Source/WebCore/rendering/RenderGrid.cpp

   1 /*
   2  * Copyright (C) 2011 Apple Inc. All rights reserved.
   3  * Copyright (C) 2013, 2014 Igalia S.L.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
  15  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  17  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
  18  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  19  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  20  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  21  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
  22  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  24  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  25  */
  26
  27 #include "config.h"
  28 #include "RenderGrid.h"
  29
  30 #if ENABLE(CSS_GRID_LAYOUT)
  31
  32 #include "GridCoordinate.h"
  33 #include "GridResolvedPosition.h"
  34 #include "LayoutRepainter.h"
  35 #include "RenderLayer.h"
  36 #include "RenderView.h"
  37 #include <wtf/NeverDestroyed.h>
  38
  39 namespace WebCore {
  40
  41 static const int infinity = -1;
  42
  43 class GridTrack {
  44 public:
  45     GridTrack() {}
  46
  47     const LayoutUnit& baseSize() const
  48     {
  49         ASSERT(isGrowthLimitBiggerThanBaseSize());
  50         return m_baseSize;
  51     }
  52
  53     const LayoutUnit& growthLimit() const
  54     {
  55         ASSERT(isGrowthLimitBiggerThanBaseSize());
  56         return m_growthLimit;
  57     }
  58
  59     void setBaseSize(LayoutUnit baseSize)
  60     {
  61         m_baseSize = baseSize;
  62         ensureGrowthLimitIsBiggerThanBaseSize();
  63     }
  64
  65     void setGrowthLimit(LayoutUnit growthLimit)
  66     {
  67         m_growthLimit = growthLimit;
  68         ensureGrowthLimitIsBiggerThanBaseSize();
  69     }
  70
  71     bool growthLimitIsInfinite() const
  72     {
  73         return m_growthLimit == infinity;
  74     }
  75
  76     bool infiniteGrowthPotential() const
  77     {
  78         return growthLimitIsInfinite() || m_infinitelyGrowable;
  79     }
  80
  81     const LayoutUnit& growthLimitIfNotInfinite() const
  82     {
  83         ASSERT(isGrowthLimitBiggerThanBaseSize());
  84         return (m_growthLimit == infinity) ? m_baseSize : m_growthLimit;
  85     }
  86
  87     const LayoutUnit& plannedSize() const { return m_plannedSize; }
  88
  89     void setPlannedSize(LayoutUnit plannedSize)
  90     {
  91         m_plannedSize = plannedSize;
  92     }
  93
  94     LayoutUnit& tempSize() { return m_tempSize; }
  95
  96     bool infinitelyGrowable() const { return m_infinitelyGrowable; }
  97
  98     void setInfinitelyGrowable(bool infinitelyGrowable)
  99     {
 100         m_infinitelyGrowable = infinitelyGrowable;
 101     }
 102
 103 private:
 104     bool isGrowthLimitBiggerThanBaseSize() const { return growthLimitIsInfinite() || m_growthLimit >= m_baseSize; }
 105
 106     void ensureGrowthLimitIsBiggerThanBaseSize()
 107     {
 108         if (m_growthLimit != infinity && m_growthLimit < m_baseSize)
 109             m_growthLimit = m_baseSize;
 110     }
 111
 112     LayoutUnit m_baseSize { 0 };
 113     LayoutUnit m_growthLimit { 0 };
 114     LayoutUnit m_plannedSize { 0 };
 115     LayoutUnit m_tempSize { 0 };
 116     bool m_infinitelyGrowable { false };
 117 };
 118
 119 struct ContentAlignmentData {
 120     WTF_MAKE_FAST_ALLOCATED;
 121 public:
 122     bool isValid() { return positionOffset >= 0 && distributionOffset >= 0; }
 123     static ContentAlignmentData defaultOffsets() { return {-1, -1}; }
 124
 125     LayoutUnit positionOffset;
 126     LayoutUnit distributionOffset;
 127 };
 128
 129 class RenderGrid::GridIterator {
 130     WTF_MAKE_NONCOPYABLE(GridIterator);
 131 public:
 132     // |direction| is the direction that is fixed to |fixedTrackIndex| so e.g
 133     // GridIterator(m_grid, ForColumns, 1) will walk over the rows of the 2nd column.
 134     GridIterator(const Vector<Vector<Vector<RenderBox*, 1>>>& grid, GridTrackSizingDirection direction, unsigned fixedTrackIndex, unsigned varyingTrackIndex = 0)
 135         : m_grid(grid)
 136         , m_direction(direction)
 137         , m_rowIndex((direction == ForColumns) ? varyingTrackIndex : fixedTrackIndex)
 138         , m_columnIndex((direction == ForColumns) ? fixedTrackIndex : varyingTrackIndex)
 139         , m_childIndex(0)
 140     {
 141         ASSERT(m_rowIndex < m_grid.size());
 142         ASSERT(m_columnIndex < m_grid[0].size());
 143     }
 144
 145     RenderBox* nextGridItem()
 146     {
 147         if (!m_grid.size())
 148             return 0;
 149
 150         unsigned& varyingTrackIndex = (m_direction == ForColumns) ? m_rowIndex : m_columnIndex;
 151         const unsigned endOfVaryingTrackIndex = (m_direction == ForColumns) ? m_grid.size() : m_grid[0].size();
 152         for (; varyingTrackIndex < endOfVaryingTrackIndex; ++varyingTrackIndex) {
 153             const auto& children = m_grid[m_rowIndex][m_columnIndex];
 154             if (m_childIndex < children.size())
 155                 return children[m_childIndex++];
 156
 157             m_childIndex = 0;
 158         }
 159         return 0;
 160     }
 161
 162     bool isEmptyAreaEnough(unsigned rowSpan, unsigned columnSpan) const
 163     {
 164         // Ignore cells outside current grid as we will grow it later if needed.
 165         unsigned maxRows = std::min<unsigned>(m_rowIndex + rowSpan, m_grid.size());
 166         unsigned maxColumns = std::min<unsigned>(m_columnIndex + columnSpan, m_grid[0].size());
 167
 168         // This adds a O(N^2) behavior that shouldn't be a big deal as we expect spanning areas to be small.
 169         for (unsigned row = m_rowIndex; row < maxRows; ++row) {
 170             for (unsigned column = m_columnIndex; column < maxColumns; ++column) {
 171                 auto& children = m_grid[row][column];
 172                 if (!children.isEmpty())
 173                     return false;
 174             }
 175         }
 176
 177         return true;
 178     }
 179
 180     std::unique_ptr<GridCoordinate> nextEmptyGridArea(unsigned fixedTrackSpan, unsigned varyingTrackSpan)
 181     {
 182         ASSERT(fixedTrackSpan >= 1 && varyingTrackSpan >= 1);
 183
 184         if (m_grid.isEmpty())
 185             return nullptr;
 186
 187         unsigned rowSpan = (m_direction == ForColumns) ? varyingTrackSpan : fixedTrackSpan;
 188         unsigned columnSpan = (m_direction == ForColumns) ? fixedTrackSpan : varyingTrackSpan;
 189
 190         unsigned& varyingTrackIndex = (m_direction == ForColumns) ? m_rowIndex : m_columnIndex;
 191         const unsigned endOfVaryingTrackIndex = (m_direction == ForColumns) ? m_grid.size() : m_grid[0].size();
 192         for (; varyingTrackIndex < endOfVaryingTrackIndex; ++varyingTrackIndex) {
 193             if (isEmptyAreaEnough(rowSpan, columnSpan)) {
 194                 std::unique_ptr<GridCoordinate> result = std::make_unique<GridCoordinate>(GridSpan(m_rowIndex, m_rowIndex + rowSpan - 1), GridSpan(m_columnIndex, m_columnIndex + columnSpan - 1));
 195                 // Advance the iterator to avoid an infinite loop where we would return the same grid area over and over.
 196                 ++varyingTrackIndex;
 197                 return result;
 198             }
 199         }
 200         return nullptr;
 201     }
 202
 203 private:
 204     const Vector<Vector<Vector<RenderBox*, 1>>>& m_grid;
 205     GridTrackSizingDirection m_direction;
 206     unsigned m_rowIndex;
 207     unsigned m_columnIndex;
 208     unsigned m_childIndex;
 209 };
 210
 211 class RenderGrid::GridSizingData {
 212     WTF_MAKE_NONCOPYABLE(GridSizingData);
 213 public:
 214     GridSizingData(unsigned gridColumnCount, unsigned gridRowCount)
 215         : columnTracks(gridColumnCount)
 216         , rowTracks(gridRowCount)
 217     {
 218     }
 219
 220     Vector<GridTrack> columnTracks;
 221     Vector<GridTrack> rowTracks;
 222     Vector<unsigned> contentSizedTracksIndex;
 223
 224     // Performance optimization: hold onto these Vectors until the end of Layout to avoid repeated malloc / free.
 225     Vector<GridTrack*> filteredTracks;
 226     Vector<GridTrack*> growBeyondGrowthLimitsTracks;
 227     Vector<GridItemWithSpan> itemsSortedByIncreasingSpan;
 228 };
 229
 230 RenderGrid::RenderGrid(Element& element, Ref<RenderStyle>&& style)
 231     : RenderBlock(element, WTF::move(style), 0)
 232     , m_orderIterator(*this)
 233 {
 234     // All of our children must be block level.
 235     setChildrenInline(false);
 236 }
 237
 238 RenderGrid::~RenderGrid()
 239 {
 240 }
 241
 242 static inline bool defaultAlignmentIsStretch(ItemPosition position)
 243 {
 244     return position == ItemPositionStretch || position == ItemPositionAuto;
 245 }
 246
 247 static inline bool defaultAlignmentChangedToStretchInRowAxis(const RenderStyle& oldStyle, const RenderStyle& newStyle)
 248 {
 249     return !defaultAlignmentIsStretch(oldStyle.justifyItemsPosition()) && defaultAlignmentIsStretch(newStyle.justifyItemsPosition());
 250 }
 251
 252 static inline bool defaultAlignmentChangedFromStretchInColumnAxis(const RenderStyle& oldStyle, const RenderStyle& newStyle)
 253 {
 254     return defaultAlignmentIsStretch(oldStyle.alignItemsPosition()) && !defaultAlignmentIsStretch(newStyle.alignItemsPosition());
 255 }
 256
 257 static inline bool selfAlignmentChangedToStretchInRowAxis(const RenderStyle& oldStyle, const RenderStyle& newStyle, const RenderStyle& childStyle)
 258 {
 259     return RenderStyle::resolveJustification(oldStyle, childStyle, ItemPositionStretch) != ItemPositionStretch
 260         && RenderStyle::resolveJustification(newStyle, childStyle, ItemPositionStretch) == ItemPositionStretch;
 261 }
 262
 263 static inline bool selfAlignmentChangedFromStretchInColumnAxis(const RenderStyle& oldStyle, const RenderStyle& newStyle, const RenderStyle& childStyle)
 264 {
 265     return RenderStyle::resolveAlignment(oldStyle, childStyle, ItemPositionStretch) == ItemPositionStretch
 266         && RenderStyle::resolveAlignment(newStyle, childStyle, ItemPositionStretch) != ItemPositionStretch;
 267 }
 268
 269 void RenderGrid::styleDidChange(StyleDifference diff, const RenderStyle* oldStyle)
 270 {
 271     RenderBlock::styleDidChange(diff, oldStyle);
 272     if (!oldStyle || diff != StyleDifferenceLayout)
 273         return;
 274
 275     const RenderStyle& newStyle = style();
 276     if (defaultAlignmentChangedToStretchInRowAxis(*oldStyle, newStyle) || defaultAlignmentChangedFromStretchInColumnAxis(*oldStyle, newStyle)) {
 277         // Grid items that were not previously stretched in row-axis need to be relayed out so we can compute new available space.
 278         // Grid items that were previously stretching in column-axis need to be relayed out so we can compute new available space.
 279         // This is only necessary for stretching since other alignment values don't change the size of the box.
 280         for (RenderBox* child = firstChildBox(); child; child = child->nextSiblingBox()) {
 281             if (child->isOutOfFlowPositioned())
 282                 continue;
 283             if (selfAlignmentChangedToStretchInRowAxis(*oldStyle, newStyle, child->style()) || selfAlignmentChangedFromStretchInColumnAxis(*oldStyle, newStyle, child->style()))
 284                 child->setChildNeedsLayout(MarkOnlyThis);
 285         }
 286     }
 287 }
 288
 289 void RenderGrid::layoutBlock(bool relayoutChildren, LayoutUnit)
 290 {
 291     ASSERT(needsLayout());
 292
 293     if (!relayoutChildren && simplifiedLayout())
 294         return;
 295
 296     // FIXME: Much of this method is boiler plate that matches RenderBox::layoutBlock and Render*FlexibleBox::layoutBlock.
 297     // It would be nice to refactor some of the duplicate code.
