRectangles();

  // xStart/yStart are the top-left corner of the top-left tile.
  nscoord xStart = FindTileStart(dirty.x, aDest.x, aRepeatSize.width);
  nscoord yStart = FindTileStart(dirty.y, aDest.y, aRepeatSize.height);
  nscoord xEnd = forceRepeatToCoverTiles ? xStart + aDest.width : dirty.XMost();
  nscoord yEnd = forceRepeatToCoverTiles ? yStart + aDest.height : dirty.YMost();

  // x and y are the top-left corner of the tile to draw
  for (nscoord y = yStart; y < yEnd; y += aRepeatSize.height) {
    for (nscoord x = xStart; x < xEnd; x += aRepeatSize.width) {
      // The coordinates of the tile
      gfxRect tileRect = nsLayoutUtils::RectToGfxRect(
                      nsRect(x, y, aDest.width, aDest.height),
                      appUnitsPerDevPixel);
      // The actual area to fill with this tile is the intersection of this
      // tile with the overall area we're supposed to be filling
      gfxRect fillRect =
        forceRepeatToCoverTiles ? areaToFill : tileRect.Intersect(areaToFill);
      // Try snapping the fill rect. Snap its top-left and bottom-right
      // independently to preserve the orientation.
      gfxPoint snappedFillRectTopLeft = fillRect.TopLeft();
      gfxPoint snappedFillRectTopRight = fillRect.TopRight();
      gfxPoint snappedFillRectBottomRight = fillRect.BottomRight();
      // Snap three points instead of just two to ensure we choose the
      // correct orientation if there's a reflection.
      if (isCTMPreservingAxisAlignedRectangles &&
          ctx->UserToDevicePixelSnapped(snappedFillRectTopLeft, true) &&
          ctx->UserToDevicePixelSnapped(snappedFillRectBottomRight, true) &&
          ctx->UserToDevicePixelSnapped(snappedFillRectTopRight, true)) {
        if (snappedFillRectTopLeft.x == snappedFillRectBottomRight.x ||
            snappedFillRectTopLeft.y == snappedFillRectBottomRight.y) {
          // Nothing to draw; avoid scaling by zero and other weirdness that
          // could put the context in an error state.
          continue;
        }
        // Set the context's transform to the transform that maps fillRect to
        // snappedFillRect. The part of the gradient that was going to
        // exactly fill fillRect will fill snappedFillRect instead.
        gfxMatrix transform = gfxUtils::TransformRectToRect(fillRect,
            snappedFillRectTopLeft, snappedFillRectTopRight,
            snappedFillRectBottomRight);
        ctx->SetMatrix(transform);
      }
      ctx->NewPath();
      ctx->Rectangle(fillRect);

      gfxRect dirtyFillRect = fillRect.Intersect(dirtyAreaToFill);
      gfxRect fillRectRelativeToTile = dirtyFillRect - tileRect.TopLeft();
      Color edgeColor;
      if (aGradient->mShape == NS_STYLE_GRADIENT_SHAPE_LINEAR && !isRepeat &&
          RectIsBeyondLinearGradientEdge(fillRectRelativeToTile, matrix, stops,
                                         gradientStart, gradientEnd, &edgeColor)) {
        ctx->SetColor(edgeColor);
      } else {
        ctx->SetMatrix(
          ctx->CurrentMatrix().Copy().Translate(tileRect.TopLeft()));
        ctx->SetPattern(gradientPattern);
      }
      ctx->Fill();
      ctx->SetMatrix(ctm);
    }
  }
}

static CompositionOp
DetermineCompositionOp(const nsCSSRendering::PaintBGParams& aParams,
                       const nsStyleImageLayers& aLayers,
                       uint32_t aLayerIndex)
{
  if (aParams.layer >= 0) {
    // When drawing a single layer, use the specified composition op.
    return aParams.compositionOp;
  }

  const nsStyleImageLayers::Layer& layer = aLayers.mLayers[aLayerIndex];
  // When drawing all layers, get the compositon op from each image layer.
  if (aParams.paintFlags & nsCSSRendering::PAINTBG_MASK_IMAGE) {
    // Always using OP_OVER mode while drawing the bottom mask layer.
    if (aLayerIndex == (aLayers.mImageCount - 1)) {
      return CompositionOp::OP_OVER;
    }

    return nsCSSRendering::GetGFXCompositeMode(layer.mComposite);
  }

  return nsCSSRendering::GetGFXBlendMode(layer.mBlendMode);
}

DrawResult
nsCSSRendering::PaintBackgroundWithSC(const PaintBGParams& aParams,
                                      nsStyleContext *aBackgroundSC,
                                      const nsStyleBorder& aBorder)
{
  NS_PRECONDITION(aParams.frame,
                  "Frame is expected to be provided to PaintBackground");

  // If we're drawing all layers, aCompositonOp is ignored, so make sure that
  // it was left at its default value.
  MOZ_ASSERT_IF(aParams.layer == -1,
                aParams.compositionOp == CompositionOp::OP_OVER);

  DrawResult result = DrawResult::SUCCESS;

  // Check to see if we have an appearance defined.  If so, we let the theme
  // renderer draw the background and bail out.
  // XXXzw this ignores aParams.bgClipRect.
  const nsStyleDisplay* displayData = aParams.frame->StyleDisplay();
  if (displayData->mAppearance) {
    nsITheme *theme = aParams.presCtx.GetTheme();
    if (theme && theme->ThemeSupportsWidget(&aParams.presCtx,
                                            aParams.frame,
                                            displayData->mAppearance)) {
      nsRect drawing(aParams.borderArea);
      theme->GetWidgetOverflow(aParams.presCtx.DeviceContext(),
                               aParams.frame, displayData->mAppearance,
                               &drawing);
      drawing.IntersectRect(drawing, aParams.dirtyRect);
      theme->DrawWidgetBackground(&aParams.renderingCtx, aParams.frame,
                                  displayData->mAppearance, aParams.borderArea,
                                  drawing);
      return DrawResult::SUCCESS;
    }
  }

  // For canvas frames (in the CSS sense) we draw the background color using
  // a solid color item that gets added in nsLayoutUtils::PaintFrame,
  // or nsSubDocumentFrame::BuildDisplayList (bug 488242). (The solid
  // color may be moved into nsDisplayCanvasBackground by
  // nsPresShell::AddCanvasBackgroundColorItem, and painted by
  // nsDisplayCanvasBackground directly.) Either way we don't need to
  // paint the background color here.
  bool isCanvasFrame = IsCanvasFrame(aParams.frame);

  // Determine whether we are drawing background images and/or
  // background colors.
  bool drawBackgroundImage;
  bool drawBackgroundColor;

  nscolor bgColor = DetermineBackgroundColor(&aParams.presCtx,
                                             aBackgroundSC,
                                             aParams.frame,
                                             drawBackgroundImage,
                                             drawBackgroundColor);

  bool paintMask = (aParams.paintFlags & PAINTBG_MASK_IMAGE);
  const nsStyleImageLayers& layers = paintMask ?
    aBackgroundSC->StyleSVGReset()->mMask :
    aBackgroundSC->StyleBackground()->mImage;
  // If we're drawing a specific layer, we don't want to draw the
  // background color.
  if ((drawBackgroundColor && aParams.layer >= 0) || paintMask) {
    drawBackgroundColor = false;
  }

  // At this point, drawBackgroundImage and drawBackgroundColor are
  // true if and only if we are actually supposed to paint an image or
  // color into aDirtyRect, respectively.
  if (!drawBackgroundImage && !drawBackgroundColor)
    return DrawResult::SUCCESS;

  // Compute the outermost boundary of the area that might be painted.
  // Same coordinate space as aParams.borderArea & aParams.bgClipRect.
  Sides skipSides = aParams.frame->GetSkipSides();
  nsRect paintBorderArea =
    ::BoxDecorationRectForBackground(aParams.frame, aParams.borderArea,
                                     skipSides, &aBorder);
  nsRect clipBorderArea =
    ::BoxDecorationRectForBorder(aParams.frame, aParams.borderArea,
                                 skipSides, &aBorder);

  // The 'bgClipArea' (used only by the image tiling logic, far below)
  // is the caller-provided aParams.bgClipRect if any, or else the area
  // determined by the value of 'background-clip' in
  // SetupCurrentBackgroundClip.  (Arguably it should be the
  // intersection, but that breaks the table painter -- in particular,
  // taking the intersection breaks reftests/bugs/403249-1[ab].)
  gfxContext* ctx = aParams.renderingCtx.ThebesContext();
  nscoord appUnitsPerPixel = aParams.presCtx.AppUnitsPerDevPixel();
  ImageLayerClipState clipState;
  if (aParams.bgClipRect) {
    clipState.mBGClipArea = *aParams.bgClipRect;
    clipState.mCustomClip = true;
    clipState.mHasRoundedCorners = false;
    SetupDirtyRects(clipState.mBGClipArea, aParams.dirtyRect, appUnitsPerPixel,
                    &clipState.mDirtyRect, &clipState.mDirtyRectGfx);
  } else {
    GetImageLayerClip(layers.BottomLayer(),
                      aParams.frame, aBorder, aParams.borderArea,
                      aParams.dirtyRect,
                      (aParams.paintFlags & PAINTBG_WILL_PAINT_BORDER),
                      appUnitsPerPixel,
                      &clipState);
  }

  // If we might be using a background color, go ahead and set it now.
  if (drawBackgroundColor && !isCanvasFrame)
    ctx->SetColor(Color::FromABGR(bgColor));

  // NOTE: no Save() yet, we do that later by calling autoSR.EnsureSaved(ctx)
  // in the cases we need it.
  gfxContextAutoSaveRestore autoSR;

  // If there is no background image, draw a color.  (If there is
  // neither a background image nor a color, we wouldn't have gotten
  // this far.)
  if (!drawBackgroundImage) {
    if (!isCanvasFrame) {
      DrawBackgroundColor(clipState, ctx, appUnitsPerPixel);
    }
    return DrawResult::SUCCESS;
  }

  if (layers.mImageCount < 1) {
    // Return if there are no background layers, all work from this point
    // onwards happens iteratively on these.
    return DrawResult::SUCCESS;
  }

  // Validate the layer range before we start iterating.
  int32_t startLayer = aParams.layer;
  int32_t nLayers = 1;
  if (startLayer < 0) {
    startLayer = (int32_t)layers.mImageCount - 1;
    nLayers = layers.mImageCount;
  }

  // Ensure we get invalidated for loads of the image.  We need to do
  // this here because this might be the only code that knows about the
  // association of the style data with the frame.
  if (aBackgroundSC != aParams.frame->StyleContext()) {
    NS_FOR_VISIBLE_IMAGE_LAYERS_BACK_TO_FRONT_WITH_RANGE(i, layers, startLayer, nLayers) {
      aParams.frame->AssociateImage(layers.mLayers[i].mImage,
                                    &aParams.presCtx);
    }
  }

  // The background color is rendered over the entire dirty area,
  // even if the image isn't.
  if (drawBackgroundColor && !isCanvasFrame) {
    DrawBackgroundColor(clipState, ctx, appUnitsPerPixel);
  }

  if (drawBackgroundImage) {
    bool clipSet = false;
    StyleGeometryBox currentBackgroundClip = StyleGeometryBox::Border;
    NS_FOR_VISIBLE_IMAGE_LAYERS_BACK_TO_FRONT_WITH_RANGE(i, layers, layers.mImageCount - 1,
                                                         nLayers + (layers.mImageCount -
                                                         startLayer - 1)) {
      const nsStyleImageLayers::Layer& layer = layers.mLayers[i];
      if (!aParams.bgClipRect) {
        if (currentBackgroundClip != layer.mClip || !clipSet) {
          currentBackgroundClip = layer.mClip;
          // If clipSet is false that means this is the bottom layer and we
          // already called GetImageLayerClip above and it stored its results
          // in clipState.
          if (clipSet) {
            autoSR.Restore(); // reset the previous one
            GetImageLayerClip(layer, aParams.frame,
                              aBorder, aParams.borderArea, aParams.dirtyRect,
                              (aParams.paintFlags & PAINTBG_WILL_PAINT_BORDER),
                              appUnitsPerPixel, &clipState);
          }
          SetupImageLayerClip(clipState, ctx, appUnitsPerPixel, &autoSR);
          clipSet = true;
          if (!clipBorderArea.IsEqualEdges(aParams.borderArea)) {
            // We're drawing the background for the joined continuation boxes
            // so we need to clip that to the slice that we want for this
            // frame.
            gfxRect clip =
              nsLayoutUtils::RectToGfxRect(aParams.borderArea, appUnitsPerPixel);
            autoSR.EnsureSaved(ctx);
            ctx->NewPath();
            ctx->SnappedRectangle(clip);
            ctx->Clip();
          }
        }
      }
      if ((aParams.layer < 0 || i == (uint32_t)startLayer) &&
          !clipState.mDirtyRectGfx.IsEmpty()) {
        CompositionOp co = DetermineCompositionOp(aParams, layers, i);
        nsBackgroundLayerState state =
          PrepareImageLayer(&aParams.presCtx, aParams.frame,
                            aParams.paintFlags, paintBorderArea, clipState.mBGClipArea,
                            layer, nullptr);
        result &= state.mImageRenderer.PrepareResult();
        if (!state.mFillArea.IsEmpty()) {
          if (co != CompositionOp::OP_OVER) {
            NS_ASSERTION(ctx->CurrentOp() == CompositionOp::OP_OVER,
                         "It is assumed the initial op is OP_OVER, when it is "
                         "restored later");
            ctx->SetOp(co);
          }

          result &=
            state.mImageRenderer.DrawBackground(&aParams.presCtx,
                                                aParams.renderingCtx,
                                                state.mDestArea, state.mFillArea,
                                                state.mAnchor + paintBorderArea.TopLeft(),
                                                clipState.mDirtyRect,
                                                state.mRepeatSize);

          if (co != CompositionOp::OP_OVER) {
            ctx->SetOp(CompositionOp::OP_OVER);
          }
        }
      }
    }
  }

  return result;
}

nsRect
nsCSSRendering::ComputeImageLayerPositioningArea(nsPresContext* aPresContext,
                                                 nsIFrame* aForFrame,
                                                 const nsRect& aBorderArea,
                                                 const nsStyleImageLayers::Layer& aLayer,
                                                 nsIFrame** aAttachedToFrame,
                                                 bool* aOutIsTransformedFixed)
{
  // Compute {background|mask} origin area relative to aBorderArea now as we
  // may need  it to compute the effective image size for a CSS gradient.
  nsRect positionArea;

  StyleGeometryBox layerOrigin =
    ComputeBoxValue(aForFrame, aLayer.mOrigin);

  if (IsSVGStyleGeometryBox(layerOrigin)) {
    MOZ_ASSERT(aForFrame->IsFrameOfType(nsIFrame::eSVG) &&
               (aForFrame->GetType() != nsGkAtoms::svgOuterSVGFrame));
    *aAttachedToFrame = aForFrame;

    positionArea =
      nsLayoutUtils::ComputeGeometryBox(aForFrame, layerOrigin);

    nsPoint toStrokeBoxOffset = nsPoint(0, 0);
    if (layerOrigin != StyleGeometryBox::Stroke) {
      nsRect strokeBox =
        nsLayoutUtils::ComputeGeometryBox(aForFrame,
                                          StyleGeometryBox::Stroke);
      toStrokeBoxOffset = positionArea.TopLeft() - strokeBox.TopLeft();
    }

    // For SVG frames, the return value is relative to the stroke box
    return nsRect(toStrokeBoxOffset, positionArea.Size());
  }

  MOZ_ASSERT(!aForFrame->IsFrameOfType(nsIFrame::eSVG) ||
             aForFrame->GetType() == nsGkAtoms::svgOuterSVGFrame);


  nsIAtom* frameType = aForFrame->GetType();
  nsIFrame* geometryFrame = aForFrame;
  if (MOZ_UNLIKELY(frameType == nsGkAtoms::scrollFrame &&
                   NS_STYLE_IMAGELAYER_ATTACHMENT_LOCAL == aLayer.mAttachment)) {
    nsIScrollableFrame* scrollableFrame = do_QueryFrame(aForFrame);
    positionArea = nsRect(
      scrollableFrame->GetScrolledFrame()->GetPosition()
        // For the dir=rtl case:
        + scrollableFrame->GetScrollRange().TopLeft(),
      scrollableFrame->GetScrolledRect().Size());
    // The ScrolledRect’s size does not include the borders or scrollbars,
    // reverse the handling of background-origin
    // compared to the common case below.
    if (layerOrigin == StyleGeometryBox::Border) {
      nsMargin border = geometryFrame->GetUsedBorder();
      border.ApplySkipSides(geometryFrame->GetSkipSides());
      positionArea.Inflate(border);
      positionArea.Inflate(scrollableFrame->GetActualScrollbarSizes());
    } else if (layerOrigin != StyleGeometryBox::Padding) {
      nsMargin padding = geometryFrame->GetUsedPadding();
      padding.ApplySkipSides(geometryFrame->GetSkipSides());
      positionArea.Deflate(padding);
      NS_ASSERTION(layerOrigin == StyleGeometryBox::Content,
                   "unknown background-origin value");
    }
    *aAttachedToFrame = aForFrame;
    return positionArea;
  }

  if (MOZ_UNLIKELY(frameType == nsGkAtoms::canvasFrame)) {
    geometryFrame = aForFrame->PrincipalChildList().FirstChild();
    // geometryFrame might be null if this canvas is a page created
    // as an overflow container (e.g. the in-flow content has already
    // finished and this page only displays the continuations of
    // absolutely positioned content).
    if (geometryFrame) {
       positionArea = geometryFrame->GetRect();
    }
  } else {
    positionArea = nsRect(nsPoint(0,0), aBorderArea.Size());
  }

