summaryrefslogtreecommitdiff
path: root/gfx/thebes/gfxFont.h
blob: ab1677b9c594f7821a38bcf1bd190bdbc2935603 (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
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 * 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/. */

#ifndef GFX_FONT_H
#define GFX_FONT_H

#include "gfxTypes.h"
#include "gfxFontEntry.h"
#include "nsString.h"
#include "gfxPoint.h"
#include "gfxPattern.h"
#include "nsTArray.h"
#include "nsTHashtable.h"
#include "nsHashKeys.h"
#include "gfxRect.h"
#include "nsExpirationTracker.h"
#include "gfxPlatform.h"
#include "nsIAtom.h"
#include "mozilla/HashFunctions.h"
#include "nsIMemoryReporter.h"
#include "nsIObserver.h"
#include "mozilla/MemoryReporting.h"
#include "mozilla/Attributes.h"
#include <algorithm>
#include "DrawMode.h"
#include "nsDataHashtable.h"
#include "harfbuzz/hb.h"
#include "mozilla/gfx/2D.h"
#include "nsColor.h"

typedef struct _cairo cairo_t;
typedef struct _cairo_scaled_font cairo_scaled_font_t;
//typedef struct gr_face            gr_face;

#ifdef DEBUG
#include <stdio.h>
#endif

class gfxContext;
class gfxTextRun;
class gfxFont;
class gfxGlyphExtents;
class gfxShapedText;
class gfxShapedWord;
class gfxSkipChars;
class gfxMathTable;

// If you change this value, also change MAX_FONT_SIZE in cairo-ft-font.c to match
#define FONT_MAX_SIZE                  2000.0

#define NO_FONT_LANGUAGE_OVERRIDE      0

#define SMALL_CAPS_SCALE_FACTOR        0.8

// The skew factor used for synthetic-italic [oblique] fonts;
// we use a platform-dependent value to harmonize with the platform's own APIs.
#ifdef XP_WIN
#define OBLIQUE_SKEW_FACTOR  0.3
#elif defined(MOZ_WIDGET_GTK)
#define OBLIQUE_SKEW_FACTOR  0.2
#else
#define OBLIQUE_SKEW_FACTOR  0.25
#endif

struct gfxTextRunDrawCallbacks;

namespace mozilla {
class SVGContextPaint;
namespace gfx {
class GlyphRenderingOptions;
} // namespace gfx
} // namespace mozilla

struct gfxFontStyle {
    gfxFontStyle();
    gfxFontStyle(uint8_t aStyle, uint16_t aWeight, int16_t aStretch,
                 gfxFloat aSize, nsIAtom *aLanguage, bool aExplicitLanguage,
                 float aSizeAdjust, bool aSystemFont,
                 bool aPrinterFont,
                 bool aWeightSynthesis, bool aStyleSynthesis,
                 const nsString& aLanguageOverride);
    gfxFontStyle(const gfxFontStyle& aStyle);

    // the language (may be an internal langGroup code rather than an actual
    // language code) specified in the document or element's lang property,
    // or inferred from the charset
    RefPtr<nsIAtom> language;

    // Features are composed of (1) features from style rules (2) features
    // from feature setttings rules and (3) family-specific features.  (1) and
    // (3) are guaranteed to be mutually exclusive

    // custom opentype feature settings
    nsTArray<gfxFontFeature> featureSettings;

    // Some font-variant property values require font-specific settings
    // defined via @font-feature-values rules.  These are resolved after
    // font matching occurs.

    // -- list of value tags for specific alternate features
    nsTArray<gfxAlternateValue> alternateValues;

    // -- object used to look these up once the font is matched
    RefPtr<gfxFontFeatureValueSet> featureValueLookup;

    // The logical size of the font, in pixels
    gfxFloat size;

    // The aspect-value (ie., the ratio actualsize:actualxheight) that any
    // actual physical font created from this font structure must have when
    // rendering or measuring a string. A value of -1.0 means no adjustment
    // needs to be done; otherwise the value must be nonnegative.
    float sizeAdjust;

    // baseline offset, used when simulating sub/superscript glyphs
    float baselineOffset;

    // Language system tag, to override document language;
    // an OpenType "language system" tag represented as a 32-bit integer
    // (see http://www.microsoft.com/typography/otspec/languagetags.htm).
    // Normally 0, so font rendering will use the document or element language
    // (see above) to control any language-specific rendering, but the author
    // can override this for cases where the options implemented in the font
    // do not directly match the actual language. (E.g. lang may be Macedonian,
    // but the font in use does not explicitly support this; the author can
    // use font-language-override to request the Serbian option in the font
    // in order to get correct glyph shapes.)
    uint32_t languageOverride;

    // The weight of the font: 100, 200, ... 900.
    uint16_t weight;

    // The stretch of the font (the sum of various NS_FONT_STRETCH_*
    // constants; see gfxFontConstants.h).
    int8_t stretch;

    // Say that this font is a system font and therefore does not
    // require certain fixup that we do for fonts from untrusted
    // sources.
    bool systemFont : 1;

    // Say that this font is used for print or print preview.
    bool printerFont : 1;

    // Used to imitate -webkit-font-smoothing: antialiased
    bool useGrayscaleAntialiasing : 1;

    // The style of font (normal, italic, oblique)
    uint8_t style : 2;

    // Whether synthetic styles are allowed
    bool allowSyntheticWeight : 1;
    bool allowSyntheticStyle : 1;

    // some variant features require fallback which complicates the shaping
    // code, so set up a bool to indicate when shaping with fallback is needed
    bool noFallbackVariantFeatures : 1;

    // whether the |language| field comes from explicit lang tagging in the
    // document, or was inferred from charset/system locale
    bool explicitLanguage : 1;

    // caps variant (small-caps, petite-caps, etc.)
    uint8_t variantCaps;

    // sub/superscript variant
    uint8_t variantSubSuper;

    // Return the final adjusted font size for the given aspect ratio.
    // Not meant to be called when sizeAdjust = -1.0.
    gfxFloat GetAdjustedSize(gfxFloat aspect) const {
        NS_ASSERTION(sizeAdjust >= 0.0, "Not meant to be called when sizeAdjust = -1.0");
        gfxFloat adjustedSize = std::max(NS_round(size*(sizeAdjust/aspect)), 1.0);
        return std::min(adjustedSize, FONT_MAX_SIZE);
    }

    PLDHashNumber Hash() const {
        return ((style + (systemFont << 7) +
            (weight << 8)) + uint32_t(size*1000) + uint32_t(sizeAdjust*1000)) ^
            nsISupportsHashKey::HashKey(language);
    }

    int8_t ComputeWeight() const;

    // Adjust this style to simulate sub/superscript (as requested in the
    // variantSubSuper field) using size and baselineOffset instead.
    void AdjustForSubSuperscript(int32_t aAppUnitsPerDevPixel);

    bool Equals(const gfxFontStyle& other) const {
        return
            (*reinterpret_cast<const uint64_t*>(&size) ==
             *reinterpret_cast<const uint64_t*>(&other.size)) &&
            (style == other.style) &&
            (variantCaps == other.variantCaps) &&
            (variantSubSuper == other.variantSubSuper) &&
            (allowSyntheticWeight == other.allowSyntheticWeight) &&
            (allowSyntheticStyle == other.allowSyntheticStyle) &&
            (systemFont == other.systemFont) &&
            (printerFont == other.printerFont) &&
            (useGrayscaleAntialiasing == other.useGrayscaleAntialiasing) &&
            (explicitLanguage == other.explicitLanguage) &&
            (weight == other.weight) &&
            (stretch == other.stretch) &&
            (language == other.language) &&
            (baselineOffset == other.baselineOffset) &&
            (*reinterpret_cast<const uint32_t*>(&sizeAdjust) ==
             *reinterpret_cast<const uint32_t*>(&other.sizeAdjust)) &&
            (featureSettings == other.featureSettings) &&
            (languageOverride == other.languageOverride) &&
            (alternateValues == other.alternateValues) &&
            (featureValueLookup == other.featureValueLookup);
    }

    static void ParseFontFeatureSettings(const nsString& aFeatureString,
                                         nsTArray<gfxFontFeature>& aFeatures);

    static uint32_t ParseFontLanguageOverride(const nsString& aLangTag);
};

struct gfxTextRange {
    enum {
        // flags for recording the kind of font-matching that was used
        kFontGroup      = 0x0001,
        kPrefsFallback  = 0x0002,
        kSystemFallback = 0x0004
    };
    gfxTextRange(uint32_t aStart, uint32_t aEnd,
                 gfxFont* aFont, uint8_t aMatchType,
                 uint16_t aOrientation)
        : start(aStart),
          end(aEnd),
          font(aFont),
          matchType(aMatchType),
          orientation(aOrientation)
    { }
    uint32_t Length() const { return end - start; }
    uint32_t start, end;
    RefPtr<gfxFont> font;
    uint8_t matchType;
    uint16_t orientation;
};


/**
 * Font cache design:
 * 
 * The mFonts hashtable contains most fonts, indexed by (gfxFontEntry*, style).
 * It does not add a reference to the fonts it contains.
 * When a font's refcount decreases to zero, instead of deleting it we
 * add it to our expiration tracker.
 * The expiration tracker tracks fonts with zero refcount. After a certain
 * period of time, such fonts expire and are deleted.
 *
 * We're using 3 generations with a ten-second generation interval, so
 * zero-refcount fonts will be deleted 20-30 seconds after their refcount
 * goes to zero, if timer events fire in a timely manner.
 *
 * The font cache also handles timed expiration of cached ShapedWords
 * for "persistent" fonts: it has a repeating timer, and notifies
 * each cached font to "age" its shaped words. The words will be released
 * by the fonts if they get aged three times without being re-used in the
 * meantime.
 *
 * Note that the ShapedWord timeout is much larger than the font timeout,
 * so that in the case of a short-lived font, we'll discard the gfxFont
 * completely, with all its words, and avoid the cost of aging the words
 * individually. That only happens with longer-lived fonts.
 */
struct FontCacheSizes {
    FontCacheSizes()
        : mFontInstances(0), mShapedWords(0)
    { }

    size_t mFontInstances; // memory used by instances of gfxFont subclasses
    size_t mShapedWords; // memory used by the per-font shapedWord caches
};

class gfxFontCache final : public nsExpirationTracker<gfxFont,3> {
public:
    enum {
        FONT_TIMEOUT_SECONDS = 10,
        SHAPED_WORD_TIMEOUT_SECONDS = 60
    };

    gfxFontCache();
    ~gfxFontCache();

    /*
     * Get the global gfxFontCache.  You must call Init() before
     * calling this method --- the result will not be null.
     */
    static gfxFontCache* GetCache() {
        return gGlobalCache;
    }

    static nsresult Init();
    // It's OK to call this even if Init() has not been called.
    static void Shutdown();