 298     LayoutRepainter repainter(*this, checkForRepaintDuringLayout());
 299     LayoutStateMaintainer statePusher(view(), *this, locationOffset(), hasTransform() || hasReflection() || style().isFlippedBlocksWritingMode());
 300
 301     preparePaginationBeforeBlockLayout(relayoutChildren);
 302
 303     LayoutSize previousSize = size();
 304
 305     setLogicalHeight(0);
 306     updateLogicalWidth();
 307
 308     layoutGridItems();
 309
 310     LayoutUnit oldClientAfterEdge = clientLogicalBottom();
 311     updateLogicalHeight();
 312
 313     if (size() != previousSize)
 314         relayoutChildren = true;
 315
 316     layoutPositionedObjects(relayoutChildren || isRoot());
 317
 318     computeOverflow(oldClientAfterEdge);
 319     statePusher.pop();
 320
 321     updateLayerTransform();
 322
 323     // Update our scroll information if we're overflow:auto/scroll/hidden now that we know if
 324     // we overflow or not.
 325     updateScrollInfoAfterLayout();
 326
 327     repainter.repaintAfterLayout();
 328
 329     clearNeedsLayout();
 330 }
 331
 332 LayoutUnit RenderGrid::guttersSize(GridTrackSizingDirection direction, size_t span) const
 333 {
 334     ASSERT(span >= 1);
 335
 336     if (span == 1)
 337         return { };
 338
 339     const Length& trackGap = direction == ForColumns ? style().gridColumnGap() : style().gridRowGap();
 340     return valueForLength(trackGap, 0) * (span - 1);
 341 }
 342
 343 void RenderGrid::computeIntrinsicLogicalWidths(LayoutUnit& minLogicalWidth, LayoutUnit& maxLogicalWidth) const
 344 {
 345     bool wasPopulated = gridWasPopulated();
 346     if (!wasPopulated)
 347         const_cast<RenderGrid*>(this)->placeItemsOnGrid();
 348
 349     GridSizingData sizingData(gridColumnCount(), gridRowCount());
 350     LayoutUnit availableLogicalSpace = 0;
 351     const_cast<RenderGrid*>(this)->computeUsedBreadthOfGridTracks(ForColumns, sizingData, availableLogicalSpace);
 352
 353     for (auto& column : sizingData.columnTracks) {
 354         LayoutUnit minTrackBreadth = column.baseSize();
 355         LayoutUnit maxTrackBreadth = column.growthLimit();
 356
 357         minLogicalWidth += minTrackBreadth;
 358         maxLogicalWidth += maxTrackBreadth;
 359     }
 360
 361     LayoutUnit totalGuttersSize = guttersSize(ForColumns, sizingData.columnTracks.size());
 362     minLogicalWidth += totalGuttersSize;
 363     maxLogicalWidth += totalGuttersSize;
 364
 365     LayoutUnit scrollbarWidth = intrinsicScrollbarLogicalWidth();
 366     minLogicalWidth += scrollbarWidth;
 367     maxLogicalWidth += scrollbarWidth;
 368
 369     if (!wasPopulated)
 370         const_cast<RenderGrid*>(this)->clearGrid();
 371 }
 372
 373 bool RenderGrid::gridElementIsShrinkToFit()
 374 {
 375     return isFloatingOrOutOfFlowPositioned();
 376 }
 377
 378 static inline double normalizedFlexFraction(const GridTrack& track, double flexFactor)
 379 {
 380     return track.baseSize() / std::max<double>(1, flexFactor);
 381 }
 382
 383 void RenderGrid::computeUsedBreadthOfGridTracks(GridTrackSizingDirection direction, GridSizingData& sizingData, LayoutUnit& availableLogicalSpace)
 384 {
 385     const LayoutUnit initialAvailableLogicalSpace = availableLogicalSpace;
 386     Vector<GridTrack>& tracks = (direction == ForColumns) ? sizingData.columnTracks : sizingData.rowTracks;
 387     Vector<unsigned> flexibleSizedTracksIndex;
 388     sizingData.contentSizedTracksIndex.shrink(0);
 389
 390     // 1. Initialize per Grid track variables.
 391     for (unsigned i = 0; i < tracks.size(); ++i) {
 392         GridTrack& track = tracks[i];
 393         const GridTrackSize& trackSize = gridTrackSize(direction, i);
 394         const GridLength& minTrackBreadth = trackSize.minTrackBreadth();
 395         const GridLength& maxTrackBreadth = trackSize.maxTrackBreadth();
 396
 397         track.setBaseSize(computeUsedBreadthOfMinLength(direction, minTrackBreadth));
 398         track.setGrowthLimit(computeUsedBreadthOfMaxLength(direction, maxTrackBreadth, track.baseSize()));
 399         track.setInfinitelyGrowable(false);
 400
 401         if (trackSize.isContentSized())
 402             sizingData.contentSizedTracksIndex.append(i);
 403         if (trackSize.maxTrackBreadth().isFlex())
 404             flexibleSizedTracksIndex.append(i);
 405     }
 406
 407     // 2. Resolve content-based TrackSizingFunctions.
 408     if (!sizingData.contentSizedTracksIndex.isEmpty())
 409         resolveContentBasedTrackSizingFunctions(direction, sizingData);
 410
 411     for (auto& track : tracks) {
 412         ASSERT(!track.growthLimitIsInfinite());
 413         availableLogicalSpace -= track.baseSize();
 414     }
 415
 416     const bool hasUndefinedRemainingSpace = (direction == ForRows) ? style().logicalHeight().isAuto() : gridElementIsShrinkToFit();
 417
 418     if (!hasUndefinedRemainingSpace && availableLogicalSpace <= 0)
 419         return;
 420
 421     // 3. Grow all Grid tracks in GridTracks from their UsedBreadth up to their MaxBreadth value until availableLogicalSpace is exhausted.
 422     if (!hasUndefinedRemainingSpace) {
 423         const unsigned tracksSize = tracks.size();
 424         Vector<GridTrack*> tracksForDistribution(tracksSize);
 425         for (unsigned i = 0; i < tracksSize; ++i) {
 426             tracksForDistribution[i] = tracks.data() + i;
 427             tracksForDistribution[i]->setPlannedSize(tracksForDistribution[i]->baseSize());
 428         }
 429
 430         distributeSpaceToTracks<MaximizeTracks>(tracksForDistribution, nullptr, availableLogicalSpace);
 431
 432         for (auto* track : tracksForDistribution)
 433             track->setBaseSize(track->plannedSize());
 434     } else {
 435         for (auto& track : tracks)
 436             track.setBaseSize(track.growthLimit());
 437     }
 438
 439     if (flexibleSizedTracksIndex.isEmpty())
 440         return;
 441
 442     // 4. Grow all Grid tracks having a fraction as the MaxTrackSizingFunction.
 443     double flexFraction = 0;
 444     if (!hasUndefinedRemainingSpace)
 445         flexFraction = findFlexFactorUnitSize(tracks, GridSpan(0, tracks.size() - 1), direction, initialAvailableLogicalSpace);
 446     else {
 447         for (const auto& trackIndex : flexibleSizedTracksIndex)
 448             flexFraction = std::max(flexFraction, normalizedFlexFraction(tracks[trackIndex], gridTrackSize(direction, trackIndex).maxTrackBreadth().flex()));
 449
 450         for (unsigned i = 0; i < flexibleSizedTracksIndex.size(); ++i) {
 451             GridIterator iterator(m_grid, direction, flexibleSizedTracksIndex[i]);
 452             while (RenderBox* gridItem = iterator.nextGridItem()) {
 453                 const GridCoordinate coordinate = cachedGridCoordinate(*gridItem);
 454                 const GridSpan span = (direction == ForColumns) ? coordinate.columns : coordinate.rows;
 455
 456                 // Do not include already processed items.
 457                 if (i > 0 && span.resolvedInitialPosition.toInt() <= flexibleSizedTracksIndex[i - 1])
 458                     continue;
 459
 460                 flexFraction = std::max(flexFraction, findFlexFactorUnitSize(tracks, span, direction, maxContentForChild(*gridItem, direction, sizingData.columnTracks)));
 461             }
 462         }
 463     }
 464
 465     for (auto trackIndex : flexibleSizedTracksIndex) {
 466         const GridTrackSize& trackSize = gridTrackSize(direction, trackIndex);
 467         GridTrack& track = tracks[trackIndex];
 468         LayoutUnit baseSize = std::max<LayoutUnit>(track.baseSize(), flexFraction * trackSize.maxTrackBreadth().flex());
 469         track.setBaseSize(baseSize);
 470         availableLogicalSpace -= baseSize;
 471     }
 472 }
 473
 474 LayoutUnit RenderGrid::computeUsedBreadthOfMinLength(GridTrackSizingDirection direction, const GridLength& gridLength) const
 475 {
 476     if (gridLength.isFlex())
 477         return 0;
 478
 479     const Length& trackLength = gridLength.length();
 480     if (trackLength.isSpecified())
 481         return computeUsedBreadthOfSpecifiedLength(direction, trackLength);
 482
 483     ASSERT(trackLength.isMinContent() || trackLength.isAuto() || trackLength.isMaxContent());
 484     return 0;
 485 }
 486
 487 LayoutUnit RenderGrid::computeUsedBreadthOfMaxLength(GridTrackSizingDirection direction, const GridLength& gridLength, LayoutUnit usedBreadth) const
 488 {
 489     if (gridLength.isFlex())
 490         return usedBreadth;
 491
 492     const Length& trackLength = gridLength.length();
 493     if (trackLength.isSpecified()) {
 494         LayoutUnit computedBreadth = computeUsedBreadthOfSpecifiedLength(direction, trackLength);
 495         ASSERT(computedBreadth != infinity);
 496         return computedBreadth;
 497     }
 498
 499     ASSERT(trackLength.isMinContent() || trackLength.isAuto() || trackLength.isMaxContent());
 500     return infinity;
 501 }
 502
 503 LayoutUnit RenderGrid::computeUsedBreadthOfSpecifiedLength(GridTrackSizingDirection direction, const Length& trackLength) const
 504 {
 505     ASSERT(trackLength.isSpecified());
 506     if (direction == ForColumns)
 507         return valueForLength(trackLength, contentLogicalWidth());
 508     return valueForLength(trackLength, computeContentLogicalHeight(MainOrPreferredSize, style().logicalHeight(), Nullopt).valueOr(0));
 509 }
 510
 511 double RenderGrid::computeFlexFactorUnitSize(const Vector<GridTrack>& tracks, GridTrackSizingDirection direction, double flexFactorSum, LayoutUnit leftOverSpace, const Vector<unsigned, 8>& flexibleTracksIndexes, std::unique_ptr<TrackIndexSet> tracksToTreatAsInflexible) const
 512 {
 513     // We want to avoid the effect of flex factors sum below 1 making the factor unit size to grow exponentially.
 514     double hypotheticalFactorUnitSize = leftOverSpace / std::max<double>(1, flexFactorSum);
 515
 516     // product of the hypothetical "flex factor unit" and any flexible track's "flex factor" must be grater than such track's "base size".
 517     bool validFlexFactorUnit = true;
 518     for (auto index : flexibleTracksIndexes) {
 519         if (tracksToTreatAsInflexible && tracksToTreatAsInflexible->contains(index))
 520             continue;
 521         LayoutUnit baseSize = tracks[index].baseSize();
 522         double flexFactor = gridTrackSize(direction, index).maxTrackBreadth().flex();
 523         // treating all such tracks as inflexible.