  // See the comment of StyleGeometryBox::Margin.
  // Hitting this assertion means we decide to turn on margin-box support for
  // positioned mask from CSS parser and style system. In this case, you
  // should *inflate* positionArea by the margin returning from
  // geometryFrame->GetUsedMargin() in the code chunk bellow.
  MOZ_ASSERT(aLayer.mOrigin != StyleGeometryBox::Margin,
             "StyleGeometryBox::Margin rendering is not supported yet.\n");

  // {background|mask} images are tiled over the '{background|mask}-clip' area
  // but the origin of the tiling is based on the '{background|mask}-origin'
  // area.
  if (layerOrigin != StyleGeometryBox::Border && geometryFrame) {
    nsMargin border = geometryFrame->GetUsedBorder();
    if (layerOrigin != StyleGeometryBox::Padding) {
      border += geometryFrame->GetUsedPadding();
      NS_ASSERTION(layerOrigin == StyleGeometryBox::Content,
                   "unknown background-origin value");
    }
    positionArea.Deflate(border);
  }

  nsIFrame* attachedToFrame = aForFrame;
  if (NS_STYLE_IMAGELAYER_ATTACHMENT_FIXED == aLayer.mAttachment) {
    // If it's a fixed background attachment, then the image is placed
    // relative to the viewport, which is the area of the root frame
    // in a screen context or the page content frame in a print context.
    attachedToFrame = aPresContext->PresShell()->FrameManager()->GetRootFrame();
    NS_ASSERTION(attachedToFrame, "no root frame");
    nsIFrame* pageContentFrame = nullptr;
    if (aPresContext->IsPaginated()) {
      pageContentFrame =
        nsLayoutUtils::GetClosestFrameOfType(aForFrame, nsGkAtoms::pageContentFrame);
      if (pageContentFrame) {
        attachedToFrame = pageContentFrame;
      }
      // else this is an embedded shell and its root frame is what we want
    }

    // If the background is affected by a transform, treat is as if it
    // wasn't fixed.
    if (nsLayoutUtils::IsTransformed(aForFrame, attachedToFrame)) {
      attachedToFrame = aForFrame;
      *aOutIsTransformedFixed = true;
    } else {
      // Set the background positioning area to the viewport's area
      // (relative to aForFrame)
      positionArea =
        nsRect(-aForFrame->GetOffsetTo(attachedToFrame), attachedToFrame->GetSize());

      if (!pageContentFrame) {
        // Subtract the size of scrollbars.
        nsIScrollableFrame* scrollableFrame =
          aPresContext->PresShell()->GetRootScrollFrameAsScrollable();
        if (scrollableFrame) {
          nsMargin scrollbars = scrollableFrame->GetActualScrollbarSizes();
          positionArea.Deflate(scrollbars);
        }
      }
    }
  }
  *aAttachedToFrame = attachedToFrame;

  return positionArea;
}

// Implementation of the formula for computation of background-repeat round
// See http://dev.w3.org/csswg/css3-background/#the-background-size
// This function returns the adjusted size of the background image.
static nscoord
ComputeRoundedSize(nscoord aCurrentSize, nscoord aPositioningSize)
{
  float repeatCount = NS_roundf(float(aPositioningSize) / float(aCurrentSize));
  if (repeatCount < 1.0f) {
    return aPositioningSize;
  }
  return nscoord(NS_lround(float(aPositioningSize) / repeatCount));
}

// Apply the CSS image sizing algorithm as it applies to background images.
// See http://www.w3.org/TR/css3-background/#the-background-size .
// aIntrinsicSize is the size that the background image 'would like to be'.
// It can be found by calling nsImageRenderer::ComputeIntrinsicSize.
static nsSize
ComputeDrawnSizeForBackground(const CSSSizeOrRatio& aIntrinsicSize,
                              const nsSize& aBgPositioningArea,
                              const nsStyleImageLayers::Size& aLayerSize,
                              uint8_t aXRepeat, uint8_t aYRepeat)
{
  nsSize imageSize;

  // Size is dictated by cover or contain rules.
  if (aLayerSize.mWidthType == nsStyleImageLayers::Size::eContain ||
      aLayerSize.mWidthType == nsStyleImageLayers::Size::eCover) {
    nsImageRenderer::FitType fitType =
      aLayerSize.mWidthType == nsStyleImageLayers::Size::eCover
        ? nsImageRenderer::COVER
        : nsImageRenderer::CONTAIN;
    imageSize = nsImageRenderer::ComputeConstrainedSize(aBgPositioningArea,
                                                        aIntrinsicSize.mRatio,
                                                        fitType);
  } else {
    // No cover/contain constraint, use default algorithm.
    CSSSizeOrRatio specifiedSize;
    if (aLayerSize.mWidthType == nsStyleImageLayers::Size::eLengthPercentage) {
      specifiedSize.SetWidth(
        aLayerSize.ResolveWidthLengthPercentage(aBgPositioningArea));
    }
    if (aLayerSize.mHeightType == nsStyleImageLayers::Size::eLengthPercentage) {
      specifiedSize.SetHeight(
        aLayerSize.ResolveHeightLengthPercentage(aBgPositioningArea));
    }

    imageSize = nsImageRenderer::ComputeConcreteSize(specifiedSize,
                                                     aIntrinsicSize,
                                                     aBgPositioningArea);
  }

  // See https://www.w3.org/TR/css3-background/#background-size .
  // "If 'background-repeat' is 'round' for one (or both) dimensions, there is a second
  //  step. The UA must scale the image in that dimension (or both dimensions) so that
  //  it fits a whole number of times in the background positioning area."
  // "If 'background-repeat' is 'round' for one dimension only and if 'background-size'
  //  is 'auto' for the other dimension, then there is a third step: that other dimension
  //  is scaled so that the original aspect ratio is restored."
  bool isRepeatRoundInBothDimensions = aXRepeat == NS_STYLE_IMAGELAYER_REPEAT_ROUND &&
                                       aYRepeat == NS_STYLE_IMAGELAYER_REPEAT_ROUND;

  // Calculate the rounded size only if the background-size computation
  // returned a correct size for the image.
  if (imageSize.width && aXRepeat == NS_STYLE_IMAGELAYER_REPEAT_ROUND) {
    imageSize.width = ComputeRoundedSize(imageSize.width, aBgPositioningArea.width);
    if (!isRepeatRoundInBothDimensions &&
        aLayerSize.mHeightType == nsStyleImageLayers::Size::DimensionType::eAuto) {
      // Restore intrinsic ratio
      if (aIntrinsicSize.mRatio) {
        imageSize.height =
            aIntrinsicSize.mRatio.Inverted().ApplyTo(imageSize.width);
      }
    }
  }

  // Calculate the rounded size only if the background-size computation
  // returned a correct size for the image.
  if (imageSize.height && aYRepeat == NS_STYLE_IMAGELAYER_REPEAT_ROUND) {
    imageSize.height = ComputeRoundedSize(imageSize.height, aBgPositioningArea.height);
    if (!isRepeatRoundInBothDimensions &&
        aLayerSize.mWidthType == nsStyleImageLayers::Size::DimensionType::eAuto) {
      // Restore intrinsic ratio
      if (aIntrinsicSize.mRatio) {
        imageSize.width = aIntrinsicSize.mRatio.ApplyTo(imageSize.height);
      }
    }
  }

  return imageSize;
}

/* ComputeSpacedRepeatSize
 * aImageDimension: the image width/height
 * aAvailableSpace: the background positioning area width/height
 * aRepeat: determine whether the image is repeated
 * Returns the image size plus gap size of app units for use as spacing
 */
static nscoord
ComputeSpacedRepeatSize(nscoord aImageDimension,
                        nscoord aAvailableSpace,
                        bool& aRepeat) {
  float ratio = static_cast<float>(aAvailableSpace) / aImageDimension;

  if (ratio < 2.0f) { // If you can't repeat at least twice, then don't repeat.
    aRepeat = false;
    return aImageDimension;
  } else {
    aRepeat = true;
    return (aAvailableSpace - aImageDimension) / (NSToIntFloor(ratio) - 1);
  }
}

/* ComputeBorderSpacedRepeatSize
 * aImageDimension: the image width/height
 * aAvailableSpace: the background positioning area width/height
 * aSpace: the space between each image
 * Returns the image size plus gap size of app units for use as spacing
 */
static nscoord
ComputeBorderSpacedRepeatSize(nscoord aImageDimension,
                              nscoord aAvailableSpace,
                              nscoord& aSpace)
{
  int32_t count = aAvailableSpace / aImageDimension;
  aSpace = (aAvailableSpace - aImageDimension * count) / (count + 1);
  return aSpace + aImageDimension;
}

nsBackgroundLayerState
nsCSSRendering::PrepareImageLayer(nsPresContext* aPresContext,
                                  nsIFrame* aForFrame,
                                  uint32_t aFlags,
                                  const nsRect& aBorderArea,
                                  const nsRect& aBGClipRect,
                                  const nsStyleImageLayers::Layer& aLayer,
                                  bool* aOutIsTransformedFixed)
{
  /*
   * The properties we need to keep in mind when drawing style image
   * layers are:
   *
   *   background-image/ mask-image
   *   background-repeat/ mask-repeat
   *   background-attachment
   *   background-position/ mask-position
   *   background-clip/ mask-clip
   *   background-origin/ mask-origin
   *   background-size/ mask-size
   *   background-blend-mode
   *   box-decoration-break
   *   mask-mode
   *   mask-composite
   *
   * (background-color applies to the entire element and not to individual
   * layers, so it is irrelevant to this method.)
   *
   * These properties have the following dependencies upon each other when
   * determining rendering:
   *
   *   background-image/ mask-image
   *     no dependencies
   *   background-repeat/ mask-repeat
   *     no dependencies
   *   background-attachment
   *     no dependencies
   *   background-position/ mask-position
   *     depends upon background-size/mask-size (for the image's scaled size)
   *     and background-break (for the background positioning area)
   *   background-clip/ mask-clip
   *     no dependencies
   *   background-origin/ mask-origin
   *     depends upon background-attachment (only in the case where that value
   *     is 'fixed')
   *   background-size/ mask-size
   *     depends upon box-decoration-break (for the background positioning area
   *     for resolving percentages), background-image (for the image's intrinsic
   *     size), background-repeat (if that value is 'round'), and
   *     background-origin (for the background painting area, when
   *     background-repeat is 'round')
   *   background-blend-mode
   *     no dependencies
   *   mask-mode
   *     no dependencies
   *   mask-composite
   *     no dependencies
   *   box-decoration-break
   *     no dependencies
   *
   * As a result of only-if dependencies we don't strictly do a topological
   * sort of the above properties when processing, but it's pretty close to one:
   *
   *   background-clip/mask-clip (by caller)
   *   background-image/ mask-image
   *   box-decoration-break, background-origin/ mask origin
   *   background-attachment (postfix for background-origin if 'fixed')
   *   background-size/ mask-size
   *   background-position/ mask-position
   *   background-repeat/ mask-repeat
   */

  uint32_t irFlags = 0;
  if (aFlags & nsCSSRendering::PAINTBG_SYNC_DECODE_IMAGES) {
    irFlags |= nsImageRenderer::FLAG_SYNC_DECODE_IMAGES;
  }
  if (aFlags & nsCSSRendering::PAINTBG_TO_WINDOW) {
    irFlags |= nsImageRenderer::FLAG_PAINTING_TO_WINDOW;
  }

  nsBackgroundLayerState state(aForFrame, &aLayer.mImage, irFlags);
  if (!state.mImageRenderer.PrepareImage()) {
    // There's no image or it's not ready to be painted.
    if (aOutIsTransformedFixed) {
      *aOutIsTransformedFixed = false;
    }
    return state;
  }

  // The frame to which the background is attached
  nsIFrame* attachedToFrame = aForFrame;
  // Is the background marked 'fixed', but affected by a transform?
  bool transformedFixed = false;
  // Compute background origin area relative to aBorderArea now as we may need
  // it to compute the effective image size for a CSS gradient.
  nsRect positionArea =
    ComputeImageLayerPositioningArea(aPresContext, aForFrame, aBorderArea,
                                     aLayer, &attachedToFrame, &transformedFixed);
  if (aOutIsTransformedFixed) {
    *aOutIsTransformedFixed = transformedFixed;
  }

  // For background-attachment:fixed backgrounds, we'll limit the area
  // where the background can be drawn to the viewport.
  nsRect bgClipRect = aBGClipRect;

  // Compute the anchor point.
  //
  // relative to aBorderArea.TopLeft() (which is where the top-left
  // of aForFrame's border-box will be rendered)
  nsPoint imageTopLeft;
  if (NS_STYLE_IMAGELAYER_ATTACHMENT_FIXED == aLayer.mAttachment && !transformedFixed) {
    if (aFlags & nsCSSRendering::PAINTBG_TO_WINDOW) {
      // Clip background-attachment:fixed backgrounds to the viewport, if we're
      // painting to the screen and not transformed. This avoids triggering
      // tiling in common cases, without affecting output since drawing is
      // always clipped to the viewport when we draw to the screen. (But it's
      // not a pure optimization since it can affect the values of pixels at the
      // edge of the viewport --- whether they're sampled from a putative "next
      // tile" or not.)
      bgClipRect.IntersectRect(bgClipRect, positionArea + aBorderArea.TopLeft());
    }
  }

  int repeatX = aLayer.mRepeat.mXRepeat;
  int repeatY = aLayer.mRepeat.mYRepeat;

  // Scale the image as specified for background-size and background-repeat.
  // Also as required for proper background positioning when background-position
  // is defined with percentages.
  CSSSizeOrRatio intrinsicSize = state.mImageRenderer.ComputeIntrinsicSize();
  nsSize bgPositionSize = positionArea.Size();
  nsSize imageSize = ComputeDrawnSizeForBackground(intrinsicSize,
                                                   bgPositionSize,
                                                   aLayer.mSize,
                                                   repeatX,
                                                   repeatY);

  if (imageSize.width <= 0 || imageSize.height <= 0)
    return state;

  state.mImageRenderer.SetPreferredSize(intrinsicSize,
                                        imageSize);

  // Compute the position of the background now that the background's size is
  // determined.
  nsImageRenderer::ComputeObjectAnchorPoint(aLayer.mPosition,
                                            bgPositionSize, imageSize,
                                            &imageTopLeft, &state.mAnchor);
  state.mRepeatSize = imageSize;
  if (repeatX == NS_STYLE_IMAGELAYER_REPEAT_SPACE) {
    bool isRepeat;
    state.mRepeatSize.width = ComputeSpacedRepeatSize(imageSize.width,
                                                      bgPositionSize.width,
                                                      isRepeat);
    if (isRepeat) {
      imageTopLeft.x = 0;
      state.mAnchor.x = 0;
    } else {
      repeatX = NS_STYLE_IMAGELAYER_REPEAT_NO_REPEAT;
    }
  }

  if (repeatY == NS_STYLE_IMAGELAYER_REPEAT_SPACE) {
    bool isRepeat;
    state.mRepeatSize.height = ComputeSpacedRepeatSize(imageSize.height,
                                                       bgPositionSize.height,
                                                       isRepeat);
    if (isRepeat) {
      imageTopLeft.y = 0;
      state.mAnchor.y = 0;
    } else {
      repeatY = NS_STYLE_IMAGELAYER_REPEAT_NO_REPEAT;
    }
  }

  imageTopLeft += positionArea.TopLeft();
  state.mAnchor += positionArea.TopLeft();
  state.mDestArea = nsRect(imageTopLeft + aBorderArea.TopLeft(), imageSize);
  state.mFillArea = state.mDestArea;

  ExtendMode repeatMode = ExtendMode::CLAMP;
  if (repeatX == NS_STYLE_IMAGELAYER_REPEAT_REPEAT ||
      repeatX == NS_STYLE_IMAGELAYER_REPEAT_ROUND ||
      repeatX == NS_STYLE_IMAGELAYER_REPEAT_SPACE) {
    state.mFillArea.x = bgClipRect.x;
    state.mFillArea.width = bgClipRect.width;
    repeatMode = ExtendMode::REPEAT_X;
  }
  if (repeatY == NS_STYLE_IMAGELAYER_REPEAT_REPEAT ||
      repeatY == NS_STYLE_IMAGELAYER_REPEAT_ROUND ||
      repeatY == NS_STYLE_IMAGELAYER_REPEAT_SPACE) {
    state.mFillArea.y = bgClipRect.y;
    state.mFillArea.height = bgClipRect.height;