    // Look up a font in the cache. Returns an addrefed pointer, or null
    // if there's nothing matching in the cache
    already_AddRefed<gfxFont>
    Lookup(const gfxFontEntry* aFontEntry,
           const gfxFontStyle* aStyle,
           const gfxCharacterMap* aUnicodeRangeMap);

    // We created a new font (presumably because Lookup returned null);
    // put it in the cache. The font's refcount should be nonzero. It is
    // allowable to add a new font even if there is one already in the
    // cache with the same key; we'll forget about the old one.
    void AddNew(gfxFont *aFont);

    // The font's refcount has gone to zero; give ownership of it to
    // the cache. We delete it if it's not acquired again after a certain
    // amount of time.
    void NotifyReleased(gfxFont *aFont);

    // This gets called when the timeout has expired on a zero-refcount
    // font; we just delete it.
    virtual void NotifyExpired(gfxFont *aFont) override;

    // Cleans out the hashtable and removes expired fonts waiting for cleanup.
    // Other gfxFont objects may be still in use but they will be pushed
    // into the expiration queues and removed.
    void Flush() {
        mFonts.Clear();
        AgeAllGenerations();
    }

    void FlushShapedWordCaches();

    void AddSizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf,
                                FontCacheSizes* aSizes) const;
    void AddSizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf,
                                FontCacheSizes* aSizes) const;

protected:
    class MemoryReporter final : public nsIMemoryReporter
    {
        ~MemoryReporter() {}
    public:
        NS_DECL_ISUPPORTS
        NS_DECL_NSIMEMORYREPORTER
    };

    // Observer for notifications that the font cache cares about
    class Observer final
        : public nsIObserver
    {
        ~Observer() {}
    public:
        NS_DECL_ISUPPORTS
        NS_DECL_NSIOBSERVER
    };

    void DestroyFont(gfxFont *aFont);

    static gfxFontCache *gGlobalCache;

    struct Key {
        const gfxFontEntry* mFontEntry;
        const gfxFontStyle* mStyle;
        const gfxCharacterMap* mUnicodeRangeMap;
        Key(const gfxFontEntry* aFontEntry, const gfxFontStyle* aStyle,
            const gfxCharacterMap* aUnicodeRangeMap)
            : mFontEntry(aFontEntry), mStyle(aStyle),
              mUnicodeRangeMap(aUnicodeRangeMap)
        {}
    };

    class HashEntry : public PLDHashEntryHdr {
    public:
        typedef const Key& KeyType;
        typedef const Key* KeyTypePointer;

        // When constructing a new entry in the hashtable, we'll leave this
        // blank. The caller of Put() will fill this in.
        explicit HashEntry(KeyTypePointer aStr) : mFont(nullptr) { }
        HashEntry(const HashEntry& toCopy) : mFont(toCopy.mFont) { }
        ~HashEntry() { }

        bool KeyEquals(const KeyTypePointer aKey) const;
        static KeyTypePointer KeyToPointer(KeyType aKey) { return &aKey; }
        static PLDHashNumber HashKey(const KeyTypePointer aKey) {
            return mozilla::HashGeneric(aKey->mStyle->Hash(), aKey->mFontEntry,
                                        aKey->mUnicodeRangeMap);
        }
        enum { ALLOW_MEMMOVE = true };

        gfxFont* mFont;
    };

    nsTHashtable<HashEntry> mFonts;

    static void WordCacheExpirationTimerCallback(nsITimer* aTimer, void* aCache);
    nsCOMPtr<nsITimer>      mWordCacheExpirationTimer;
};

class gfxTextPerfMetrics {
public:

    struct TextCounts {
        uint32_t    numContentTextRuns;
        uint32_t    numChromeTextRuns;
        uint32_t    numChars;
        uint32_t    maxTextRunLen;
        uint32_t    wordCacheSpaceRules;
        uint32_t    wordCacheLong;
        uint32_t    wordCacheHit;
        uint32_t    wordCacheMiss;
        uint32_t    fallbackPrefs;
        uint32_t    fallbackSystem;
        uint32_t    textrunConst;
        uint32_t    textrunDestr;
        uint32_t    genericLookups;
    };

    uint32_t reflowCount;

    // counts per reflow operation
    TextCounts current;

    // totals for the lifetime of a document
    TextCounts cumulative;

    gfxTextPerfMetrics() {
        memset(this, 0, sizeof(gfxTextPerfMetrics));
    }

    // add current totals to cumulative ones
    void Accumulate() {
        if (current.numChars == 0) {
            return;
        }
        cumulative.numContentTextRuns += current.numContentTextRuns;
        cumulative.numChromeTextRuns += current.numChromeTextRuns;
        cumulative.numChars += current.numChars;
        if (current.maxTextRunLen > cumulative.maxTextRunLen) {
            cumulative.maxTextRunLen = current.maxTextRunLen;
        }
        cumulative.wordCacheSpaceRules += current.wordCacheSpaceRules;
        cumulative.wordCacheLong += current.wordCacheLong;
        cumulative.wordCacheHit += current.wordCacheHit;
        cumulative.wordCacheMiss += current.wordCacheMiss;
        cumulative.fallbackPrefs += current.fallbackPrefs;
        cumulative.fallbackSystem += current.fallbackSystem;
        cumulative.textrunConst += current.textrunConst;
        cumulative.textrunDestr += current.textrunDestr;
        cumulative.genericLookups += current.genericLookups;
        memset(&current, 0, sizeof(current));
    }
};

class gfxTextRunFactory {
    NS_INLINE_DECL_REFCOUNTING(gfxTextRunFactory)

public:
    typedef mozilla::gfx::DrawTarget DrawTarget;

    // Flags in the mask 0xFFFF0000 are reserved for textrun clients
    // Flags in the mask 0x0000F000 are reserved for per-platform fonts
    // Flags in the mask 0x00000FFF are set by the textrun creator.
    enum {
        CACHE_TEXT_FLAGS    = 0xF0000000,
        USER_TEXT_FLAGS     = 0x0FFF0000,
        TEXTRUN_TEXT_FLAGS  = 0x0000FFFF,
        SETTABLE_FLAGS      = CACHE_TEXT_FLAGS | USER_TEXT_FLAGS,

        /**
         * When set, the text string pointer used to create the text run
         * is guaranteed to be available during the lifetime of the text run.
         */
        TEXT_IS_PERSISTENT           = 0x0001,
        /**
         * When set, the text is known to be all-ASCII (< 128).
         */
        TEXT_IS_ASCII                = 0x0002,
        /**
         * When set, the text is RTL.
         */
        TEXT_IS_RTL                  = 0x0004,
        /**
         * When set, spacing is enabled and the textrun needs to call GetSpacing
         * on the spacing provider.
         */
        TEXT_ENABLE_SPACING          = 0x0008,
        /**
         * When set, GetHyphenationBreaks may return true for some character
         * positions, otherwise it will always return false for all characters.
         */
        TEXT_ENABLE_HYPHEN_BREAKS    = 0x0010,
        /**
         * When set, the text has no characters above 255 and it is stored
         * in the textrun in 8-bit format.
         */
        TEXT_IS_8BIT                 = 0x0020,
        /**
         * When set, the RunMetrics::mBoundingBox field will be initialized
         * properly based on glyph extents, in particular, glyph extents that
         * overflow the standard font-box (the box defined by the ascent, descent
         * and advance width of the glyph). When not set, it may just be the
         * standard font-box even if glyphs overflow.
         */
        TEXT_NEED_BOUNDING_BOX       = 0x0040,
        /**
         * When set, optional ligatures are disabled. Ligatures that are
         * required for legible text should still be enabled.
         */
        TEXT_DISABLE_OPTIONAL_LIGATURES = 0x0080,
        /**
         * When set, the textrun should favour speed of construction over
         * quality. This may involve disabling ligatures and/or kerning or
         * other effects.
         */
        TEXT_OPTIMIZE_SPEED          = 0x0100,
        /**
         * For internal use by the memory reporter when accounting for
         * storage used by textruns.
         * Because the reporter may visit each textrun multiple times while
         * walking the frame trees and textrun cache, it needs to mark
         * textruns that have been seen so as to avoid multiple-accounting.
         */
        TEXT_RUN_SIZE_ACCOUNTED      = 0x0200,
        /**
         * When set, the textrun should discard control characters instead of
         * turning them into hexboxes.
         */
        TEXT_HIDE_CONTROL_CHARACTERS = 0x0400,

        /**
         * Field for orientation of the textrun and glyphs within it.
         * Possible values of the TEXT_ORIENT_MASK field:
         *   TEXT_ORIENT_HORIZONTAL
         *   TEXT_ORIENT_VERTICAL_UPRIGHT
         *   TEXT_ORIENT_VERTICAL_SIDEWAYS_RIGHT
         *   TEXT_ORIENT_VERTICAL_SIDEWAYS_LEFT
         *   TEXT_ORIENT_VERTICAL_MIXED
         * For all VERTICAL settings, the x and y coordinates of glyph
         * positions are exchanged, so that simple advances are vertical.
         *
         * The MIXED value indicates vertical textRuns for which the CSS
         * text-orientation property is 'mixed', but is never used for
         * individual glyphRuns; it will be resolved to either UPRIGHT
         * or SIDEWAYS_RIGHT according to the UTR50 properties of the
         * characters, and separate glyphRuns created for the resulting
         * glyph orientations.
         */
        TEXT_ORIENT_MASK                    = 0xF000,
        TEXT_ORIENT_HORIZONTAL              = 0x0000,
        TEXT_ORIENT_VERTICAL_UPRIGHT        = 0x1000,
        TEXT_ORIENT_VERTICAL_SIDEWAYS_RIGHT = 0x2000,
        TEXT_ORIENT_VERTICAL_SIDEWAYS_LEFT  = 0x4000,
        TEXT_ORIENT_VERTICAL_MIXED          = 0x8000,

        /**
         * nsTextFrameThebes sets these, but they're defined here rather than
         * in nsTextFrameUtils.h because ShapedWord creation/caching also needs
         * to check the _INCOMING flag
         */
        TEXT_TRAILING_ARABICCHAR = 0x20000000,
        /**
         * When set, the previous character for this textrun was an Arabic
         * character.  This is used for the context detection necessary for
         * bidi.numeral implementation.
         */
        TEXT_INCOMING_ARABICCHAR = 0x40000000,

        // Set if the textrun should use the OpenType 'math' script.
        TEXT_USE_MATH_SCRIPT = 0x80000000,
    };

    /**
     * This record contains all the parameters needed to initialize a textrun.
     */
    struct Parameters {
        // Shape text params suggesting where the textrun will be rendered
        DrawTarget   *mDrawTarget;
        // Pointer to arbitrary user data (which should outlive the textrun)
        void         *mUserData;
        // A description of which characters have been stripped from the original
        // DOM string to produce the characters in the textrun. May be null
        // if that information is not relevant.
        gfxSkipChars *mSkipChars;
        // A list of where linebreaks are currently placed in the textrun. May
        // be null if mInitialBreakCount is zero.
        uint32_t     *mInitialBreaks;
        uint32_t      mInitialBreakCount;
        // The ratio to use to convert device pixels to application layout units
        int32_t       mAppUnitsPerDevUnit;
    };

protected:
    // Protected destructor, to discourage deletion outside of Release():
    virtual ~gfxTextRunFactory() {}
};

