summaryrefslogtreecommitdiff
path: root/layout/tables/FixedTableLayoutStrategy.cpp
blob: 42776579585890c170b8eecca2f5c81b2e11061e (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
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
// vim:cindent:ts=2:et:sw=2:
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/*
 * Algorithms that determine column and table inline sizes used for
 * CSS2's 'table-layout: fixed'.
 */

#include "FixedTableLayoutStrategy.h"
#include "nsTableFrame.h"
#include "nsTableColFrame.h"
#include "nsTableCellFrame.h"
#include <algorithm>

FixedTableLayoutStrategy::FixedTableLayoutStrategy(nsTableFrame *aTableFrame)
  : nsITableLayoutStrategy(nsITableLayoutStrategy::Fixed)
  , mTableFrame(aTableFrame)
{
  MarkIntrinsicISizesDirty();
}

/* virtual */
FixedTableLayoutStrategy::~FixedTableLayoutStrategy()
{
}

/* virtual */ nscoord
FixedTableLayoutStrategy::GetMinISize(nsRenderingContext* aRenderingContext)
{
  DISPLAY_MIN_WIDTH(mTableFrame, mMinISize);
  if (mMinISize != NS_INTRINSIC_WIDTH_UNKNOWN) {
    return mMinISize;
  }

  // It's theoretically possible to do something much better here that
  // depends only on the columns and the first row (where we look at
  // intrinsic inline sizes inside the first row and then reverse the
  // algorithm to find the narrowest inline size that would hold all of
  // those intrinsic inline sizes), but it wouldn't be compatible with
  // other browsers, or with the use of GetMinISize by
  // nsTableFrame::ComputeSize to determine the inline size of a fixed
  // layout table, since CSS2.1 says:
  //   The width of the table is then the greater of the value of the
  //   'width' property for the table element and the sum of the column
  //   widths (plus cell spacing or borders).

  // XXX Should we really ignore 'min-width' and 'max-width'?
  // XXX Should we really ignore widths on column groups?

  nsTableCellMap *cellMap = mTableFrame->GetCellMap();
  int32_t colCount = cellMap->GetColCount();

  nscoord result = 0;

  if (colCount > 0) {
    result += mTableFrame->GetColSpacing(-1, colCount);
  }

  WritingMode wm = mTableFrame->GetWritingMode();
  for (int32_t col = 0; col < colCount; ++col) {
    nsTableColFrame *colFrame = mTableFrame->GetColFrame(col);
    if (!colFrame) {
      NS_ERROR("column frames out of sync with cell map");
      continue;
    }
    nscoord spacing = mTableFrame->GetColSpacing(col);
    const nsStyleCoord *styleISize = &colFrame->StylePosition()->ISize(wm);
    if (styleISize->ConvertsToLength()) {
      result += colFrame->ComputeISizeValue(aRenderingContext,
                                            0, 0, 0, *styleISize);
    } else if (styleISize->GetUnit() == eStyleUnit_Percent) {
      // do nothing
    } else {
      NS_ASSERTION(styleISize->GetUnit() == eStyleUnit_Auto ||
                   styleISize->GetUnit() == eStyleUnit_Enumerated ||
                   (styleISize->IsCalcUnit() && styleISize->CalcHasPercent()),
                   "bad inline size");

      // The 'table-layout: fixed' algorithm considers only cells in the
      // first row.
      bool originates;
      int32_t colSpan;
      nsTableCellFrame *cellFrame = cellMap->GetCellInfoAt(0, col, &originates,
                                                           &colSpan);
      if (cellFrame) {
        styleISize = &cellFrame->StylePosition()->ISize(wm);
        if (styleISize->ConvertsToLength() ||
            (styleISize->GetUnit() == eStyleUnit_Enumerated &&
             (styleISize->GetIntValue() == NS_STYLE_WIDTH_MAX_CONTENT ||
              styleISize->GetIntValue() == NS_STYLE_WIDTH_MIN_CONTENT))) {
          nscoord cellISize =
            nsLayoutUtils::IntrinsicForContainer(aRenderingContext, cellFrame,
                                                 nsLayoutUtils::MIN_ISIZE);
          if (colSpan > 1) {
            // If a column-spanning cell is in the first row, split up
            // the space evenly.  (XXX This isn't quite right if some of
            // the columns it's in have specified inline sizes.  Should
            // we care?)
            cellISize = ((cellISize + spacing) / colSpan) - spacing;
          }
          result += cellISize;
        } else if (styleISize->GetUnit() == eStyleUnit_Percent) {
          if (colSpan > 1) {
            // XXX Can this force columns to negative inline sizes?
            result -= spacing * (colSpan - 1);
          }
        }
        // else, for 'auto', '-moz-available', '-moz-fit-content',
        // and 'calc()' with percentages, do nothing
      }
    }
  }