    /***
     * We're repeating on the X axis already,
     * so if we have to repeat in the Y axis,
     * we really need to repeat in both directions.
     */
    if (repeatMode == ExtendMode::REPEAT_X) {
      repeatMode = ExtendMode::REPEAT;
    } else {
      repeatMode = ExtendMode::REPEAT_Y;
    }
  }
  state.mImageRenderer.SetExtendMode(repeatMode);
  state.mImageRenderer.SetMaskOp(aLayer.mMaskMode);

  state.mFillArea.IntersectRect(state.mFillArea, bgClipRect);

  return state;
}

nsRect
nsCSSRendering::GetBackgroundLayerRect(nsPresContext* aPresContext,
                                       nsIFrame* aForFrame,
                                       const nsRect& aBorderArea,
                                       const nsRect& aClipRect,
                                       const nsStyleImageLayers::Layer& aLayer,
                                       uint32_t aFlags)
{
  Sides skipSides = aForFrame->GetSkipSides();
  nsRect borderArea =
    ::BoxDecorationRectForBackground(aForFrame, aBorderArea, skipSides);
  nsBackgroundLayerState state =
      PrepareImageLayer(aPresContext, aForFrame, aFlags, borderArea,
                             aClipRect, aLayer);
  return state.mFillArea;
}

static DrawResult
DrawBorderImage(nsPresContext*       aPresContext,
                nsRenderingContext&  aRenderingContext,
                nsIFrame*            aForFrame,
                const nsRect&        aBorderArea,
                const nsStyleBorder& aStyleBorder,
                const nsRect&        aDirtyRect,
                Sides                aSkipSides,
                PaintBorderFlags     aFlags)
{
  NS_PRECONDITION(aStyleBorder.IsBorderImageLoaded(),
                  "drawing border image that isn't successfully loaded");

  if (aDirtyRect.IsEmpty()) {
    return DrawResult::SUCCESS;
  }

  uint32_t irFlags = 0;
  if (aFlags & PaintBorderFlags::SYNC_DECODE_IMAGES) {
    irFlags |= nsImageRenderer::FLAG_SYNC_DECODE_IMAGES;
  }
  nsImageRenderer renderer(aForFrame, &aStyleBorder.mBorderImageSource, irFlags);

  // Ensure we get invalidated for loads and animations of the image.
  // We need to do this here because this might be the only code that
  // knows about the association of the style data with the frame.
  // XXX We shouldn't really... since if anybody is passing in a
  // different style, they'll potentially have the wrong size for the
  // border too.
  aForFrame->AssociateImage(aStyleBorder.mBorderImageSource, aPresContext);

  if (!renderer.PrepareImage()) {
    return renderer.PrepareResult();
  }

  // NOTE: no Save() yet, we do that later by calling autoSR.EnsureSaved()
  // in case we need it.
  gfxContextAutoSaveRestore autoSR;

  // Determine the border image area, which by default corresponds to the
  // border box but can be modified by 'border-image-outset'.
  // Note that 'border-radius' do not apply to 'border-image' borders per
  // <http://dev.w3.org/csswg/css-backgrounds/#corner-clipping>.
  nsRect borderImgArea;
  nsMargin borderWidths(aStyleBorder.GetComputedBorder());
  nsMargin imageOutset(aStyleBorder.GetImageOutset());
  if (::IsBoxDecorationSlice(aStyleBorder) && !aSkipSides.IsEmpty()) {
    borderImgArea = ::BoxDecorationRectForBorder(aForFrame, aBorderArea,
                                                 aSkipSides, &aStyleBorder);
    if (borderImgArea.IsEqualEdges(aBorderArea)) {
      // No need for a clip, just skip the sides we don't want.
      borderWidths.ApplySkipSides(aSkipSides);
      imageOutset.ApplySkipSides(aSkipSides);
      borderImgArea.Inflate(imageOutset);
    } else {
      // We're drawing borders around the joined continuation boxes so we need
      // to clip that to the slice that we want for this frame.
      borderImgArea.Inflate(imageOutset);
      imageOutset.ApplySkipSides(aSkipSides);
      nsRect clip = aBorderArea;
      clip.Inflate(imageOutset);
      autoSR.EnsureSaved(aRenderingContext.ThebesContext());
      aRenderingContext.ThebesContext()->
        Clip(NSRectToSnappedRect(clip,
                                 aForFrame->PresContext()->AppUnitsPerDevPixel(),
                                 *aRenderingContext.GetDrawTarget()));
    }
  } else {
    borderImgArea = aBorderArea;
    borderImgArea.Inflate(imageOutset);
  }

  // Calculate the image size used to compute slice points.
  CSSSizeOrRatio intrinsicSize = renderer.ComputeIntrinsicSize();
  nsSize imageSize = nsImageRenderer::ComputeConcreteSize(CSSSizeOrRatio(),
                                                          intrinsicSize,
                                                          borderImgArea.Size());
  renderer.SetPreferredSize(intrinsicSize, imageSize);

  // Compute the used values of 'border-image-slice' and 'border-image-width';
  // we do them together because the latter can depend on the former.
  nsMargin slice;
  nsMargin border;
  NS_FOR_CSS_SIDES(s) {
    nsStyleCoord coord = aStyleBorder.mBorderImageSlice.Get(s);
    int32_t imgDimension = NS_SIDE_IS_VERTICAL(s)
                           ? imageSize.width : imageSize.height;
    nscoord borderDimension = NS_SIDE_IS_VERTICAL(s)
                           ? borderImgArea.width : borderImgArea.height;
    double value;
    switch (coord.GetUnit()) {
      case eStyleUnit_Percent:
        value = coord.GetPercentValue() * imgDimension;
        break;
      case eStyleUnit_Factor:
        value = nsPresContext::CSSPixelsToAppUnits(
          NS_lround(coord.GetFactorValue()));
        break;
      default:
        NS_NOTREACHED("unexpected CSS unit for image slice");
        value = 0;
        break;
    }
    if (value < 0)
      value = 0;
    if (value > imgDimension)
      value = imgDimension;
    slice.Side(s) = value;

    coord = aStyleBorder.mBorderImageWidth.Get(s);
    switch (coord.GetUnit()) {
      case eStyleUnit_Coord: // absolute dimension
        value = coord.GetCoordValue();
        break;
      case eStyleUnit_Percent:
        value = coord.GetPercentValue() * borderDimension;
        break;
      case eStyleUnit_Factor:
        value = coord.GetFactorValue() * borderWidths.Side(s);
        break;
      case eStyleUnit_Auto:  // same as the slice value, in CSS pixels
        value = slice.Side(s);
        break;
      default:
        NS_NOTREACHED("unexpected CSS unit for border image area division");
        value = 0;
        break;
    }
    // NSToCoordRoundWithClamp rounds towards infinity, but that's OK
    // because we expect value to be non-negative.
    MOZ_ASSERT(value >= 0);
    border.Side(s) = NSToCoordRoundWithClamp(value);
    MOZ_ASSERT(border.Side(s) >= 0);
  }

  // "If two opposite border-image-width offsets are large enough that they
  // overlap, their used values are proportionately reduced until they no
  // longer overlap."
  uint32_t combinedBorderWidth = uint32_t(border.left) +
                                 uint32_t(border.right);
  double scaleX = combinedBorderWidth > uint32_t(borderImgArea.width)
                  ? borderImgArea.width / double(combinedBorderWidth)
                  : 1.0;
  uint32_t combinedBorderHeight = uint32_t(border.top) +
                                  uint32_t(border.bottom);
  double scaleY = combinedBorderHeight > uint32_t(borderImgArea.height)
                  ? borderImgArea.height / double(combinedBorderHeight)
                  : 1.0;
  double scale = std::min(scaleX, scaleY);
  if (scale < 1.0) {
    border.left *= scale;
    border.right *= scale;
    border.top *= scale;
    border.bottom *= scale;
    NS_ASSERTION(border.left + border.right <= borderImgArea.width &&
                 border.top + border.bottom <= borderImgArea.height,
                 "rounding error in width reduction???");
  }

  // These helper tables recharacterize the 'slice' and 'width' margins
  // in a more convenient form: they are the x/y/width/height coords
  // required for various bands of the border, and they have been transformed
  // to be relative to the innerRect (for 'slice') or the page (for 'border').
  enum {
    LEFT, MIDDLE, RIGHT,
    TOP = LEFT, BOTTOM = RIGHT
  };
  const nscoord borderX[3] = {
    borderImgArea.x + 0,
    borderImgArea.x + border.left,
    borderImgArea.x + borderImgArea.width - border.right,
  };
  const nscoord borderY[3] = {
    borderImgArea.y + 0,
    borderImgArea.y + border.top,
    borderImgArea.y + borderImgArea.height - border.bottom,
  };
  const nscoord borderWidth[3] = {
    border.left,
    borderImgArea.width - border.left - border.right,
    border.right,
  };
  const nscoord borderHeight[3] = {
    border.top,
    borderImgArea.height - border.top - border.bottom,
    border.bottom,
  };
  const int32_t sliceX[3] = {
    0,
    slice.left,
    imageSize.width - slice.right,
  };
  const int32_t sliceY[3] = {
    0,
    slice.top,
    imageSize.height - slice.bottom,
  };
  const int32_t sliceWidth[3] = {
    slice.left,
    std::max(imageSize.width - slice.left - slice.right, 0),
    slice.right,
  };
  const int32_t sliceHeight[3] = {
    slice.top,
    std::max(imageSize.height - slice.top - slice.bottom, 0),
    slice.bottom,
  };

  DrawResult result = DrawResult::SUCCESS;

  // intrinsicSize.CanComputeConcreteSize() return false means we can not
  // read intrinsic size from aStyleBorder.mBorderImageSource.
  // In this condition, we pass imageSize(a resolved size comes from
  // default sizing algorithm) to renderer as the viewport size.
  Maybe<nsSize> svgViewportSize = intrinsicSize.CanComputeConcreteSize() ?
    Nothing() : Some(imageSize);
  bool hasIntrinsicRatio = intrinsicSize.HasRatio();
  renderer.PurgeCacheForViewportChange(svgViewportSize, hasIntrinsicRatio);

  for (int i = LEFT; i <= RIGHT; i++) {
    for (int j = TOP; j <= BOTTOM; j++) {
      uint8_t fillStyleH, fillStyleV;
      nsSize unitSize;

      if (i == MIDDLE && j == MIDDLE) {
        // Discard the middle portion unless set to fill.
        if (NS_STYLE_BORDER_IMAGE_SLICE_NOFILL ==
            aStyleBorder.mBorderImageFill) {
          continue;
        }

        NS_ASSERTION(NS_STYLE_BORDER_IMAGE_SLICE_FILL ==
                     aStyleBorder.mBorderImageFill,
                     "Unexpected border image fill");

        // css-background:
        //     The middle image's width is scaled by the same factor as the
        //     top image unless that factor is zero or infinity, in which
        //     case the scaling factor of the bottom is substituted, and
        //     failing that, the width is not scaled. The height of the
        //     middle image is scaled by the same factor as the left image
        //     unless that factor is zero or infinity, in which case the
        //     scaling factor of the right image is substituted, and failing
        //     that, the height is not scaled.
        gfxFloat hFactor, vFactor;

        if (0 < border.left && 0 < slice.left)
          vFactor = gfxFloat(border.left)/slice.left;
        else if (0 < border.right && 0 < slice.right)
          vFactor = gfxFloat(border.right)/slice.right;
        else
          vFactor = 1;

        if (0 < border.top && 0 < slice.top)
          hFactor = gfxFloat(border.top)/slice.top;
        else if (0 < border.bottom && 0 < slice.bottom)
          hFactor = gfxFloat(border.bottom)/slice.bottom;
        else
          hFactor = 1;

        unitSize.width = sliceWidth[i]*hFactor;
        unitSize.height = sliceHeight[j]*vFactor;
        fillStyleH = aStyleBorder.mBorderImageRepeatH;
        fillStyleV = aStyleBorder.mBorderImageRepeatV;

      } else if (i == MIDDLE) { // top, bottom
        // Sides are always stretched to the thickness of their border,
        // and stretched proportionately on the other axis.
        gfxFloat factor;
        if (0 < borderHeight[j] && 0 < sliceHeight[j])
          factor = gfxFloat(borderHeight[j])/sliceHeight[j];
        else
          factor = 1;

        unitSize.width = sliceWidth[i]*factor;
        unitSize.height = borderHeight[j];
        fillStyleH = aStyleBorder.mBorderImageRepeatH;
        fillStyleV = NS_STYLE_BORDER_IMAGE_REPEAT_STRETCH;

      } else if (j == MIDDLE) { // left, right
        gfxFloat factor;
        if (0 < borderWidth[i] && 0 < sliceWidth[i])
          factor = gfxFloat(borderWidth[i])/sliceWidth[i];
        else
          factor = 1;

        unitSize.width = borderWidth[i];
        unitSize.height = sliceHeight[j]*factor;
        fillStyleH = NS_STYLE_BORDER_IMAGE_REPEAT_STRETCH;
        fillStyleV = aStyleBorder.mBorderImageRepeatV;

      } else {
        // Corners are always stretched to fit the corner.
        unitSize.width = borderWidth[i];
        unitSize.height = borderHeight[j];
        fillStyleH = NS_STYLE_BORDER_IMAGE_REPEAT_STRETCH;
        fillStyleV = NS_STYLE_BORDER_IMAGE_REPEAT_STRETCH;
      }

      nsRect destArea(borderX[i], borderY[j], borderWidth[i], borderHeight[j]);
      nsRect subArea(sliceX[i], sliceY[j], sliceWidth[i], sliceHeight[j]);
      if (subArea.IsEmpty())
        continue;

      nsIntRect intSubArea = subArea.ToOutsidePixels(nsPresContext::AppUnitsPerCSSPixel());
      result &=
        renderer.DrawBorderImageComponent(aPresContext,
                                          aRenderingContext, aDirtyRect,
                                          destArea, CSSIntRect(intSubArea.x,
                                                               intSubArea.y,
                                                               intSubArea.width,
                                                               intSubArea.height),
                                          fillStyleH, fillStyleV,
                                          unitSize, j * (RIGHT + 1) + i,
                                          svgViewportSize, hasIntrinsicRatio);
    }
  }

  return result;
}

// Begin table border-collapsing section
// These functions were written to not disrupt the normal ones and yet satisfy some additional requirements
// At some point, all functions should be unified to include the additional functionality that these provide

static nscoord
RoundIntToPixel(nscoord aValue,
                nscoord aTwipsPerPixel,
                bool    aRoundDown = false)
{
  if (aTwipsPerPixel <= 0)
    // We must be rendering to a device that has a resolution greater than Twips!
    // In that case, aValue is as accurate as it's going to get.
    return aValue;

  nscoord halfPixel = NSToCoordRound(aTwipsPerPixel / 2.0f);
  nscoord extra = aValue % aTwipsPerPixel;
  nscoord finalValue = (!aRoundDown && (extra >= halfPixel)) ? aValue + (aTwipsPerPixel - extra) : aValue - extra;
  return finalValue;
}

static nscoord
RoundFloatToPixel(float   aValue,
                  nscoord aTwipsPerPixel,
                  bool    aRoundDown = false)
{
  return RoundIntToPixel(NSToCoordRound(aValue), aTwipsPerPixel, aRoundDown);
}

static void SetPoly(const Rect& aRect, Point* poly)
{
  poly[0].x = aRect.x;
  poly[0].y = aRect.y;
  poly[1].x = aRect.x + aRect.width;
  poly[1].y = aRect.y;
  poly[2].x = aRect.x + aRect.width;
  poly[2].y = aRect.y + aRect.height;
  poly[3].x = aRect.x;
  poly[3].y = aRect.y + aRect.height;
}

static void
DrawDashedSegment(DrawTarget&          aDrawTarget,
                  nsRect               aRect,
                  nscoord              aDashLength,
                  nscolor              aColor,
                  int32_t              aAppUnitsPerDevPixel,
                  nscoord              aTwipsPerPixel,
                  bool                 aHorizontal)
{
  ColorPattern color(ToDeviceColor(aColor));
  DrawOptions drawOptions(1.f, CompositionOp::OP_OVER, AntialiasMode::NONE);
  StrokeOptions strokeOptions;