/**
 * gfxFontShaper
 *
 * This class implements text shaping (character to glyph mapping and
 * glyph layout). There is a gfxFontShaper subclass for each text layout
 * technology (uniscribe, core text, harfbuzz,....) we support.
 *
 * The shaper is responsible for setting up glyph data in gfxTextRuns.
 *
 * A generic, platform-independent shaper relies only on the standard
 * gfxFont interface and can work with any concrete subclass of gfxFont.
 *
 * Platform-specific implementations designed to interface to platform
 * shaping APIs such as Uniscribe or CoreText may rely on features of a
 * specific font subclass to access native font references
 * (such as CTFont, HFONT, DWriteFont, etc).
 */

class gfxFontShaper {
public:
    typedef mozilla::gfx::DrawTarget DrawTarget;
    typedef mozilla::unicode::Script Script;

    explicit gfxFontShaper(gfxFont *aFont)
        : mFont(aFont)
    {
        NS_ASSERTION(aFont, "shaper requires a valid font!");
    }

    virtual ~gfxFontShaper() { }

    // Shape a piece of text and store the resulting glyph data into
    // aShapedText. Parameters aOffset/aLength indicate the range of
    // aShapedText to be updated; aLength is also the length of aText.
    virtual bool ShapeText(DrawTarget     *aDrawTarget,
                           const char16_t *aText,
                           uint32_t        aOffset,
                           uint32_t        aLength,
                           Script          aScript,
                           bool            aVertical,
                           gfxShapedText  *aShapedText) = 0;

    gfxFont *GetFont() const { return mFont; }

    static void
    MergeFontFeatures(const gfxFontStyle *aStyle,
                      const nsTArray<gfxFontFeature>& aFontFeatures,
                      bool aDisableLigatures,
                      const nsAString& aFamilyName,
                      bool aAddSmallCaps,
                      void (*aHandleFeature)(const uint32_t&,
                                             uint32_t&, void*),
                      void* aHandleFeatureData);

protected:
    // Work out whether cairo will snap inter-glyph spacing to pixels.
    static void GetRoundOffsetsToPixels(DrawTarget* aDrawTarget,
                                        bool* aRoundX, bool* aRoundY);

    // the font this shaper is working with. The font owns a UniquePtr reference
    // to this object, and will destroy it before it dies. Thus, mFont will always
    // be valid.
    gfxFont* MOZ_NON_OWNING_REF mFont;
};


/*
 * gfxShapedText is an abstract superclass for gfxShapedWord and gfxTextRun.
 * These are objects that store a list of zero or more glyphs for each character.
 * For each glyph we store the glyph ID, the advance, and possibly x/y-offsets.
 * The idea is that a string is rendered by a loop that draws each glyph
 * at its designated offset from the current point, then advances the current
 * point by the glyph's advance in the direction of the textrun (LTR or RTL).
 * Each glyph advance is always rounded to the nearest appunit; this ensures
 * consistent results when dividing the text in a textrun into multiple text
 * frames (frame boundaries are always aligned to appunits). We optimize
 * for the case where a character has a single glyph and zero xoffset and yoffset,
 * and the glyph ID and advance are in a reasonable range so we can pack all
 * necessary data into 32 bits.
 *
 * gfxFontShaper can shape text into either a gfxShapedWord (cached by a gfxFont)
 * or directly into a gfxTextRun (for cases where we want to shape textruns in
 * their entirety rather than using cached words, because there may be layout
 * features that depend on the inter-word spaces).
 */
class gfxShapedText
{
public:
    typedef mozilla::unicode::Script Script;

    gfxShapedText(uint32_t aLength, uint32_t aFlags,
                  int32_t aAppUnitsPerDevUnit)
        : mLength(aLength)
        , mFlags(aFlags)
        , mAppUnitsPerDevUnit(aAppUnitsPerDevUnit)
    { }

    virtual ~gfxShapedText() { }

    /**
     * This class records the information associated with a character in the
     * input string. It's optimized for the case where there is one glyph
     * representing that character alone.
     * 
     * A character can have zero or more associated glyphs. Each glyph
     * has an advance width and an x and y offset.
     * A character may be the start of a cluster.
     * A character may be the start of a ligature group.
     * A character can be "missing", indicating that the system is unable
     * to render the character.
     * 
     * All characters in a ligature group conceptually share all the glyphs
     * associated with the characters in a group.
     */
    class CompressedGlyph {
    public:
        CompressedGlyph() { mValue = 0; }

        enum {
            // Indicates that a cluster and ligature group starts at this
            // character; this character has a single glyph with a reasonable
            // advance and zero offsets. A "reasonable" advance
            // is one that fits in the available bits (currently 12) (specified
            // in appunits).
            FLAG_IS_SIMPLE_GLYPH  = 0x80000000U,

            // Indicates whether a linebreak is allowed before this character;
            // this is a two-bit field that holds a FLAG_BREAK_TYPE_xxx value
            // indicating the kind of linebreak (if any) allowed here.
            FLAGS_CAN_BREAK_BEFORE = 0x60000000U,

            FLAGS_CAN_BREAK_SHIFT = 29,
            FLAG_BREAK_TYPE_NONE   = 0,
            FLAG_BREAK_TYPE_NORMAL = 1,
            FLAG_BREAK_TYPE_HYPHEN = 2,

            FLAG_CHAR_IS_SPACE     = 0x10000000U,

            // The advance is stored in appunits
            ADVANCE_MASK  = 0x0FFF0000U,
            ADVANCE_SHIFT = 16,

            GLYPH_MASK = 0x0000FFFFU,

            // Non-simple glyphs may or may not have glyph data in the
            // corresponding mDetailedGlyphs entry. They have the following
            // flag bits:

            // When NOT set, indicates that this character corresponds to a
            // missing glyph and should be skipped (or possibly, render the character
            // Unicode value in some special way). If there are glyphs,
            // the mGlyphID is actually the UTF16 character code. The bit is
            // inverted so we can memset the array to zero to indicate all missing.
            FLAG_NOT_MISSING              = 0x01,
            FLAG_NOT_CLUSTER_START        = 0x02,
            FLAG_NOT_LIGATURE_GROUP_START = 0x04,

            FLAG_CHAR_IS_TAB              = 0x08,
            FLAG_CHAR_IS_NEWLINE          = 0x10,
            // Per CSS Text Decoration Module Level 3, emphasis marks are not
            // drawn for any character in Unicode categories Z*, Cc, Cf, and Cn
            // which is not combined with any combining characters. This flag is
            // set for all those characters except 0x20 whitespace.
            FLAG_CHAR_NO_EMPHASIS_MARK    = 0x20,
            CHAR_TYPE_FLAGS_MASK          = 0x38,

            GLYPH_COUNT_MASK = 0x00FFFF00U,
            GLYPH_COUNT_SHIFT = 8
        };

        // "Simple glyphs" have a simple glyph ID, simple advance and their
        // x and y offsets are zero. Also the glyph extents do not overflow
        // the font-box defined by the font ascent, descent and glyph advance width.
        // These case is optimized to avoid storing DetailedGlyphs.

        // Returns true if the glyph ID aGlyph fits into the compressed representation
        static bool IsSimpleGlyphID(uint32_t aGlyph) {
            return (aGlyph & GLYPH_MASK) == aGlyph;
        }
        // Returns true if the advance aAdvance fits into the compressed representation.
        // aAdvance is in appunits.
        static bool IsSimpleAdvance(uint32_t aAdvance) {
            return (aAdvance & (ADVANCE_MASK >> ADVANCE_SHIFT)) == aAdvance;
        }

        bool IsSimpleGlyph() const { return (mValue & FLAG_IS_SIMPLE_GLYPH) != 0; }
        uint32_t GetSimpleAdvance() const { return (mValue & ADVANCE_MASK) >> ADVANCE_SHIFT; }
        uint32_t GetSimpleGlyph() const { return mValue & GLYPH_MASK; }

        bool IsMissing() const { return (mValue & (FLAG_NOT_MISSING|FLAG_IS_SIMPLE_GLYPH)) == 0; }
        bool IsClusterStart() const {
            return (mValue & FLAG_IS_SIMPLE_GLYPH) || !(mValue & FLAG_NOT_CLUSTER_START);
        }
        bool IsLigatureGroupStart() const {
            return (mValue & FLAG_IS_SIMPLE_GLYPH) || !(mValue & FLAG_NOT_LIGATURE_GROUP_START);
        }
        bool IsLigatureContinuation() const {
            return (mValue & FLAG_IS_SIMPLE_GLYPH) == 0 &&
                (mValue & (FLAG_NOT_LIGATURE_GROUP_START | FLAG_NOT_MISSING)) ==
                    (FLAG_NOT_LIGATURE_GROUP_START | FLAG_NOT_MISSING);
        }

        // Return true if the original character was a normal (breakable,
        // trimmable) space (U+0020). Not true for other characters that
        // may happen to map to the space glyph (U+00A0).
        bool CharIsSpace() const {
            return (mValue & FLAG_CHAR_IS_SPACE) != 0;
        }

        bool CharIsTab() const {
            return !IsSimpleGlyph() && (mValue & FLAG_CHAR_IS_TAB) != 0;
        }
        bool CharIsNewline() const {
            return !IsSimpleGlyph() && (mValue & FLAG_CHAR_IS_NEWLINE) != 0;
        }
        bool CharMayHaveEmphasisMark() const {
            return !CharIsSpace() &&
                (IsSimpleGlyph() || !(mValue & FLAG_CHAR_NO_EMPHASIS_MARK));
        }

        uint32_t CharTypeFlags() const {
            return IsSimpleGlyph() ? 0 : (mValue & CHAR_TYPE_FLAGS_MASK);
        }

        void SetClusterStart(bool aIsClusterStart) {
            NS_ASSERTION(!IsSimpleGlyph(),
                         "can't call SetClusterStart on simple glyphs");
            if (aIsClusterStart) {
                mValue &= ~FLAG_NOT_CLUSTER_START;
            } else {
                mValue |= FLAG_NOT_CLUSTER_START;
            }
        }

        uint8_t CanBreakBefore() const {
            return (mValue & FLAGS_CAN_BREAK_BEFORE) >> FLAGS_CAN_BREAK_SHIFT;
        }
        // Returns FLAGS_CAN_BREAK_BEFORE if the setting changed, 0 otherwise
        uint32_t SetCanBreakBefore(uint8_t aCanBreakBefore) {
            NS_ASSERTION(aCanBreakBefore <= 2,
                         "Bogus break-before value!");
            uint32_t breakMask = (uint32_t(aCanBreakBefore) << FLAGS_CAN_BREAK_SHIFT);
            uint32_t toggle = breakMask ^ (mValue & FLAGS_CAN_BREAK_BEFORE);
            mValue ^= toggle;
            return toggle;
        }

