[CSS Grid Layout] Combining Content and Self Alignment with span items

Source/core/layout/LayoutGrid.cpp

 /*
  * Copyright (C) 2011 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 1737 matching lines @@
         // crbug.com/234191
         return GridAxisStart;
     case ItemPositionAuto:
         break;
     }
 
     ASSERT_NOT_REACHED();
     return GridAxisStart;
 }
 
+static inline LayoutUnit offsetBetweenTracks(ContentDistributionType distribution, const Vector<LayoutUnit>& trackPositions, const LayoutUnit& childBreadth)
+{
+    return (distribution == ContentDistributionStretch || ContentDistributionStretch == ContentDistributionDefault) ? LayoutUnit(0) : trackPositions[1] - trackPositions[0] - childBreadth;

[cbiesinger, 2015/09/30 15:09:10]

Use LayoutUnit() instead of specifying the explicit zero, it's a bit faster

+
+}
+
 LayoutUnit LayoutGrid::columnAxisOffsetForChild(const LayoutBox& child) const
 {
     const GridCoordinate& coordinate = cachedGridCoordinate(child);
-    LayoutUnit startOfRow = m_rowPositions[coordinate.rows.resolvedInitialPosition.toInt()];
+    size_t childStartLine = coordinate.rows.resolvedInitialPosition.toInt();
+    LayoutUnit startOfRow = m_rowPositions[childStartLine];
     LayoutUnit startPosition = startOfRow + marginBeforeForChild(child);
     GridAxisPosition axisPosition = columnAxisPositionForChild(child);
     switch (axisPosition) {
     case GridAxisStart:
         return startPosition;
     case GridAxisEnd:
     case GridAxisCenter: {
-        LayoutUnit endOfRow = m_rowPositions[coordinate.rows.resolvedFinalPosition.next().toInt()];
-        LayoutUnit offsetFromStartPosition = computeOverflowAlignmentOffset(child.styleRef().alignSelfOverflowAlignment(), endOfRow - startOfRow, child.logicalHeight() + child.marginLogicalHeight());
+        size_t childEndLine = coordinate.rows.resolvedFinalPosition.next().toInt();
+        LayoutUnit endOfRow = m_rowPositions[childEndLine];
+        LayoutUnit childBreadth = child.logicalHeight() + child.marginLogicalHeight();
+        if (childEndLine - childStartLine > 1 && childEndLine < m_rowPositions.size() - 1)
+            endOfRow -= offsetBetweenTracks(styleRef().alignContentDistribution(), m_rowPositions, childBreadth);
+        LayoutUnit offsetFromStartPosition = computeOverflowAlignmentOffset(child.styleRef().alignSelfOverflowAlignment(), endOfRow - startOfRow, childBreadth);
         return startPosition + (axisPosition == GridAxisEnd ? offsetFromStartPosition : offsetFromStartPosition / 2);
     }
     }
 
     ASSERT_NOT_REACHED();
     return 0;
 }
 
 LayoutUnit LayoutGrid::rowAxisOffsetForChild(const LayoutBox& child) const
 {
     const GridCoordinate& coordinate = cachedGridCoordinate(child);
-    LayoutUnit startOfColumn = m_columnPositions[coordinate.columns.resolvedInitialPosition.toInt()];
+    size_t childStartLine = coordinate.columns.resolvedInitialPosition.toInt();
+    LayoutUnit startOfColumn = m_columnPositions[childStartLine];
     LayoutUnit startPosition = startOfColumn + marginStartForChild(child);
     GridAxisPosition axisPosition = rowAxisPositionForChild(child);
     switch (axisPosition) {
     case GridAxisStart:
         return startPosition;
     case GridAxisEnd:
     case GridAxisCenter: {
-        LayoutUnit endOfColumn = m_columnPositions[coordinate.columns.resolvedFinalPosition.next().toInt()];
-        LayoutUnit offsetFromStartPosition = computeOverflowAlignmentOffset(child.styleRef().justifySelfOverflowAlignment(), endOfColumn - startOfColumn, child.logicalWidth() + child.marginLogicalWidth());
+        size_t childEndLine = coordinate.columns.resolvedFinalPosition.next().toInt();
+        LayoutUnit endOfColumn = m_columnPositions[childEndLine];
+        LayoutUnit childBreadth = child.logicalWidth() + child.marginLogicalWidth();
+        if (childEndLine - childStartLine > 1 && childEndLine < m_columnPositions.size() - 1)
+            endOfColumn -= offsetBetweenTracks(styleRef().justifyContentDistribution(), m_columnPositions, childBreadth);
+        LayoutUnit offsetFromStartPosition = computeOverflowAlignmentOffset(child.styleRef().justifySelfOverflowAlignment(), endOfColumn - startOfColumn, childBreadth);
         return startPosition + (axisPosition == GridAxisEnd ? offsetFromStartPosition : offsetFromStartPosition / 2);
     }
     }
 
     ASSERT_NOT_REACHED();
     return 0;
 }
 
 ContentPosition static resolveContentDistributionFallback(ContentDistributionType distribution)
 {
@@ skipping 121 matching lines @@
 
     return LayoutPoint(rowAxisOffset, columnAxisOffsetForChild(child));
 }
 
 void LayoutGrid::paintChildren(const PaintInfo& paintInfo, const LayoutPoint& paintOffset)
 {
     GridPainter(*this).paintChildren(paintInfo, paintOffset);
 }
 
 } // namespace blink