  Float dash[2];
  dash[0] = Float(aDashLength) / aAppUnitsPerDevPixel;
  dash[1] = dash[0];

  strokeOptions.mDashPattern = dash;
  strokeOptions.mDashLength = MOZ_ARRAY_LENGTH(dash);

  if (aHorizontal) {
    nsPoint left = (aRect.TopLeft() + aRect.BottomLeft()) / 2;
    nsPoint right = (aRect.TopRight() + aRect.BottomRight()) / 2;
    strokeOptions.mLineWidth = Float(aRect.height) / aAppUnitsPerDevPixel;
    StrokeLineWithSnapping(left, right,
                           aAppUnitsPerDevPixel, aDrawTarget,
                           color, strokeOptions, drawOptions);
  } else {
    nsPoint top = (aRect.TopLeft() + aRect.TopRight()) / 2;
    nsPoint bottom = (aRect.BottomLeft() + aRect.BottomRight()) / 2;
    strokeOptions.mLineWidth = Float(aRect.width) / aAppUnitsPerDevPixel;
    StrokeLineWithSnapping(top, bottom,
                           aAppUnitsPerDevPixel, aDrawTarget,
                           color, strokeOptions, drawOptions);
  }
}

static void
DrawSolidBorderSegment(DrawTarget&          aDrawTarget,
                       nsRect               aRect,
                       nscolor              aColor,
                       int32_t              aAppUnitsPerDevPixel,
                       nscoord              aTwipsPerPixel,
                       uint8_t              aStartBevelSide = 0,
                       nscoord              aStartBevelOffset = 0,
                       uint8_t              aEndBevelSide = 0,
                       nscoord              aEndBevelOffset = 0)
{
  ColorPattern color(ToDeviceColor(aColor));
  DrawOptions drawOptions(1.f, CompositionOp::OP_OVER, AntialiasMode::NONE);

  // We don't need to bevel single pixel borders
  if ((aRect.width == aTwipsPerPixel) || (aRect.height == aTwipsPerPixel) ||
      ((0 == aStartBevelOffset) && (0 == aEndBevelOffset))) {
    // simple rectangle
    aDrawTarget.FillRect(NSRectToSnappedRect(aRect, aAppUnitsPerDevPixel,
                                             aDrawTarget),
                         color, drawOptions);
  }
  else {
    // polygon with beveling
    Point poly[4];
    SetPoly(NSRectToSnappedRect(aRect, aAppUnitsPerDevPixel, aDrawTarget),
            poly);

    Float startBevelOffset =
      NSAppUnitsToFloatPixels(aStartBevelOffset, aAppUnitsPerDevPixel);
    switch(aStartBevelSide) {
    case NS_SIDE_TOP:
      poly[0].x += startBevelOffset;
      break;
    case NS_SIDE_BOTTOM:
      poly[3].x += startBevelOffset;
      break;
    case NS_SIDE_RIGHT:
      poly[1].y += startBevelOffset;
      break;
    case NS_SIDE_LEFT:
      poly[0].y += startBevelOffset;
    }

    Float endBevelOffset =
      NSAppUnitsToFloatPixels(aEndBevelOffset, aAppUnitsPerDevPixel);
    switch(aEndBevelSide) {
    case NS_SIDE_TOP:
      poly[1].x -= endBevelOffset;
      break;
    case NS_SIDE_BOTTOM:
      poly[2].x -= endBevelOffset;
      break;
    case NS_SIDE_RIGHT:
      poly[2].y -= endBevelOffset;
      break;
    case NS_SIDE_LEFT:
      poly[3].y -= endBevelOffset;
    }

    RefPtr<PathBuilder> builder = aDrawTarget.CreatePathBuilder();
    builder->MoveTo(poly[0]);
    builder->LineTo(poly[1]);
    builder->LineTo(poly[2]);
    builder->LineTo(poly[3]);
    builder->Close();
    RefPtr<Path> path = builder->Finish();
    aDrawTarget.Fill(path, color, drawOptions);
  }
}

static void
GetDashInfo(nscoord  aBorderLength,
            nscoord  aDashLength,
            nscoord  aTwipsPerPixel,
            int32_t& aNumDashSpaces,
            nscoord& aStartDashLength,
            nscoord& aEndDashLength)
{
  aNumDashSpaces = 0;
  if (aStartDashLength + aDashLength + aEndDashLength >= aBorderLength) {
    aStartDashLength = aBorderLength;
    aEndDashLength = 0;
  }
  else {
    aNumDashSpaces = (aBorderLength - aDashLength)/ (2 * aDashLength); // round down
    nscoord extra = aBorderLength - aStartDashLength - aEndDashLength - (((2 * aNumDashSpaces) - 1) * aDashLength);
    if (extra > 0) {
      nscoord half = RoundIntToPixel(extra / 2, aTwipsPerPixel);
      aStartDashLength += half;
      aEndDashLength += (extra - half);
    }
  }
}

void
nsCSSRendering::DrawTableBorderSegment(DrawTarget&              aDrawTarget,
                                       uint8_t                  aBorderStyle,
                                       nscolor                  aBorderColor,
                                       const nsStyleBackground* aBGColor,
                                       const nsRect&            aBorder,
                                       int32_t                  aAppUnitsPerDevPixel,
                                       int32_t                  aAppUnitsPerCSSPixel,
                                       uint8_t                  aStartBevelSide,
                                       nscoord                  aStartBevelOffset,
                                       uint8_t                  aEndBevelSide,
                                       nscoord                  aEndBevelOffset)
{
  bool horizontal = ((NS_SIDE_TOP == aStartBevelSide) || (NS_SIDE_BOTTOM == aStartBevelSide));
  nscoord twipsPerPixel = NSIntPixelsToAppUnits(1, aAppUnitsPerCSSPixel);
  uint8_t ridgeGroove = NS_STYLE_BORDER_STYLE_RIDGE;

  if ((twipsPerPixel >= aBorder.width) || (twipsPerPixel >= aBorder.height) ||
      (NS_STYLE_BORDER_STYLE_DASHED == aBorderStyle) || (NS_STYLE_BORDER_STYLE_DOTTED == aBorderStyle)) {
    // no beveling for 1 pixel border, dash or dot
    aStartBevelOffset = 0;
    aEndBevelOffset = 0;
  }

  switch (aBorderStyle) {
  case NS_STYLE_BORDER_STYLE_NONE:
  case NS_STYLE_BORDER_STYLE_HIDDEN:
    //NS_ASSERTION(false, "style of none or hidden");
    break;
  case NS_STYLE_BORDER_STYLE_DOTTED:
  case NS_STYLE_BORDER_STYLE_DASHED:
    {
      nscoord dashLength = (NS_STYLE_BORDER_STYLE_DASHED == aBorderStyle) ? DASH_LENGTH : DOT_LENGTH;
      // make the dash length proportional to the border thickness
      dashLength *= (horizontal) ? aBorder.height : aBorder.width;
      // make the min dash length for the ends 1/2 the dash length
      nscoord minDashLength = (NS_STYLE_BORDER_STYLE_DASHED == aBorderStyle)
                              ? RoundFloatToPixel(((float)dashLength) / 2.0f, twipsPerPixel) : dashLength;
      minDashLength = std::max(minDashLength, twipsPerPixel);
      nscoord numDashSpaces = 0;
      nscoord startDashLength = minDashLength;
      nscoord endDashLength   = minDashLength;
      if (horizontal) {
        GetDashInfo(aBorder.width, dashLength, twipsPerPixel, numDashSpaces,
                    startDashLength, endDashLength);
        nsRect rect(aBorder.x, aBorder.y, startDashLength, aBorder.height);
        DrawSolidBorderSegment(aDrawTarget, rect, aBorderColor,
                               aAppUnitsPerDevPixel, twipsPerPixel);

        rect.x += startDashLength + dashLength;
        rect.width = aBorder.width
                     - (startDashLength + endDashLength + dashLength);
        DrawDashedSegment(aDrawTarget, rect, dashLength, aBorderColor,
                          aAppUnitsPerDevPixel, twipsPerPixel, horizontal);

        rect.x += rect.width;
        rect.width = endDashLength;
        DrawSolidBorderSegment(aDrawTarget, rect, aBorderColor,
                               aAppUnitsPerDevPixel, twipsPerPixel);
      }
      else {
        GetDashInfo(aBorder.height, dashLength, twipsPerPixel, numDashSpaces,
                    startDashLength, endDashLength);
        nsRect rect(aBorder.x, aBorder.y, aBorder.width, startDashLength);
        DrawSolidBorderSegment(aDrawTarget, rect, aBorderColor,
                               aAppUnitsPerDevPixel, twipsPerPixel);

        rect.y += rect.height + dashLength;
        rect.height = aBorder.height
                      - (startDashLength + endDashLength + dashLength);
        DrawDashedSegment(aDrawTarget, rect, dashLength, aBorderColor,
                          aAppUnitsPerDevPixel, twipsPerPixel, horizontal);

        rect.y += rect.height;
        rect.height = endDashLength;
        DrawSolidBorderSegment(aDrawTarget, rect, aBorderColor,
                               aAppUnitsPerDevPixel, twipsPerPixel);
      }
    }
    break;
  case NS_STYLE_BORDER_STYLE_GROOVE:
    ridgeGroove = NS_STYLE_BORDER_STYLE_GROOVE; // and fall through to ridge
    [[fallthrough]];
  case NS_STYLE_BORDER_STYLE_RIDGE:
    if ((horizontal && (twipsPerPixel >= aBorder.height)) ||
        (!horizontal && (twipsPerPixel >= aBorder.width))) {
      // a one pixel border
      DrawSolidBorderSegment(aDrawTarget, aBorder, aBorderColor,
                             aAppUnitsPerDevPixel, twipsPerPixel,
                             aStartBevelSide, aStartBevelOffset,
                             aEndBevelSide, aEndBevelOffset);
    }
    else {
      nscoord startBevel = (aStartBevelOffset > 0)
                            ? RoundFloatToPixel(0.5f * (float)aStartBevelOffset, twipsPerPixel, true) : 0;
      nscoord endBevel =   (aEndBevelOffset > 0)
                            ? RoundFloatToPixel(0.5f * (float)aEndBevelOffset, twipsPerPixel, true) : 0;
      mozilla::css::Side ridgeGrooveSide = (horizontal) ? NS_SIDE_TOP : NS_SIDE_LEFT;
      // FIXME: In theory, this should use the visited-dependent
      // background color, but I don't care.
      nscolor bevelColor = MakeBevelColor(ridgeGrooveSide, ridgeGroove,
                                          aBGColor->mBackgroundColor,
                                          aBorderColor);
      nsRect rect(aBorder);
      nscoord half;
      if (horizontal) { // top, bottom
        half = RoundFloatToPixel(0.5f * (float)aBorder.height, twipsPerPixel);
        rect.height = half;
        if (NS_SIDE_TOP == aStartBevelSide) {
          rect.x += startBevel;
          rect.width -= startBevel;
        }
        if (NS_SIDE_TOP == aEndBevelSide) {
          rect.width -= endBevel;
        }
        DrawSolidBorderSegment(aDrawTarget, rect, bevelColor,
                               aAppUnitsPerDevPixel, twipsPerPixel,
                               aStartBevelSide, startBevel, aEndBevelSide,
                               endBevel);
      }
      else { // left, right
        half = RoundFloatToPixel(0.5f * (float)aBorder.width, twipsPerPixel);
        rect.width = half;
        if (NS_SIDE_LEFT == aStartBevelSide) {
          rect.y += startBevel;
          rect.height -= startBevel;
        }
        if (NS_SIDE_LEFT == aEndBevelSide) {
          rect.height -= endBevel;
        }
        DrawSolidBorderSegment(aDrawTarget, rect, bevelColor,
                               aAppUnitsPerDevPixel, twipsPerPixel,
                               aStartBevelSide, startBevel, aEndBevelSide,
                               endBevel);
      }

      rect = aBorder;
      ridgeGrooveSide = (NS_SIDE_TOP == ridgeGrooveSide) ? NS_SIDE_BOTTOM : NS_SIDE_RIGHT;
      // FIXME: In theory, this should use the visited-dependent
      // background color, but I don't care.
      bevelColor = MakeBevelColor(ridgeGrooveSide, ridgeGroove,
                                  aBGColor->mBackgroundColor, aBorderColor);
      if (horizontal) {
        rect.y = rect.y + half;
        rect.height = aBorder.height - half;
        if (NS_SIDE_BOTTOM == aStartBevelSide) {
          rect.x += startBevel;
          rect.width -= startBevel;
        }
        if (NS_SIDE_BOTTOM == aEndBevelSide) {
          rect.width -= endBevel;
        }
        DrawSolidBorderSegment(aDrawTarget, rect, bevelColor,
                               aAppUnitsPerDevPixel, twipsPerPixel,
                               aStartBevelSide, startBevel, aEndBevelSide,
                               endBevel);
      }
      else {
        rect.x = rect.x + half;
        rect.width = aBorder.width - half;
        if (NS_SIDE_RIGHT == aStartBevelSide) {
          rect.y += aStartBevelOffset - startBevel;
          rect.height -= startBevel;
        }
        if (NS_SIDE_RIGHT == aEndBevelSide) {
          rect.height -= endBevel;
        }
        DrawSolidBorderSegment(aDrawTarget, rect, bevelColor,
                               aAppUnitsPerDevPixel, twipsPerPixel,
                               aStartBevelSide, startBevel, aEndBevelSide,
                               endBevel);
      }
    }
    break;
  case NS_STYLE_BORDER_STYLE_DOUBLE:
    // We can only do "double" borders if the thickness of the border
    // is more than 2px.  Otherwise, we fall through to painting a
    // solid border.
    if ((aBorder.width > 2*twipsPerPixel || horizontal) &&
        (aBorder.height > 2*twipsPerPixel || !horizontal)) {
      nscoord startBevel = (aStartBevelOffset > 0)
                            ? RoundFloatToPixel(0.333333f * (float)aStartBevelOffset, twipsPerPixel) : 0;
      nscoord endBevel =   (aEndBevelOffset > 0)
                            ? RoundFloatToPixel(0.333333f * (float)aEndBevelOffset, twipsPerPixel) : 0;
      if (horizontal) { // top, bottom
        nscoord thirdHeight = RoundFloatToPixel(0.333333f * (float)aBorder.height, twipsPerPixel);

        // draw the top line or rect
        nsRect topRect(aBorder.x, aBorder.y, aBorder.width, thirdHeight);
        if (NS_SIDE_TOP == aStartBevelSide) {
          topRect.x += aStartBevelOffset - startBevel;
          topRect.width -= aStartBevelOffset - startBevel;
        }
        if (NS_SIDE_TOP == aEndBevelSide) {
          topRect.width -= aEndBevelOffset - endBevel;
        }
        DrawSolidBorderSegment(aDrawTarget, topRect, aBorderColor,
                               aAppUnitsPerDevPixel, twipsPerPixel,
                               aStartBevelSide, startBevel, aEndBevelSide,
                               endBevel);

        // draw the botom line or rect
        nscoord heightOffset = aBorder.height - thirdHeight;
        nsRect bottomRect(aBorder.x, aBorder.y + heightOffset, aBorder.width, aBorder.height - heightOffset);
        if (NS_SIDE_BOTTOM == aStartBevelSide) {
          bottomRect.x += aStartBevelOffset - startBevel;
          bottomRect.width -= aStartBevelOffset - startBevel;
        }
        if (NS_SIDE_BOTTOM == aEndBevelSide) {
          bottomRect.width -= aEndBevelOffset - endBevel;
        }
        DrawSolidBorderSegment(aDrawTarget, bottomRect, aBorderColor,
                               aAppUnitsPerDevPixel, twipsPerPixel,
                               aStartBevelSide, startBevel, aEndBevelSide,
                               endBevel);
      }
      else { // left, right
        nscoord thirdWidth = RoundFloatToPixel(0.333333f * (float)aBorder.width, twipsPerPixel);

        nsRect leftRect(aBorder.x, aBorder.y, thirdWidth, aBorder.height);
        if (NS_SIDE_LEFT == aStartBevelSide) {
          leftRect.y += aStartBevelOffset - startBevel;
          leftRect.height -= aStartBevelOffset - startBevel;
        }
        if (NS_SIDE_LEFT == aEndBevelSide) {
          leftRect.height -= aEndBevelOffset - endBevel;
        }
        DrawSolidBorderSegment(aDrawTarget, leftRect, aBorderColor,
                               aAppUnitsPerDevPixel, twipsPerPixel,
                               aStartBevelSide, startBevel, aEndBevelSide,
                               endBevel);

        nscoord widthOffset = aBorder.width - thirdWidth;
        nsRect rightRect(aBorder.x + widthOffset, aBorder.y, aBorder.width - widthOffset, aBorder.height);
        if (NS_SIDE_RIGHT == aStartBevelSide) {
          rightRect.y += aStartBevelOffset - startBevel;
          rightRect.height -= aStartBevelOffset - startBevel;
        }
        if (NS_SIDE_RIGHT == aEndBevelSide) {
          rightRect.height -= aEndBevelOffset - endBevel;
        }
        DrawSolidBorderSegment(aDrawTarget, rightRect, aBorderColor,
                               aAppUnitsPerDevPixel, twipsPerPixel,
                               aStartBevelSide, startBevel, aEndBevelSide,
                               endBevel);
      }
      break;
    }
    // else fall through to solid
    [[fallthrough]];
  case NS_STYLE_BORDER_STYLE_SOLID:
    DrawSolidBorderSegment(aDrawTarget, aBorder, aBorderColor,
                           aAppUnitsPerDevPixel, twipsPerPixel, aStartBevelSide,
                           aStartBevelOffset, aEndBevelSide, aEndBevelOffset);
    break;
  case NS_STYLE_BORDER_STYLE_OUTSET:
  case NS_STYLE_BORDER_STYLE_INSET:
    NS_ASSERTION(false, "inset, outset should have been converted to groove, ridge");
    break;
  case NS_STYLE_BORDER_STYLE_AUTO:
    NS_ASSERTION(false, "Unexpected 'auto' table border");
    break;
  }
}

