Correct flowThreadTranslationAtOffset() for vertical-rl writing mode.

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

 // Copyright 2015 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/layout/MultiColumnFragmentainerGroup.h"
 
 #include "core/layout/ColumnBalancer.h"
 #include "core/layout/FragmentationContext.h"
 #include "core/layout/LayoutMultiColumnSet.h"
 
@@ skipping 92 matching lines @@
     LayoutMultiColumnFlowThread* flowThread = m_columnSet.multiColumnFlowThread();
 
     // A column out of range doesn't have a flow thread portion, so we need to clamp to make sure
     // that we stay within the actual columns. This means that content in the overflow area will be
     // mapped to the last actual column, instead of being mapped to an imaginary column further
     // ahead.
     unsigned columnIndex = offsetInFlowThread >= logicalBottomInFlowThread() ? actualColumnCount() - 1 : columnIndexAtOffset(offsetInFlowThread, rule);
 
     LayoutRect portionRect(flowThreadPortionRectAt(columnIndex));
     flowThread->flipForWritingMode(portionRect);
+    portionRect.moveBy(flowThread->topLeftLocation());
+
     LayoutRect columnRect(columnRectAt(columnIndex));
+    columnRect.move(offsetFromColumnSet());
     m_columnSet.flipForWritingMode(columnRect);
-    LayoutSize translationRelativeToGroup = columnRect.location() - portionRect.location();
-    LayoutSize translationRelativeToFlowThread = translationRelativeToGroup + offsetFromColumnSet() + m_columnSet.topLeftLocationOffset() - flowThread->topLeftLocationOffset();
+    columnRect.moveBy(m_columnSet.topLeftLocation());
+
+    LayoutSize translationRelativeToFlowThread = columnRect.location() - portionRect.location();
     if (mode == CoordinateSpaceConversion::Containing)
         return translationRelativeToFlowThread;
 
     LayoutSize enclosingTranslation;
     if (LayoutMultiColumnFlowThread* enclosingFlowThread = flowThread->enclosingFlowThread()) {
         const MultiColumnFragmentainerGroup& firstRow = flowThread->firstMultiColumnSet()->firstFragmentainerGroup();
         // Translation that would map points in the coordinate space of the outermost flow thread to
         // visual points in the first column in the first fragmentainer group (row) in our multicol
         // container.
         LayoutSize enclosingTranslationOrigin = enclosingFlowThread->flowThreadTranslationAtOffset(firstRow.blockOffsetInEnclosingFragmentationContext(), LayoutBox::AssociateWithLatterPage, mode);
@@ skipping 353 matching lines @@
     append(MultiColumnFragmentainerGroup(m_columnSet));
     return last();
 }
 
 void MultiColumnFragmentainerGroupList::deleteExtraGroups()
 {
     shrink(1);
 }
 
 } // namespace blink