  return (mMinISize = result);
}

/* virtual */ nscoord
FixedTableLayoutStrategy::GetPrefISize(nsRenderingContext* aRenderingContext,
                                       bool aComputingSize)
{
  // It's theoretically possible to do something much better here that
  // depends only on the columns and the first row (where we look at
  // intrinsic inline sizes inside the first row and then reverse the
  // algorithm to find the narrowest inline size that would hold all of
  // those intrinsic inline sizes), but it wouldn't be compatible with
  // other browsers.
  nscoord result = nscoord_MAX;
  DISPLAY_PREF_WIDTH(mTableFrame, result);
  return result;
}

/* virtual */ void
FixedTableLayoutStrategy::MarkIntrinsicISizesDirty()
{
  mMinISize = NS_INTRINSIC_WIDTH_UNKNOWN;
  mLastCalcISize = nscoord_MIN;
}

static inline nscoord
AllocateUnassigned(nscoord aUnassignedSpace, float aShare)
{
  if (aShare == 1.0f) {
    // This happens when the numbers we're dividing to get aShare are
    // equal.  We want to return unassignedSpace exactly, even if it
    // can't be precisely round-tripped through float.
    return aUnassignedSpace;
  }
  return NSToCoordRound(float(aUnassignedSpace) * aShare);
}

/* virtual */ void
FixedTableLayoutStrategy::ComputeColumnISizes(const ReflowInput& aReflowInput)
{
  nscoord tableISize = aReflowInput.ComputedISize();

  if (mLastCalcISize == tableISize) {
    return;
  }
  mLastCalcISize = tableISize;

  nsTableCellMap *cellMap = mTableFrame->GetCellMap();
  int32_t colCount = cellMap->GetColCount();

  if (colCount == 0) {
    // No Columns - nothing to compute
    return;
  }

  // border-spacing isn't part of the basis for percentages.
  tableISize -= mTableFrame->GetColSpacing(-1, colCount);

  // store the old column inline sizes. We might call SetFinalISize
  // multiple times on the columns, due to this we can't compare at the
  // last call that the inline size has changed with respect to the last
  // call to ComputeColumnISizes. In order to overcome this we store the
  // old values in this array. A single call to SetFinalISize would make
  // it possible to call GetFinalISize before and to compare when
  // setting the final inline size.
  nsTArray<nscoord> oldColISizes;

  // XXX This ignores the 'min-width' and 'max-width' properties
  // throughout.  Then again, that's what the CSS spec says to do.

  // XXX Should we really ignore widths on column groups?

  uint32_t unassignedCount = 0;
  nscoord unassignedSpace = tableISize;
  const nscoord unassignedMarker = nscoord_MIN;

  // We use the PrefPercent on the columns to store the percentages
  // used to compute column inline sizes in case we need to shrink or
  // expand the columns.
  float pctTotal = 0.0f;

  // Accumulate the total specified (non-percent) on the columns for
  // distributing excess inline size to the columns.
  nscoord specTotal = 0;

  WritingMode wm = mTableFrame->GetWritingMode();
  for (int32_t col = 0; col < colCount; ++col) {
    nsTableColFrame *colFrame = mTableFrame->GetColFrame(col);
    if (!colFrame) {
      oldColISizes.AppendElement(0);
      NS_ERROR("column frames out of sync with cell map");
      continue;
    }
    oldColISizes.AppendElement(colFrame->GetFinalISize());
    colFrame->ResetPrefPercent();
    const nsStyleCoord *styleISize = &colFrame->StylePosition()->ISize(wm);
    nscoord colISize;
    if (styleISize->ConvertsToLength()) {
      colISize = colFrame->ComputeISizeValue(aReflowInput.mRenderingContext,
                                             0, 0, 0, *styleISize);
      specTotal += colISize;
    } else if (styleISize->GetUnit() == eStyleUnit_Percent) {
      float pct = styleISize->GetPercentValue();
      colISize = NSToCoordFloor(pct * float(tableISize));
      colFrame->AddPrefPercent(pct);
      pctTotal += pct;
    } else {
      NS_ASSERTION(styleISize->GetUnit() == eStyleUnit_Auto ||
                   styleISize->GetUnit() == eStyleUnit_Enumerated ||
                   (styleISize->IsCalcUnit() && styleISize->CalcHasPercent()),
                   "bad inline size");

