Translate flow thread coords to the nearest enclosing coord space when appropriate.

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

Index: third_party/WebKit/Source/core/layout/LayoutMultiColumnFlowThread.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutMultiColumnFlowThread.cpp b/third_party/WebKit/Source/core/layout/LayoutMultiColumnFlowThread.cpp
index 1e843382ff795cb3e5bb68a17f3df988c1596894..ea48c2380e124d0da0c44b8e16061b2ed5f886ba 100644
--- a/third_party/WebKit/Source/core/layout/LayoutMultiColumnFlowThread.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutMultiColumnFlowThread.cpp
@@ -302,12 +302,7 @@ LayoutUnit LayoutMultiColumnFlowThread::tallestUnbreakableLogicalHeight(LayoutUn
 
 LayoutSize LayoutMultiColumnFlowThread::columnOffset(const LayoutPoint& point) const
 {
-    if (!hasValidColumnSetInfo())
-        return LayoutSize(0, 0);
-
-    LayoutPoint flowThreadPoint = flipForWritingMode(point);
-    LayoutUnit blockOffset = isHorizontalWritingMode() ? flowThreadPoint.y() : flowThreadPoint.x();
-    return flowThreadTranslationAtOffset(blockOffset);
+    return flowThreadTranslationAtPoint(point, CoordinateSpaceConversion::Containing);
 }
 
 bool LayoutMultiColumnFlowThread::needsNewWidth() const
@@ -325,12 +320,26 @@ bool LayoutMultiColumnFlowThread::isPageLogicalHeightKnown() const
     return false;
 }
 
-LayoutSize LayoutMultiColumnFlowThread::flowThreadTranslationAtOffset(LayoutUnit offsetInFlowThread) const
+LayoutSize LayoutMultiColumnFlowThread::flowThreadTranslationAtOffset(LayoutUnit offsetInFlowThread, CoordinateSpaceConversion mode) const
 {
+    if (!hasValidColumnSetInfo())
+        return LayoutSize(0, 0);
     LayoutMultiColumnSet* columnSet = columnSetAtBlockOffset(offsetInFlowThread);
     if (!columnSet)
         return LayoutSize(0, 0);
-    return columnSet->flowThreadTranslationAtOffset(offsetInFlowThread);
+    return columnSet->flowThreadTranslationAtOffset(offsetInFlowThread, mode);
+}
+
+LayoutSize LayoutMultiColumnFlowThread::flowThreadTranslationAtPoint(const LayoutPoint& flowThreadPoint, CoordinateSpaceConversion mode) const
+{
+    LayoutPoint flippedPoint = flipForWritingMode(flowThreadPoint);
+    LayoutUnit blockOffset = isHorizontalWritingMode() ? flippedPoint.y() : flippedPoint.x();

[Xianzhu, 2016/04/20 20:50:12]

This CL also changes how we handle writing-mode in several methods. Is this
covered by any test? What's the rule of coordinate spaces of the results from
these methods?

[mstensho (USE GERRIT), 2016/04/20 21:02:24]

Yes, we have tests for multicol + writing modes, but this CL shouldn't change
how we handle writing modes. This is code that used to sit in the columnOffset()
implementation. Just moved it here instead.

There was one caller of columnOffset() that wanted to translate to the visual
coordinate space, while all other callers just want the nearest containing
coordinate space. So now columnOffset() always does what all the other callers
wanted, while the one that used to call columnOffset() and wanted the other
behavior (that's flowThreadPointToVisualPoint() in LayoutFlowThread()) now calls
directly into flowThreadTranslationAtPoint() instead, so that it can specify
that it wants it converted to the visual coordinate space.

+    return flowThreadTranslationAtOffset(blockOffset, mode);
+}
+
+LayoutPoint LayoutMultiColumnFlowThread::flowThreadPointToVisualPoint(const LayoutPoint& flowThreadPoint) const
+{
+    return flowThreadPoint + flowThreadTranslationAtPoint(flowThreadPoint, CoordinateSpaceConversion::Visual);
 }
 
 LayoutPoint LayoutMultiColumnFlowThread::visualPointToFlowThreadPoint(const LayoutPoint& visualPoint) const