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

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

 /*
  * 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 18 matching lines @@
 
 #include "core/CoreExport.h"
 #include "core/layout/FragmentationContext.h"
 #include "core/layout/LayoutFlowThread.h"
 
 namespace blink {
 
 class LayoutMultiColumnSet;
 class LayoutMultiColumnSpannerPlaceholder;
 
+// What to translate *to* when translating from a flow thread coordinate space.
+enum class CoordinateSpaceConversion {
+    // Just translate to the nearest containing coordinate space (i.e. where our multicol container
+    // lives) of this flow thread, i.e. don't walk ancestral flow threads, if any.
+    Containing,
+
+    // Translate to visual coordinates, by walking all ancestral flow threads.
+    Visual
+};
+
 // Flow thread implementation for CSS multicol. This will be inserted as an anonymous child block of
 // the actual multicol container (i.e. the LayoutBlockFlow whose style computes to non-auto
 // column-count and/or column-width). LayoutMultiColumnFlowThread is the heart of the multicol
 // implementation, and there is only one instance per multicol container. Child content of the
 // multicol container is parented into the flow thread at the time of layoutObject insertion.
 //
 // Apart from this flow thread child, the multicol container will also have LayoutMultiColumnSet
 // children, which are used to position the columns visually. The flow thread is in charge
 // of layout, and, after having calculated the column width, it lays out content as if everything
 // were in one tall single column, except that there will typically be some amount of blank space
@@ skipping 125 matching lines @@
 
     LayoutUnit tallestUnbreakableLogicalHeight(LayoutUnit offsetInFlowThread) const;
 
     LayoutSize columnOffset(const LayoutPoint&) const final;
 
     // Do we need to set a new width and lay out?
     virtual bool needsNewWidth() const;
 
     bool isPageLogicalHeightKnown() const final;
 
-    LayoutSize flowThreadTranslationAtOffset(LayoutUnit) const;
+    LayoutSize flowThreadTranslationAtOffset(LayoutUnit, CoordinateSpaceConversion) const;
+    LayoutSize flowThreadTranslationAtPoint(const LayoutPoint& flowThreadPoint, CoordinateSpaceConversion) const;
 
+    LayoutPoint flowThreadPointToVisualPoint(const LayoutPoint& flowThreadPoint) const override;
     LayoutPoint visualPointToFlowThreadPoint(const LayoutPoint& visualPoint) const override;
 
     int inlineBlockBaseline(LineDirectionMode) const override;
 
     LayoutMultiColumnSet* columnSetAtBlockOffset(LayoutUnit) const final;
 
     void layoutColumns(SubtreeLayoutScope&);
 
     // Skip past a column spanner during flow thread layout. Spanners are not laid out inside the
     // flow thread, since the flow thread is not in a spanner's containing block chain (since the
@@ skipping 73 matching lines @@
     bool m_isBeingEvacuated;
 };
 
 // Cannot use DEFINE_LAYOUT_OBJECT_TYPE_CASTS here, because isMultiColumnFlowThread() is defined in
 // LayoutFlowThread, not in LayoutObject.
 DEFINE_TYPE_CASTS(LayoutMultiColumnFlowThread, LayoutFlowThread, object, object->isLayoutMultiColumnFlowThread(), object.isLayoutMultiColumnFlowThread());
 
 } // namespace blink
 
 #endif // LayoutMultiColumnFlowThread_h