 524         if (baseSize > hypotheticalFactorUnitSize * flexFactor) {
 525             leftOverSpace -= baseSize;
 526             flexFactorSum -= flexFactor;
 527             if (!tracksToTreatAsInflexible)
 528                 tracksToTreatAsInflexible = std::unique_ptr<TrackIndexSet>(new TrackIndexSet());
 529             tracksToTreatAsInflexible->add(index);
 530             validFlexFactorUnit = false;
 531         }
 532     }
 533     if (!validFlexFactorUnit)
 534         return computeFlexFactorUnitSize(tracks, direction, flexFactorSum, leftOverSpace, flexibleTracksIndexes, WTF::move(tracksToTreatAsInflexible));
 535     return hypotheticalFactorUnitSize;
 536 }
 537
 538 double RenderGrid::findFlexFactorUnitSize(const Vector<GridTrack>& tracks, const GridSpan& tracksSpan, GridTrackSizingDirection direction, LayoutUnit leftOverSpace) const
 539 {
 540     if (leftOverSpace <= 0)
 541         return 0;
 542
 543     double flexFactorSum = 0;
 544     Vector<unsigned, 8> flexibleTracksIndexes;
 545     for (const auto& resolvedPosition : tracksSpan) {
 546         unsigned trackIndex = resolvedPosition.toInt();
 547         GridTrackSize trackSize = gridTrackSize(direction, trackIndex);
 548         if (!trackSize.maxTrackBreadth().isFlex())
 549             leftOverSpace -= tracks[trackIndex].baseSize();
 550         else {
 551             double flexFactor = trackSize.maxTrackBreadth().flex();
 552             flexibleTracksIndexes.append(trackIndex);
 553             flexFactorSum += flexFactor;
 554         }
 555     }
 556
 557     // The function is not called if we don't have <flex> grid tracks
 558     ASSERT(!flexibleTracksIndexes.isEmpty());
 559
 560     return computeFlexFactorUnitSize(tracks, direction, flexFactorSum, leftOverSpace, flexibleTracksIndexes);
 561 }
 562
 563 bool RenderGrid::hasDefiniteLogicalSize(GridTrackSizingDirection direction) const
 564 {
 565     return (direction == ForRows) ? hasDefiniteLogicalHeight() : hasDefiniteLogicalWidth();
 566 }
 567
 568 GridTrackSize RenderGrid::gridTrackSize(GridTrackSizingDirection direction, unsigned i) const
 569 {
 570     bool isForColumns = (direction == ForColumns);
 571     auto& trackStyles =  isForColumns ? style().gridColumns() : style().gridRows();
 572     auto& trackSize = (i >= trackStyles.size()) ? (isForColumns ? style().gridAutoColumns() : style().gridAutoRows()) : trackStyles[i];
 573
 574     GridLength minTrackBreadth = trackSize.minTrackBreadth();
 575     GridLength maxTrackBreadth = trackSize.maxTrackBreadth();
 576
 577     if (minTrackBreadth.isPercentage() || maxTrackBreadth.isPercentage()) {
 578         if (!hasDefiniteLogicalSize(direction)) {
 579             if (minTrackBreadth.isPercentage())
 580                 minTrackBreadth = Length(MinContent);
 581             if (maxTrackBreadth.isPercentage())
 582                 maxTrackBreadth = Length(MaxContent);
 583         }
 584     }
 585
 586     return GridTrackSize(minTrackBreadth, maxTrackBreadth);
 587 }
 588
 589 LayoutUnit RenderGrid::logicalContentHeightForChild(RenderBox& child, Vector<GridTrack>& columnTracks)
 590 {
 591     Optional<LayoutUnit> oldOverrideContainingBlockContentLogicalWidth = child.hasOverrideContainingBlockLogicalWidth() ? child.overrideContainingBlockContentLogicalWidth() : LayoutUnit();
 592     LayoutUnit overrideContainingBlockContentLogicalWidth = gridAreaBreadthForChild(child, ForColumns, columnTracks);
 593     if (child.hasRelativeLogicalHeight() || !oldOverrideContainingBlockContentLogicalWidth || oldOverrideContainingBlockContentLogicalWidth.value() != overrideContainingBlockContentLogicalWidth) {
 594         child.setNeedsLayout(MarkOnlyThis);
 595         // We need to clear the stretched height to properly compute logical height during layout.
 596         child.clearOverrideLogicalContentHeight();
 597     }
 598
 599     child.setOverrideContainingBlockContentLogicalWidth(overrideContainingBlockContentLogicalWidth);
 600     // If |child| has a relative logical height, we shouldn't let it override its intrinsic height, which is
 601     // what we are interested in here. Thus we need to set the override logical height to Nullopt (no possible resolution).
 602     if (child.hasRelativeLogicalHeight())
 603         child.setOverrideContainingBlockContentLogicalHeight(Nullopt);
 604     child.layoutIfNeeded();
 605     return child.logicalHeight() + child.marginLogicalHeight();
 606 }
 607
 608 LayoutUnit RenderGrid::minSizeForChild(RenderBox& child, GridTrackSizingDirection direction, Vector<GridTrack>& columnTracks)
 609 {
 610     bool hasOrthogonalWritingMode = child.isHorizontalWritingMode() != isHorizontalWritingMode();
 611     // FIXME: Properly support orthogonal writing mode.
 612     if (hasOrthogonalWritingMode)
 613         return { };
 614
 615     const Length& childMinSize = direction == ForColumns ? child.style().logicalMinWidth() : child.style().logicalMinHeight();
 616     if (childMinSize.isAuto()) {
 617         // FIXME: Implement intrinsic aspect ratio support (transferred size in specs).
 618         return minContentForChild(child, direction, columnTracks);
 619     }
 620
 621     if (direction == ForColumns)
 622         return child.computeLogicalWidthInRegionUsing(MinSize, childMinSize, contentLogicalWidth(), this, nullptr);
 623
 624     return child.computeContentAndScrollbarLogicalHeightUsing(MinSize, childMinSize, child.logicalHeight()).valueOr(0);
 625 }
 626
 627 LayoutUnit RenderGrid::minContentForChild(RenderBox& child, GridTrackSizingDirection direction, Vector<GridTrack>& columnTracks)
 628 {
 629     bool hasOrthogonalWritingMode = child.isHorizontalWritingMode() != isHorizontalWritingMode();
 630     // FIXME: Properly support orthogonal writing mode.
 631     if (hasOrthogonalWritingMode)
 632         return 0;
 633
 634     if (direction == ForColumns) {
 635         // If |child| has a relative logical width, we shouldn't let it override its intrinsic width, which is
 636         // what we are interested in here. Thus we need to set the override logical width to Nullopt (no possible resolution).
 637         if (child.hasRelativeLogicalWidth())
 638             child.setOverrideContainingBlockContentLogicalWidth(Nullopt);
 639
 640         // FIXME: It's unclear if we should return the intrinsic width or the preferred width.
 641         // See http://lists.w3.org/Archives/Public/www-style/2013Jan/0245.html
 642         return child.minPreferredLogicalWidth() + marginIntrinsicLogicalWidthForChild(child);
 643     }
 644
 645     return logicalContentHeightForChild(child, columnTracks);
 646 }
 647
 648 LayoutUnit RenderGrid::maxContentForChild(RenderBox& child, GridTrackSizingDirection direction, Vector<GridTrack>& columnTracks)
 649 {
 650     bool hasOrthogonalWritingMode = child.isHorizontalWritingMode() != isHorizontalWritingMode();
 651     // FIXME: Properly support orthogonal writing mode.
 652     if (hasOrthogonalWritingMode)
 653         return LayoutUnit();
 654
 655     if (direction == ForColumns) {
 656         // If |child| has a relative logical width, we shouldn't let it override its intrinsic width, which is
 657         // what we are interested in here. Thus we need to set the override logical width to Nullopt (no possible resolution).
 658         if (child.hasRelativeLogicalWidth())
 659             child.setOverrideContainingBlockContentLogicalWidth(Nullopt);
 660
 661         // FIXME: It's unclear if we should return the intrinsic width or the preferred width.
 662         // See http://lists.w3.org/Archives/Public/www-style/2013Jan/0245.html
 663         return child.maxPreferredLogicalWidth() + marginIntrinsicLogicalWidthForChild(child);
 664     }
 665
 666     return logicalContentHeightForChild(child, columnTracks);
 667 }
 668
 669 class GridItemWithSpan {
 670 public:
 671     GridItemWithSpan(RenderBox& gridItem, GridCoordinate coordinate, GridTrackSizingDirection direction)
 672         : m_gridItem(gridItem)
 673         , m_coordinate(coordinate)
 674     {
 675         const GridSpan& span = (direction == ForRows) ? coordinate.rows : coordinate.columns;
 676         m_span = span.resolvedFinalPosition.toInt() - span.resolvedInitialPosition.toInt() + 1;
 677     }
 678
 679     RenderBox& gridItem() const { return m_gridItem; }
 680     GridCoordinate coordinate() const { return m_coordinate; }
 681 #if !ASSERT_DISABLED
 682     size_t span() const { return m_span; }
 683 #endif
 684
 685     bool operator<(const GridItemWithSpan other) const
 686     {
 687         return m_span < other.m_span;
 688     }
 689
 690 private:
 691     std::reference_wrapper<RenderBox> m_gridItem;
 692     GridCoordinate m_coordinate;
 693     unsigned m_span;
 694 };
 695
 696 bool RenderGrid::spanningItemCrossesFlexibleSizedTracks(const GridCoordinate& coordinate, GridTrackSizingDirection direction) const
 697 {
 698     const GridSpan itemSpan = (direction == ForColumns) ? coordinate.columns : coordinate.rows;
 699     for (auto trackPosition : itemSpan) {
 700         const GridTrackSize& trackSize = gridTrackSize(direction, trackPosition.toInt());
 701         if (trackSize.minTrackBreadth().isFlex() || trackSize.maxTrackBreadth().isFlex())
 702             return true;
 703     }
 704
 705     return false;
 706 }
 707
 708 static inline unsigned integerSpanForDirection(const GridCoordinate& coordinate, GridTrackSizingDirection direction)
 709 {
 710     return (direction == ForRows) ? coordinate.rows.integerSpan() : coordinate.columns.integerSpan();
 711 }
 712
 713 struct GridItemsSpanGroupRange {
 714     Vector<GridItemWithSpan>::iterator rangeStart;
 715     Vector<GridItemWithSpan>::iterator rangeEnd;
 716 };
 717
 718 void RenderGrid::resolveContentBasedTrackSizingFunctions(GridTrackSizingDirection direction, GridSizingData& sizingData)
 719 {
 720     sizingData.itemsSortedByIncreasingSpan.shrink(0);
 721     HashSet<RenderBox*> itemsSet;
 722     for (auto trackIndex : sizingData.contentSizedTracksIndex) {
 723         GridIterator iterator(m_grid, direction, trackIndex);
 724         GridTrack& track = (direction == ForColumns) ? sizingData.columnTracks[trackIndex] : sizingData.rowTracks[trackIndex];
 725
 726         while (RenderBox* gridItem = iterator.nextGridItem()) {
 727             if (itemsSet.add(gridItem).isNewEntry) {
 728                 const GridCoordinate& coordinate = cachedGridCoordinate(*gridItem);
 729                 if (integerSpanForDirection(coordinate, direction) == 1)
 730                     resolveContentBasedTrackSizingFunctionsForNonSpanningItems(direction, coordinate, *gridItem, track, sizingData.columnTracks);
 731                 else if (!spanningItemCrossesFlexibleSizedTracks(coordinate, direction))
 732                     sizingData.itemsSortedByIncreasingSpan.append(GridItemWithSpan(*gridItem, coordinate, direction));
 733             }
 734         }
 735     }
 736     std::sort(sizingData.itemsSortedByIncreasingSpan.begin(), sizingData.itemsSortedByIncreasingSpan.end());
 737
 738     auto it = sizingData.itemsSortedByIncreasingSpan.begin();
 739     auto end = sizingData.itemsSortedByIncreasingSpan.end();
 740     while (it != end) {
 741         GridItemsSpanGroupRange spanGroupRange = { it, std::upper_bound(it, end, *it) };
 742         resolveContentBasedTrackSizingFunctionsForItems<ResolveIntrinsicMinimums>(direction, sizingData, spanGroupRange);
 743         resolveContentBasedTrackSizingFunctionsForItems<ResolveContentBasedMinimums>(direction, sizingData, spanGroupRange);
