Handle exclusive end offsets when translating from flow thread coordinates.

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

 /*
  * Copyright (C) 2012 Apple Inc.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 314 matching lines @@
     return newWidth != logicalWidth();
 }
 
 bool LayoutMultiColumnFlowThread::isPageLogicalHeightKnown() const
 {
     if (LayoutMultiColumnSet* columnSet = lastMultiColumnSet())
         return columnSet->isPageLogicalHeightKnown();
     return false;
 }
 
-LayoutSize LayoutMultiColumnFlowThread::flowThreadTranslationAtOffset(LayoutUnit offsetInFlowThread, CoordinateSpaceConversion mode) const
+LayoutSize LayoutMultiColumnFlowThread::flowThreadTranslationAtOffset(LayoutUnit offsetInFlowThread, PageBoundaryRule rule, CoordinateSpaceConversion mode) const
 {
     if (!hasValidColumnSetInfo())
         return LayoutSize(0, 0);
     LayoutMultiColumnSet* columnSet = columnSetAtBlockOffset(offsetInFlowThread);
     if (!columnSet)
         return LayoutSize(0, 0);
-    return columnSet->flowThreadTranslationAtOffset(offsetInFlowThread, mode);
+    return columnSet->flowThreadTranslationAtOffset(offsetInFlowThread, rule, mode);
 }
 
 LayoutSize LayoutMultiColumnFlowThread::flowThreadTranslationAtPoint(const LayoutPoint& flowThreadPoint, CoordinateSpaceConversion mode) const
 {
     LayoutPoint flippedPoint = flipForWritingMode(flowThreadPoint);
     LayoutUnit blockOffset = isHorizontalWritingMode() ? flippedPoint.y() : flippedPoint.x();
-    return flowThreadTranslationAtOffset(blockOffset, mode);
+
+    // If block direction is flipped, points at a column boundary belong in the former column, not
+    // the latter.
+    PageBoundaryRule rule = hasFlippedBlocksWritingMode() ? AssociateWithFormerPage : AssociateWithLatterPage;
+
+    return flowThreadTranslationAtOffset(blockOffset, rule, mode);
 }
 
 LayoutPoint LayoutMultiColumnFlowThread::flowThreadPointToVisualPoint(const LayoutPoint& flowThreadPoint) const
 {
     return flowThreadPoint + flowThreadTranslationAtPoint(flowThreadPoint, CoordinateSpaceConversion::Visual);
 }
 
 LayoutPoint LayoutMultiColumnFlowThread::visualPointToFlowThreadPoint(const LayoutPoint& visualPoint) const
 {
     LayoutUnit blockOffset = isHorizontalWritingMode() ? visualPoint.y() : visualPoint.x();
@@ skipping 691 matching lines @@
 {
     return MultiColumnLayoutState(m_lastSetWorkedOn);
 }
 
 void LayoutMultiColumnFlowThread::restoreMultiColumnLayoutState(const MultiColumnLayoutState& state)
 {
     m_lastSetWorkedOn = state.columnSet();
 }
 
 } // namespace blink