// End table border-collapsing section

Rect
nsCSSRendering::ExpandPaintingRectForDecorationLine(
                  nsIFrame* aFrame,
                  const uint8_t aStyle,
                  const Rect& aClippedRect,
                  const Float aICoordInFrame,
                  const Float aCycleLength,
                  bool aVertical)
{
  switch (aStyle) {
    case NS_STYLE_TEXT_DECORATION_STYLE_DOTTED:
    case NS_STYLE_TEXT_DECORATION_STYLE_DASHED:
    case NS_STYLE_TEXT_DECORATION_STYLE_WAVY:
      break;
    default:
      NS_ERROR("Invalid style was specified");
      return aClippedRect;
  }

  nsBlockFrame* block = nullptr;
  // Note that when we paint the decoration lines in relative positioned
  // box, we should paint them like all of the boxes are positioned as static.
  nscoord framePosInBlockAppUnits = 0;
  for (nsIFrame* f = aFrame; f; f = f->GetParent()) {
    block = do_QueryFrame(f);
    if (block) {
      break;
    }
    framePosInBlockAppUnits += aVertical ?
      f->GetNormalPosition().y : f->GetNormalPosition().x;
  }

  NS_ENSURE_TRUE(block, aClippedRect);

  nsPresContext *pc = aFrame->PresContext();
  Float framePosInBlock = Float(pc->AppUnitsToGfxUnits(framePosInBlockAppUnits));
  int32_t rectPosInBlock =
    int32_t(NS_round(framePosInBlock + aICoordInFrame));
  int32_t extraStartEdge =
    rectPosInBlock - (rectPosInBlock / int32_t(aCycleLength) * aCycleLength);
  Rect rect(aClippedRect);
  if (aVertical) {
    rect.y -= extraStartEdge;
    rect.height += extraStartEdge;
  } else {
    rect.x -= extraStartEdge;
    rect.width += extraStartEdge;
  }
  return rect;
}

void
nsCSSRendering::PaintDecorationLine(nsIFrame* aFrame, DrawTarget& aDrawTarget,
                                    const PaintDecorationLineParams& aParams)
{
  NS_ASSERTION(aParams.style != NS_STYLE_TEXT_DECORATION_STYLE_NONE,
               "aStyle is none");

  Rect rect = ToRect(GetTextDecorationRectInternal(aParams.pt, aParams));
  if (rect.IsEmpty() || !rect.Intersects(aParams.dirtyRect)) {
    return;
  }

  if (aParams.decoration != NS_STYLE_TEXT_DECORATION_LINE_UNDERLINE &&
      aParams.decoration != NS_STYLE_TEXT_DECORATION_LINE_OVERLINE &&
      aParams.decoration != NS_STYLE_TEXT_DECORATION_LINE_LINE_THROUGH) {
    NS_ERROR("Invalid decoration value!");
    return;
  }

  Float lineThickness = std::max(NS_round(aParams.lineSize.height), 1.0);

  ColorPattern color(ToDeviceColor(aParams.color));
  StrokeOptions strokeOptions(lineThickness);
  DrawOptions drawOptions;

  Float dash[2];

  AutoPopClips autoPopClips(&aDrawTarget);

  switch (aParams.style) {
    case NS_STYLE_TEXT_DECORATION_STYLE_SOLID:
    case NS_STYLE_TEXT_DECORATION_STYLE_DOUBLE:
      break;
    case NS_STYLE_TEXT_DECORATION_STYLE_DASHED: {
      autoPopClips.PushClipRect(rect);
      Float dashWidth = lineThickness * DOT_LENGTH * DASH_LENGTH;
      dash[0] = dashWidth;
      dash[1] = dashWidth;
      strokeOptions.mDashPattern = dash;
      strokeOptions.mDashLength = MOZ_ARRAY_LENGTH(dash);
      strokeOptions.mLineCap = CapStyle::BUTT;
      rect = ExpandPaintingRectForDecorationLine(aFrame, aParams.style,
                                                 rect, aParams.icoordInFrame,
                                                 dashWidth * 2,
                                                 aParams.vertical);
      // We should continue to draw the last dash even if it is not in the rect.
      rect.width += dashWidth;
      break;
    }
    case NS_STYLE_TEXT_DECORATION_STYLE_DOTTED: {
      autoPopClips.PushClipRect(rect);
      Float dashWidth = lineThickness * DOT_LENGTH;
      if (lineThickness > 2.0) {
        dash[0] = 0.f;
        dash[1] = dashWidth * 2.f;
        strokeOptions.mLineCap = CapStyle::ROUND;
      } else {
        dash[0] = dashWidth;
        dash[1] = dashWidth;
      }
      strokeOptions.mDashPattern = dash;
      strokeOptions.mDashLength = MOZ_ARRAY_LENGTH(dash);
      rect = ExpandPaintingRectForDecorationLine(aFrame, aParams.style,
                                                 rect, aParams.icoordInFrame,
                                                 dashWidth * 2,
                                                 aParams.vertical);
      // We should continue to draw the last dot even if it is not in the rect.
      rect.width += dashWidth;
      break;
    }
    case NS_STYLE_TEXT_DECORATION_STYLE_WAVY:
      autoPopClips.PushClipRect(rect);
      if (lineThickness > 2.0) {
        drawOptions.mAntialiasMode = AntialiasMode::SUBPIXEL;
      } else {
        // Don't use anti-aliasing here.  Because looks like lighter color wavy
        // line at this case.  And probably, users don't think the
        // non-anti-aliased wavy line is not pretty.
        drawOptions.mAntialiasMode = AntialiasMode::NONE;
      }
      break;
    default:
      NS_ERROR("Invalid style value!");
      return;
  }

  // The block-direction position should be set to the middle of the line.
  if (aParams.vertical) {
    rect.x += lineThickness / 2;
  } else {
    rect.y += lineThickness / 2;
  }

  switch (aParams.style) {
    case NS_STYLE_TEXT_DECORATION_STYLE_SOLID:
    case NS_STYLE_TEXT_DECORATION_STYLE_DOTTED:
    case NS_STYLE_TEXT_DECORATION_STYLE_DASHED: {
      Point p1 = rect.TopLeft();
      Point p2 = aParams.vertical ? rect.BottomLeft() : rect.TopRight();
      aDrawTarget.StrokeLine(p1, p2, color, strokeOptions, drawOptions);
      return;
    }
    case NS_STYLE_TEXT_DECORATION_STYLE_DOUBLE: {
      /**
       *  We are drawing double line as:
       *
       * +-------------------------------------------+
       * |XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX| ^
       * |XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX| | lineThickness
       * |XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX| v
       * |                                           |
       * |                                           |
       * |XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX| ^
       * |XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX| | lineThickness
       * |XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX| v
       * +-------------------------------------------+
       */
      Point p1 = rect.TopLeft();
      Point p2 = aParams.vertical ? rect.BottomLeft() : rect.TopRight();
      aDrawTarget.StrokeLine(p1, p2, color, strokeOptions, drawOptions);

      if (aParams.vertical) {
        rect.width -= lineThickness;
      } else {
        rect.height -= lineThickness;
      }

      p1 = aParams.vertical ? rect.TopRight() : rect.BottomLeft();
      p2 = rect.BottomRight();
      aDrawTarget.StrokeLine(p1, p2, color, strokeOptions, drawOptions);
      return;
    }
    case NS_STYLE_TEXT_DECORATION_STYLE_WAVY: {
      /**
       *  We are drawing wavy line as:
       *
       *  P: Path, X: Painted pixel
       *
       *     +---------------------------------------+
       *   XX|X            XXXXXX            XXXXXX  |
       *   PP|PX          XPPPPPPX          XPPPPPPX |    ^
       *   XX|XPX        XPXXXXXXPX        XPXXXXXXPX|    |
       *     | XPX      XPX      XPX      XPX      XP|X   |adv
       *     |  XPXXXXXXPX        XPXXXXXXPX        X|PX  |
       *     |   XPPPPPPX          XPPPPPPX          |XPX v
       *     |    XXXXXX            XXXXXX           | XX
       *     +---------------------------------------+
       *      <---><--->                                ^
       *      adv  flatLengthAtVertex                   rightMost
       *
       *  1. Always starts from top-left of the drawing area, however, we need
       *     to draw  the line from outside of the rect.  Because the start
       *     point of the line is not good style if we draw from inside it.
       *  2. First, draw horizontal line from outside the rect to top-left of
       *     the rect;
       *  3. Goes down to bottom of the area at 45 degrees.
       *  4. Slides to right horizontaly, see |flatLengthAtVertex|.
       *  5. Goes up to top of the area at 45 degrees.
       *  6. Slides to right horizontaly.
       *  7. Repeat from 2 until reached to right-most edge of the area.
       *
       * In the vertical case, swap horizontal and vertical coordinates and
       * directions in the above description.
       */

      Float& rectICoord = aParams.vertical ? rect.y : rect.x;
      Float& rectISize = aParams.vertical ? rect.height : rect.width;
      const Float rectBSize = aParams.vertical ? rect.width : rect.height;

      const Float adv = rectBSize - lineThickness;
      const Float flatLengthAtVertex =
        std::max((lineThickness - 1.0) * 2.0, 1.0);

      // Align the start of wavy lines to the nearest ancestor block.
      const Float cycleLength = 2 * (adv + flatLengthAtVertex);
      rect = ExpandPaintingRectForDecorationLine(aFrame, aParams.style, rect,
                                                 aParams.icoordInFrame,
                                                 cycleLength, aParams.vertical);
      // figure out if we can trim whole cycles from the left and right edges
      // of the line, to try and avoid creating an unnecessarily long and
      // complex path
      const Float dirtyRectICoord = aParams.vertical ? aParams.dirtyRect.y
                                                     : aParams.dirtyRect.x;
      int32_t skipCycles = floor((dirtyRectICoord - rectICoord) / cycleLength);
      if (skipCycles > 0) {
        rectICoord += skipCycles * cycleLength;
        rectISize -= skipCycles * cycleLength;
      }

      rectICoord += lineThickness / 2.0;
      Point pt(rect.TopLeft());
      Float& ptICoord = aParams.vertical ? pt.y : pt.x;
      Float& ptBCoord = aParams.vertical ? pt.x : pt.y;
      if (aParams.vertical) {
        ptBCoord += adv + lineThickness / 2.0;
      }
      Float iCoordLimit = ptICoord + rectISize + lineThickness;

      const Float dirtyRectIMost = aParams.vertical ?
        aParams.dirtyRect.YMost() : aParams.dirtyRect.XMost();
      skipCycles = floor((iCoordLimit - dirtyRectIMost) / cycleLength);
      if (skipCycles > 0) {
        iCoordLimit -= skipCycles * cycleLength;
      }

      RefPtr<PathBuilder> builder = aDrawTarget.CreatePathBuilder();
      RefPtr<Path> path;

      ptICoord -= lineThickness;
      builder->MoveTo(pt); // 1

      ptICoord = rectICoord;
      builder->LineTo(pt); // 2

      // In vertical mode, to go "down" relative to the text we need to
      // decrease the block coordinate, whereas in horizontal we increase
      // it. So the sense of this flag is effectively inverted.
      bool goDown = aParams.vertical ? false : true;
      uint32_t iter = 0;
      while (ptICoord < iCoordLimit) {
        if (++iter > 1000) {
          // stroke the current path and start again, to avoid pathological
          // behavior in cairo with huge numbers of path segments
          path = builder->Finish();
          aDrawTarget.Stroke(path, color, strokeOptions, drawOptions);
          builder = aDrawTarget.CreatePathBuilder();
          builder->MoveTo(pt);
          iter = 0;
        }
        ptICoord += adv;
        ptBCoord += goDown ? adv : -adv;

        builder->LineTo(pt); // 3 and 5

        ptICoord += flatLengthAtVertex;
        builder->LineTo(pt); // 4 and 6

        goDown = !goDown;
      }
      path = builder->Finish();
      aDrawTarget.Stroke(path, color, strokeOptions, drawOptions);
      return;
    }
    default:
      NS_ERROR("Invalid style value!");
  }
}

Rect
nsCSSRendering::DecorationLineToPath(const PaintDecorationLineParams& aParams)
{
  NS_ASSERTION(aParams.style != NS_STYLE_TEXT_DECORATION_STYLE_NONE,
               "aStyle is none");

  Rect path; // To benefit from RVO, we return this from all return points

  Rect rect = ToRect(GetTextDecorationRectInternal(aParams.pt, aParams));
  if (rect.IsEmpty() || !rect.Intersects(aParams.dirtyRect)) {
    return path;
  }

  if (aParams.decoration != NS_STYLE_TEXT_DECORATION_LINE_UNDERLINE &&
      aParams.decoration != NS_STYLE_TEXT_DECORATION_LINE_OVERLINE &&
      aParams.decoration != NS_STYLE_TEXT_DECORATION_LINE_LINE_THROUGH) {
    NS_ERROR("Invalid decoration value!");
    return path;
  }

  if (aParams.style != NS_STYLE_TEXT_DECORATION_STYLE_SOLID) {
    // For the moment, we support only solid text decorations.
    return path;
  }

  Float lineThickness = std::max(NS_round(aParams.lineSize.height), 1.0);

  // The block-direction position should be set to the middle of the line.
  if (aParams.vertical) {
    rect.x += lineThickness / 2;
    path = Rect(rect.TopLeft() - Point(lineThickness / 2, 0.0),
                Size(lineThickness, rect.Height()));
  } else {
    rect.y += lineThickness / 2;
    path = Rect(rect.TopLeft() - Point(0.0, lineThickness / 2),
                Size(rect.Width(), lineThickness));
  }

  return path;
}

nsRect
nsCSSRendering::GetTextDecorationRect(nsPresContext* aPresContext,
                                      const DecorationRectParams& aParams)
{
  NS_ASSERTION(aPresContext, "aPresContext is null");
  NS_ASSERTION(aParams.style != NS_STYLE_TEXT_DECORATION_STYLE_NONE,
               "aStyle is none");

  gfxRect rect = GetTextDecorationRectInternal(Point(0, 0), aParams);
  // The rect values are already rounded to nearest device pixels.
  nsRect r;
  r.x = aPresContext->GfxUnitsToAppUnits(rect.X());
  r.y = aPresContext->GfxUnitsToAppUnits(rect.Y());
  r.width = aPresContext->GfxUnitsToAppUnits(rect.Width());
  r.height = aPresContext->GfxUnitsToAppUnits(rect.Height());
  return r;
}

gfxRect
nsCSSRendering::GetTextDecorationRectInternal(const Point& aPt,
                                              const DecorationRectParams& aParams)
{
  NS_ASSERTION(aParams.style <= NS_STYLE_TEXT_DECORATION_STYLE_WAVY,
               "Invalid aStyle value");

  if (aParams.style == NS_STYLE_TEXT_DECORATION_STYLE_NONE)
    return gfxRect(0, 0, 0, 0);

  bool canLiftUnderline = aParams.descentLimit >= 0.0;

  gfxFloat iCoord = aParams.vertical ? aPt.y : aPt.x;
  gfxFloat bCoord = aParams.vertical ? aPt.x : aPt.y;

  // 'left' and 'right' are relative to the line, so for vertical writing modes
  // they will actually become top and bottom of the rendered line.
  // Similarly, aLineSize.width and .height are actually length and thickness
  // of the line, which runs horizontally or vertically according to aVertical.
  const gfxFloat left  = floor(iCoord + 0.5),
                 right = floor(iCoord + aParams.lineSize.width + 0.5);