        CompressedGlyph& SetSimpleGlyph(uint32_t aAdvanceAppUnits, uint32_t aGlyph) {
            NS_ASSERTION(IsSimpleAdvance(aAdvanceAppUnits), "Advance overflow");
            NS_ASSERTION(IsSimpleGlyphID(aGlyph), "Glyph overflow");
            NS_ASSERTION(!CharTypeFlags(), "Char type flags lost");
            mValue = (mValue & (FLAGS_CAN_BREAK_BEFORE | FLAG_CHAR_IS_SPACE)) |
                FLAG_IS_SIMPLE_GLYPH |
                (aAdvanceAppUnits << ADVANCE_SHIFT) | aGlyph;
            return *this;
        }
        CompressedGlyph& SetComplex(bool aClusterStart, bool aLigatureStart,
                uint32_t aGlyphCount) {
            mValue = (mValue & (FLAGS_CAN_BREAK_BEFORE | FLAG_CHAR_IS_SPACE)) |
                FLAG_NOT_MISSING |
                CharTypeFlags() |
                (aClusterStart ? 0 : FLAG_NOT_CLUSTER_START) |
                (aLigatureStart ? 0 : FLAG_NOT_LIGATURE_GROUP_START) |
                (aGlyphCount << GLYPH_COUNT_SHIFT);
            return *this;
        }
        /**
         * Missing glyphs are treated as ligature group starts; don't mess with
         * the cluster-start flag (see bugs 618870 and 619286).
         */
        CompressedGlyph& SetMissing(uint32_t aGlyphCount) {
            mValue = (mValue & (FLAGS_CAN_BREAK_BEFORE | FLAG_NOT_CLUSTER_START |
                                FLAG_CHAR_IS_SPACE)) |
                CharTypeFlags() |
                (aGlyphCount << GLYPH_COUNT_SHIFT);
            return *this;
        }
        uint32_t GetGlyphCount() const {
            NS_ASSERTION(!IsSimpleGlyph(), "Expected non-simple-glyph");
            return (mValue & GLYPH_COUNT_MASK) >> GLYPH_COUNT_SHIFT;
        }

        void SetIsSpace() {
            mValue |= FLAG_CHAR_IS_SPACE;
        }
        void SetIsTab() {
            NS_ASSERTION(!IsSimpleGlyph(), "Expected non-simple-glyph");
            mValue |= FLAG_CHAR_IS_TAB;
        }
        void SetIsNewline() {
            NS_ASSERTION(!IsSimpleGlyph(), "Expected non-simple-glyph");
            mValue |= FLAG_CHAR_IS_NEWLINE;
        }
        void SetNoEmphasisMark() {
            NS_ASSERTION(!IsSimpleGlyph(), "Expected non-simple-glyph");
            mValue |= FLAG_CHAR_NO_EMPHASIS_MARK;
        }

    private:
        uint32_t mValue;
    };

    // Accessor for the array of CompressedGlyph records, which will be in
    // a different place in gfxShapedWord vs gfxTextRun
    virtual const CompressedGlyph *GetCharacterGlyphs() const = 0;
    virtual CompressedGlyph *GetCharacterGlyphs() = 0;

    /**
     * When the glyphs for a character don't fit into a CompressedGlyph record
     * in SimpleGlyph format, we use an array of DetailedGlyphs instead.
     */
    struct DetailedGlyph {
        /** The glyphID, or the Unicode character
         * if this is a missing glyph */
        uint32_t mGlyphID;
        /** The advance, x-offset and y-offset of the glyph, in appunits
         *  mAdvance is in the text direction (RTL or LTR)
         *  mXOffset is always from left to right
         *  mYOffset is always from top to bottom */   
        int32_t  mAdvance;
        float    mXOffset, mYOffset;
    };

    void SetGlyphs(uint32_t aCharIndex, CompressedGlyph aGlyph,
                   const DetailedGlyph *aGlyphs);

    void SetMissingGlyph(uint32_t aIndex, uint32_t aChar, gfxFont *aFont);

    void SetIsSpace(uint32_t aIndex) {
        GetCharacterGlyphs()[aIndex].SetIsSpace();
    }

    bool HasDetailedGlyphs() const {
        return mDetailedGlyphs != nullptr;
    }

    bool IsLigatureGroupStart(uint32_t aPos) {
        NS_ASSERTION(aPos < GetLength(), "aPos out of range");
        return GetCharacterGlyphs()[aPos].IsLigatureGroupStart();
    }

    // NOTE that this must not be called for a character offset that does
    // not have any DetailedGlyph records; callers must have verified that
    // GetCharacterGlyphs()[aCharIndex].GetGlyphCount() is greater than zero.
    DetailedGlyph *GetDetailedGlyphs(uint32_t aCharIndex) const {
        NS_ASSERTION(GetCharacterGlyphs() && HasDetailedGlyphs() &&
                     !GetCharacterGlyphs()[aCharIndex].IsSimpleGlyph() &&
                     GetCharacterGlyphs()[aCharIndex].GetGlyphCount() > 0,
                     "invalid use of GetDetailedGlyphs; check the caller!");
        return mDetailedGlyphs->Get(aCharIndex);
    }

    void AdjustAdvancesForSyntheticBold(float aSynBoldOffset,
                                        uint32_t aOffset, uint32_t aLength);

    // Mark clusters in the CompressedGlyph records, starting at aOffset,
    // based on the Unicode properties of the text in aString.
    // This is also responsible to set the IsSpace flag for space characters.
    void SetupClusterBoundaries(uint32_t         aOffset,
                                const char16_t *aString,
                                uint32_t         aLength);
    // In 8-bit text, there won't actually be any clusters, but we still need
    // the space-marking functionality.
    void SetupClusterBoundaries(uint32_t       aOffset,
                                const uint8_t *aString,
                                uint32_t       aLength);

    uint32_t GetFlags() const {
        return mFlags;
    }

    bool IsVertical() const {
        return (GetFlags() & gfxTextRunFactory::TEXT_ORIENT_MASK) !=
                gfxTextRunFactory::TEXT_ORIENT_HORIZONTAL;
    }

    bool UseCenterBaseline() const {
        uint32_t orient = GetFlags() & gfxTextRunFactory::TEXT_ORIENT_MASK;
        return orient == gfxTextRunFactory::TEXT_ORIENT_VERTICAL_MIXED ||
               orient == gfxTextRunFactory::TEXT_ORIENT_VERTICAL_UPRIGHT;
    }

    bool IsRightToLeft() const {
        return (GetFlags() & gfxTextRunFactory::TEXT_IS_RTL) != 0;
    }

    bool IsSidewaysLeft() const {
        return (GetFlags() & gfxTextRunFactory::TEXT_ORIENT_MASK) ==
               gfxTextRunFactory::TEXT_ORIENT_VERTICAL_SIDEWAYS_LEFT;
    }

    // Return true if the logical inline direction is reversed compared to
    // normal physical coordinates (i.e. if it is leftwards or upwards)
    bool IsInlineReversed() const {
        return IsSidewaysLeft() != IsRightToLeft();
    }

    gfxFloat GetDirection() const {
        return IsInlineReversed() ? -1.0f : 1.0f;
    }

    bool DisableLigatures() const {
        return (GetFlags() &
                gfxTextRunFactory::TEXT_DISABLE_OPTIONAL_LIGATURES) != 0;
    }

    bool TextIs8Bit() const {
        return (GetFlags() & gfxTextRunFactory::TEXT_IS_8BIT) != 0;
    }

    int32_t GetAppUnitsPerDevUnit() const {
        return mAppUnitsPerDevUnit;
    }

    uint32_t GetLength() const {
        return mLength;
    }

    bool FilterIfIgnorable(uint32_t aIndex, uint32_t aCh);

protected:
    // Allocate aCount DetailedGlyphs for the given index
    DetailedGlyph *AllocateDetailedGlyphs(uint32_t aCharIndex,
                                          uint32_t aCount);

    // Ensure the glyph on the given index is complex glyph so that we can use
    // it to record specific characters that layout may need to detect.
    void EnsureComplexGlyph(uint32_t aIndex, CompressedGlyph& aGlyph)
    {
        MOZ_ASSERT(GetCharacterGlyphs() + aIndex == &aGlyph);
        if (aGlyph.IsSimpleGlyph()) {
            DetailedGlyph details = {
                aGlyph.GetSimpleGlyph(),
                (int32_t) aGlyph.GetSimpleAdvance(),
                0, 0
            };
            SetGlyphs(aIndex, CompressedGlyph().SetComplex(true, true, 1),
                      &details);
        }
    }

    // For characters whose glyph data does not fit the "simple" glyph criteria
    // in CompressedGlyph, we use a sorted array to store the association
    // between the source character offset and an index into an array 
    // DetailedGlyphs. The CompressedGlyph record includes a count of
    // the number of DetailedGlyph records that belong to the character,
    // starting at the given index.
    class DetailedGlyphStore {
    public:
        DetailedGlyphStore()
            : mLastUsed(0)
        { }

        // This is optimized for the most common calling patterns:
        // we rarely need random access to the records, access is most commonly
        // sequential through the textRun, so we record the last-used index
        // and check whether the caller wants the same record again, or the
        // next; if not, it's most likely we're starting over from the start
        // of the run, so we check the first entry before resorting to binary
        // search as a last resort.
        // NOTE that this must not be called for a character offset that does
        // not have any DetailedGlyph records; callers must have verified that
        // mCharacterGlyphs[aOffset].GetGlyphCount() is greater than zero
        // before calling this, otherwise the assertions here will fire (in a
        // debug build), and we'll probably crash.
        DetailedGlyph* Get(uint32_t aOffset) {
            NS_ASSERTION(mOffsetToIndex.Length() > 0,
                         "no detailed glyph records!");
            DetailedGlyph* details = mDetails.Elements();
            // check common cases (fwd iteration, initial entry, etc) first
            if (mLastUsed < mOffsetToIndex.Length() - 1 &&
                aOffset == mOffsetToIndex[mLastUsed + 1].mOffset) {
                ++mLastUsed;
            } else if (aOffset == mOffsetToIndex[0].mOffset) {
                mLastUsed = 0;
            } else if (aOffset == mOffsetToIndex[mLastUsed].mOffset) {
                // do nothing
            } else if (mLastUsed > 0 &&
                       aOffset == mOffsetToIndex[mLastUsed - 1].mOffset) {
                --mLastUsed;
            } else {
                mLastUsed =
                    mOffsetToIndex.BinaryIndexOf(aOffset, CompareToOffset());
            }
            NS_ASSERTION(mLastUsed != nsTArray<DGRec>::NoIndex,
                         "detailed glyph record missing!");
            return details + mOffsetToIndex[mLastUsed].mIndex;
        }