 744         resolveContentBasedTrackSizingFunctionsForItems<ResolveMaxContentMinimums>(direction, sizingData, spanGroupRange);
 745         resolveContentBasedTrackSizingFunctionsForItems<ResolveIntrinsicMaximums>(direction, sizingData, spanGroupRange);
 746         resolveContentBasedTrackSizingFunctionsForItems<ResolveMaxContentMaximums>(direction, sizingData, spanGroupRange);
 747         it = spanGroupRange.rangeEnd;
 748     }
 749
 750     for (auto trackIndex : sizingData.contentSizedTracksIndex) {
 751         GridTrack& track = (direction == ForColumns) ? sizingData.columnTracks[trackIndex] : sizingData.rowTracks[trackIndex];
 752         if (track.growthLimitIsInfinite())
 753             track.setGrowthLimit(track.baseSize());
 754     }
 755 }
 756
 757 void RenderGrid::resolveContentBasedTrackSizingFunctionsForNonSpanningItems(GridTrackSizingDirection direction, const GridCoordinate& coordinate, RenderBox& gridItem, GridTrack& track, Vector<GridTrack>& columnTracks)
 758 {
 759     const GridResolvedPosition trackPosition = (direction == ForColumns) ? coordinate.columns.resolvedInitialPosition : coordinate.rows.resolvedInitialPosition;
 760     GridTrackSize trackSize = gridTrackSize(direction, trackPosition.toInt());
 761
 762     if (trackSize.hasMinContentMinTrackBreadth())
 763         track.setBaseSize(std::max(track.baseSize(), minContentForChild(gridItem, direction, columnTracks)));
 764     else if (trackSize.hasMaxContentMinTrackBreadth())
 765         track.setBaseSize(std::max(track.baseSize(), maxContentForChild(gridItem, direction, columnTracks)));
 766     else if (trackSize.hasAutoMinTrackBreadth())
 767         track.setBaseSize(std::max(track.baseSize(), minSizeForChild(gridItem, direction, columnTracks)));
 768
 769     if (trackSize.hasMinContentMaxTrackBreadth())
 770         track.setGrowthLimit(std::max(track.growthLimit(), minContentForChild(gridItem, direction, columnTracks)));
 771     else if (trackSize.hasMaxContentOrAutoMaxTrackBreadth())
 772         track.setGrowthLimit(std::max(track.growthLimit(), maxContentForChild(gridItem, direction, columnTracks)));
 773 }
 774
 775 const LayoutUnit& RenderGrid::trackSizeForTrackSizeComputationPhase(TrackSizeComputationPhase phase, GridTrack& track, TrackSizeRestriction restriction)
 776 {
 777     switch (phase) {
 778     case ResolveIntrinsicMinimums:
 779     case ResolveContentBasedMinimums:
 780     case ResolveMaxContentMinimums:
 781     case MaximizeTracks:
 782         return track.baseSize();
 783     case ResolveIntrinsicMaximums:
 784     case ResolveMaxContentMaximums:
 785         return restriction == AllowInfinity ? track.growthLimit() : track.growthLimitIfNotInfinite();
 786     }
 787
 788     ASSERT_NOT_REACHED();
 789     return track.baseSize();
 790 }
 791
 792 bool RenderGrid::shouldProcessTrackForTrackSizeComputationPhase(TrackSizeComputationPhase phase, const GridTrackSize& trackSize)
 793 {
 794     switch (phase) {
 795     case ResolveIntrinsicMinimums:
 796         return trackSize.hasIntrinsicMinTrackBreadth();
 797     case ResolveContentBasedMinimums:
 798         return trackSize.hasMinOrMaxContentMinTrackBreadth();
 799     case ResolveMaxContentMinimums:
 800         return trackSize.hasMaxContentMinTrackBreadth();
 801     case ResolveIntrinsicMaximums:
 802         return trackSize.hasMinOrMaxContentMaxTrackBreadth();
 803     case ResolveMaxContentMaximums:
 804         return trackSize.hasMaxContentOrAutoMaxTrackBreadth();
 805     case MaximizeTracks:
 806         ASSERT_NOT_REACHED();
 807         return false;
 808     }
 809
 810     ASSERT_NOT_REACHED();
 811     return false;
 812 }
 813
 814 bool RenderGrid::trackShouldGrowBeyondGrowthLimitsForTrackSizeComputationPhase(TrackSizeComputationPhase phase, const GridTrackSize& trackSize)
 815 {
 816     switch (phase) {
 817     case ResolveIntrinsicMinimums:
 818     case ResolveContentBasedMinimums:
 819         return trackSize.hasAutoOrMinContentMinTrackBreadthAndIntrinsicMaxTrackBreadth();
 820     case ResolveMaxContentMinimums:
 821         return trackSize.hasMaxContentMinTrackBreadthAndMaxContentMaxTrackBreadth();
 822     case ResolveIntrinsicMaximums:
 823     case ResolveMaxContentMaximums:
 824         return true;
 825     case MaximizeTracks:
 826         ASSERT_NOT_REACHED();
 827         return false;
 828     }
 829
 830     ASSERT_NOT_REACHED();
 831     return false;
 832 }
 833
 834 void RenderGrid::markAsInfinitelyGrowableForTrackSizeComputationPhase(TrackSizeComputationPhase phase, GridTrack& track)
 835 {
 836     switch (phase) {
 837     case ResolveIntrinsicMinimums:
 838     case ResolveContentBasedMinimums:
 839     case ResolveMaxContentMinimums:
 840         return;
 841     case ResolveIntrinsicMaximums:
 842         if (trackSizeForTrackSizeComputationPhase(phase, track, AllowInfinity) == infinity  && track.plannedSize() != infinity)
 843             track.setInfinitelyGrowable(true);
 844         return;
 845     case ResolveMaxContentMaximums:
 846         if (track.infinitelyGrowable())
 847             track.setInfinitelyGrowable(false);
 848         return;
 849     case MaximizeTracks:
 850         ASSERT_NOT_REACHED();
 851         return;
 852     }
 853
 854     ASSERT_NOT_REACHED();
 855 }
 856
 857 void RenderGrid::updateTrackSizeForTrackSizeComputationPhase(TrackSizeComputationPhase phase, GridTrack& track)
 858 {
 859     switch (phase) {
 860     case ResolveIntrinsicMinimums:
 861     case ResolveContentBasedMinimums:
 862     case ResolveMaxContentMinimums:
 863         track.setBaseSize(track.plannedSize());
 864         return;
 865     case ResolveIntrinsicMaximums:
 866     case ResolveMaxContentMaximums:
 867         track.setGrowthLimit(track.plannedSize());
 868         return;
 869     case MaximizeTracks:
 870         ASSERT_NOT_REACHED();
 871         return;
 872     }
 873
 874     ASSERT_NOT_REACHED();
 875 }
 876
 877 LayoutUnit RenderGrid::currentItemSizeForTrackSizeComputationPhase(TrackSizeComputationPhase phase, RenderBox& gridItem, GridTrackSizingDirection direction, Vector<GridTrack>& columnTracks)
 878 {
 879     switch (phase) {
 880     case ResolveIntrinsicMinimums:
 881         return minSizeForChild(gridItem, direction, columnTracks);
 882     case ResolveContentBasedMinimums:
 883     case ResolveIntrinsicMaximums:
 884         return minContentForChild(gridItem, direction, columnTracks);
 885     case ResolveMaxContentMinimums:
 886     case ResolveMaxContentMaximums:
 887         return maxContentForChild(gridItem, direction, columnTracks);
 888     case MaximizeTracks:
 889         ASSERT_NOT_REACHED();
 890         return 0;
 891     }
 892
 893     ASSERT_NOT_REACHED();
 894     return 0;
 895 }
 896
 897 template <RenderGrid::TrackSizeComputationPhase phase>
 898 void RenderGrid::resolveContentBasedTrackSizingFunctionsForItems(GridTrackSizingDirection direction, GridSizingData& sizingData, const GridItemsSpanGroupRange& gridItemsWithSpan)
 899 {
 900     Vector<GridTrack>& tracks = (direction == ForColumns) ? sizingData.columnTracks : sizingData.rowTracks;
 901     for (const auto& trackIndex : sizingData.contentSizedTracksIndex) {
 902         GridTrack& track = tracks[trackIndex];
 903         track.setPlannedSize(trackSizeForTrackSizeComputationPhase(phase, track, AllowInfinity));
 904     }
 905
 906     for (auto it = gridItemsWithSpan.rangeStart; it != gridItemsWithSpan.rangeEnd; ++it) {
 907         GridItemWithSpan& gridItemWithSpan = *it;
 908         ASSERT(gridItemWithSpan.span() > 1);
 909         const GridCoordinate& coordinate = gridItemWithSpan.coordinate();
 910         const GridSpan& itemSpan = (direction == ForColumns) ? coordinate.columns : coordinate.rows;
 911
 912         sizingData.filteredTracks.shrink(0);
 913         sizingData.growBeyondGrowthLimitsTracks.shrink(0);
 914         LayoutUnit spanningTracksSize;
 915         for (auto& trackPosition : itemSpan) {
 916             const GridTrackSize& trackSize = gridTrackSize(direction, trackPosition.toInt());
 917             GridTrack& track = (direction == ForColumns) ? sizingData.columnTracks[trackPosition.toInt()] : sizingData.rowTracks[trackPosition.toInt()];
 918             spanningTracksSize += trackSizeForTrackSizeComputationPhase(phase, track, ForbidInfinity);
 919             if (!shouldProcessTrackForTrackSizeComputationPhase(phase, trackSize))
 920                 continue;
 921
 922             sizingData.filteredTracks.append(&track);
 923
 924             if (trackShouldGrowBeyondGrowthLimitsForTrackSizeComputationPhase(phase, trackSize))
 925                 sizingData.growBeyondGrowthLimitsTracks.append(&track);
 926         }
 927
 928         if (sizingData.filteredTracks.isEmpty())
 929             continue;
 930
 931         spanningTracksSize += guttersSize(direction, itemSpan.integerSpan());
 932
 933         LayoutUnit extraSpace = currentItemSizeForTrackSizeComputationPhase(phase, gridItemWithSpan.gridItem(), direction, sizingData.columnTracks) - spanningTracksSize;
 934         extraSpace = std::max<LayoutUnit>(extraSpace, 0);
 935         auto& tracksToGrowBeyondGrowthLimits = sizingData.growBeyondGrowthLimitsTracks.isEmpty() ? sizingData.filteredTracks : sizingData.growBeyondGrowthLimitsTracks;
 936         distributeSpaceToTracks<phase>(sizingData.filteredTracks, &tracksToGrowBeyondGrowthLimits, extraSpace);
 937     }
 938
 939     for (const auto& trackIndex : sizingData.contentSizedTracksIndex) {
 940         GridTrack& track = tracks[trackIndex];
 941         markAsInfinitelyGrowableForTrackSizeComputationPhase(phase, track);
 942         updateTrackSizeForTrackSizeComputationPhase(phase, track);
 943     }
 944 }
 945
 946 static bool sortByGridTrackGrowthPotential(const GridTrack* track1, const GridTrack* track2)
 947 {
 948     // This check ensures that we respect the irreflexivity property of the strict weak ordering required by std::sort
 949     // (forall x: NOT x < x).
 950     if (track1->infiniteGrowthPotential() && track2->infiniteGrowthPotential())
 951         return false;
 952
 953     if (track1->infiniteGrowthPotential() || track2->infiniteGrowthPotential())
 954         return track2->infiniteGrowthPotential();
 955
 956     return (track1->growthLimit() - track1->baseSize()) < (track2->growthLimit() - track2->baseSize());
 957 }
 958
 959 template <RenderGrid::TrackSizeComputationPhase phase>
 960 void RenderGrid::distributeSpaceToTracks(Vector<GridTrack*>& tracks, const Vector<GridTrack*>* growBeyondGrowthLimitsTracks, LayoutUnit& availableLogicalSpace)
 961 {
 962     ASSERT(availableLogicalSpace >= 0);
 963
 964     for (auto* track : tracks)
 965         track->tempSize() = trackSizeForTrackSizeComputationPhase(phase, *track, ForbidInfinity);
 966
 967     if (availableLogicalSpace > 0) {
 968         std::sort(tracks.begin(), tracks.end(), sortByGridTrackGrowthPotential);
 969
 970         unsigned tracksSize = tracks.size();
 971         for (unsigned i = 0; i < tracksSize; ++i) {
 972             GridTrack& track = *tracks[i];
 973             const LayoutUnit& trackBreadth = trackSizeForTrackSizeComputationPhase(phase, track, ForbidInfinity);
 974             bool infiniteGrowthPotential = track.infiniteGrowthPotential();
 975             LayoutUnit trackGrowthPotential = infiniteGrowthPotential ? track.growthLimit() : track.growthLimit() - trackBreadth;
 976             // Let's avoid computing availableLogicalSpaceShare as much as possible as it's a hot spot in performance tests.