  // We compute |r| as if for a horizontal text run, and then swap vertical
  // and horizontal coordinates at the end if vertical was requested.
  gfxRect r(left, 0, right - left, 0);

  gfxFloat lineThickness = NS_round(aParams.lineSize.height);
  lineThickness = std::max(lineThickness, 1.0);

  gfxFloat ascent = NS_round(aParams.ascent);
  gfxFloat descentLimit = floor(aParams.descentLimit);

  gfxFloat suggestedMaxRectHeight = std::max(std::min(ascent, descentLimit), 1.0);
  r.height = lineThickness;
  if (aParams.style == NS_STYLE_TEXT_DECORATION_STYLE_DOUBLE) {
    /**
     *  We will draw double line as:
     *
     * +-------------------------------------------+
     * |XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX| ^
     * |XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX| | lineThickness
     * |XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX| v
     * |                                           | ^
     * |                                           | | gap
     * |                                           | v
     * |XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX| ^
     * |XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX| | lineThickness
     * |XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX| v
     * +-------------------------------------------+
     */
    gfxFloat gap = NS_round(lineThickness / 2.0);
    gap = std::max(gap, 1.0);
    r.height = lineThickness * 2.0 + gap;
    if (canLiftUnderline) {
      if (r.Height() > suggestedMaxRectHeight) {
        // Don't shrink the line height, because the thickness has some meaning.
        // We can just shrink the gap at this time.
        r.height = std::max(suggestedMaxRectHeight, lineThickness * 2.0 + 1.0);
      }
    }
  } else if (aParams.style == NS_STYLE_TEXT_DECORATION_STYLE_WAVY) {
    /**
     *  We will draw wavy line as:
     *
     * +-------------------------------------------+
     * |XXXXX            XXXXXX            XXXXXX  | ^
     * |XXXXXX          XXXXXXXX          XXXXXXXX | | lineThickness
     * |XXXXXXX        XXXXXXXXXX        XXXXXXXXXX| v
     * |     XXX      XXX      XXX      XXX      XX|
     * |      XXXXXXXXXX        XXXXXXXXXX        X|
     * |       XXXXXXXX          XXXXXXXX          |
     * |        XXXXXX            XXXXXX           |
     * +-------------------------------------------+
     */
    r.height = lineThickness > 2.0 ? lineThickness * 4.0 : lineThickness * 3.0;
    if (canLiftUnderline) {
      if (r.Height() > suggestedMaxRectHeight) {
        // Don't shrink the line height even if there is not enough space,
        // because the thickness has some meaning.  E.g., the 1px wavy line and
        // 2px wavy line can be used for different meaning in IME selections
        // at same time.
        r.height = std::max(suggestedMaxRectHeight, lineThickness * 2.0);
      }
    }
  }

  gfxFloat baseline = floor(bCoord + aParams.ascent + 0.5);
  gfxFloat offset = 0.0;
  switch (aParams.decoration) {
    case NS_STYLE_TEXT_DECORATION_LINE_UNDERLINE:
      offset = aParams.offset;
      if (canLiftUnderline) {
        if (descentLimit < -offset + r.Height()) {
          // If we can ignore the offset and the decoration line is overflowing,
          // we should align the bottom edge of the decoration line rect if it's
          // possible.  Otherwise, we should lift up the top edge of the rect as
          // far as possible.
          gfxFloat offsetBottomAligned = -descentLimit + r.Height();
          gfxFloat offsetTopAligned = 0.0;
          offset = std::min(offsetBottomAligned, offsetTopAligned);
        }
      }
      break;
    case NS_STYLE_TEXT_DECORATION_LINE_OVERLINE:
      offset = aParams.offset - lineThickness + r.Height();
      break;
    case NS_STYLE_TEXT_DECORATION_LINE_LINE_THROUGH: {
      gfxFloat extra = floor(r.Height() / 2.0 + 0.5);
      extra = std::max(extra, lineThickness);
      offset = aParams.offset - lineThickness + extra;
      break;
    }
    default:
      NS_ERROR("Invalid decoration value!");
  }

  if (aParams.vertical) {
    r.y = baseline + floor(offset + 0.5);
    Swap(r.x, r.y);
    Swap(r.width, r.height);
  } else {
    r.y = baseline - floor(offset + 0.5);
  }

  return r;
}

// ------------------
// ImageRenderer
// ------------------
nsImageRenderer::nsImageRenderer(nsIFrame* aForFrame,
                                 const nsStyleImage* aImage,
                                 uint32_t aFlags)
  : mForFrame(aForFrame)
  , mImage(aImage)
  , mType(aImage->GetType())
  , mImageContainer(nullptr)
  , mGradientData(nullptr)
  , mPaintServerFrame(nullptr)
  , mPrepareResult(DrawResult::NOT_READY)
  , mSize(0, 0)
  , mFlags(aFlags)
  , mExtendMode(ExtendMode::CLAMP)
  , mMaskOp(NS_STYLE_MASK_MODE_MATCH_SOURCE)
{
}

nsImageRenderer::~nsImageRenderer()
{
}

static bool
ShouldTreatAsCompleteDueToSyncDecode(const nsStyleImage* aImage,
                                     uint32_t aFlags)
{
  if (!(aFlags & nsImageRenderer::FLAG_SYNC_DECODE_IMAGES)) {
    return false;
  }

  if (aImage->GetType() != eStyleImageType_Image) {
    return false;
  }

  imgRequestProxy* req = aImage->GetImageData();
  if (!req) {
    return false;
  }

  uint32_t status = 0;
  if (NS_FAILED(req->GetImageStatus(&status))) {
    return false;
  }

  if (status & imgIRequest::STATUS_ERROR) {
    // The image is "complete" since it's a corrupt image. If we created an
    // imgIContainer at all, return true.
    nsCOMPtr<imgIContainer> image;
    req->GetImage(getter_AddRefs(image));
    return bool(image);
  }

  if (!(status & imgIRequest::STATUS_LOAD_COMPLETE)) {
    // We must have loaded all of the image's data and the size must be
    // available, or else sync decoding won't be able to decode the image.
    return false;
  }

  return true;
}

bool
nsImageRenderer::PrepareImage()
{
  if (mImage->IsEmpty()) {
    mPrepareResult = DrawResult::BAD_IMAGE;
    return false;
  }

  if (!mImage->IsComplete()) {
    // Make sure the image is actually decoding.
    mImage->StartDecoding();

    // Check again to see if we finished.
    // We cannot prepare the image for rendering if it is not fully loaded.
    // Special case: If we requested a sync decode and the image has loaded, push
    // on through because the Draw() will do a sync decode then.
    if (!mImage->IsComplete() &&
        !ShouldTreatAsCompleteDueToSyncDecode(mImage, mFlags)) {
      mPrepareResult = DrawResult::NOT_READY;
      return false;
    }
  }

  switch (mType) {
    case eStyleImageType_Image: {
      MOZ_ASSERT(mImage->GetImageData(),
                 "must have image data, since we checked IsEmpty above");
      nsCOMPtr<imgIContainer> srcImage;
      DebugOnly<nsresult> rv =
        mImage->GetImageData()->GetImage(getter_AddRefs(srcImage));
      MOZ_ASSERT(NS_SUCCEEDED(rv) && srcImage,
                 "If GetImage() is failing, mImage->IsComplete() "
                 "should have returned false");

      if (!mImage->GetCropRect()) {
        mImageContainer.swap(srcImage);
      } else {
        nsIntRect actualCropRect;
        bool isEntireImage;
        bool success =
          mImage->ComputeActualCropRect(actualCropRect, &isEntireImage);
        NS_ASSERTION(success, "ComputeActualCropRect() should not fail here");
        if (!success || actualCropRect.IsEmpty()) {
          // The cropped image has zero size
          mPrepareResult = DrawResult::BAD_IMAGE;
          return false;
        }
        if (isEntireImage) {
          // The cropped image is identical to the source image
          mImageContainer.swap(srcImage);
        } else {
          nsCOMPtr<imgIContainer> subImage = ImageOps::Clip(srcImage,
                                                            actualCropRect,
                                                            Nothing());
          mImageContainer.swap(subImage);
        }
      }
      mPrepareResult = DrawResult::SUCCESS;
      break;
    }
    case eStyleImageType_Gradient:
      mGradientData = mImage->GetGradientData();
      mPrepareResult = DrawResult::SUCCESS;
      break;
    case eStyleImageType_Element:
    {
      nsAutoString elementId =
        NS_LITERAL_STRING("#") + nsDependentString(mImage->GetElementId());
      nsCOMPtr<nsIURI> targetURI;
      nsCOMPtr<nsIURI> base = mForFrame->GetContent()->GetBaseURI();
      nsContentUtils::NewURIWithDocumentCharset(getter_AddRefs(targetURI), elementId,
                                                mForFrame->GetContent()->GetUncomposedDoc(), base);
      nsSVGPaintingProperty* property = nsSVGEffects::GetPaintingPropertyForURI(
          targetURI, mForFrame->FirstContinuation(),
          nsSVGEffects::BackgroundImageProperty());
      if (!property) {
        mPrepareResult = DrawResult::BAD_IMAGE;
        return false;
      }

      // If the referenced element is an <img>, <canvas>, or <video> element,
      // prefer SurfaceFromElement as it's more reliable.
      mImageElementSurface =
        nsLayoutUtils::SurfaceFromElement(property->GetReferencedElement());
      if (!mImageElementSurface.GetSourceSurface()) {
        nsIFrame* paintServerFrame = property->GetReferencedFrame();
        // If there's no referenced frame, or the referenced frame is
        // non-displayable SVG, then we have nothing valid to paint.
        if (!paintServerFrame ||
            (paintServerFrame->IsFrameOfType(nsIFrame::eSVG) &&
             !paintServerFrame->IsFrameOfType(nsIFrame::eSVGPaintServer) &&
             !static_cast<nsISVGChildFrame*>(do_QueryFrame(paintServerFrame)))) {
          mPrepareResult = DrawResult::BAD_IMAGE;
          return false;
        }
        mPaintServerFrame = paintServerFrame;
      }

      mPrepareResult = DrawResult::SUCCESS;
      break;
    }
    case eStyleImageType_Null:
    default:
      break;
  }

  return IsReady();
}

nsSize
CSSSizeOrRatio::ComputeConcreteSize() const
{
  NS_ASSERTION(CanComputeConcreteSize(), "Cannot compute");
  if (mHasWidth && mHasHeight) {
    return nsSize(mWidth, mHeight);
  }
  if (mHasWidth) {
    return nsSize(mWidth, mRatio.Inverted().ApplyTo(mWidth));
  }

  MOZ_ASSERT(mHasHeight);
  return nsSize(mRatio.ApplyTo(mHeight), mHeight);
}

CSSSizeOrRatio
nsImageRenderer::ComputeIntrinsicSize()
{
  NS_ASSERTION(IsReady(), "Ensure PrepareImage() has returned true "
                          "before calling me");

  CSSSizeOrRatio result;
  switch (mType) {
    case eStyleImageType_Image:
    {
      bool haveWidth, haveHeight;
      CSSIntSize imageIntSize;
      nsLayoutUtils::ComputeSizeForDrawing(mImageContainer, imageIntSize,
                                           result.mRatio, haveWidth, haveHeight);
      if (haveWidth) {
        result.SetWidth(nsPresContext::CSSPixelsToAppUnits(imageIntSize.width));
      }
      if (haveHeight) {
        result.SetHeight(nsPresContext::CSSPixelsToAppUnits(imageIntSize.height));
      }

      if (!haveHeight && haveWidth && result.mRatio) {
        nscoord intrinsicHeight =
            result.mRatio.Inverted().ApplyTo(imageIntSize.width);
        result.SetHeight(nsPresContext::CSSPixelsToAppUnits(intrinsicHeight));
      } else if (haveHeight && !haveWidth && result.mRatio) {
        nscoord intrinsicWidth = result.mRatio.ApplyTo(imageIntSize.height);
        result.SetWidth(nsPresContext::CSSPixelsToAppUnits(intrinsicWidth));
      }

      break;
    }
    case eStyleImageType_Element:
    {
      // XXX element() should have the width/height of the referenced element,
      //     and that element's ratio, if it matches.  If it doesn't match, it
      //     should have no width/height or ratio.  See element() in CSS images:
      //     <http://dev.w3.org/csswg/css-images-4/#element-notation>.
      //     Make sure to change nsStyleImageLayers::Size::DependsOnFrameSize
      //     when fixing this!
      if (mPaintServerFrame) {
        // SVG images have no intrinsic size
        if (!mPaintServerFrame->IsFrameOfType(nsIFrame::eSVG)) {
          // The intrinsic image size for a generic nsIFrame paint server is
          // the union of the border-box rects of all of its continuations,
          // rounded to device pixels.
          int32_t appUnitsPerDevPixel =
            mForFrame->PresContext()->AppUnitsPerDevPixel();
          result.SetSize(
            IntSizeToAppUnits(
              nsSVGIntegrationUtils::GetContinuationUnionSize(mPaintServerFrame).
                ToNearestPixels(appUnitsPerDevPixel),
              appUnitsPerDevPixel));
        }
      } else {
        NS_ASSERTION(mImageElementSurface.GetSourceSurface(),
                     "Surface should be ready.");
        IntSize surfaceSize = mImageElementSurface.mSize;
        result.SetSize(
          nsSize(nsPresContext::CSSPixelsToAppUnits(surfaceSize.width),
                 nsPresContext::CSSPixelsToAppUnits(surfaceSize.height)));
      }
      break;
    }
    case eStyleImageType_Gradient:
      // Per <http://dev.w3.org/csswg/css3-images/#gradients>, gradients have no
      // intrinsic dimensions.
    case eStyleImageType_Null:
    default:
      break;
  }

  return result;
}

/* static */ nsSize
nsImageRenderer::ComputeConcreteSize(const CSSSizeOrRatio& aSpecifiedSize,
                                     const CSSSizeOrRatio& aIntrinsicSize,
                                     const nsSize& aDefaultSize)
{
  // The specified size is fully specified, just use that
  if (aSpecifiedSize.IsConcrete()) {
    return aSpecifiedSize.ComputeConcreteSize();
  }

  MOZ_ASSERT(!aSpecifiedSize.mHasWidth || !aSpecifiedSize.mHasHeight);

  if (!aSpecifiedSize.mHasWidth && !aSpecifiedSize.mHasHeight) {
    // no specified size, try using the intrinsic size
    if (aIntrinsicSize.CanComputeConcreteSize()) {
      return aIntrinsicSize.ComputeConcreteSize();
    }

    if (aIntrinsicSize.mHasWidth) {
      return nsSize(aIntrinsicSize.mWidth, aDefaultSize.height);
    }
    if (aIntrinsicSize.mHasHeight) {
      return nsSize(aDefaultSize.width, aIntrinsicSize.mHeight);
    }

    // couldn't use the intrinsic size either, revert to using the default size
    return ComputeConstrainedSize(aDefaultSize,
                                  aIntrinsicSize.mRatio,
                                  CONTAIN);
  }

  MOZ_ASSERT(aSpecifiedSize.mHasWidth || aSpecifiedSize.mHasHeight);

  // The specified height is partial, try to compute the missing part.
  if (aSpecifiedSize.mHasWidth) {
    nscoord height;
    if (aIntrinsicSize.HasRatio()) {
      height = aIntrinsicSize.mRatio.Inverted().ApplyTo(aSpecifiedSize.mWidth);
    } else if (aIntrinsicSize.mHasHeight) {
      height = aIntrinsicSize.mHeight;
    } else {
      height = aDefaultSize.height;
    }
    return nsSize(aSpecifiedSize.mWidth, height);
  }

  MOZ_ASSERT(aSpecifiedSize.mHasHeight);
  nscoord width;
  if (aIntrinsicSize.HasRatio()) {
    width = aIntrinsicSize.mRatio.ApplyTo(aSpecifiedSize.mHeight);
  } else if (aIntrinsicSize.mHasWidth) {
    width = aIntrinsicSize.mWidth;
  } else {
    width = aDefaultSize.width;
  }
  return nsSize(width, aSpecifiedSize.mHeight);
}

/* static */ nsSize
nsImageRenderer::ComputeConstrainedSize(const nsSize& aConstrainingSize,
                                        const AspectRatio& aIntrinsicRatio,
                                        FitType aFitType)
{
  if (!aIntrinsicRatio) {
    return aConstrainingSize;
  }

  // Suppose we're doing a "contain" fit. If the image's aspect ratio has a
  // "fatter" shape than the constraint area, then we need to use the
  // constraint area's full width, and we need to use the aspect ratio to
  // produce a height. ON the other hand, if the aspect ratio is "skinnier", we
  // use the constraint area's full height, and we use the aspect ratio to
  // produce a width. (If instead we're doing a "cover" fit, then it can easily
  // be seen that we should do precisely the opposite.)
  //
  // This is equivalent to the more descriptive alternative:
  //
  //   AspectRatio::FromSize(aConstrainingSize) < aIntrinsicRatio
  //
  // But gracefully handling the case where one of the two dimensions from
  // aConstrainingSize is zero. This is easy to prove since:
  //
  //   aConstrainingSize.width / aConstrainingSize.height < aIntrinsicRatio
  //
  // Is trivially equivalent to:
  //
  //   aIntrinsicRatio.width < aIntrinsicRatio * aConstrainingSize.height
  //
  // For the cases where height is not zero.
  //
  // We use float math here to avoid losing precision for very lareg backgrounds
  // since we use saturating nscoord math otherwise.
  const float constraintWidth = float(aConstrainingSize.width);
  const float hypotheticalWidth =
      aIntrinsicRatio.ApplyToFloat(aConstrainingSize.height);

  nsSize size;
  if ((aFitType == CONTAIN) == (constraintWidth < hypotheticalWidth)) {
    size.width = aConstrainingSize.width;
    size.height = aIntrinsicRatio.Inverted().ApplyTo(aConstrainingSize.width);
    // If we're reducing the size by less than one css pixel, then just use the
    // constraining size.
    if (aFitType == CONTAIN && aConstrainingSize.height - size.height < nsPresContext::AppUnitsPerCSSPixel()) {
      size.height = aConstrainingSize.height;
    }
  } else {
    size.height = aConstrainingSize.height;
    size.width = aIntrinsicRatio.ApplyTo(aConstrainingSize.height);
    if (aFitType == CONTAIN && aConstrainingSize.width - size.width < nsPresContext::AppUnitsPerCSSPixel()) {
      size.width = aConstrainingSize.width;
    }
  }
  return size;
}

