[css-grid] Fix painting in RTL

third_party/WebKit/Source/core/paint/GridPainter.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/paint/GridPainter.h"
 
 #include "core/layout/LayoutGrid.h"
 #include "core/paint/BlockPainter.h"
 #include "core/paint/PaintInfo.h"
 #include <algorithm>
@@ skipping 28 matching lines @@
     }
 };
 
 void GridPainter::paintChildren(const PaintInfo& paintInfo, const LayoutPoint& paintOffset)
 {
     ASSERT(!m_layoutGrid.needsLayout());
 
     LayoutRect localPaintInvalidationRect = LayoutRect(paintInfo.cullRect().m_rect);
     localPaintInvalidationRect.moveBy(-paintOffset);
 
-    GridSpan dirtiedColumns = dirtiedGridAreas(m_layoutGrid.columnPositions(), localPaintInvalidationRect.x(), localPaintInvalidationRect.maxX());
+    Vector<LayoutUnit> columnPositions = m_layoutGrid.columnPositions();
+    if (!m_layoutGrid.styleRef().isLeftToRightDirection()) {
+        // Translate columnPositions in RTL as we need the physical coordinates of the columns in order to call dirtiedGridAreas().
+        for (size_t i = 0; i < columnPositions.size(); i++)
+            columnPositions[i] = m_layoutGrid.translateRTLCoordinate(columnPositions[i]);
+        // We change the order of tracks in columnPositions, as in RTL the leftmost track will be the last one.
+        std::sort(columnPositions.begin(), columnPositions.end());
+    }
+
+    GridSpan dirtiedColumns = dirtiedGridAreas(columnPositions, localPaintInvalidationRect.x(), localPaintInvalidationRect.maxX());
     GridSpan dirtiedRows = dirtiedGridAreas(m_layoutGrid.rowPositions(), localPaintInvalidationRect.y(), localPaintInvalidationRect.maxY());
 
+    if (!m_layoutGrid.styleRef().isLeftToRightDirection()) {
+        // As we changed the order of tracks previously, we need to swap the dirtied columns in RTL.
+        size_t lastLine = columnPositions.size() - 1;
+        dirtiedColumns = GridSpan::translatedDefiniteGridSpan(lastLine - dirtiedColumns.endLine(), lastLine - dirtiedColumns.startLine());
+    }
+
     Vector<std::pair<LayoutBox*, size_t>> gridItemsToBePainted;
 
     for (const auto& row : dirtiedRows) {
         for (const auto& column : dirtiedColumns) {
             const Vector<LayoutBox*, 1>& children = m_layoutGrid.gridCell(row, column);
             for (auto* child : children)
                 gridItemsToBePainted.append(std::make_pair(child, m_layoutGrid.paintIndexForGridItem(child)));
         }
     }
 
@@ skipping 13 matching lines @@
         LayoutBox* current = gridItemAndPaintIndex.first;
         if (current == previous)
             continue;
 
         BlockPainter(m_layoutGrid).paintAllChildPhasesAtomically(*current, paintInfo, paintOffset);
         previous = current;
     }
 }
 
 } // namespace blink