 977             if (trackGrowthPotential > 0 || infiniteGrowthPotential) {
 978                 LayoutUnit availableLogicalSpaceShare = availableLogicalSpace / (tracksSize - i);
 979                 LayoutUnit growthShare = infiniteGrowthPotential ? availableLogicalSpaceShare : std::min(availableLogicalSpaceShare, trackGrowthPotential);
 980                 ASSERT_WITH_MESSAGE(growthShare >= 0, "We should never shrink any grid track or else we can't guarantee we abide by our min-sizing function. We can still have 0 as growthShare if the amount of tracks greatly exceeds the availableLogicalSpace.");
 981                 track.tempSize() += growthShare;
 982                 availableLogicalSpace -= growthShare;
 983             }
 984         }
 985     }
 986
 987     if (availableLogicalSpace > 0 && growBeyondGrowthLimitsTracks) {
 988         unsigned tracksGrowingBeyondGrowthLimitsSize = growBeyondGrowthLimitsTracks->size();
 989         for (unsigned i = 0; i < tracksGrowingBeyondGrowthLimitsSize; ++i) {
 990             GridTrack* track = growBeyondGrowthLimitsTracks->at(i);
 991             LayoutUnit growthShare = availableLogicalSpace / (tracksGrowingBeyondGrowthLimitsSize - i);
 992             track->tempSize() += growthShare;
 993             availableLogicalSpace -= growthShare;
 994         }
 995     }
 996
 997     for (auto* track : tracks)
 998         track->setPlannedSize(track->plannedSize() == infinity ? track->tempSize() : std::max(track->plannedSize(), track->tempSize()));
 999 }
1000
1001 #ifndef NDEBUG
1002 bool RenderGrid::tracksAreWiderThanMinTrackBreadth(GridTrackSizingDirection direction, const Vector<GridTrack>& tracks)
1003 {
1004     for (unsigned i = 0; i < tracks.size(); ++i) {
1005         const GridTrackSize& trackSize = gridTrackSize(direction, i);
1006         const GridLength& minTrackBreadth = trackSize.minTrackBreadth();
1007         if (computeUsedBreadthOfMinLength(direction, minTrackBreadth) > tracks[i].baseSize())
1008             return false;
1009     }
1010     return true;
1011 }
1012 #endif
1013
1014 void RenderGrid::ensureGridSize(unsigned maximumRowIndex, unsigned maximumColumnIndex)
1015 {
1016     const unsigned oldRowCount = gridRowCount();
1017     if (maximumRowIndex >= oldRowCount) {
1018         m_grid.grow(maximumRowIndex + 1);
1019         for (unsigned row = oldRowCount; row < gridRowCount(); ++row)
1020             m_grid[row].grow(gridColumnCount());
1021     }
1022
1023     if (maximumColumnIndex >= gridColumnCount()) {
1024         for (unsigned row = 0; row < gridRowCount(); ++row)
1025             m_grid[row].grow(maximumColumnIndex + 1);
1026     }
1027 }
1028
1029 void RenderGrid::insertItemIntoGrid(RenderBox& child, const GridCoordinate& coordinate)
1030 {
1031     ensureGridSize(coordinate.rows.resolvedFinalPosition.toInt(), coordinate.columns.resolvedFinalPosition.toInt());
1032
1033     for (auto& row : coordinate.rows) {
1034         for (auto& column : coordinate.columns)
1035             m_grid[row.toInt()][column.toInt()].append(&child);
1036     }
1037     m_gridItemCoordinate.set(&child, coordinate);
1038 }
1039
1040 void RenderGrid::placeItemsOnGrid()
1041 {
1042     ASSERT(!gridWasPopulated());
1043     ASSERT(m_gridItemCoordinate.isEmpty());
1044
1045     populateExplicitGridAndOrderIterator();
1046
1047     Vector<RenderBox*> autoMajorAxisAutoGridItems;
1048     Vector<RenderBox*> specifiedMajorAxisAutoGridItems;
1049     for (RenderBox* child = m_orderIterator.first(); child; child = m_orderIterator.next()) {
1050         auto unresolvedRowPositions = GridResolvedPosition::unresolvedSpanFromStyle(style(), *child, ForRows);
1051         auto unresolvedColumnPositions = GridResolvedPosition::unresolvedSpanFromStyle(style(), *child, ForColumns);
1052
1053         if (unresolvedRowPositions.requiresAutoPlacement() || unresolvedColumnPositions.requiresAutoPlacement()) {
1054
1055             bool majorAxisDirectionIsForColumns = autoPlacementMajorAxisDirection() == ForColumns;
1056             if ((majorAxisDirectionIsForColumns && unresolvedColumnPositions.requiresAutoPlacement())
1057                 || (!majorAxisDirectionIsForColumns && unresolvedRowPositions.requiresAutoPlacement()))
1058                 autoMajorAxisAutoGridItems.append(child);
1059             else
1060                 specifiedMajorAxisAutoGridItems.append(child);
1061             continue;
1062         }
1063         GridSpan rowPositions = GridResolvedPosition::resolveGridPositionsFromStyle(unresolvedRowPositions, style());
1064         GridSpan columnPositions = GridResolvedPosition::resolveGridPositionsFromStyle(unresolvedColumnPositions, style());
1065         insertItemIntoGrid(*child, GridCoordinate(rowPositions, columnPositions));
1066     }
1067
1068     ASSERT(gridRowCount() >= GridResolvedPosition::explicitGridRowCount(style()));
1069     ASSERT(gridColumnCount() >= GridResolvedPosition::explicitGridColumnCount(style()));
1070
1071     placeSpecifiedMajorAxisItemsOnGrid(specifiedMajorAxisAutoGridItems);
1072     placeAutoMajorAxisItemsOnGrid(autoMajorAxisAutoGridItems);
1073 }
1074
1075 void RenderGrid::populateExplicitGridAndOrderIterator()
1076 {
1077     OrderIteratorPopulator populator(m_orderIterator);
1078     unsigned maximumRowIndex = std::max<unsigned>(1, GridResolvedPosition::explicitGridRowCount(style()));
1079     unsigned maximumColumnIndex = std::max<unsigned>(1, GridResolvedPosition::explicitGridColumnCount(style()));
1080
1081     for (RenderBox* child = firstChildBox(); child; child = child->nextSiblingBox()) {
1082         populator.collectChild(*child);
1083
1084         auto unresolvedRowPositions = GridResolvedPosition::unresolvedSpanFromStyle(style(), *child, ForRows);
1085         if (!unresolvedRowPositions.requiresAutoPlacement()) {
1086             GridSpan rowPositions = GridResolvedPosition::resolveGridPositionsFromStyle(unresolvedRowPositions, style());
1087             maximumRowIndex = std::max(maximumRowIndex, rowPositions.resolvedFinalPosition.next().toInt());
1088         } else {
1089             // Grow the grid for items with a definite row span, getting the largest such span.
1090             GridSpan positions = GridResolvedPosition::resolveGridPositionsFromAutoPlacementPosition(style(), *child, ForRows, GridResolvedPosition(0));
1091             maximumRowIndex = std::max(maximumRowIndex, positions.resolvedFinalPosition.next().toInt());
1092         }
1093
1094         auto unresolvedColumnPositions = GridResolvedPosition::unresolvedSpanFromStyle(style(), *child, ForColumns);
1095         if (!unresolvedColumnPositions.requiresAutoPlacement()) {
1096             GridSpan columnPositions = GridResolvedPosition::resolveGridPositionsFromStyle(unresolvedColumnPositions, style());
1097             maximumColumnIndex = std::max(maximumColumnIndex, columnPositions.resolvedFinalPosition.next().toInt());
1098         } else {
1099             // Grow the grid for items with a definite column span, getting the largest such span.
1100             GridSpan positions = GridResolvedPosition::resolveGridPositionsFromAutoPlacementPosition(style(), *child, ForColumns, GridResolvedPosition(0));
1101             maximumColumnIndex = std::max(maximumColumnIndex, positions.resolvedFinalPosition.next().toInt());
1102         }
1103     }
1104
1105     m_grid.grow(maximumRowIndex);
1106     for (auto& column : m_grid)
1107         column.grow(maximumColumnIndex);
1108 }
1109
1110 std::unique_ptr<GridCoordinate> RenderGrid::createEmptyGridAreaAtSpecifiedPositionsOutsideGrid(const RenderBox& gridItem, GridTrackSizingDirection specifiedDirection, const GridSpan& specifiedPositions) const
1111 {
1112     GridTrackSizingDirection crossDirection = specifiedDirection == ForColumns ? ForRows : ForColumns;
1113     const unsigned endOfCrossDirection = crossDirection == ForColumns ? gridColumnCount() : gridRowCount();
1114     GridSpan crossDirectionPositions = GridResolvedPosition::resolveGridPositionsFromAutoPlacementPosition(style(), gridItem, crossDirection, GridResolvedPosition(endOfCrossDirection));
1115     return std::make_unique<GridCoordinate>(specifiedDirection == ForColumns ? crossDirectionPositions : specifiedPositions, specifiedDirection == ForColumns ? specifiedPositions : crossDirectionPositions);
1116 }
1117
1118 void RenderGrid::placeSpecifiedMajorAxisItemsOnGrid(const Vector<RenderBox*>& autoGridItems)
1119 {
1120     bool isForColumns = autoPlacementMajorAxisDirection() == ForColumns;
1121     bool isGridAutoFlowDense = style().isGridAutoFlowAlgorithmDense();
1122
1123     // Mapping between the major axis tracks (rows or columns) and the last auto-placed item's position inserted on
1124     // that track. This is needed to implement "sparse" packing for items locked to a given track.
1125     // See http://dev.w3.org/csswg/css-grid/#auto-placement-algo
1126     HashMap<unsigned, unsigned, DefaultHash<unsigned>::Hash, WTF::UnsignedWithZeroKeyHashTraits<unsigned>> minorAxisCursors;
1127
1128     for (auto& autoGridItem : autoGridItems) {
1129         auto unresolvedMajorAxisPositions = GridResolvedPosition::unresolvedSpanFromStyle(style(), *autoGridItem, autoPlacementMajorAxisDirection());
1130         ASSERT(!unresolvedMajorAxisPositions.requiresAutoPlacement());
1131         GridSpan majorAxisPositions = GridResolvedPosition::resolveGridPositionsFromStyle(unresolvedMajorAxisPositions, style());
1132         GridSpan minorAxisPositions = GridResolvedPosition::resolveGridPositionsFromAutoPlacementPosition(style(), *autoGridItem, autoPlacementMinorAxisDirection(), GridResolvedPosition(0));
1133         unsigned majorAxisInitialPosition = majorAxisPositions.resolvedInitialPosition.toInt();
1134
1135         GridIterator iterator(m_grid, autoPlacementMajorAxisDirection(), majorAxisPositions.resolvedInitialPosition.toInt(), isGridAutoFlowDense ? 0 : minorAxisCursors.get(majorAxisInitialPosition));
1136         std::unique_ptr<GridCoordinate> emptyGridArea = iterator.nextEmptyGridArea(majorAxisPositions.integerSpan(), minorAxisPositions.integerSpan());
1137         if (!emptyGridArea)
1138             emptyGridArea = createEmptyGridAreaAtSpecifiedPositionsOutsideGrid(*autoGridItem, autoPlacementMajorAxisDirection(), majorAxisPositions);
1139         insertItemIntoGrid(*autoGridItem, *emptyGridArea);
1140
1141         if (!isGridAutoFlowDense)
1142             minorAxisCursors.set(majorAxisInitialPosition, isForColumns ? emptyGridArea->rows.resolvedInitialPosition.toInt() : emptyGridArea->columns.resolvedInitialPosition.toInt());
1143     }
1144 }
1145
1146 void RenderGrid::placeAutoMajorAxisItemsOnGrid(const Vector<RenderBox*>& autoGridItems)
1147 {
1148     AutoPlacementCursor autoPlacementCursor = {0, 0};
1149     bool isGridAutoFlowDense = style().isGridAutoFlowAlgorithmDense();
1150
1151     for (auto& autoGridItem : autoGridItems) {
1152         placeAutoMajorAxisItemOnGrid(*autoGridItem, autoPlacementCursor);
1153
1154         if (isGridAutoFlowDense) {
1155             autoPlacementCursor.first = 0;
1156             autoPlacementCursor.second = 0;
1157         }
1158     }
1159 }
1160
1161 void RenderGrid::placeAutoMajorAxisItemOnGrid(RenderBox& gridItem, AutoPlacementCursor& autoPlacementCursor)
1162 {
1163     ASSERT(GridResolvedPosition::unresolvedSpanFromStyle(style(), gridItem, autoPlacementMajorAxisDirection()).requiresAutoPlacement());
1164     GridSpan majorAxisPositions = GridResolvedPosition::resolveGridPositionsFromAutoPlacementPosition(style(), gridItem, autoPlacementMajorAxisDirection(), GridResolvedPosition(0));
1165
1166     const unsigned endOfMajorAxis = (autoPlacementMajorAxisDirection() == ForColumns) ? gridColumnCount() : gridRowCount();
1167     unsigned majorAxisAutoPlacementCursor = autoPlacementMajorAxisDirection() == ForColumns ? autoPlacementCursor.second : autoPlacementCursor.first;
1168     unsigned minorAxisAutoPlacementCursor = autoPlacementMajorAxisDirection() == ForColumns ? autoPlacementCursor.first : autoPlacementCursor.second;
1169
1170     std::unique_ptr<GridCoordinate> emptyGridArea;
1171     auto unresolvedMinorAxisPositions = GridResolvedPosition::unresolvedSpanFromStyle(style(), gridItem, autoPlacementMinorAxisDirection());
1172     if (!unresolvedMinorAxisPositions.requiresAutoPlacement()) {
1173         GridSpan minorAxisPositions = GridResolvedPosition::resolveGridPositionsFromStyle(unresolvedMinorAxisPositions, style());
1174
1175         // Move to the next track in major axis if initial position in minor axis is before auto-placement cursor.
1176         if (minorAxisPositions.resolvedInitialPosition.toInt() < minorAxisAutoPlacementCursor)
1177             majorAxisAutoPlacementCursor++;
1178
1179         if (majorAxisAutoPlacementCursor < endOfMajorAxis) {
1180             GridIterator iterator(m_grid, autoPlacementMinorAxisDirection(), minorAxisPositions.resolvedInitialPosition.toInt(), majorAxisAutoPlacementCursor);
1181             emptyGridArea = iterator.nextEmptyGridArea(minorAxisPositions.integerSpan(), majorAxisPositions.integerSpan());
1182         }
1183
1184         if (!emptyGridArea)
1185             emptyGridArea = createEmptyGridAreaAtSpecifiedPositionsOutsideGrid(gridItem, autoPlacementMinorAxisDirection(), minorAxisPositions);
1186     } else {
1187         GridSpan minorAxisPositions = GridResolvedPosition::resolveGridPositionsFromAutoPlacementPosition(style(), gridItem, autoPlacementMinorAxisDirection(), GridResolvedPosition(0));
1188
1189         for (unsigned majorAxisIndex = majorAxisAutoPlacementCursor; majorAxisIndex < endOfMajorAxis; ++majorAxisIndex) {
1190             GridIterator iterator(m_grid, autoPlacementMajorAxisDirection(), majorAxisIndex, minorAxisAutoPlacementCursor);
1191             emptyGridArea = iterator.nextEmptyGridArea(majorAxisPositions.integerSpan(), minorAxisPositions.integerSpan());
1192
1193             if (emptyGridArea) {
1194                 // Check that it fits in the minor axis direction, as we shouldn't grow in that direction here (it was already managed in populateExplicitGridAndOrderIterator()).
1195                 GridResolvedPosition minorAxisFinalPositionIndex = autoPlacementMinorAxisDirection() == ForColumns ? emptyGridArea->columns.resolvedFinalPosition : emptyGridArea->rows.resolvedFinalPosition;
1196                 const unsigned endOfMinorAxis = autoPlacementMinorAxisDirection() == ForColumns ? gridColumnCount() : gridRowCount();
1197                 if (minorAxisFinalPositionIndex.toInt() < endOfMinorAxis)
1198                     break;
1199
1200                 // Discard empty grid area as it does not fit in the minor axis direction.