      // The 'table-layout: fixed' algorithm considers only cells in the
      // first row.
      bool originates;
      int32_t colSpan;
      nsTableCellFrame *cellFrame = cellMap->GetCellInfoAt(0, col, &originates,
                                                           &colSpan);
      if (cellFrame) {
        const nsStylePosition* cellStylePos = cellFrame->StylePosition();
        styleISize = &cellStylePos->ISize(wm);
        if (styleISize->ConvertsToLength() ||
            (styleISize->GetUnit() == eStyleUnit_Enumerated &&
             (styleISize->GetIntValue() == NS_STYLE_WIDTH_MAX_CONTENT ||
              styleISize->GetIntValue() == NS_STYLE_WIDTH_MIN_CONTENT))) {
          // XXX This should use real percentage padding
          // Note that the difference between MIN_ISIZE and PREF_ISIZE
          // shouldn't matter for any of these values of styleISize; use
          // MIN_ISIZE for symmetry with GetMinISize above, just in case
          // there is a difference.
          colISize =
            nsLayoutUtils::IntrinsicForContainer(aReflowInput.mRenderingContext,
                                                 cellFrame,
                                                 nsLayoutUtils::MIN_ISIZE);
        } else if (styleISize->GetUnit() == eStyleUnit_Percent) {
          // XXX This should use real percentage padding
          float pct = styleISize->GetPercentValue();
          colISize = NSToCoordFloor(pct * float(tableISize));

          if (cellStylePos->mBoxSizing == StyleBoxSizing::Content) {
            nsIFrame::IntrinsicISizeOffsetData offsets =
              cellFrame->IntrinsicISizeOffsets();
            colISize += offsets.hPadding + offsets.hBorder;
          }

          pct /= float(colSpan);
          colFrame->AddPrefPercent(pct);
          pctTotal += pct;
        } else {
          // 'auto', '-moz-available', '-moz-fit-content', and 'calc()'
          // with percentages
          colISize = unassignedMarker;
        }
        if (colISize != unassignedMarker) {
          if (colSpan > 1) {
            // If a column-spanning cell is in the first row, split up
            // the space evenly.  (XXX This isn't quite right if some of
            // the columns it's in have specified iSizes.  Should we
            // care?)
            nscoord spacing = mTableFrame->GetColSpacing(col);
            colISize = ((colISize + spacing) / colSpan) - spacing;
            if (colISize < 0) {
              colISize = 0;
            }
          }
          if (styleISize->GetUnit() != eStyleUnit_Percent) {
            specTotal += colISize;
          }
        }
      } else {
        colISize = unassignedMarker;
      }
    }

    colFrame->SetFinalISize(colISize);

    if (colISize == unassignedMarker) {
      ++unassignedCount;
    } else {
      unassignedSpace -= colISize;
    }
  }

  if (unassignedSpace < 0) {
    if (pctTotal > 0) {
      // If the columns took up too much space, reduce those that had
      // percentage inline sizes.  The spec doesn't say to do this, but
      // we've always done it in the past, and so does WinIE6.
      nscoord pctUsed = NSToCoordFloor(pctTotal * float(tableISize));
      nscoord reduce = std::min(pctUsed, -unassignedSpace);
      float reduceRatio = float(reduce) / pctTotal;
      for (int32_t col = 0; col < colCount; ++col) {
        nsTableColFrame *colFrame = mTableFrame->GetColFrame(col);
        if (!colFrame) {
          NS_ERROR("column frames out of sync with cell map");
          continue;
        }
        nscoord colISize = colFrame->GetFinalISize();
        colISize -= NSToCoordFloor(colFrame->GetPrefPercent() * reduceRatio);
        if (colISize < 0) {
          colISize = 0;
        }
        colFrame->SetFinalISize(colISize);
      }
    }
    unassignedSpace = 0;
  }