        DetailedGlyph* Allocate(uint32_t aOffset, uint32_t aCount) {
            uint32_t detailIndex = mDetails.Length();
            DetailedGlyph *details = mDetails.AppendElements(aCount);
            // We normally set up glyph records sequentially, so the common case
            // here is to append new records to the mOffsetToIndex array;
            // test for that before falling back to the InsertElementSorted
            // method.
            if (mOffsetToIndex.Length() == 0 ||
                aOffset > mOffsetToIndex[mOffsetToIndex.Length() - 1].mOffset) {
                mOffsetToIndex.AppendElement(DGRec(aOffset, detailIndex));
            } else {
                mOffsetToIndex.InsertElementSorted(DGRec(aOffset, detailIndex),
                                                   CompareRecordOffsets());
            }
            return details;
        }

        size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) {
            return aMallocSizeOf(this) +
                mDetails.ShallowSizeOfExcludingThis(aMallocSizeOf) +
                mOffsetToIndex.ShallowSizeOfExcludingThis(aMallocSizeOf);
        }

    private:
        struct DGRec {
            DGRec(const uint32_t& aOffset, const uint32_t& aIndex)
                : mOffset(aOffset), mIndex(aIndex) { }
            uint32_t mOffset; // source character offset in the textrun
            uint32_t mIndex;  // index where this char's DetailedGlyphs begin
        };

        struct CompareToOffset {
            bool Equals(const DGRec& a, const uint32_t& b) const {
                return a.mOffset == b;
            }
            bool LessThan(const DGRec& a, const uint32_t& b) const {
                return a.mOffset < b;
            }
        };

        struct CompareRecordOffsets {
            bool Equals(const DGRec& a, const DGRec& b) const {
                return a.mOffset == b.mOffset;
            }
            bool LessThan(const DGRec& a, const DGRec& b) const {
                return a.mOffset < b.mOffset;
            }
        };

        // Concatenated array of all the DetailedGlyph records needed for the
        // textRun; individual character offsets are associated with indexes
        // into this array via the mOffsetToIndex table.
        nsTArray<DetailedGlyph>     mDetails;

        // For each character offset that needs DetailedGlyphs, we record the
        // index in mDetails where the list of glyphs begins. This array is
        // sorted by mOffset.
        nsTArray<DGRec>             mOffsetToIndex;

        // Records the most recently used index into mOffsetToIndex, so that
        // we can support sequential access more quickly than just doing
        // a binary search each time.
        nsTArray<DGRec>::index_type mLastUsed;
    };

    mozilla::UniquePtr<DetailedGlyphStore>   mDetailedGlyphs;

    // Number of char16_t characters and CompressedGlyph glyph records
    uint32_t                        mLength;

    // Shaping flags (direction, ligature-suppression)
    uint32_t                        mFlags;

    int32_t                         mAppUnitsPerDevUnit;
};

/*
 * gfxShapedWord: an individual (space-delimited) run of text shaped with a
 * particular font, without regard to external context.
 *
 * The glyph data is copied into gfxTextRuns as needed from the cache of
 * ShapedWords associated with each gfxFont instance.
 */
class gfxShapedWord final : public gfxShapedText
{
public:
    typedef mozilla::unicode::Script Script;

    // Create a ShapedWord that can hold glyphs for aLength characters,
    // with mCharacterGlyphs sized appropriately.
    //
    // Returns null on allocation failure (does NOT use infallible alloc)
    // so caller must check for success.
    //
    // This does NOT perform shaping, so the returned word contains no
    // glyph data; the caller must call gfxFont::ShapeText() with appropriate
    // parameters to set up the glyphs.
    static gfxShapedWord* Create(const uint8_t *aText, uint32_t aLength,
                                 Script aRunScript,
                                 int32_t aAppUnitsPerDevUnit,
                                 uint32_t aFlags) {
        NS_ASSERTION(aLength <= gfxPlatform::GetPlatform()->WordCacheCharLimit(),
                     "excessive length for gfxShapedWord!");

        // Compute size needed including the mCharacterGlyphs array
        // and a copy of the original text
        uint32_t size =
            offsetof(gfxShapedWord, mCharGlyphsStorage) +
            aLength * (sizeof(CompressedGlyph) + sizeof(uint8_t));
        void *storage = malloc(size);
        if (!storage) {
            return nullptr;
        }

        // Construct in the pre-allocated storage, using placement new
        return new (storage) gfxShapedWord(aText, aLength, aRunScript,
                                           aAppUnitsPerDevUnit, aFlags);
    }

    static gfxShapedWord* Create(const char16_t *aText, uint32_t aLength,
                                 Script aRunScript,
                                 int32_t aAppUnitsPerDevUnit,
                                 uint32_t aFlags) {
        NS_ASSERTION(aLength <= gfxPlatform::GetPlatform()->WordCacheCharLimit(),
                     "excessive length for gfxShapedWord!");

        // In the 16-bit version of Create, if the TEXT_IS_8BIT flag is set,
        // then we convert the text to an 8-bit version and call the 8-bit
        // Create function instead.
        if (aFlags & gfxTextRunFactory::TEXT_IS_8BIT) {
            nsAutoCString narrowText;
            LossyAppendUTF16toASCII(nsDependentSubstring(aText, aLength),
                                    narrowText);
            return Create((const uint8_t*)(narrowText.BeginReading()),
                          aLength, aRunScript, aAppUnitsPerDevUnit, aFlags);
        }

        uint32_t size =
            offsetof(gfxShapedWord, mCharGlyphsStorage) +
            aLength * (sizeof(CompressedGlyph) + sizeof(char16_t));
        void *storage = malloc(size);
        if (!storage) {
            return nullptr;
        }

        return new (storage) gfxShapedWord(aText, aLength, aRunScript,
                                           aAppUnitsPerDevUnit, aFlags);
    }

    // Override operator delete to properly free the object that was
    // allocated via malloc.
    void operator delete(void* p) {
        free(p);
    }

    virtual const CompressedGlyph *GetCharacterGlyphs() const override {
        return &mCharGlyphsStorage[0];
    }
    virtual CompressedGlyph *GetCharacterGlyphs() override {
        return &mCharGlyphsStorage[0];
    }

    const uint8_t* Text8Bit() const {
        NS_ASSERTION(TextIs8Bit(), "invalid use of Text8Bit()");
        return reinterpret_cast<const uint8_t*>(mCharGlyphsStorage + GetLength());
    }

    const char16_t* TextUnicode() const {
        NS_ASSERTION(!TextIs8Bit(), "invalid use of TextUnicode()");
        return reinterpret_cast<const char16_t*>(mCharGlyphsStorage + GetLength());
    }

    char16_t GetCharAt(uint32_t aOffset) const {
        NS_ASSERTION(aOffset < GetLength(), "aOffset out of range");
        return TextIs8Bit() ?
            char16_t(Text8Bit()[aOffset]) : TextUnicode()[aOffset];
    }

    Script GetScript() const {
        return mScript;
    }

    void ResetAge() {
        mAgeCounter = 0;
    }
    uint32_t IncrementAge() {
        return ++mAgeCounter;
    }

    // Helper used when hashing a word for the shaped-word caches
    static uint32_t HashMix(uint32_t aHash, char16_t aCh)
    {
        return (aHash >> 28) ^ (aHash << 4) ^ aCh;
    }

private:
    // so that gfxTextRun can share our DetailedGlyphStore class
    friend class gfxTextRun;

    // Construct storage for a ShapedWord, ready to receive glyph data
    gfxShapedWord(const uint8_t *aText, uint32_t aLength,
                  Script aRunScript,
                  int32_t aAppUnitsPerDevUnit, uint32_t aFlags)
        : gfxShapedText(aLength, aFlags | gfxTextRunFactory::TEXT_IS_8BIT,
                        aAppUnitsPerDevUnit)
        , mScript(aRunScript)
        , mAgeCounter(0)
    {
        memset(mCharGlyphsStorage, 0, aLength * sizeof(CompressedGlyph));
        uint8_t *text = reinterpret_cast<uint8_t*>(&mCharGlyphsStorage[aLength]);
        memcpy(text, aText, aLength * sizeof(uint8_t));
    }

    gfxShapedWord(const char16_t *aText, uint32_t aLength,
                  Script aRunScript,
                  int32_t aAppUnitsPerDevUnit, uint32_t aFlags)
        : gfxShapedText(aLength, aFlags, aAppUnitsPerDevUnit)
        , mScript(aRunScript)
        , mAgeCounter(0)
    {
        memset(mCharGlyphsStorage, 0, aLength * sizeof(CompressedGlyph));
        char16_t *text = reinterpret_cast<char16_t*>(&mCharGlyphsStorage[aLength]);
        memcpy(text, aText, aLength * sizeof(char16_t));
        SetupClusterBoundaries(0, aText, aLength);
    }

    Script           mScript;

    uint32_t         mAgeCounter;

    // The mCharGlyphsStorage array is actually a variable-size member;
    // when the ShapedWord is created, its size will be increased as necessary
    // to allow the proper number of glyphs to be stored.
    // The original text, in either 8-bit or 16-bit form, will be stored
    // immediately following the CompressedGlyphs.
    CompressedGlyph  mCharGlyphsStorage[1];
};

class GlyphBufferAzure;
struct TextRunDrawParams;
struct FontDrawParams;
struct EmphasisMarkDrawParams;

class gfxFont {

    friend class gfxHarfBuzzShaper;
    friend class gfxGraphiteShaper;

protected:
    typedef mozilla::gfx::DrawTarget DrawTarget;
    typedef mozilla::unicode::Script Script;
    typedef mozilla::SVGContextPaint SVGContextPaint;

public:
    nsrefcnt AddRef(void) {
        NS_PRECONDITION(int32_t(mRefCnt) >= 0, "illegal refcnt");
        if (mExpirationState.IsTracked()) {
            gfxFontCache::GetCache()->RemoveObject(this);
        }
        ++mRefCnt;
        NS_LOG_ADDREF(this, mRefCnt, "gfxFont", sizeof(*this));
        return mRefCnt;
    }
    nsrefcnt Release(void) {
        NS_PRECONDITION(0 != mRefCnt, "dup release");
        --mRefCnt;
        NS_LOG_RELEASE(this, mRefCnt, "gfxFont");
        if (mRefCnt == 0) {
            NotifyReleased();
            // |this| may have been deleted.
            return 0;
        }
        return mRefCnt;
    }

    int32_t GetRefCount() { return mRefCnt; }

    // options to specify the kind of AA to be used when creating a font
    typedef enum {
        kAntialiasDefault,
        kAntialiasNone,
        kAntialiasGrayscale,
        kAntialiasSubpixel
    } AntialiasOption;

protected:
    nsAutoRefCnt mRefCnt;
    cairo_scaled_font_t *mScaledFont;

    void NotifyReleased() {
        gfxFontCache *cache = gfxFontCache::GetCache();
        if (cache) {
            // Don't delete just yet; return the object to the cache for
            // possibly recycling within some time limit
            cache->NotifyReleased(this);
        } else {
            // The cache may have already been shut down.
            delete this;
        }
    }

