Introduce SelectionPaintRange in LayoutSelection

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

Index: third_party/WebKit/Source/core/editing/LayoutSelection.h
diff --git a/third_party/WebKit/Source/core/editing/LayoutSelection.h b/third_party/WebKit/Source/core/editing/LayoutSelection.h
index 17b7c6dc7f5b15a0e312cb984899cfd2868aed52..7005099327dad10716a60144cb4403e5f6933b65 100644
--- a/third_party/WebKit/Source/core/editing/LayoutSelection.h
+++ b/third_party/WebKit/Source/core/editing/LayoutSelection.h
@@ -30,6 +30,42 @@ namespace blink {
 
 class FrameSelection;
 
+// This class represents a selection range in layout tree for painting and
+// paint invalidation.
+// The current selection to be painted is represented as 2 pairs of
+// (LayoutObject, offset).
+// 2 LayoutObjects are only valid for |Text| node without 'transform' or
+// 'first-letter'.
+// TODO(editing-dev): Clarify the meaning of "offset".
+// editing/ passes them as offsets in the DOM tree but layout uses them as
+// offset in the layout tree. This doesn't work in the cases of
+// CSS first-letter or character transform. See crbug.com/17528.
+class SelectionPaintRange {
+  DISALLOW_NEW();
+
+ public:
+  SelectionPaintRange() = default;
+  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;
+
+  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) {
@@ -47,10 +83,7 @@ class LayoutSelection final : public GarbageCollected<LayoutSelection> {
     kPaintInvalidationNewMinusOld
   };
   void SetSelection(
-      LayoutObject* start,
-      int start_pos,
-      LayoutObject*,
-      int end_pos,
+      const SelectionPaintRange&,
       SelectionPaintInvalidationMode = kPaintInvalidationNewXOROld);
   void ClearSelection();
   std::pair<int, int> SelectionStartEnd();
@@ -67,24 +100,7 @@ class LayoutSelection final : public GarbageCollected<LayoutSelection> {
   Member<FrameSelection> frame_selection_;
   bool has_pending_selection_ : 1;
 
-  // The current selection represented as 2 boundaries.
-  // Selection boundaries are represented in LayoutView by a tuple
-  // (LayoutObject, DOM node offset).
-  // See http://www.w3.org/TR/dom/#range for more information.
-  //
-  // |m_selectionStartPos| and |m_selectionEndPos| are only valid for
-  // |Text| node without 'transform' or 'first-letter'.
-  //
-  // Those are used for selection painting and paint invalidation upon
-  // selection change.
-  LayoutObject* selection_start_;
-  LayoutObject* selection_end_;
-
-  // TODO(yosin): Clarify the meaning of these variables. editing/ passes
-  // them as offsets in the DOM tree  but layout uses them as offset in the
-  // layout tree.
-  int selection_start_pos_;
-  int selection_end_pos_;
+  SelectionPaintRange paint_range_;
 };
 
 }  // namespace blink