  if (unassignedCount > 0) {
    // The spec says to distribute the remaining space evenly among
    // the columns.
    nscoord toAssign = unassignedSpace / unassignedCount;
    for (int32_t col = 0; col < colCount; ++col) {
      nsTableColFrame *colFrame = mTableFrame->GetColFrame(col);
      if (!colFrame) {
        NS_ERROR("column frames out of sync with cell map");
        continue;
      }
      if (colFrame->GetFinalISize() == unassignedMarker) {
        colFrame->SetFinalISize(toAssign);
      }
    }
  } else if (unassignedSpace > 0) {
    // The spec doesn't say how to distribute the unassigned space.
    if (specTotal > 0) {
      // Distribute proportionally to non-percentage columns.
      nscoord specUndist = specTotal;
      for (int32_t col = 0; col < colCount; ++col) {
        nsTableColFrame *colFrame = mTableFrame->GetColFrame(col);
        if (!colFrame) {
          NS_ERROR("column frames out of sync with cell map");
          continue;
        }
        if (colFrame->GetPrefPercent() == 0.0f) {
          NS_ASSERTION(colFrame->GetFinalISize() <= specUndist,
                       "inline sizes don't add up");
          nscoord toAdd = AllocateUnassigned(unassignedSpace,
                                             float(colFrame->GetFinalISize()) /
                                              float(specUndist));
          specUndist -= colFrame->GetFinalISize();
          colFrame->SetFinalISize(colFrame->GetFinalISize() + toAdd);
          unassignedSpace -= toAdd;
          if (specUndist <= 0) {
            NS_ASSERTION(specUndist == 0, "math should be exact");
            break;
          }
        }
      }
      NS_ASSERTION(unassignedSpace == 0, "failed to redistribute");
    } else if (pctTotal > 0) {
      // Distribute proportionally to percentage columns.
      float pctUndist = pctTotal;
      for (int32_t col = 0; col < colCount; ++col) {
        nsTableColFrame *colFrame = mTableFrame->GetColFrame(col);
        if (!colFrame) {
          NS_ERROR("column frames out of sync with cell map");
          continue;
        }
        if (pctUndist < colFrame->GetPrefPercent()) {
          // This can happen with floating-point math.
          NS_ASSERTION(colFrame->GetPrefPercent() - pctUndist < 0.0001,
                       "inline sizes don't add up");
          pctUndist = colFrame->GetPrefPercent();
        }
        nscoord toAdd = AllocateUnassigned(unassignedSpace,
                                           colFrame->GetPrefPercent() /
                                             pctUndist);
        colFrame->SetFinalISize(colFrame->GetFinalISize() + toAdd);
        unassignedSpace -= toAdd;
        pctUndist -= colFrame->GetPrefPercent();
        if (pctUndist <= 0.0f) {
          break;
        }
      }
      NS_ASSERTION(unassignedSpace == 0, "failed to redistribute");
    } else {
      // Distribute equally to the zero-iSize columns.
      int32_t colsRemaining = colCount;
      for (int32_t col = 0; col < colCount; ++col) {
        nsTableColFrame *colFrame = mTableFrame->GetColFrame(col);
        if (!colFrame) {
          NS_ERROR("column frames out of sync with cell map");
          continue;
        }
        NS_ASSERTION(colFrame->GetFinalISize() == 0, "yikes");
        nscoord toAdd = AllocateUnassigned(unassignedSpace,
                                           1.0f / float(colsRemaining));
        colFrame->SetFinalISize(toAdd);
        unassignedSpace -= toAdd;
        --colsRemaining;
      }
      NS_ASSERTION(unassignedSpace == 0, "failed to redistribute");
    }
  }
  for (int32_t col = 0; col < colCount; ++col) {
    nsTableColFrame *colFrame = mTableFrame->GetColFrame(col);
    if (!colFrame) {
      NS_ERROR("column frames out of sync with cell map");
      continue;
    }
    if (oldColISizes.ElementAt(col) != colFrame->GetFinalISize()) {
      mTableFrame->DidResizeColumns();
      break;
    }
  }
}