    gfxFont(gfxFontEntry *aFontEntry, const gfxFontStyle *aFontStyle,
            AntialiasOption anAAOption = kAntialiasDefault,
            cairo_scaled_font_t *aScaledFont = nullptr);

public:
    virtual ~gfxFont();

    bool Valid() const {
        return mIsValid;
    }

    // options for the kind of bounding box to return from measurement
    typedef enum {
        LOOSE_INK_EXTENTS,
            // A box that encloses all the painted pixels, and may
            // include sidebearings and/or additional ascent/descent
            // within the glyph cell even if the ink is smaller.
        TIGHT_INK_EXTENTS,
            // A box that tightly encloses all the painted pixels
            // (although actually on Windows, at least, it may be
            // slightly larger than strictly necessary because
            // we can't get precise extents with ClearType).
        TIGHT_HINTED_OUTLINE_EXTENTS
            // A box that tightly encloses the glyph outline,
            // ignoring possible antialiasing pixels that extend
            // beyond this.
            // NOTE: The default implementation of gfxFont::Measure(),
            // which works with the glyph extents cache, does not
            // differentiate between this and TIGHT_INK_EXTENTS.
            // Whether the distinction is important depends on the
            // antialiasing behavior of the platform; currently the
            // distinction is only implemented in the gfxWindowsFont
            // subclass, because of ClearType's tendency to paint
            // outside the hinted outline.
            // Also NOTE: it is relatively expensive to request this,
            // as it does not use cached glyph extents in the font.
    } BoundingBoxType;

    const nsString& GetName() const { return mFontEntry->Name(); }
    const gfxFontStyle *GetStyle() const { return &mStyle; }

    virtual cairo_scaled_font_t* GetCairoScaledFont() { return mScaledFont; }

    virtual gfxFont* CopyWithAntialiasOption(AntialiasOption anAAOption) {
        // platforms where this actually matters should override
        return nullptr;
    }

    gfxFloat GetAdjustedSize() const {
        return mAdjustedSize > 0.0
                 ? mAdjustedSize
                 : (mStyle.sizeAdjust == 0.0 ? 0.0 : mStyle.size);
    }

    float FUnitsToDevUnitsFactor() const {
        // check this was set up during font initialization
        NS_ASSERTION(mFUnitsConvFactor >= 0.0f, "mFUnitsConvFactor not valid");
        return mFUnitsConvFactor;
    }

    // check whether this is an sfnt we can potentially use with harfbuzz
    bool FontCanSupportHarfBuzz() {
        return mFontEntry->HasCmapTable();
    }

    // check whether this is an sfnt we can potentially use with Graphite
    bool FontCanSupportGraphite() {
        return mFontEntry->HasGraphiteTables();
    }

    // Whether this is a font that may be doing full-color rendering,
    // and therefore needs us to use a mask for text-shadow even when
    // we're not actually blurring.
    bool AlwaysNeedsMaskForShadow() {
        return mFontEntry->TryGetColorGlyphs() ||
               mFontEntry->TryGetSVGData(this) ||
               mFontEntry->HasFontTable(TRUETYPE_TAG('C','B','D','T')) ||
               mFontEntry->HasFontTable(TRUETYPE_TAG('s','b','i','x'));
    }

    // whether a feature is supported by the font (limited to a small set
    // of features for which some form of fallback needs to be implemented)
    bool SupportsFeature(Script aScript, uint32_t aFeatureTag);

    // whether the font supports "real" small caps, petite caps etc.
    // aFallbackToSmallCaps true when petite caps should fallback to small caps
    bool SupportsVariantCaps(Script aScript, uint32_t aVariantCaps,
                             bool& aFallbackToSmallCaps,
                             bool& aSyntheticLowerToSmallCaps,
                             bool& aSyntheticUpperToSmallCaps);

    // whether the font supports subscript/superscript feature
    // for fallback, need to verify that all characters in the run
    // have variant substitutions
    bool SupportsSubSuperscript(uint32_t aSubSuperscript,
                                const uint8_t *aString,
                                uint32_t aLength,
                                Script aRunScript);

    bool SupportsSubSuperscript(uint32_t aSubSuperscript,
                                const char16_t *aString,
                                uint32_t aLength,
                                Script aRunScript);

    // Subclasses may choose to look up glyph ids for characters.
    // If they do not override this, gfxHarfBuzzShaper will fetch the cmap
    // table and use that.
    virtual bool ProvidesGetGlyph() const {
        return false;
    }
    // Map unicode character to glyph ID.
    // Only used if ProvidesGetGlyph() returns true.
    virtual uint32_t GetGlyph(uint32_t unicode, uint32_t variation_selector) {
        return 0;
    }
    // Return the horizontal advance of a glyph.
    gfxFloat GetGlyphHAdvance(DrawTarget* aDrawTarget, uint16_t aGID);

    // Return Azure GlyphRenderingOptions for drawing this font.
    virtual already_AddRefed<mozilla::gfx::GlyphRenderingOptions>
      GetGlyphRenderingOptions(const TextRunDrawParams* aRunParams = nullptr)
    { return nullptr; }

    gfxFloat SynthesizeSpaceWidth(uint32_t aCh);

    // Font metrics
    struct Metrics {
        gfxFloat capHeight;
        gfxFloat xHeight;
        gfxFloat strikeoutSize;
        gfxFloat strikeoutOffset;
        gfxFloat underlineSize;
        gfxFloat underlineOffset;

        gfxFloat internalLeading;
        gfxFloat externalLeading;

        gfxFloat emHeight;
        gfxFloat emAscent;
        gfxFloat emDescent;
        gfxFloat maxHeight;
        gfxFloat maxAscent;
        gfxFloat maxDescent;
        gfxFloat maxAdvance;

        gfxFloat aveCharWidth;
        gfxFloat spaceWidth;
        gfxFloat zeroOrAveCharWidth;  // width of '0', or if there is
                                      // no '0' glyph in this font,
                                      // equal to .aveCharWidth
    };

    enum Orientation {
        eHorizontal,
        eVertical
    };

    const Metrics& GetMetrics(Orientation aOrientation)
    {
        if (aOrientation == eHorizontal) {
            return GetHorizontalMetrics();
        }
        if (!mVerticalMetrics) {
            mVerticalMetrics.reset(CreateVerticalMetrics());
        }
        return *mVerticalMetrics;
    }

    /**
     * We let layout specify spacing on either side of any
     * character. We need to specify both before and after
     * spacing so that substring measurement can do the right things.
     * These values are in appunits. They're always an integral number of
     * appunits, but we specify them in floats in case very large spacing
     * values are required.
     */
    struct Spacing {
        gfxFloat mBefore;
        gfxFloat mAfter;
    };
    /**
     * Metrics for a particular string
     */
    struct RunMetrics {
        RunMetrics() {
            mAdvanceWidth = mAscent = mDescent = 0.0;
        }

        void CombineWith(const RunMetrics& aOther, bool aOtherIsOnLeft);

        // can be negative (partly due to negative spacing).
        // Advance widths should be additive: the advance width of the
        // (offset1, length1) plus the advance width of (offset1 + length1,
        // length2) should be the advance width of (offset1, length1 + length2)
        gfxFloat mAdvanceWidth;
        
        // For zero-width substrings, these must be zero!
        gfxFloat mAscent;  // always non-negative
        gfxFloat mDescent; // always non-negative
        
        // Bounding box that is guaranteed to include everything drawn.
        // If a tight boundingBox was requested when these metrics were
        // generated, this will tightly wrap the glyphs, otherwise it is
        // "loose" and may be larger than the true bounding box.
        // Coordinates are relative to the baseline left origin, so typically
        // mBoundingBox.y == -mAscent
        gfxRect  mBoundingBox;
    };

    /**
     * Draw a series of glyphs to aContext. The direction of aTextRun must
     * be honoured.
     * @param aStart the first character to draw
     * @param aEnd draw characters up to here
     * @param aPt the baseline origin; the left end of the baseline
     * for LTR textruns, the right end for RTL textruns.
     * On return, this will be updated to the other end of the baseline.
     * In application units, really!
     * @param aRunParams record with drawing parameters, see TextRunDrawParams.
     * Particular fields of interest include
     * .spacing  spacing to insert before and after characters (for RTL
     *   glyphs, before-spacing is inserted to the right of characters). There
     *   are aEnd - aStart elements in this array, unless it's null to indicate
     *   that there is no spacing.
     * .drawMode  specifies whether the fill or stroke of the glyph should be
     *   drawn, or if it should be drawn into the current path
     * .contextPaint  information about how to construct the fill and
     *   stroke pattern. Can be nullptr if we are not stroking the text, which
     *   indicates that the current source from context should be used for fill
     * .context  the Thebes graphics context to which we're drawing
     * .dt  Moz2D DrawTarget to which we're drawing
     *
     * Callers guarantee:
     * -- aStart and aEnd are aligned to cluster and ligature boundaries
     * -- all glyphs use this font
     */
    void Draw(const gfxTextRun *aTextRun, uint32_t aStart, uint32_t aEnd,
              gfxPoint *aPt, const TextRunDrawParams& aRunParams,
              uint16_t aOrientation);

    /**
     * Draw the emphasis marks for the given text run. Its prerequisite
     * and output are similiar to the method Draw().
     * @param aPt the baseline origin of the emphasis marks.
     * @param aParams some drawing parameters, see EmphasisMarkDrawParams.
     */
    void DrawEmphasisMarks(const gfxTextRun* aShapedText, gfxPoint* aPt,
                           uint32_t aOffset, uint32_t aCount,
                           const EmphasisMarkDrawParams& aParams);

    /**
     * Measure a run of characters. See gfxTextRun::Metrics.
     * @param aTight if false, then return the union of the glyph extents
     * with the font-box for the characters (the rectangle with x=0,width=
     * the advance width for the character run,y=-(font ascent), and height=
     * font ascent + font descent). Otherwise, we must return as tight as possible
     * an approximation to the area actually painted by glyphs.
     * @param aDrawTargetForTightBoundingBox when aTight is true, this must
     * be non-null.
     * @param aSpacing spacing to insert before and after glyphs. The bounding box
     * need not include the spacing itself, but the spacing affects the glyph
     * positions. null if there is no spacing.
     * 
     * Callers guarantee:
     * -- aStart and aEnd are aligned to cluster and ligature boundaries
     * -- all glyphs use this font
     * 
     * The default implementation just uses font metrics and aTextRun's
     * advances, and assumes no characters fall outside the font box. In
     * general this is insufficient, because that assumption is not always true.
     */
    virtual RunMetrics Measure(const gfxTextRun *aTextRun,
                               uint32_t aStart, uint32_t aEnd,
                               BoundingBoxType aBoundingBoxType,
                               DrawTarget* aDrawTargetForTightBoundingBox,
                               Spacing *aSpacing, uint16_t aOrientation);
    /**
     * Line breaks have been changed at the beginning and/or end of a substring
     * of the text. Reshaping may be required; glyph updating is permitted.
     * @return true if anything was changed, false otherwise
     */
    bool NotifyLineBreaksChanged(gfxTextRun *aTextRun,
                                   uint32_t aStart, uint32_t aLength)
    { return false; }