/**
 * mSize is the image's "preferred" size for this particular rendering, while
 * the drawn (aka concrete) size is the actual rendered size after accounting
 * for background-size etc..  The preferred size is most often the image's
 * intrinsic dimensions.  But for images with incomplete intrinsic dimensions,
 * the preferred size varies, depending on the specified and default sizes, see
 * nsImageRenderer::Compute*Size.
 *
 * This distinction is necessary because the components of a vector image are
 * specified with respect to its preferred size for a rendering situation, not
 * to its actual rendered size.  For example, consider a 4px wide background
 * vector image with no height which contains a left-aligned
 * 2px wide black rectangle with height 100%.  If the background-size width is
 * auto (or 4px), the vector image will render 4px wide, and the black rectangle
 * will be 2px wide.  If the background-size width is 8px, the vector image will
 * render 8px wide, and the black rectangle will be 4px wide -- *not* 2px wide.
 * In both cases mSize.width will be 4px; but in the first case the returned
 * width will be 4px, while in the second case the returned width will be 8px.
 */
void
nsImageRenderer::SetPreferredSize(const CSSSizeOrRatio& aIntrinsicSize,
                                  const nsSize& aDefaultSize)
{
  mSize.width = aIntrinsicSize.mHasWidth
                  ? aIntrinsicSize.mWidth
                  : aDefaultSize.width;
  mSize.height = aIntrinsicSize.mHasHeight
                  ? aIntrinsicSize.mHeight
                  : aDefaultSize.height;
}

// Convert from nsImageRenderer flags to the flags we want to use for drawing in
// the imgIContainer namespace.
static uint32_t
ConvertImageRendererToDrawFlags(uint32_t aImageRendererFlags)
{
  uint32_t drawFlags = imgIContainer::FLAG_NONE;
  if (aImageRendererFlags & nsImageRenderer::FLAG_SYNC_DECODE_IMAGES) {
    drawFlags |= imgIContainer::FLAG_SYNC_DECODE;
  }
  if (aImageRendererFlags & nsImageRenderer::FLAG_PAINTING_TO_WINDOW) {
    drawFlags |= imgIContainer::FLAG_HIGH_QUALITY_SCALING;
  }
  return drawFlags;
}

/*
 *  SVG11: A luminanceToAlpha operation is equivalent to the following matrix operation:                                                   |
 *  | R' |     |      0        0        0  0  0 |   | R |
 *  | G' |     |      0        0        0  0  0 |   | G |
 *  | B' |  =  |      0        0        0  0  0 | * | B |
 *  | A' |     | 0.2125   0.7154   0.0721  0  0 |   | A |
 *  | 1  |     |      0        0        0  0  1 |   | 1 |
 */
static void
RGBALuminanceOperation(uint8_t *aData,
                       int32_t aStride,
                       const IntSize &aSize)
{
  int32_t redFactor = 55;    // 256 * 0.2125
  int32_t greenFactor = 183; // 256 * 0.7154
  int32_t blueFactor = 18;   // 256 * 0.0721

  for (int32_t y = 0; y < aSize.height; y++) {
    uint32_t *pixel = (uint32_t*)(aData + aStride * y);
    for (int32_t x = 0; x < aSize.width; x++) {
      *pixel = (((((*pixel & 0x00FF0000) >> 16) * redFactor) +
                 (((*pixel & 0x0000FF00) >>  8) * greenFactor) +
                  ((*pixel & 0x000000FF)        * blueFactor)) >> 8) << 24;
      pixel++;
    }
  }
}


DrawResult
nsImageRenderer::Draw(nsPresContext*       aPresContext,
                      nsRenderingContext&  aRenderingContext,
                      const nsRect&        aDirtyRect,
                      const nsRect&        aDest,
                      const nsRect&        aFill,
                      const nsPoint&       aAnchor,
                      const nsSize&        aRepeatSize,
                      const CSSIntRect&    aSrc)
{
  if (!IsReady()) {
    NS_NOTREACHED("Ensure PrepareImage() has returned true before calling me");
    return DrawResult::TEMPORARY_ERROR;
  }
  if (aDest.IsEmpty() || aFill.IsEmpty() ||
      mSize.width <= 0 || mSize.height <= 0) {
    return DrawResult::SUCCESS;
  }

  SamplingFilter samplingFilter = nsLayoutUtils::GetSamplingFilterForFrame(mForFrame);
  DrawResult result = DrawResult::SUCCESS;
  RefPtr<gfxContext> ctx = aRenderingContext.ThebesContext();
  IntRect tmpDTRect;

  if (ctx->CurrentOp() != CompositionOp::OP_OVER || mMaskOp == NS_STYLE_MASK_MODE_LUMINANCE) {
    gfxRect clipRect = ctx->GetClipExtents();
    tmpDTRect = RoundedOut(ToRect(clipRect));
    if (tmpDTRect.IsEmpty()) {
      return DrawResult::SUCCESS;
    }
    RefPtr<DrawTarget> tempDT =
      gfxPlatform::GetPlatform()->CreateSimilarSoftwareDrawTarget(ctx->GetDrawTarget(),
                                                                  tmpDTRect.Size(),
                                                                  SurfaceFormat::B8G8R8A8);
    if (!tempDT || !tempDT->IsValid()) {
      gfxDevCrash(LogReason::InvalidContext) << "ImageRenderer::Draw problem " << gfx::hexa(tempDT);
      return DrawResult::TEMPORARY_ERROR;
    }
    tempDT->SetTransform(Matrix::Translation(-tmpDTRect.TopLeft()));
    ctx = gfxContext::CreatePreservingTransformOrNull(tempDT);
    if (!ctx) {
      gfxDevCrash(LogReason::InvalidContext) << "ImageRenderer::Draw problem " << gfx::hexa(tempDT);
      return DrawResult::TEMPORARY_ERROR;
    }
  }

  switch (mType) {
    case eStyleImageType_Image:
    {
      CSSIntSize imageSize(nsPresContext::AppUnitsToIntCSSPixels(mSize.width),
                           nsPresContext::AppUnitsToIntCSSPixels(mSize.height));
      result =
        nsLayoutUtils::DrawBackgroundImage(*ctx,
                                           aPresContext,
                                           mImageContainer, imageSize,
                                           samplingFilter,
                                           aDest, aFill, aRepeatSize,
                                           aAnchor, aDirtyRect,
                                           ConvertImageRendererToDrawFlags(mFlags),
                                           mExtendMode);
      break;
    }
    case eStyleImageType_Gradient:
    {
      nsCSSRendering::PaintGradient(aPresContext, aRenderingContext,
                                    mGradientData, aDirtyRect,
                                    aDest, aFill, aRepeatSize, aSrc, mSize);
      break;
    }
    case eStyleImageType_Element:
    {
      RefPtr<gfxDrawable> drawable = DrawableForElement(aDest,
                                                          aRenderingContext);
      if (!drawable) {
        NS_WARNING("Could not create drawable for element");
        return DrawResult::TEMPORARY_ERROR;
      }

      nsCOMPtr<imgIContainer> image(ImageOps::CreateFromDrawable(drawable));
      result =
        nsLayoutUtils::DrawImage(*ctx,
                                 aPresContext, image,
                                 samplingFilter, aDest, aFill, aAnchor, aDirtyRect,
                                 ConvertImageRendererToDrawFlags(mFlags));
      break;
    }
    case eStyleImageType_Null:
    default:
      break;
  }

  if (!tmpDTRect.IsEmpty()) {
    RefPtr<SourceSurface> surf = ctx->GetDrawTarget()->Snapshot();
    if (mMaskOp == NS_STYLE_MASK_MODE_LUMINANCE) {
      RefPtr<DataSourceSurface> maskData = surf->GetDataSurface();
      DataSourceSurface::MappedSurface map;
      if (!maskData->Map(DataSourceSurface::MapType::WRITE, &map)) {
        return result;
      }

      RGBALuminanceOperation(map.mData, map.mStride, maskData->GetSize());
      maskData->Unmap();
      surf = maskData;
    }

    DrawTarget* dt = aRenderingContext.ThebesContext()->GetDrawTarget();
    dt->DrawSurface(surf, Rect(tmpDTRect.x, tmpDTRect.y, tmpDTRect.width, tmpDTRect.height),
                    Rect(0, 0, tmpDTRect.width, tmpDTRect.height),
                    DrawSurfaceOptions(SamplingFilter::POINT),
                    DrawOptions(1.0f, aRenderingContext.ThebesContext()->CurrentOp()));
  }

  return result;
}

already_AddRefed<gfxDrawable>
nsImageRenderer::DrawableForElement(const nsRect& aImageRect,
                                    nsRenderingContext&  aRenderingContext)
{
  NS_ASSERTION(mType == eStyleImageType_Element,
               "DrawableForElement only makes sense if backed by an element");
  if (mPaintServerFrame) {
    // XXX(seth): In order to not pass FLAG_SYNC_DECODE_IMAGES here,
    // DrawableFromPaintServer would have to return a DrawResult indicating
    // whether any images could not be painted because they weren't fully
    // decoded. Even always passing FLAG_SYNC_DECODE_IMAGES won't eliminate all
    // problems, as it won't help if there are image which haven't finished
    // loading, but it's better than nothing.
    int32_t appUnitsPerDevPixel = mForFrame->PresContext()->AppUnitsPerDevPixel();
    nsRect destRect = aImageRect - aImageRect.TopLeft();
    nsIntSize roundedOut = destRect.ToOutsidePixels(appUnitsPerDevPixel).Size();
    IntSize imageSize(roundedOut.width, roundedOut.height);
    RefPtr<gfxDrawable> drawable =
      nsSVGIntegrationUtils::DrawableFromPaintServer(
        mPaintServerFrame, mForFrame, mSize, imageSize,
        aRenderingContext.GetDrawTarget(),
        aRenderingContext.ThebesContext()->CurrentMatrix(),
        nsSVGIntegrationUtils::FLAG_SYNC_DECODE_IMAGES);

    return drawable.forget();
  }
  NS_ASSERTION(mImageElementSurface.GetSourceSurface(), "Surface should be ready.");
  RefPtr<gfxDrawable> drawable = new gfxSurfaceDrawable(
                                mImageElementSurface.GetSourceSurface().get(),
                                mImageElementSurface.mSize);
  return drawable.forget();
}

DrawResult
nsImageRenderer::DrawBackground(nsPresContext*       aPresContext,
                                nsRenderingContext&  aRenderingContext,
                                const nsRect&        aDest,
                                const nsRect&        aFill,
                                const nsPoint&       aAnchor,
                                const nsRect&        aDirty,
                                const nsSize&        aRepeatSize)
{
  if (!IsReady()) {
    NS_NOTREACHED("Ensure PrepareImage() has returned true before calling me");
    return DrawResult::TEMPORARY_ERROR;
  }
  if (aDest.IsEmpty() || aFill.IsEmpty() ||
      mSize.width <= 0 || mSize.height <= 0) {
    return DrawResult::SUCCESS;
  }

  return Draw(aPresContext, aRenderingContext,
              aDirty, aDest, aFill, aAnchor, aRepeatSize,
              CSSIntRect(0, 0,
                         nsPresContext::AppUnitsToIntCSSPixels(mSize.width),
                         nsPresContext::AppUnitsToIntCSSPixels(mSize.height)));
}

/**
 * Compute the size and position of the master copy of the image. I.e., a single
 * tile used to fill the dest rect.
 * aFill The destination rect to be filled
 * aHFill and aVFill are the repeat patterns for the component -
 * NS_STYLE_BORDER_IMAGE_REPEAT_* - i.e., how a tiling unit is used to fill aFill
 * aUnitSize The size of the source rect in dest coords.
 */
static nsRect
ComputeTile(nsRect&              aFill,
            uint8_t              aHFill,
            uint8_t              aVFill,
            const nsSize&        aUnitSize,
            nsSize&              aRepeatSize)
{
  nsRect tile;
  switch (aHFill) {
  case NS_STYLE_BORDER_IMAGE_REPEAT_STRETCH:
    tile.x = aFill.x;
    tile.width = aFill.width;
    aRepeatSize.width = tile.width;
    break;
  case NS_STYLE_BORDER_IMAGE_REPEAT_REPEAT:
    tile.x = aFill.x + aFill.width/2 - aUnitSize.width/2;
    tile.width = aUnitSize.width;
    aRepeatSize.width = tile.width;
    break;
  case NS_STYLE_BORDER_IMAGE_REPEAT_ROUND:
    tile.x = aFill.x;
    tile.width = ComputeRoundedSize(aUnitSize.width, aFill.width);
    aRepeatSize.width = tile.width;
    break;
  case NS_STYLE_BORDER_IMAGE_REPEAT_SPACE:
    {
      nscoord space;
      aRepeatSize.width =
        ComputeBorderSpacedRepeatSize(aUnitSize.width, aFill.width, space);
      tile.x = aFill.x + space;
      tile.width = aUnitSize.width;
      aFill.x = tile.x;
      aFill.width = aFill.width - space * 2;
    }
    break;
  default:
    NS_NOTREACHED("unrecognized border-image fill style");
  }

  switch (aVFill) {
  case NS_STYLE_BORDER_IMAGE_REPEAT_STRETCH:
    tile.y = aFill.y;
    tile.height = aFill.height;
    aRepeatSize.height = tile.height;
    break;
  case NS_STYLE_BORDER_IMAGE_REPEAT_REPEAT:
    tile.y = aFill.y + aFill.height/2 - aUnitSize.height/2;
    tile.height = aUnitSize.height;
    aRepeatSize.height = tile.height;
    break;
  case NS_STYLE_BORDER_IMAGE_REPEAT_ROUND:
    tile.y = aFill.y;
    tile.height = ComputeRoundedSize(aUnitSize.height, aFill.height);
    aRepeatSize.height = tile.height;
    break;
  case NS_STYLE_BORDER_IMAGE_REPEAT_SPACE:
    {
      nscoord space;
      aRepeatSize.height =
        ComputeBorderSpacedRepeatSize(aUnitSize.height, aFill.height, space);
      tile.y = aFill.y + space;
      tile.height = aUnitSize.height;
      aFill.y = tile.y;
      aFill.height = aFill.height - space * 2;
    }
    break;
  default:
    NS_NOTREACHED("unrecognized border-image fill style");
  }

  return tile;
}

/**
 * Returns true if the given set of arguments will require the tiles which fill
 * the dest rect to be scaled from the source tile. See comment on ComputeTile
 * for argument descriptions.
 */
static bool
RequiresScaling(const nsRect&        aFill,
                uint8_t              aHFill,
                uint8_t              aVFill,
                const nsSize&        aUnitSize)
{
  // If we have no tiling in either direction, we can skip the intermediate
  // scaling step.
  return (aHFill != NS_STYLE_BORDER_IMAGE_REPEAT_STRETCH ||
          aVFill != NS_STYLE_BORDER_IMAGE_REPEAT_STRETCH) &&
         (aUnitSize.width != aFill.width ||
          aUnitSize.height != aFill.height);
}

DrawResult
nsImageRenderer::DrawBorderImageComponent(nsPresContext*       aPresContext,
                                          nsRenderingContext&  aRenderingContext,
                                          const nsRect&        aDirtyRect,
                                          const nsRect&        aFill,
                                          const CSSIntRect&    aSrc,
                                          uint8_t              aHFill,
                                          uint8_t              aVFill,
                                          const nsSize&        aUnitSize,
                                          uint8_t              aIndex,
                                          const Maybe<nsSize>& aSVGViewportSize,
                                          const bool           aHasIntrinsicRatio)
{
  if (!IsReady()) {
    NS_NOTREACHED("Ensure PrepareImage() has returned true before calling me");
    return DrawResult::BAD_ARGS;
  }
  if (aFill.IsEmpty() || aSrc.IsEmpty()) {
    return DrawResult::SUCCESS;
  }

  if (mType == eStyleImageType_Image || mType == eStyleImageType_Element) {
    nsCOMPtr<imgIContainer> subImage;

    // To draw one portion of an image into a border component, we stretch that
    // portion to match the size of that border component and then draw onto.
    // However, preserveAspectRatio attribute of a SVG image may break this rule.
    // To get correct rendering result, we add
    // FLAG_FORCE_PRESERVEASPECTRATIO_NONE flag here, to tell mImage to ignore
    // preserveAspectRatio attribute, and always do non-uniform stretch.
    uint32_t drawFlags = ConvertImageRendererToDrawFlags(mFlags) |
                           imgIContainer::FLAG_FORCE_PRESERVEASPECTRATIO_NONE;
    // For those SVG image sources which don't have fixed aspect ratio (i.e.
    // without viewport size and viewBox), we should scale the source uniformly
    // after the viewport size is decided by "Default Sizing Algorithm".
    if (!aHasIntrinsicRatio) {
      drawFlags = drawFlags | imgIContainer::FLAG_FORCE_UNIFORM_SCALING;
    }
    // Retrieve or create the subimage we'll draw.
    nsIntRect srcRect(aSrc.x, aSrc.y, aSrc.width, aSrc.height);
    if (mType == eStyleImageType_Image) {
      if ((subImage = mImage->GetSubImage(aIndex)) == nullptr) {
        subImage = ImageOps::Clip(mImageContainer, srcRect, aSVGViewportSize);
        mImage->SetSubImage(aIndex, subImage);
      }
    } else {
      // This path, for eStyleImageType_Element, is currently slower than it
      // needs to be because we don't cache anything. (In particular, if we have
      // to draw to a temporary surface inside ClippedImage, we don't cache that
      // temporary surface since we immediately throw the ClippedImage we create
      // here away.) However, if we did cache, we'd need to know when to
      // invalidate that cache, and it's not clear that it's worth the trouble
      // since using border-image with -moz-element is rare.