1201                 // We don't need to create a new empty grid area yet as we might find a valid one in the next iteration.
1202                 emptyGridArea = nullptr;
1203             }
1204
1205             // As we're moving to the next track in the major axis we should reset the auto-placement cursor in the minor axis.
1206             minorAxisAutoPlacementCursor = 0;
1207         }
1208
1209         if (!emptyGridArea)
1210             emptyGridArea = createEmptyGridAreaAtSpecifiedPositionsOutsideGrid(gridItem, autoPlacementMinorAxisDirection(), minorAxisPositions);
1211     }
1212
1213     insertItemIntoGrid(gridItem, *emptyGridArea);
1214     autoPlacementCursor.first = emptyGridArea->rows.resolvedInitialPosition.toInt();
1215     autoPlacementCursor.second = emptyGridArea->columns.resolvedInitialPosition.toInt();
1216 }
1217
1218 GridTrackSizingDirection RenderGrid::autoPlacementMajorAxisDirection() const
1219 {
1220     return style().isGridAutoFlowDirectionColumn() ? ForColumns : ForRows;
1221 }
1222
1223 GridTrackSizingDirection RenderGrid::autoPlacementMinorAxisDirection() const
1224 {
1225     return style().isGridAutoFlowDirectionColumn() ? ForRows : ForColumns;
1226 }
1227
1228 void RenderGrid::clearGrid()
1229 {
1230     m_grid.clear();
1231     m_gridItemCoordinate.clear();
1232 }
1233
1234 void RenderGrid::applyStretchAlignmentToTracksIfNeeded(GridTrackSizingDirection direction, GridSizingData& sizingData, LayoutUnit availableSpace)
1235 {
1236     if (availableSpace <= 0
1237         || (direction == ForColumns && style().resolvedJustifyContentDistribution() != ContentDistributionStretch)
1238         || (direction == ForRows && style().resolvedAlignContentDistribution() != ContentDistributionStretch))
1239         return;
1240
1241     // Spec defines auto-sized tracks as the ones with an 'auto' max-sizing function.
1242     Vector<GridTrack>& tracks = (direction == ForColumns) ? sizingData.columnTracks : sizingData.rowTracks;
1243     Vector<unsigned> autoSizedTracksIndex;
1244     for (unsigned i = 0; i < tracks.size(); ++i) {
1245         const GridTrackSize& trackSize = gridTrackSize(direction, i);
1246         if (trackSize.hasAutoMaxTrackBreadth())
1247             autoSizedTracksIndex.append(i);
1248     }
1249
1250     unsigned numberOfAutoSizedTracks = autoSizedTracksIndex.size();
1251     if (numberOfAutoSizedTracks < 1)
1252         return;
1253
1254     LayoutUnit sizeToIncrease = availableSpace / numberOfAutoSizedTracks;
1255     for (const auto& trackIndex : autoSizedTracksIndex) {
1256         auto& track = tracks[trackIndex];
1257         track.setBaseSize(track.baseSize() + sizeToIncrease);
1258     }
1259 }
1260
1261 void RenderGrid::layoutGridItems()
1262 {
1263     placeItemsOnGrid();
1264
1265     LayoutUnit availableSpaceForColumns = availableLogicalWidth();
1266     LayoutUnit availableSpaceForRows = availableLogicalHeight(IncludeMarginBorderPadding);
1267
1268     // Remove space consumed by gutters from the available logical space.
1269     availableSpaceForColumns -= guttersSize(ForColumns, gridColumnCount());
1270     availableSpaceForRows -= guttersSize(ForRows, gridRowCount());
1271
1272     GridSizingData sizingData(gridColumnCount(), gridRowCount());
1273     computeUsedBreadthOfGridTracks(ForColumns, sizingData, availableSpaceForColumns);
1274     ASSERT(tracksAreWiderThanMinTrackBreadth(ForColumns, sizingData.columnTracks));
1275     computeUsedBreadthOfGridTracks(ForRows, sizingData, availableSpaceForRows);
1276     ASSERT(tracksAreWiderThanMinTrackBreadth(ForRows, sizingData.rowTracks));
1277
1278     applyStretchAlignmentToTracksIfNeeded(ForColumns, sizingData, availableSpaceForColumns);
1279     applyStretchAlignmentToTracksIfNeeded(ForRows, sizingData, availableSpaceForRows);
1280
1281     populateGridPositions(sizingData, availableSpaceForColumns, availableSpaceForRows);
1282
1283     for (RenderBox* child = firstChildBox(); child; child = child->nextSiblingBox()) {
1284         // Because the grid area cannot be styled, we don't need to adjust
1285         // the grid breadth to account for 'box-sizing'.
1286         Optional<LayoutUnit> oldOverrideContainingBlockContentLogicalWidth = child->hasOverrideContainingBlockLogicalWidth() ? child->overrideContainingBlockContentLogicalWidth() : LayoutUnit();
1287         Optional<LayoutUnit> oldOverrideContainingBlockContentLogicalHeight = child->hasOverrideContainingBlockLogicalHeight() ? child->overrideContainingBlockContentLogicalHeight() : LayoutUnit();
1288
1289         LayoutUnit overrideContainingBlockContentLogicalWidth = gridAreaBreadthForChildIncludingAlignmentOffsets(*child, ForColumns, sizingData);
1290         LayoutUnit overrideContainingBlockContentLogicalHeight = gridAreaBreadthForChildIncludingAlignmentOffsets(*child, ForRows, sizingData);
1291         if (!oldOverrideContainingBlockContentLogicalWidth || oldOverrideContainingBlockContentLogicalWidth.value() != overrideContainingBlockContentLogicalWidth
1292             || ((!oldOverrideContainingBlockContentLogicalHeight || oldOverrideContainingBlockContentLogicalHeight.value() != overrideContainingBlockContentLogicalHeight)
1293                 && child->hasRelativeLogicalHeight()))
1294             child->setNeedsLayout(MarkOnlyThis);
1295
1296         child->setOverrideContainingBlockContentLogicalWidth(overrideContainingBlockContentLogicalWidth);
1297         child->setOverrideContainingBlockContentLogicalHeight(overrideContainingBlockContentLogicalHeight);
1298
1299         LayoutRect oldChildRect = child->frameRect();
1300
1301         // Stretching logic might force a child layout, so we need to run it before the layoutIfNeeded
1302         // call to avoid unnecessary relayouts. This might imply that child margins, needed to correctly
1303         // determine the available space before stretching, are not set yet.
1304         applyStretchAlignmentToChildIfNeeded(*child);
1305
1306         child->layoutIfNeeded();
1307
1308         // We need pending layouts to be done in order to compute auto-margins properly.
1309         updateAutoMarginsInColumnAxisIfNeeded(*child);
1310         updateAutoMarginsInRowAxisIfNeeded(*child);
1311
1312         child->setLogicalLocation(findChildLogicalPosition(*child));
1313
1314         // If the child moved, we have to repaint it as well as any floating/positioned
1315         // descendants. An exception is if we need a layout. In this case, we know we're going to
1316         // repaint ourselves (and the child) anyway.
1317         if (!selfNeedsLayout() && child->checkForRepaintDuringLayout())
1318             child->repaintDuringLayoutIfMoved(oldChildRect);
1319     }
1320
1321     LayoutUnit height = borderAndPaddingLogicalHeight() + scrollbarLogicalHeight();
1322     for (auto& row : sizingData.rowTracks)
1323         height += row.baseSize();
1324
1325     height += guttersSize(ForRows, sizingData.rowTracks.size());
1326     // min / max logical height is handled in updateLogicalHeight().
1327     if (hasLineIfEmpty()) {
1328         LayoutUnit minHeight = borderAndPaddingLogicalHeight()
1329             + lineHeight(true, isHorizontalWritingMode() ? HorizontalLine : VerticalLine, PositionOfInteriorLineBoxes)
1330             + scrollbarLogicalHeight();
1331         height = std::max(height, minHeight);
1332     }
1333     setLogicalHeight(height);
1334
1335     clearGrid();
1336 }
1337
1338 GridCoordinate RenderGrid::cachedGridCoordinate(const RenderBox& gridItem) const
1339 {
1340     ASSERT(m_gridItemCoordinate.contains(&gridItem));
1341     return m_gridItemCoordinate.get(&gridItem);
1342 }
1343
1344 LayoutUnit RenderGrid::gridAreaBreadthForChild(const RenderBox& child, GridTrackSizingDirection direction, const Vector<GridTrack>& tracks) const
1345 {
1346     const GridCoordinate& coordinate = cachedGridCoordinate(child);
1347     const GridSpan& span = (direction == ForColumns) ? coordinate.columns : coordinate.rows;
1348     LayoutUnit gridAreaBreadth = 0;
1349     for (auto& trackPosition : span)
1350         gridAreaBreadth += tracks[trackPosition.toInt()].baseSize();
1351
1352     gridAreaBreadth += guttersSize(direction, span.integerSpan());
1353
1354     return gridAreaBreadth;
1355 }
1356
1357 LayoutUnit RenderGrid::gridAreaBreadthForChildIncludingAlignmentOffsets(const RenderBox& child, GridTrackSizingDirection direction, const GridSizingData& sizingData) const
1358 {
1359     // We need the cached value when available because Content Distribution alignment properties
1360     // may have some influence in the final grid area breadth.
1361     const auto& tracks = (direction == ForColumns) ? sizingData.columnTracks : sizingData.rowTracks;
1362     const auto& coordinate = cachedGridCoordinate(child);
1363     const auto& span = (direction == ForColumns) ? coordinate.columns : coordinate.rows;
1364     const auto& linePositions = (direction == ForColumns) ? m_columnPositions : m_rowPositions;
1365
1366     LayoutUnit initialTrackPosition = linePositions[span.resolvedInitialPosition.toInt()];
1367     LayoutUnit finalTrackPosition = linePositions[span.resolvedFinalPosition.toInt()];
1368
1369     // Track Positions vector stores the 'start' grid line of each track, so we have to add last track's baseSize.
1370     return finalTrackPosition - initialTrackPosition + tracks[span.resolvedFinalPosition.toInt()].baseSize();
1371 }
1372
1373 void RenderGrid::populateGridPositions(GridSizingData& sizingData, LayoutUnit availableSpaceForColumns, LayoutUnit availableSpaceForRows)
1374 {
1375     // Since we add alignment offsets and track gutters, grid lines are not always adjacent. Hence we will have to
1376     // assume from now on that we just store positions of the initial grid lines of each track,
1377     // except the last one, which is the only one considered as a final grid line of a track.
1378     // FIXME: This will affect the computed style value of grid tracks size, since we are
1379     // using these positions to compute them.
1380
1381     unsigned numberOfTracks = sizingData.columnTracks.size();
1382     unsigned numberOfLines = numberOfTracks + 1;
1383     unsigned lastLine = numberOfLines - 1;
1384     unsigned nextToLastLine = numberOfLines - 2;
1385     ContentAlignmentData offset = computeContentPositionAndDistributionOffset(ForColumns, availableSpaceForColumns, numberOfTracks);
1386     LayoutUnit trackGap = guttersSize(ForColumns, 2);
1387     m_columnPositions.resize(numberOfLines);
1388     m_columnPositions[0] = borderAndPaddingStart() + offset.positionOffset;
1389     for (unsigned i = 0; i < lastLine; ++i)
1390         m_columnPositions[i + 1] = m_columnPositions[i] + offset.distributionOffset + sizingData.columnTracks[i].baseSize() + trackGap;
1391     m_columnPositions[lastLine] = m_columnPositions[nextToLastLine] + sizingData.columnTracks[nextToLastLine].baseSize();
1392
1393     numberOfTracks = sizingData.rowTracks.size();
1394     numberOfLines = numberOfTracks + 1;
1395     lastLine = numberOfLines - 1;
1396     nextToLastLine = numberOfLines - 2;
1397     offset = computeContentPositionAndDistributionOffset(ForRows, availableSpaceForRows, numberOfTracks);
1398     trackGap = guttersSize(ForRows, 2);
1399     m_rowPositions.resize(numberOfLines);
1400     m_rowPositions[0] = borderAndPaddingBefore() + offset.positionOffset;
1401     for (unsigned i = 0; i < lastLine; ++i)
1402         m_rowPositions[i + 1] = m_rowPositions[i] + offset.distributionOffset + sizingData.rowTracks[i].baseSize() + trackGap;
1403     m_rowPositions[lastLine] = m_rowPositions[nextToLastLine] + sizingData.rowTracks[nextToLastLine].baseSize();
1404 }
1405
1406 static inline LayoutUnit computeOverflowAlignmentOffset(OverflowAlignment overflow, LayoutUnit trackBreadth, LayoutUnit childBreadth)
1407 {
1408     LayoutUnit offset = trackBreadth - childBreadth;
1409     switch (overflow) {
1410     case OverflowAlignmentSafe:
1411         // If overflow is 'safe', we have to make sure we don't overflow the 'start'
1412         // edge (potentially cause some data loss as the overflow is unreachable).