    // Expiration tracking
    nsExpirationState *GetExpirationState() { return &mExpirationState; }

    // Get the glyphID of a space
    virtual uint32_t GetSpaceGlyph() = 0;

    gfxGlyphExtents *GetOrCreateGlyphExtents(int32_t aAppUnitsPerDevUnit);

    // You need to call SetupCairoFont on aDrawTarget just before calling this.
    virtual void SetupGlyphExtents(DrawTarget* aDrawTarget, uint32_t aGlyphID,
                                   bool aNeedTight, gfxGlyphExtents *aExtents);

    // This is called by the default Draw() implementation above.
    virtual bool SetupCairoFont(DrawTarget* aDrawTarget) = 0;

    virtual bool AllowSubpixelAA() { return true; }

    bool IsSyntheticBold() { return mApplySyntheticBold; }

    // Amount by which synthetic bold "fattens" the glyphs:
    // For size S up to a threshold size T, we use (0.25 + 3S / 4T),
    // so that the result ranges from 0.25 to 1.0; thereafter,
    // simply use (S / T).
    gfxFloat GetSyntheticBoldOffset() {
        gfxFloat size = GetAdjustedSize();
        const gfxFloat threshold = 48.0;
        return size < threshold ? (0.25 + 0.75 * size / threshold) :
                                  (size / threshold);
    }

    gfxFontEntry *GetFontEntry() const { return mFontEntry.get(); }
    bool HasCharacter(uint32_t ch) {
        if (!mIsValid ||
            (mUnicodeRangeMap && !mUnicodeRangeMap->test(ch))) {
            return false;
        }
        return mFontEntry->HasCharacter(ch); 
    }

    const gfxCharacterMap* GetUnicodeRangeMap() const {
        return mUnicodeRangeMap.get();
    }

    void SetUnicodeRangeMap(gfxCharacterMap* aUnicodeRangeMap) {
        mUnicodeRangeMap = aUnicodeRangeMap;
    }

    uint16_t GetUVSGlyph(uint32_t aCh, uint32_t aVS) {
        if (!mIsValid) {
            return 0;
        }
        return mFontEntry->GetUVSGlyph(aCh, aVS); 
    }

    template<typename T>
    bool InitFakeSmallCapsRun(DrawTarget *aDrawTarget,
                              gfxTextRun *aTextRun,
                              const T    *aText,
                              uint32_t    aOffset,
                              uint32_t    aLength,
                              uint8_t     aMatchType,
                              uint16_t    aOrientation,
                              Script      aScript,
                              bool        aSyntheticLower,
                              bool        aSyntheticUpper);

    // call the (virtual) InitTextRun method to do glyph generation/shaping,
    // limiting the length of text passed by processing the run in multiple
    // segments if necessary
    template<typename T>
    bool SplitAndInitTextRun(DrawTarget *aDrawTarget,
                             gfxTextRun *aTextRun,
                             const T *aString,
                             uint32_t aRunStart,
                             uint32_t aRunLength,
                             Script aRunScript,
                             bool aVertical);

    // Get a ShapedWord representing the given text (either 8- or 16-bit)
    // for use in setting up a gfxTextRun.
    template<typename T>
    gfxShapedWord* GetShapedWord(DrawTarget *aDrawTarget,
                                 const T *aText,
                                 uint32_t aLength,
                                 uint32_t aHash,
                                 Script aRunScript,
                                 bool aVertical,
                                 int32_t aAppUnitsPerDevUnit,
                                 uint32_t aFlags,
                                 gfxTextPerfMetrics *aTextPerf);

    // Ensure the ShapedWord cache is initialized. This MUST be called before
    // any attempt to use GetShapedWord().
    void InitWordCache() {
        if (!mWordCache) {
            mWordCache = mozilla::MakeUnique<nsTHashtable<CacheHashEntry>>();
        }
    }

    // Called by the gfxFontCache timer to increment the age of all the words,
    // so that they'll expire after a sufficient period of non-use
    void AgeCachedWords();

    // Discard all cached word records; called on memory-pressure notification.
    void ClearCachedWords() {
        if (mWordCache) {
            mWordCache->Clear();
        }
    }

    // Glyph rendering/geometry has changed, so invalidate data as necessary.
    void NotifyGlyphsChanged();

    virtual void AddSizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf,
                                        FontCacheSizes* aSizes) const;
    virtual void AddSizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf,
                                        FontCacheSizes* aSizes) const;

    typedef enum {
        FONT_TYPE_DWRITE,
        FONT_TYPE_GDI,
        FONT_TYPE_FT2,
        FONT_TYPE_MAC,
        FONT_TYPE_OS2,
        FONT_TYPE_CAIRO,
        FONT_TYPE_FONTCONFIG
    } FontType;

    virtual FontType GetType() const = 0;

    virtual already_AddRefed<mozilla::gfx::ScaledFont> GetScaledFont(DrawTarget* aTarget)
    { return gfxPlatform::GetPlatform()->GetScaledFontForFont(aTarget, this); }

    bool KerningDisabled() {
        return mKerningSet && !mKerningEnabled;
    }

    /**
     * Subclass this object to be notified of glyph changes. Delete the object
     * when no longer needed.
     */
    class GlyphChangeObserver {
    public:
        virtual ~GlyphChangeObserver()
        {
            if (mFont) {
                mFont->RemoveGlyphChangeObserver(this);
            }
        }
        // This gets called when the gfxFont dies.
        void ForgetFont() { mFont = nullptr; }
        virtual void NotifyGlyphsChanged() = 0;
    protected:
        explicit GlyphChangeObserver(gfxFont *aFont) : mFont(aFont)
        {
            mFont->AddGlyphChangeObserver(this);
        }
        // This pointer is nulled by ForgetFont in the gfxFont's
        // destructor. Before the gfxFont dies.
        gfxFont* MOZ_NON_OWNING_REF mFont;
    };
    friend class GlyphChangeObserver;

    bool GlyphsMayChange()
    {
        // Currently only fonts with SVG glyphs can have animated glyphs
        return mFontEntry->TryGetSVGData(this);
    }

    static void DestroySingletons() {
        delete sScriptTagToCode;
        delete sDefaultFeatures;
    }

    // Call TryGetMathTable() to try and load the Open Type MATH table.
    // If (and ONLY if) TryGetMathTable() has returned true, the MathTable()
    // method may be called to access the gfxMathTable data.
    bool          TryGetMathTable();
    gfxMathTable* MathTable() {
        MOZ_RELEASE_ASSERT(mMathTable, "A successful call to TryGetMathTable() must be performed before calling this function");
        return mMathTable.get();
    }

    // return a cloned font resized and offset to simulate sub/superscript glyphs
    virtual already_AddRefed<gfxFont>
    GetSubSuperscriptFont(int32_t aAppUnitsPerDevPixel);

    /**
     * Return the reference cairo_t object from aDT.
     */
    static cairo_t* RefCairo(mozilla::gfx::DrawTarget* aDT);

protected:
    virtual const Metrics& GetHorizontalMetrics() = 0;

    const Metrics* CreateVerticalMetrics();

    // Output a single glyph at *aPt, which is updated by the glyph's advance.
    // Normal glyphs are simply accumulated in aBuffer until it is full and
    // gets flushed, but SVG or color-font glyphs will instead be rendered
    // directly to the destination (found from the buffer's parameters).
    void DrawOneGlyph(uint32_t           aGlyphID,
                      double             aAdvance,
                      gfxPoint          *aPt,
                      GlyphBufferAzure&  aBuffer,
                      bool              *aEmittedGlyphs) const;

    // Output a run of glyphs at *aPt, which is updated to follow the last glyph
    // in the run. This method also takes account of any letter-spacing provided
    // in aRunParams.
    bool DrawGlyphs(const gfxShapedText      *aShapedText,
                    uint32_t                  aOffset, // offset in the textrun
                    uint32_t                  aCount, // length of run to draw
                    gfxPoint                 *aPt,
                    const TextRunDrawParams&  aRunParams,
                    const FontDrawParams&     aFontParams);

    // set the font size and offset used for
    // synthetic subscript/superscript glyphs
    void CalculateSubSuperSizeAndOffset(int32_t aAppUnitsPerDevPixel,
                                        gfxFloat& aSubSuperSizeRatio,
                                        float& aBaselineOffset);

    // Return a font that is a "clone" of this one, but reduced to 80% size
    // (and with variantCaps set to normal).
    // Default implementation relies on gfxFontEntry::CreateFontInstance;
    // backends that don't implement that will need to override this and use
    // an alternative technique. (gfxFontconfigFonts, I'm looking at you...)
    virtual already_AddRefed<gfxFont> GetSmallCapsFont();

    // subclasses may provide (possibly hinted) glyph widths (in font units);
    // if they do not override this, harfbuzz will use unhinted widths
    // derived from the font tables
    virtual bool ProvidesGlyphWidths() const {
        return false;
    }

    // The return value is interpreted as a horizontal advance in 16.16 fixed
    // point format.
    virtual int32_t GetGlyphWidth(DrawTarget& aDrawTarget, uint16_t aGID) {
        return -1;
    }

    bool IsSpaceGlyphInvisible(DrawTarget* aRefDrawTarget,
                               const gfxTextRun* aTextRun);

    void AddGlyphChangeObserver(GlyphChangeObserver *aObserver);
    void RemoveGlyphChangeObserver(GlyphChangeObserver *aObserver);

    // whether font contains substitution lookups containing spaces
    bool HasSubstitutionRulesWithSpaceLookups(Script aRunScript);

    // do spaces participate in shaping rules? if so, can't used word cache
    bool SpaceMayParticipateInShaping(Script aRunScript);

    // For 8-bit text, expand to 16-bit and then call the following method.
    bool ShapeText(DrawTarget    *aContext,
                   const uint8_t *aText,
                   uint32_t       aOffset, // dest offset in gfxShapedText
                   uint32_t       aLength,
                   Script         aScript,
                   bool           aVertical,
                   gfxShapedText *aShapedText); // where to store the result

    // Call the appropriate shaper to generate glyphs for aText and store
    // them into aShapedText.
    virtual bool ShapeText(DrawTarget      *aContext,
                           const char16_t *aText,
                           uint32_t         aOffset,
                           uint32_t         aLength,
                           Script           aScript,
                           bool             aVertical,
                           gfxShapedText   *aShapedText);

    // Helper to adjust for synthetic bold and set character-type flags
    // in the shaped text; implementations of ShapeText should call this
    // after glyph shaping has been completed.
    void PostShapingFixup(DrawTarget*     aContext,
                          const char16_t* aText,
                          uint32_t        aOffset, // position within aShapedText
                          uint32_t        aLength,
                          bool            aVertical,
                          gfxShapedText*  aShapedText);

