Paint backgrounds of a table section/row in one display item

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

Index: third_party/WebKit/Source/core/layout/LayoutTableRow.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutTableRow.cpp b/third_party/WebKit/Source/core/layout/LayoutTableRow.cpp
index 3184ad5c5a4ef04f7f70463640b98b687cc92e81..d9bc0f0223ff1235d5bbbf5d6826e10dd9eecc22 100644
--- a/third_party/WebKit/Source/core/layout/LayoutTableRow.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutTableRow.cpp
@@ -305,11 +305,16 @@ void LayoutTableRow::addOverflowFromCell(const LayoutTableCell* cell) {
   // The cell and the row share the section's coordinate system. However
   // the visual overflow should be determined in the coordinate system of
   // the row, that's why we shift it below.
-  LayoutUnit cellOffsetLogicalTopDifference =
-      cell->location().y() - location().y();
-  cellVisualOverflowRect.move(LayoutUnit(), cellOffsetLogicalTopDifference);
-
+  cellVisualOverflowRect.moveBy(-location());

[chrishtr, 2017/03/31 22:59:06]

Why this change?

[Xianzhu, 2017/03/31 23:26:30]

The original code happens to be correct for horizontal layout (when
location().x() is zero), but is incorrect for vertical layout. The changed code
is consistent with other places where we adjust cell location in row.

Found the issue when adding line 311-317 which needs the similar logic.

   addContentsVisualOverflow(cellVisualOverflowRect);
+
+  // Table row paints its background behind cells. If the cell spans multiple
+  // rows, the row's visual rect should be expanded to cover the cell.
+  if (styleRef().hasBackground()) {
+    LayoutRect cellBackgroundRect = cell->frameRect();
+    cellBackgroundRect.moveBy(-location());
+    addSelfVisualOverflow(cellBackgroundRect);
+  }
 }
 
 bool LayoutTableRow::isFirstRowInSectionAfterHeader() const {