[WIP][b:eae_mywip_paint] Paint Selection NG.

third_party/WebKit/Source/core/editing/LayoutSelection.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2006 Apple Computer, Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 60 matching lines @@
   SelectionPaintRange(LayoutObject* start_layout_object,
                       int start_offset,
                       LayoutObject* end_layout_object,
                       int end_offset);
 
   bool operator==(const SelectionPaintRange& other) const;
 
   LayoutObject* StartLayoutObject() const;
   int StartOffset() const;
   LayoutObject* EndLayoutObject() const;
   int EndOffset() const;

[yoichio, 2017/06/27 07:54:52]

Having LayoutNGBlockFlow, textcontent offset and item_index.
Having item_index to get InlineItem and its Layoutobject in O(1).

 
   bool IsNull() const { return !start_layout_object_; }
 
  private:
   LayoutObject* start_layout_object_ = nullptr;
   int start_offset_ = -1;
   LayoutObject* end_layout_object_ = nullptr;
   int end_offset_ = -1;
 };
 
 class LayoutSelection final : public GarbageCollected<LayoutSelection> {
  public:
   static LayoutSelection* Create(FrameSelection& frame_selection) {
     return new LayoutSelection(frame_selection);
   }
 
   bool HasPendingSelection() const { return has_pending_selection_; }
   void SetHasPendingSelection() { has_pending_selection_ = true; }
   void Commit();
 
   IntRect SelectionBounds();
   void InvalidatePaintForSelection();
 
   void ClearSelection();
+  // TODO(yoichio): Returns pair<Union<NGOffset, DOMOffset>, Union<NGOffset,
+  // DOMOffset>>. Content of the Union is decided by if
+  // paint_range_.Start(End)LayoutObject() is NG or not. LayoutObject painter
+  // calliing this should know if the LayoutObject is NG and
+  // LayoutObject.SelectionState because SelectionStartEnd().first doesn't make
+  // sense for SelectionState::kEnd LayoutObject.
   std::pair<int, int> SelectionStartEnd();
   void OnDocumentShutdown();
 
   DECLARE_TRACE();
 
  private:
   LayoutSelection(FrameSelection&);
 
   Member<FrameSelection> frame_selection_;
   bool has_pending_selection_ : 1;
@@ skipping 31 matching lines @@
 
  private:
   Member<NGTextOffsetMap> offset_map_;
 
   DISALLOW_COPY_AND_ASSIGN(Builder);
 };
 
 }  // namespace blink
 
 #endif