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

Source/core/layout/LayoutGrid.cpp

Index: Source/core/layout/LayoutGrid.cpp
diff --git a/Source/core/layout/LayoutGrid.cpp b/Source/core/layout/LayoutGrid.cpp
index 56826d06c9350e129bc8fc841290ceabc90320d6..b93e33b48afd9e83efcb5ab33d6956835e2c9d24 100644
--- a/Source/core/layout/LayoutGrid.cpp
+++ b/Source/core/layout/LayoutGrid.cpp
@@ -1755,10 +1755,17 @@ GridAxisPosition LayoutGrid::rowAxisPositionForChild(const LayoutBox& child) con
     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) {
@@ -1766,8 +1773,12 @@ LayoutUnit LayoutGrid::columnAxisOffsetForChild(const LayoutBox& child) const
         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);
     }
     }
@@ -1779,7 +1790,8 @@ LayoutUnit LayoutGrid::columnAxisOffsetForChild(const LayoutBox& child) const
 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) {
@@ -1787,8 +1799,12 @@ LayoutUnit LayoutGrid::rowAxisOffsetForChild(const LayoutBox& child) const
         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);
     }
     }