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

third_party/WebKit/Source/core/layout/LayoutGrid.cpp

Index: third_party/WebKit/Source/core/layout/LayoutGrid.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutGrid.cpp b/third_party/WebKit/Source/core/layout/LayoutGrid.cpp
index ea88af2bb3a676f3f5f48e4f8fc7b7d10fbe8d93..d091cc586c04ce095de9becd8d11bf3104d2df4d 100644
--- a/third_party/WebKit/Source/core/layout/LayoutGrid.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutGrid.cpp
@@ -1793,10 +1793,17 @@ 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() : trackPositions[1] - trackPositions[0] - childBreadth;
+
+}
+
 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);
     if (hasAutoMarginsInColumnAxis(child))
         return startPosition;
@@ -1806,8 +1813,12 @@ 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);
     }
     }
@@ -1819,7 +1830,8 @@ 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);
     if (hasAutoMarginsInRowAxis(child))
         return startPosition;
@@ -1829,8 +1841,12 @@ 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);
     }
     }