1413         return std::max<LayoutUnit>(0, offset);
1414     case OverflowAlignmentTrue:
1415     case OverflowAlignmentDefault:
1416         // If we overflow our alignment container and overflow is 'true' (default), we
1417         // ignore the overflow and just return the value regardless (which may cause data
1418         // loss as we overflow the 'start' edge).
1419         return offset;
1420     }
1421
1422     ASSERT_NOT_REACHED();
1423     return 0;
1424 }
1425
1426 // FIXME: This logic is shared by RenderFlexibleBox, so it should be moved to RenderBox.
1427 bool RenderGrid::needToStretchChildLogicalHeight(const RenderBox& child) const
1428 {
1429     if (RenderStyle::resolveAlignment(style(), child.style(), ItemPositionStretch) != ItemPositionStretch)
1430         return false;
1431
1432     return isHorizontalWritingMode() && child.style().height().isAuto();
1433 }
1434
1435 // FIXME: This logic is shared by RenderFlexibleBox, so it should be moved to RenderBox.
1436 LayoutUnit RenderGrid::marginLogicalHeightForChild(const RenderBox& child) const
1437 {
1438     return isHorizontalWritingMode() ? child.verticalMarginExtent() : child.horizontalMarginExtent();
1439 }
1440
1441 LayoutUnit RenderGrid::computeMarginLogicalHeightForChild(const RenderBox& child) const
1442 {
1443     if (!child.style().hasMargin())
1444         return 0;
1445
1446     LayoutUnit marginBefore;
1447     LayoutUnit marginAfter;
1448     child.computeBlockDirectionMargins(this, marginBefore, marginAfter);
1449
1450     return marginBefore + marginAfter;
1451 }
1452
1453 LayoutUnit RenderGrid::availableAlignmentSpaceForChildBeforeStretching(LayoutUnit gridAreaBreadthForChild, const RenderBox& child) const
1454 {
1455     // Because we want to avoid multiple layouts, stretching logic might be performed before
1456     // children are laid out, so we can't use the child cached values. Hence, we need to
1457     // compute margins in order to determine the available height before stretching.
1458     return gridAreaBreadthForChild - (child.needsLayout() ? computeMarginLogicalHeightForChild(child) : marginLogicalHeightForChild(child));
1459 }
1460
1461 // FIXME: This logic is shared by RenderFlexibleBox, so it should be moved to RenderBox.
1462 void RenderGrid::applyStretchAlignmentToChildIfNeeded(RenderBox& child)
1463 {
1464     ASSERT(child.overrideContainingBlockContentLogicalWidth() && child.overrideContainingBlockContentLogicalHeight());
1465
1466     // We clear both width and height override values because we will decide now whether they
1467     // are allowed or not, evaluating the conditions which might have changed since the old
1468     // values were set.
1469     child.clearOverrideSize();
1470
1471     auto& gridStyle = style();
1472     auto& childStyle = child.style();
1473     bool isHorizontalMode = isHorizontalWritingMode();
1474     bool hasAutoSizeInRowAxis = isHorizontalMode ? childStyle.width().isAuto() : childStyle.height().isAuto();
1475     bool allowedToStretchChildAlongRowAxis = hasAutoSizeInRowAxis && !childStyle.marginStartUsing(&gridStyle).isAuto() && !childStyle.marginEndUsing(&gridStyle).isAuto();
1476     if (!allowedToStretchChildAlongRowAxis || RenderStyle::resolveJustification(gridStyle, childStyle, ItemPositionStretch) != ItemPositionStretch) {
1477         bool hasAutoMinSizeInRowAxis = isHorizontalMode ? childStyle.minWidth().isAuto() : childStyle.minHeight().isAuto();
1478         bool canShrinkToFitInRowAxisForChild = !hasAutoMinSizeInRowAxis || child.minPreferredLogicalWidth() <= child.overrideContainingBlockContentLogicalWidth().value();
1479         // TODO(lajava): how to handle orthogonality in this case ?.
1480         // TODO(lajava): grid track sizing and positioning do not support orthogonal modes yet.
1481         if (hasAutoSizeInRowAxis && canShrinkToFitInRowAxisForChild) {
1482             LayoutUnit childWidthToFitContent = std::max(std::min(child.maxPreferredLogicalWidth(), child.overrideContainingBlockContentLogicalWidth().value() - child.marginLogicalWidth()), child.minPreferredLogicalWidth());
1483             LayoutUnit desiredLogicalWidth = child.constrainLogicalHeightByMinMax(childWidthToFitContent, Nullopt);
1484             child.setOverrideLogicalContentWidth(desiredLogicalWidth - child.borderAndPaddingLogicalWidth());
1485             if (desiredLogicalWidth != child.logicalWidth())
1486                 child.setNeedsLayout();
1487         }
1488     }
1489
1490     bool hasAutoSizeInColumnAxis = isHorizontalMode ? childStyle.height().isAuto() : childStyle.width().isAuto();
1491     bool allowedToStretchChildAlongColumnAxis = hasAutoSizeInColumnAxis && !childStyle.marginBeforeUsing(&gridStyle).isAuto() && !childStyle.marginAfterUsing(&gridStyle).isAuto();
1492     if (allowedToStretchChildAlongColumnAxis && RenderStyle::resolveAlignment(gridStyle, childStyle, ItemPositionStretch) == ItemPositionStretch) {
1493         // TODO (lajava): If the child has orthogonal flow, then it already has an override height set, so use it.
1494         // TODO (lajava): grid track sizing and positioning do not support orthogonal modes yet.
1495         if (child.isHorizontalWritingMode() == isHorizontalMode) {
1496             LayoutUnit stretchedLogicalHeight = availableAlignmentSpaceForChildBeforeStretching(child.overrideContainingBlockContentLogicalHeight().value(), child);
1497             LayoutUnit desiredLogicalHeight = child.constrainLogicalHeightByMinMax(stretchedLogicalHeight, Nullopt);
1498             child.setOverrideLogicalContentHeight(desiredLogicalHeight - child.borderAndPaddingLogicalHeight());
1499             if (desiredLogicalHeight != child.logicalHeight()) {
1500                 // TODO (lajava): Can avoid laying out here in some cases. See https://webkit.org/b/87905.
1501                 child.setLogicalHeight(0);
1502                 child.setNeedsLayout();
1503             }
1504         }
1505     }
1506 }
1507
1508 // FIXME: This logic is shared by RenderFlexibleBox, so it should be moved to RenderBox.
1509 bool RenderGrid::hasAutoMarginsInColumnAxis(const RenderBox& child) const
1510 {
1511     if (isHorizontalWritingMode())
1512         return child.style().marginTop().isAuto() || child.style().marginBottom().isAuto();
1513     return child.style().marginLeft().isAuto() || child.style().marginRight().isAuto();
1514 }
1515
1516 // FIXME: This logic is shared by RenderFlexibleBox, so it should be moved to RenderBox.
1517 bool RenderGrid::hasAutoMarginsInRowAxis(const RenderBox& child) const
1518 {
1519     if (isHorizontalWritingMode())
1520         return child.style().marginLeft().isAuto() || child.style().marginRight().isAuto();
1521     return child.style().marginTop().isAuto() || child.style().marginBottom().isAuto();
1522 }
1523
1524 // FIXME: This logic is shared by RenderFlexibleBox, so it should be moved to RenderBox.
1525 void RenderGrid::updateAutoMarginsInRowAxisIfNeeded(RenderBox& child)
1526 {
1527     ASSERT(!child.isOutOfFlowPositioned());
1528
1529     LayoutUnit availableAlignmentSpace = child.overrideContainingBlockContentLogicalWidth().value() - child.logicalWidth();
1530     if (availableAlignmentSpace <= 0)
1531         return;
1532
1533     const RenderStyle& parentStyle = style();
1534     Length marginStart = child.style().marginStartUsing(&parentStyle);
1535     Length marginEnd = child.style().marginEndUsing(&parentStyle);
1536     if (marginStart.isAuto() && marginEnd.isAuto()) {
1537         child.setMarginStart(availableAlignmentSpace / 2, &parentStyle);
1538         child.setMarginEnd(availableAlignmentSpace / 2, &parentStyle);
1539     } else if (marginStart.isAuto()) {
1540         child.setMarginStart(availableAlignmentSpace, &parentStyle);
1541     } else if (marginEnd.isAuto()) {
1542         child.setMarginEnd(availableAlignmentSpace, &parentStyle);
1543     }
1544 }
1545
1546 // FIXME: This logic is shared by RenderFlexibleBox, so it should be moved to RenderBox.
1547 void RenderGrid::updateAutoMarginsInColumnAxisIfNeeded(RenderBox& child)
1548 {
1549     ASSERT(!child.isOutOfFlowPositioned());
1550
1551     LayoutUnit availableAlignmentSpace = child.overrideContainingBlockContentLogicalHeight().value() - child.logicalHeight();
1552     if (availableAlignmentSpace <= 0)
1553         return;
1554
1555     const RenderStyle& parentStyle = style();
1556     Length marginBefore = child.style().marginBeforeUsing(&parentStyle);
1557     Length marginAfter = child.style().marginAfterUsing(&parentStyle);
1558     if (marginBefore.isAuto() && marginAfter.isAuto()) {
1559         child.setMarginBefore(availableAlignmentSpace / 2, &parentStyle);
1560         child.setMarginAfter(availableAlignmentSpace / 2, &parentStyle);
1561     } else if (marginBefore.isAuto()) {
1562         child.setMarginBefore(availableAlignmentSpace, &parentStyle);
1563     } else if (marginAfter.isAuto()) {
1564         child.setMarginAfter(availableAlignmentSpace, &parentStyle);
1565     }
1566 }
1567
1568 GridAxisPosition RenderGrid::columnAxisPositionForChild(const RenderBox& child) const
1569 {
1570     bool hasOrthogonalWritingMode = child.isHorizontalWritingMode() != isHorizontalWritingMode();
1571     bool hasSameWritingMode = child.style().writingMode() == style().writingMode();
1572
1573     switch (RenderStyle::resolveAlignment(style(), child.style(), ItemPositionStretch)) {
1574     case ItemPositionSelfStart:
1575         // If orthogonal writing-modes, this computes to 'start'.
1576         // FIXME: grid track sizing and positioning do not support orthogonal modes yet.
1577         // self-start is based on the child's block axis direction. That's why we need to check against the grid container's block flow.
1578         return (hasOrthogonalWritingMode || hasSameWritingMode) ? GridAxisStart : GridAxisEnd;
1579     case ItemPositionSelfEnd:
1580         // If orthogonal writing-modes, this computes to 'end'.
1581         // FIXME: grid track sizing and positioning do not support orthogonal modes yet.
1582         // self-end is based on the child's block axis direction. That's why we need to check against the grid container's block flow.
1583         return (hasOrthogonalWritingMode || hasSameWritingMode) ? GridAxisEnd : GridAxisStart;
1584     case ItemPositionLeft:
1585         // The alignment axis (column axis) and the inline axis are parallell in
1586         // orthogonal writing mode. Otherwise this this is equivalent to 'start'.
1587         // FIXME: grid track sizing and positioning do not support orthogonal modes yet.
1588         return GridAxisStart;
1589     case ItemPositionRight:
1590         // The alignment axis (column axis) and the inline axis are parallell in
1591         // orthogonal writing mode. Otherwise this this is equivalent to 'start'.
1592         // FIXME: grid track sizing and positioning do not support orthogonal modes yet.
1593         return hasOrthogonalWritingMode ? GridAxisEnd : GridAxisStart;
1594     case ItemPositionCenter:
1595         return GridAxisCenter;
1596     case ItemPositionFlexStart: // Only used in flex layout, otherwise equivalent to 'start'.
1597     case ItemPositionStart:
1598         return GridAxisStart;
1599     case ItemPositionFlexEnd: // Only used in flex layout, otherwise equivalent to 'end'.
1600     case ItemPositionEnd:
1601         return GridAxisEnd;
1602     case ItemPositionStretch:
1603         return GridAxisStart;
1604     case ItemPositionBaseline:
1605     case ItemPositionLastBaseline:
1606         // FIXME: Implement the previous values. For now, we always 'start' align the child.
1607         return GridAxisStart;
1608     case ItemPositionAuto:
1609         break;
1610     }
1611
1612     ASSERT_NOT_REACHED();
1613     return GridAxisStart;
1614 }
1615
1616 GridAxisPosition RenderGrid::rowAxisPositionForChild(const RenderBox& child) const
1617 {
1618     bool hasOrthogonalWritingMode = child.isHorizontalWritingMode() != isHorizontalWritingMode();
1619     bool hasSameDirection = child.style().direction() == style().direction();
1620     bool isLTR = style().isLeftToRightDirection();
1621
1622     switch (RenderStyle::resolveJustification(style(), child.style(), ItemPositionStretch)) {
1623     case ItemPositionSelfStart:
1624         // For orthogonal writing-modes, this computes to 'start'
1625         // FIXME: grid track sizing and positioning do not support orthogonal modes yet.
1626         // self-start is based on the child's direction. That's why we need to check against the grid container's direction.