      RefPtr<gfxDrawable> drawable = DrawableForElement(nsRect(nsPoint(), mSize),
                                                          aRenderingContext);
      if (!drawable) {
        NS_WARNING("Could not create drawable for element");
        return DrawResult::TEMPORARY_ERROR;
      }

      nsCOMPtr<imgIContainer> image(ImageOps::CreateFromDrawable(drawable));
      subImage = ImageOps::Clip(image, srcRect, aSVGViewportSize);
    }

    MOZ_ASSERT_IF(aSVGViewportSize,
                  subImage->GetType() == imgIContainer::TYPE_VECTOR);

    SamplingFilter samplingFilter = nsLayoutUtils::GetSamplingFilterForFrame(mForFrame);

    if (!RequiresScaling(aFill, aHFill, aVFill, aUnitSize)) {
      return nsLayoutUtils::DrawSingleImage(*aRenderingContext.ThebesContext(),
                                            aPresContext,
                                            subImage,
                                            samplingFilter,
                                            aFill, aDirtyRect,
                                            nullptr,
                                            drawFlags);
    }

    nsSize repeatSize;
    nsRect fillRect(aFill);
    nsRect tile = ComputeTile(fillRect, aHFill, aVFill, aUnitSize, repeatSize);
    CSSIntSize imageSize(srcRect.width, srcRect.height);
    return nsLayoutUtils::DrawBackgroundImage(*aRenderingContext.ThebesContext(),
                                              aPresContext,
                                              subImage, imageSize, samplingFilter,
                                              tile, fillRect, repeatSize,
                                              tile.TopLeft(), aDirtyRect,
                                              drawFlags,
                                              ExtendMode::CLAMP);
  }

  nsSize repeatSize(aFill.Size());
  nsRect fillRect(aFill);
  nsRect destTile = RequiresScaling(fillRect, aHFill, aVFill, aUnitSize)
                  ? ComputeTile(fillRect, aHFill, aVFill, aUnitSize, repeatSize)
                  : fillRect;
  return Draw(aPresContext, aRenderingContext, aDirtyRect, destTile,
              fillRect, destTile.TopLeft(), repeatSize, aSrc);
}

bool
nsImageRenderer::IsRasterImage()
{
  if (mType != eStyleImageType_Image || !mImageContainer)
    return false;
  return mImageContainer->GetType() == imgIContainer::TYPE_RASTER;
}

bool
nsImageRenderer::IsAnimatedImage()
{
  if (mType != eStyleImageType_Image || !mImageContainer)
    return false;
  bool animated = false;
  if (NS_SUCCEEDED(mImageContainer->GetAnimated(&animated)) && animated)
    return true;

  return false;
}

already_AddRefed<imgIContainer>
nsImageRenderer::GetImage()
{
  if (mType != eStyleImageType_Image || !mImageContainer) {
    return nullptr;
  }

  nsCOMPtr<imgIContainer> image = mImageContainer;
  return image.forget();
}

void
nsImageRenderer::PurgeCacheForViewportChange(
  const Maybe<nsSize>& aSVGViewportSize, const bool aHasIntrinsicRatio)
{
  // Check if we should flush the cached data - only vector images need to do
  // the check since they might not have fixed ratio.
  if (mImageContainer &&
      mImageContainer->GetType() == imgIContainer::TYPE_VECTOR) {
    mImage->PurgeCacheForViewportChange(aSVGViewportSize, aHasIntrinsicRatio);
  }
}

#define MAX_BLUR_RADIUS 300
#define MAX_SPREAD_RADIUS 50

static inline gfxPoint ComputeBlurStdDev(nscoord aBlurRadius,
                                         int32_t aAppUnitsPerDevPixel,
                                         gfxFloat aScaleX,
                                         gfxFloat aScaleY)
{
  // http://dev.w3.org/csswg/css3-background/#box-shadow says that the
  // standard deviation of the blur should be half the given blur value.
  gfxFloat blurStdDev = gfxFloat(aBlurRadius) / gfxFloat(aAppUnitsPerDevPixel);

  return gfxPoint(std::min((blurStdDev * aScaleX),
                           gfxFloat(MAX_BLUR_RADIUS)) / 2.0,
                  std::min((blurStdDev * aScaleY),
                           gfxFloat(MAX_BLUR_RADIUS)) / 2.0);
}

static inline IntSize
ComputeBlurRadius(nscoord aBlurRadius,
                  int32_t aAppUnitsPerDevPixel,
                  gfxFloat aScaleX = 1.0,
                  gfxFloat aScaleY = 1.0)
{
  gfxPoint scaledBlurStdDev = ComputeBlurStdDev(aBlurRadius, aAppUnitsPerDevPixel,
                                                aScaleX, aScaleY);
  return
    gfxAlphaBoxBlur::CalculateBlurRadius(scaledBlurStdDev);
}

// -----
// nsContextBoxBlur
// -----
gfxContext*
nsContextBoxBlur::Init(const nsRect& aRect, nscoord aSpreadRadius,
                       nscoord aBlurRadius,
                       int32_t aAppUnitsPerDevPixel,
                       gfxContext* aDestinationCtx,
                       const nsRect& aDirtyRect,
                       const gfxRect* aSkipRect,
                       uint32_t aFlags)
{
  if (aRect.IsEmpty()) {
    mContext = nullptr;
    return nullptr;
  }

  IntSize blurRadius;
  IntSize spreadRadius;
  GetBlurAndSpreadRadius(aDestinationCtx->GetDrawTarget(), aAppUnitsPerDevPixel,
                         aBlurRadius, aSpreadRadius,
                         blurRadius, spreadRadius);

  mDestinationCtx = aDestinationCtx;

  // If not blurring, draw directly onto the destination device
  if (blurRadius.width <= 0 && blurRadius.height <= 0 &&
      spreadRadius.width <= 0 && spreadRadius.height <= 0 &&
      !(aFlags & FORCE_MASK)) {
    mContext = aDestinationCtx;
    return mContext;
  }

  // Convert from app units to device pixels
  gfxRect rect = nsLayoutUtils::RectToGfxRect(aRect, aAppUnitsPerDevPixel);

  gfxRect dirtyRect =
    nsLayoutUtils::RectToGfxRect(aDirtyRect, aAppUnitsPerDevPixel);
  dirtyRect.RoundOut();

  gfxMatrix transform = aDestinationCtx->CurrentMatrix();
  rect = transform.TransformBounds(rect);

  mPreTransformed = !transform.IsIdentity();

  // Create the temporary surface for blurring
  dirtyRect = transform.TransformBounds(dirtyRect);
  if (aSkipRect) {
    gfxRect skipRect = transform.TransformBounds(*aSkipRect);
    mContext = mAlphaBoxBlur.Init(aDestinationCtx, rect, spreadRadius,
                                  blurRadius, &dirtyRect, &skipRect);
  } else {
    mContext = mAlphaBoxBlur.Init(aDestinationCtx, rect, spreadRadius,
                                  blurRadius, &dirtyRect, nullptr);
  }

  if (mContext) {
    // we don't need to blur if skipRect is equal to rect
    // and mContext will be nullptr
    mContext->Multiply(transform);
  }
  return mContext;
}

void
nsContextBoxBlur::DoPaint()
{
  if (mContext == mDestinationCtx) {
    return;
  }

  gfxContextMatrixAutoSaveRestore saveMatrix(mDestinationCtx);

  if (mPreTransformed) {
    mDestinationCtx->SetMatrix(gfxMatrix());
  }

  mAlphaBoxBlur.Paint(mDestinationCtx);
}

gfxContext*
nsContextBoxBlur::GetContext()
{
  return mContext;
}

/* static */ nsMargin
nsContextBoxBlur::GetBlurRadiusMargin(nscoord aBlurRadius,
                                      int32_t aAppUnitsPerDevPixel)
{
  IntSize blurRadius = ComputeBlurRadius(aBlurRadius, aAppUnitsPerDevPixel);

  nsMargin result;
  result.top = result.bottom = blurRadius.height * aAppUnitsPerDevPixel;
  result.left = result.right = blurRadius.width  * aAppUnitsPerDevPixel;
  return result;
}

/* static */ void
nsContextBoxBlur::BlurRectangle(gfxContext* aDestinationCtx,
                                const nsRect& aRect,
                                int32_t aAppUnitsPerDevPixel,
                                RectCornerRadii* aCornerRadii,
                                nscoord aBlurRadius,
                                const Color& aShadowColor,
                                const nsRect& aDirtyRect,
                                const gfxRect& aSkipRect)
{
  DrawTarget& aDestDrawTarget = *aDestinationCtx->GetDrawTarget();

  if (aRect.IsEmpty()) {
    return;
  }

  Rect shadowGfxRect = NSRectToRect(aRect, aAppUnitsPerDevPixel);

  if (aBlurRadius <= 0) {
    ColorPattern color(ToDeviceColor(aShadowColor));
    if (aCornerRadii) {
      RefPtr<Path> roundedRect = MakePathForRoundedRect(aDestDrawTarget,
                                                        shadowGfxRect,
                                                        *aCornerRadii);
      aDestDrawTarget.Fill(roundedRect, color);
    } else {
      aDestDrawTarget.FillRect(shadowGfxRect, color);
    }
    return;
  }

  gfxFloat scaleX = 1;
  gfxFloat scaleY = 1;

  // Do blurs in device space when possible.
  // Chrome/Skia always does the blurs in device space
  // and will sometimes get incorrect results (e.g. rotated blurs)
  gfxMatrix transform = aDestinationCtx->CurrentMatrix();
  // XXX: we could probably handle negative scales but for now it's easier just to fallback
  if (!transform.HasNonAxisAlignedTransform() && transform._11 > 0.0 && transform._22 > 0.0) {
    scaleX = transform._11;
    scaleY = transform._22;
    aDestinationCtx->SetMatrix(gfxMatrix());
  } else {
    transform = gfxMatrix();
  }

  gfxPoint blurStdDev = ComputeBlurStdDev(aBlurRadius, aAppUnitsPerDevPixel, scaleX, scaleY);

  gfxRect dirtyRect =
    nsLayoutUtils::RectToGfxRect(aDirtyRect, aAppUnitsPerDevPixel);
  dirtyRect.RoundOut();

  gfxRect shadowThebesRect = transform.TransformBounds(ThebesRect(shadowGfxRect));
  dirtyRect = transform.TransformBounds(dirtyRect);
  gfxRect skipRect = transform.TransformBounds(aSkipRect);

  if (aCornerRadii) {
    aCornerRadii->Scale(scaleX, scaleY);
  }

  gfxAlphaBoxBlur::BlurRectangle(aDestinationCtx,
                                 shadowThebesRect,
                                 aCornerRadii,
                                 blurStdDev,
                                 aShadowColor,
                                 dirtyRect,
                                 skipRect);
}

/* static */ void
nsContextBoxBlur::GetBlurAndSpreadRadius(DrawTarget* aDestDrawTarget,
                                         int32_t aAppUnitsPerDevPixel,
                                         nscoord aBlurRadius,
                                         nscoord aSpreadRadius,
                                         IntSize& aOutBlurRadius,
                                         IntSize& aOutSpreadRadius,
                                         bool aConstrainSpreadRadius)
{
  // Do blurs in device space when possible.
  // Chrome/Skia always does the blurs in device space
  // and will sometimes get incorrect results (e.g. rotated blurs)
  Matrix transform = aDestDrawTarget->GetTransform();
  // XXX: we could probably handle negative scales but for now it's easier just to fallback
  gfxFloat scaleX, scaleY;
  if (transform.HasNonAxisAlignedTransform() || transform._11 <= 0.0 || transform._22 <= 0.0) {
    scaleX = 1;
    scaleY = 1;
  } else {
    scaleX = transform._11;
    scaleY = transform._22;
  }

  // compute a large or smaller blur radius
  aOutBlurRadius = ComputeBlurRadius(aBlurRadius, aAppUnitsPerDevPixel, scaleX, scaleY);
  aOutSpreadRadius =
      IntSize(int32_t(aSpreadRadius * scaleX / aAppUnitsPerDevPixel),
              int32_t(aSpreadRadius * scaleY / aAppUnitsPerDevPixel));


  if (aConstrainSpreadRadius) {
    aOutSpreadRadius.width = std::min(aOutSpreadRadius.width, int32_t(MAX_SPREAD_RADIUS));
    aOutSpreadRadius.height = std::min(aOutSpreadRadius.height, int32_t(MAX_SPREAD_RADIUS));
  }
}

/* static */ bool
nsContextBoxBlur::InsetBoxBlur(gfxContext* aDestinationCtx,
                               Rect aDestinationRect,
                               Rect aShadowClipRect,
                               Color& aShadowColor,
                               nscoord aBlurRadiusAppUnits,
                               nscoord aSpreadDistanceAppUnits,
                               int32_t aAppUnitsPerDevPixel,
                               bool aHasBorderRadius,
                               RectCornerRadii& aInnerClipRectRadii,
                               Rect aSkipRect, Point aShadowOffset)
{
  if (aDestinationRect.IsEmpty()) {
    mContext = nullptr;
    return false;
  }

  gfxContextAutoSaveRestore autoRestore(aDestinationCtx);

  IntSize blurRadius;
  IntSize spreadRadius;
  // Convert the blur and spread radius to device pixels
  bool constrainSpreadRadius = false;
  GetBlurAndSpreadRadius(aDestinationCtx->GetDrawTarget(), aAppUnitsPerDevPixel,
                         aBlurRadiusAppUnits, aSpreadDistanceAppUnits,
                         blurRadius, spreadRadius, constrainSpreadRadius);

  // The blur and spread radius are scaled already, so scale all
  // input data to the blur. This way, we don't have to scale the min
  // inset blur to the invert of the dest context, then rescale it back
  // when we draw to the destination surface.
  gfxSize scale = aDestinationCtx->CurrentMatrix().ScaleFactors(true);
  Matrix transform = ToMatrix(aDestinationCtx->CurrentMatrix());

  // XXX: we could probably handle negative scales but for now it's easier just to fallback
  if (!transform.HasNonAxisAlignedTransform() && transform._11 > 0.0 && transform._22 > 0.0) {
    // If we don't have a rotation, we're pre-transforming all the rects.
    aDestinationCtx->SetMatrix(gfxMatrix());
  } else {
    // Don't touch anything, we have a rotation.
    transform = Matrix();
  }

  Rect transformedDestRect = transform.TransformBounds(aDestinationRect);
  Rect transformedShadowClipRect = transform.TransformBounds(aShadowClipRect);
  Rect transformedSkipRect = transform.TransformBounds(aSkipRect);

  transformedDestRect.Round();
  transformedShadowClipRect.Round();
  transformedSkipRect.RoundIn();

  for (size_t i = 0; i < 4; i++) {
    aInnerClipRectRadii[i].width = std::floor(scale.width * aInnerClipRectRadii[i].width);
    aInnerClipRectRadii[i].height = std::floor(scale.height * aInnerClipRectRadii[i].height);
  }

  mAlphaBoxBlur.BlurInsetBox(aDestinationCtx, transformedDestRect,
                             transformedShadowClipRect,
                             blurRadius, aShadowColor,
                             aHasBorderRadius ? &aInnerClipRectRadii : nullptr,
                             transformedSkipRect, aShadowOffset);
  return true;
}