    // Shape text directly into a range within a textrun, without using the
    // font's word cache. Intended for use when the font has layout features
    // that involve space, and therefore require shaping complete runs rather
    // than isolated words, or for long strings that are inefficient to cache.
    // This will split the text on "invalid" characters (tab/newline) that are
    // not handled via normal shaping, but does not otherwise divide up the
    // text.
    template<typename T>
    bool ShapeTextWithoutWordCache(DrawTarget *aDrawTarget,
                                   const T    *aText,
                                   uint32_t    aOffset,
                                   uint32_t    aLength,
                                   Script      aScript,
                                   bool        aVertical,
                                   gfxTextRun *aTextRun);

    // Shape a fragment of text (a run that is known to contain only
    // "valid" characters, no newlines/tabs/other control chars).
    // All non-wordcache shaping goes through here; this is the function
    // that will ensure we don't pass excessively long runs to the various
    // platform shapers.
    template<typename T>
    bool ShapeFragmentWithoutWordCache(DrawTarget *aDrawTarget,
                                       const T    *aText,
                                       uint32_t    aOffset,
                                       uint32_t    aLength,
                                       Script      aScript,
                                       bool        aVertical,
                                       gfxTextRun *aTextRun);

    void CheckForFeaturesInvolvingSpace();

    // whether a given feature is included in feature settings from both the
    // font and the style. aFeatureOn set if resolved feature value is non-zero
    bool HasFeatureSet(uint32_t aFeature, bool& aFeatureOn);

    // used when analyzing whether a font has space contextual lookups
    static nsDataHashtable<nsUint32HashKey,Script> *sScriptTagToCode;
    static nsTHashtable<nsUint32HashKey>           *sDefaultFeatures;

    RefPtr<gfxFontEntry> mFontEntry;

    struct CacheHashKey {
        union {
            const uint8_t   *mSingle;
            const char16_t *mDouble;
        }                mText;
        uint32_t         mLength;
        uint32_t         mFlags;
        Script           mScript;
        int32_t          mAppUnitsPerDevUnit;
        PLDHashNumber    mHashKey;
        bool             mTextIs8Bit;

        CacheHashKey(const uint8_t *aText, uint32_t aLength,
                     uint32_t aStringHash,
                     Script aScriptCode, int32_t aAppUnitsPerDevUnit,
                     uint32_t aFlags)
            : mLength(aLength),
              mFlags(aFlags),
              mScript(aScriptCode),
              mAppUnitsPerDevUnit(aAppUnitsPerDevUnit),
              mHashKey(aStringHash + static_cast<int32_t>(aScriptCode) +
                  aAppUnitsPerDevUnit * 0x100 + aFlags * 0x10000),
              mTextIs8Bit(true)
        {
            NS_ASSERTION(aFlags & gfxTextRunFactory::TEXT_IS_8BIT,
                         "8-bit flag should have been set");
            mText.mSingle = aText;
        }

        CacheHashKey(const char16_t *aText, uint32_t aLength,
                     uint32_t aStringHash,
                     Script aScriptCode, int32_t aAppUnitsPerDevUnit,
                     uint32_t aFlags)
            : mLength(aLength),
              mFlags(aFlags),
              mScript(aScriptCode),
              mAppUnitsPerDevUnit(aAppUnitsPerDevUnit),
              mHashKey(aStringHash + static_cast<int32_t>(aScriptCode) +
                  aAppUnitsPerDevUnit * 0x100 + aFlags * 0x10000),
              mTextIs8Bit(false)
        {
            // We can NOT assert that TEXT_IS_8BIT is false in aFlags here,
            // because this might be an 8bit-only word from a 16-bit textrun,
            // in which case the text we're passed is still in 16-bit form,
            // and we'll have to use an 8-to-16bit comparison in KeyEquals.
            mText.mDouble = aText;
        }
    };

    class CacheHashEntry : public PLDHashEntryHdr {
    public:
        typedef const CacheHashKey &KeyType;
        typedef const CacheHashKey *KeyTypePointer;

        // When constructing a new entry in the hashtable, the caller of Put()
        // will fill us in.
        explicit CacheHashEntry(KeyTypePointer aKey) { }
        CacheHashEntry(const CacheHashEntry& toCopy) { NS_ERROR("Should not be called"); }
        ~CacheHashEntry() { }

        bool KeyEquals(const KeyTypePointer aKey) const;

        static KeyTypePointer KeyToPointer(KeyType aKey) { return &aKey; }

        static PLDHashNumber HashKey(const KeyTypePointer aKey) {
            return aKey->mHashKey;
        }

        size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
        {
            return aMallocSizeOf(mShapedWord.get());
        }

        enum { ALLOW_MEMMOVE = true };

        mozilla::UniquePtr<gfxShapedWord> mShapedWord;
    };

    mozilla::UniquePtr<nsTHashtable<CacheHashEntry> > mWordCache;

    static const uint32_t  kShapedWordCacheMaxAge = 3;

    bool                       mIsValid;

    // use synthetic bolding for environments where this is not supported
    // by the platform
    bool                       mApplySyntheticBold;

    bool                       mKerningSet;     // kerning explicitly set?
    bool                       mKerningEnabled; // if set, on or off?

    bool                       mMathInitialized; // TryGetMathTable() called?

    nsExpirationState          mExpirationState;
    gfxFontStyle               mStyle;
    nsTArray<mozilla::UniquePtr<gfxGlyphExtents>> mGlyphExtentsArray;
    mozilla::UniquePtr<nsTHashtable<nsPtrHashKey<GlyphChangeObserver>>>
                               mGlyphChangeObservers;

    gfxFloat                   mAdjustedSize;

    // Conversion factor from font units to dev units; note that this may be
    // zero (in the degenerate case where mAdjustedSize has become zero).
    // This is OK because we only multiply by this factor, never divide.
    float                      mFUnitsConvFactor;

    // the AA setting requested for this font - may affect glyph bounds
    AntialiasOption            mAntialiasOption;

    // a copy of the font without antialiasing, if needed for separate
    // measurement by mathml code
    mozilla::UniquePtr<gfxFont>         mNonAAFont;

    // we create either or both of these shapers when needed, depending
    // whether the font has graphite tables, and whether graphite shaping
    // is actually enabled
    mozilla::UniquePtr<gfxFontShaper>   mHarfBuzzShaper;
    mozilla::UniquePtr<gfxFontShaper>   mGraphiteShaper;

    // if a userfont with unicode-range specified, contains map of *possible*
    // ranges supported by font
    RefPtr<gfxCharacterMap> mUnicodeRangeMap;

    RefPtr<mozilla::gfx::ScaledFont> mAzureScaledFont;

    // For vertical metrics, created on demand.
    mozilla::UniquePtr<const Metrics> mVerticalMetrics;

    // Table used for MathML layout.
    mozilla::UniquePtr<gfxMathTable> mMathTable;

    // Helper for subclasses that want to initialize standard metrics from the
    // tables of sfnt (TrueType/OpenType) fonts.
    // This will use mFUnitsConvFactor if it is already set, else compute it
    // from mAdjustedSize and the unitsPerEm in the font's 'head' table.
    // Returns TRUE and sets mIsValid=TRUE if successful;
    // Returns TRUE but leaves mIsValid=FALSE if the font seems to be broken.
    // Returns FALSE if the font does not appear to be an sfnt at all,
    // and should be handled (if possible) using other APIs.
    bool InitMetricsFromSfntTables(Metrics& aMetrics);

    // Helper to calculate various derived metrics from the results of
    // InitMetricsFromSfntTables or equivalent platform code
    void CalculateDerivedMetrics(Metrics& aMetrics);

    // some fonts have bad metrics, this method sanitize them.
    // if this font has bad underline offset, aIsBadUnderlineFont should be true.
    void SanitizeMetrics(Metrics *aMetrics, bool aIsBadUnderlineFont);

    bool RenderSVGGlyph(gfxContext *aContext, gfxPoint aPoint,
                        uint32_t aGlyphId, SVGContextPaint* aContextPaint) const;
    bool RenderSVGGlyph(gfxContext *aContext, gfxPoint aPoint,
                        uint32_t aGlyphId, SVGContextPaint* aContextPaint,
                        gfxTextRunDrawCallbacks *aCallbacks,
                        bool& aEmittedGlyphs) const;

    bool RenderColorGlyph(DrawTarget* aDrawTarget,
                          gfxContext* aContext,
                          mozilla::gfx::ScaledFont* scaledFont,
                          mozilla::gfx::GlyphRenderingOptions* renderingOptions,
                          mozilla::gfx::DrawOptions drawOptions,
                          const mozilla::gfx::Point& aPoint,
                          uint32_t aGlyphId) const;

    // Bug 674909. When synthetic bolding text by drawing twice, need to
    // render using a pixel offset in device pixels, otherwise text
    // doesn't appear bolded, it appears as if a bad text shadow exists
    // when a non-identity transform exists.  Use an offset factor so that
    // the second draw occurs at a constant offset in device pixels.
    // This helper calculates the scale factor we need to apply to the
    // synthetic-bold offset.
    static double CalcXScale(DrawTarget* aDrawTarget);
};

// proportion of ascent used for x-height, if unable to read value from font
#define DEFAULT_XHEIGHT_FACTOR 0.56f

// Parameters passed to gfxFont methods for drawing glyphs from a textrun.
// The TextRunDrawParams are set up once per textrun; the FontDrawParams
// are dependent on the specific font, so they are set per GlyphRun.

struct TextRunDrawParams {
    RefPtr<mozilla::gfx::DrawTarget> dt;
    gfxContext              *context;
    gfxFont::Spacing        *spacing;
    gfxTextRunDrawCallbacks *callbacks;
    mozilla::SVGContextPaint *runContextPaint;
    mozilla::gfx::Color      fontSmoothingBGColor;
    gfxFloat                 direction;
    double                   devPerApp;
    nscolor                  textStrokeColor;
    gfxPattern              *textStrokePattern;
    const mozilla::gfx::StrokeOptions *strokeOpts;
    const mozilla::gfx::DrawOptions   *drawOpts;
    DrawMode                 drawMode;
    bool                     isVerticalRun;
    bool                     isRTL;
    bool                     paintSVGGlyphs;
};

struct FontDrawParams {
    RefPtr<mozilla::gfx::ScaledFont>            scaledFont;
    RefPtr<mozilla::gfx::GlyphRenderingOptions> renderingOptions;
    mozilla::SVGContextPaint *contextPaint;
    mozilla::gfx::Matrix     *passedInvMatrix;
    mozilla::gfx::Matrix      matInv;
    double                    synBoldOnePixelOffset;
    int32_t                   extraStrikes;
    mozilla::gfx::DrawOptions drawOptions;
    bool                      isVerticalFont;
    bool                      haveSVGGlyphs;
    bool                      haveColorGlyphs;
};

struct EmphasisMarkDrawParams {
    gfxContext* context;
    gfxFont::Spacing* spacing;
    gfxTextRun* mark;
    gfxFloat advance;
    gfxFloat direction;
    bool isVertical;
};

#endif