1627         return (hasOrthogonalWritingMode || hasSameDirection) ? GridAxisStart : GridAxisEnd;
1628     case ItemPositionSelfEnd:
1629         // For orthogonal writing-modes, this computes to 'start'
1630         // FIXME: grid track sizing and positioning do not support orthogonal modes yet.
1631         return (hasOrthogonalWritingMode || hasSameDirection) ? GridAxisEnd : GridAxisStart;
1632     case ItemPositionLeft:
1633         return isLTR ? GridAxisStart : GridAxisEnd;
1634     case ItemPositionRight:
1635         return isLTR ? GridAxisEnd : GridAxisStart;
1636     case ItemPositionCenter:
1637         return GridAxisCenter;
1638     case ItemPositionFlexStart: // Only used in flex layout, otherwise equivalent to 'start'.
1639     case ItemPositionStart:
1640         return GridAxisStart;
1641     case ItemPositionFlexEnd: // Only used in flex layout, otherwise equivalent to 'end'.
1642     case ItemPositionEnd:
1643         return GridAxisEnd;
1644     case ItemPositionStretch:
1645         return GridAxisStart;
1646     case ItemPositionBaseline:
1647     case ItemPositionLastBaseline:
1648         // FIXME: Implement the previous values. For now, we always 'start' align the child.
1649         return GridAxisStart;
1650     case ItemPositionAuto:
1651         break;
1652     }
1653
1654     ASSERT_NOT_REACHED();
1655     return GridAxisStart;
1656 }
1657
1658 static inline LayoutUnit offsetBetweenTracks(ContentDistributionType distribution, const Vector<LayoutUnit>& trackPositions, const LayoutUnit& childBreadth)
1659 {
1660     return (distribution == ContentDistributionStretch || ContentDistributionStretch == ContentDistributionDefault) ? LayoutUnit() : trackPositions[1] - trackPositions[0] - childBreadth;
1661 }
1662
1663 LayoutUnit RenderGrid::columnAxisOffsetForChild(const RenderBox& child) const
1664 {
1665     const GridCoordinate& coordinate = cachedGridCoordinate(child);
1666     unsigned childStartLine = coordinate.rows.resolvedInitialPosition.toInt();
1667     LayoutUnit startOfRow = m_rowPositions[childStartLine];
1668     LayoutUnit startPosition = startOfRow + marginBeforeForChild(child);
1669     if (hasAutoMarginsInColumnAxis(child))
1670         return startPosition;
1671     GridAxisPosition axisPosition = columnAxisPositionForChild(child);
1672     switch (axisPosition) {
1673     case GridAxisStart:
1674         return startPosition;
1675     case GridAxisEnd:
1676     case GridAxisCenter: {
1677         unsigned childEndLine = coordinate.rows.resolvedFinalPosition.next().toInt();
1678         LayoutUnit endOfRow = m_rowPositions[childEndLine];
1679         // m_rowPositions include gutters so we need to substract them to get the actual end position for a given
1680         // row (this does not have to be done for the last track as there are no more m_rowPositions after it)
1681         if (childEndLine < m_rowPositions.size() - 1)
1682             endOfRow -= guttersSize(ForRows, 2);
1683         LayoutUnit childBreadth = child.logicalHeight() + child.marginLogicalHeight();
1684         // In order to properly adjust the Self Alignment values we need to consider the offset between tracks.
1685         if (childEndLine - childStartLine > 1 && childEndLine < m_rowPositions.size() - 1)
1686             endOfRow -= offsetBetweenTracks(style().resolvedAlignContentDistribution(), m_rowPositions, childBreadth);
1687         LayoutUnit offsetFromStartPosition = computeOverflowAlignmentOffset(RenderStyle::resolveAlignmentOverflow(style(), child.style()), endOfRow - startOfRow, childBreadth);
1688         return startPosition + (axisPosition == GridAxisEnd ? offsetFromStartPosition : offsetFromStartPosition / 2);
1689     }
1690     }
1691
1692     ASSERT_NOT_REACHED();
1693     return 0;
1694 }
1695
1696
1697 LayoutUnit RenderGrid::rowAxisOffsetForChild(const RenderBox& child) const
1698 {
1699     const GridCoordinate& coordinate = cachedGridCoordinate(child);
1700     unsigned childStartLine = coordinate.columns.resolvedInitialPosition.toInt();
1701     LayoutUnit startOfColumn = m_columnPositions[childStartLine];
1702     LayoutUnit startPosition = startOfColumn + marginStartForChild(child);
1703     if (hasAutoMarginsInRowAxis(child))
1704         return startPosition;
1705     GridAxisPosition axisPosition = rowAxisPositionForChild(child);
1706     switch (axisPosition) {
1707     case GridAxisStart:
1708         return startPosition;
1709     case GridAxisEnd:
1710     case GridAxisCenter: {
1711         unsigned childEndLine = coordinate.columns.resolvedFinalPosition.next().toInt();
1712         LayoutUnit endOfColumn = m_columnPositions[childEndLine];
1713         // m_columnPositions include gutters so we need to substract them to get the actual end position for a given
1714         // column (this does not have to be done for the last track as there are no more m_columnPositions after it)
1715         if (childEndLine < m_columnPositions.size() - 1)
1716             endOfColumn -= guttersSize(ForColumns, 2);
1717         LayoutUnit childBreadth = child.logicalWidth() + child.marginLogicalWidth();
1718         // In order to properly adjust the Self Alignment values we need to consider the offset between tracks.
1719         if (childEndLine - childStartLine > 1 && childEndLine < m_columnPositions.size() - 1)
1720             endOfColumn -= offsetBetweenTracks(style().resolvedJustifyContentDistribution(), m_columnPositions, childBreadth);
1721         LayoutUnit offsetFromStartPosition = computeOverflowAlignmentOffset(RenderStyle::resolveJustificationOverflow(style(), child.style()), endOfColumn - startOfColumn, childBreadth);
1722         return startPosition + (axisPosition == GridAxisEnd ? offsetFromStartPosition : offsetFromStartPosition / 2);
1723     }
1724     }
1725
1726     ASSERT_NOT_REACHED();
1727     return 0;
1728 }
1729
1730 ContentPosition static resolveContentDistributionFallback(ContentDistributionType distribution)
1731 {
1732     switch (distribution) {
1733     case ContentDistributionSpaceBetween:
1734         return ContentPositionStart;
1735     case ContentDistributionSpaceAround:
1736         return ContentPositionCenter;
1737     case ContentDistributionSpaceEvenly:
1738         return ContentPositionCenter;
1739     case ContentDistributionStretch:
1740         return ContentPositionStart;
1741     case ContentDistributionDefault:
1742         return ContentPositionAuto;
1743     }
1744
1745     ASSERT_NOT_REACHED();
1746     return ContentPositionAuto;
1747 }
1748
1749 static inline LayoutUnit offsetToStartEdge(bool isLeftToRight, LayoutUnit availableSpace)
1750 {
1751     return isLeftToRight ? LayoutUnit() : availableSpace;
1752 }
1753
1754 static inline LayoutUnit offsetToEndEdge(bool isLeftToRight, LayoutUnit availableSpace)
1755 {
1756     return !isLeftToRight ? LayoutUnit() : availableSpace;
1757 }
1758
1759 static ContentAlignmentData contentDistributionOffset(LayoutUnit availableFreeSpace, ContentPosition& fallbackPosition, ContentDistributionType distribution, unsigned numberOfGridTracks)
1760 {
1761     if (distribution != ContentDistributionDefault && fallbackPosition == ContentPositionAuto)
1762         fallbackPosition = resolveContentDistributionFallback(distribution);
1763
1764     if (availableFreeSpace <= 0)
1765         return ContentAlignmentData::defaultOffsets();
1766
1767     LayoutUnit distributionOffset;
1768     switch (distribution) {
1769     case ContentDistributionSpaceBetween:
1770         if (numberOfGridTracks < 2)
1771             return ContentAlignmentData::defaultOffsets();
1772         return {0, availableFreeSpace / (numberOfGridTracks - 1)};
1773     case ContentDistributionSpaceAround:
1774         if (numberOfGridTracks < 1)
1775             return ContentAlignmentData::defaultOffsets();
1776         distributionOffset = availableFreeSpace / numberOfGridTracks;
1777         return {distributionOffset / 2, distributionOffset};
1778     case ContentDistributionSpaceEvenly:
1779         distributionOffset = availableFreeSpace / (numberOfGridTracks + 1);
1780         return {distributionOffset, distributionOffset};
1781     case ContentDistributionStretch:
1782         return {0, 0};
1783     case ContentDistributionDefault:
1784         return ContentAlignmentData::defaultOffsets();
1785     }
1786
1787     ASSERT_NOT_REACHED();
1788     return ContentAlignmentData::defaultOffsets();
1789 }
1790
1791 ContentAlignmentData RenderGrid::computeContentPositionAndDistributionOffset(GridTrackSizingDirection direction, LayoutUnit availableFreeSpace, unsigned numberOfGridTracks) const
1792 {
1793     bool isRowAxis = direction == ForColumns;
1794     ContentPosition position = isRowAxis ? style().resolvedJustifyContentPosition() : style().resolvedAlignContentPosition();
1795     ContentDistributionType distribution = isRowAxis ? style().resolvedJustifyContentDistribution() : style().resolvedAlignContentDistribution();
1796     // If <content-distribution> value can't be applied, 'position' will become the associated
1797     // <content-position> fallback value.
1798     ContentAlignmentData contentAlignment = contentDistributionOffset(availableFreeSpace, position, distribution, numberOfGridTracks);
1799     if (contentAlignment.isValid())
1800         return contentAlignment;
1801
1802     OverflowAlignment overflow = isRowAxis ? style().justifyContentOverflowAlignment() : style().alignContentOverflowAlignment();
1803     if (availableFreeSpace <= 0 && overflow == OverflowAlignmentSafe)
1804         return {0, 0};
1805
1806     switch (position) {
1807     case ContentPositionLeft:
1808         // The align-content's axis is always orthogonal to the inline-axis.
1809         return {0, 0};
1810     case ContentPositionRight:
1811         if (isRowAxis)
1812             return {availableFreeSpace, 0};
1813         // The align-content's axis is always orthogonal to the inline-axis.
1814         return {0, 0};
1815     case ContentPositionCenter:
1816         return {availableFreeSpace / 2, 0};
1817     case ContentPositionFlexEnd: // Only used in flex layout, for other layout, it's equivalent to 'end'.
1818     case ContentPositionEnd:
1819         if (isRowAxis)
1820             return {offsetToEndEdge(style().isLeftToRightDirection(), availableFreeSpace), 0};
1821         return {availableFreeSpace, 0};
1822     case ContentPositionFlexStart: // Only used in flex layout, for other layout, it's equivalent to 'start'.
1823     case ContentPositionStart:
1824         if (isRowAxis)
1825             return {offsetToStartEdge(style().isLeftToRightDirection(), availableFreeSpace), 0};
1826         return {0, 0};
1827     case ContentPositionBaseline:
1828     case ContentPositionLastBaseline:
1829         // FIXME: Implement the previous values. For now, we always 'start' align.
1830         // http://webkit.org/b/145566
1831         if (isRowAxis)
1832             return {offsetToStartEdge(style().isLeftToRightDirection(), availableFreeSpace), 0};
1833         return {0, 0};
1834     case ContentPositionAuto:
1835         break;
1836     }
1837
1838     ASSERT_NOT_REACHED();
1839     return {0, 0};
1840 }
1841
1842 LayoutPoint RenderGrid::findChildLogicalPosition(const RenderBox& child) const
1843 {
1844     LayoutUnit rowAxisOffset = rowAxisOffsetForChild(child);
1845     // We stored m_columnPositions's data ignoring the direction, hence we might need now
1846     // to translate positions from RTL to LTR, as it's more convenient for painting.
1847     if (!style().isLeftToRightDirection()) {
1848         LayoutUnit alignmentOffset =  m_columnPositions[0] - borderAndPaddingStart();
1849         LayoutUnit rightGridEdgePosition = m_columnPositions[m_columnPositions.size() - 1] + alignmentOffset + borderAndPaddingLogicalLeft();
1850         rowAxisOffset = rightGridEdgePosition - (rowAxisOffset + child.logicalWidth());
1851     }
1852
1853     return LayoutPoint(rowAxisOffset, columnAxisOffsetForChild(child));
1854 }
1855
1856 void RenderGrid::paintChildren(PaintInfo& paintInfo, const LayoutPoint& paintOffset, PaintInfo& forChild, bool usePrintRect)
1857 {
1858     for (RenderBox* child = m_orderIterator.first(); child; child = m_orderIterator.next())
1859         paintChild(*child, paintInfo, paintOffset, forChild, usePrintRect, PaintAsInlineBlock);
1860 }
1861
1862 const char* RenderGrid::renderName() const
1863 {
1864     if (isFloating())
1865         return "RenderGrid (floating)";
1866     if (isOutOfFlowPositioned())
1867         return "RenderGrid (positioned)";
1868     if (isAnonymous())
1869         return "RenderGrid (generated)";
1870     if (isRelPositioned())
1871         return "RenderGrid (relative positioned)";
1872     return "RenderGrid";
1873 }
1874
1875 } // namespace WebCore
1876
1877 #endif /* ENABLE(CSS_GRID_LAYOUT) */