Implement Pango RenderText for Linux.

ui/gfx/render_text.h

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_GFX_RENDER_TEXT_H_
 #define UI_GFX_RENDER_TEXT_H_
 #pragma once
 
 #include <algorithm>
 #include <vector>
@@ skipping 103 matching lines @@
   CaretPlacement caret_placement() const { return caret_placement_; }
   void set_caret_placement(CaretPlacement placement) {
     caret_placement_ = placement;
   }
 
   bool Equals(const SelectionModel& sel) const;
 
  private:
   void Init(size_t start, size_t end, size_t pos, CaretPlacement status);
 
-  // Logical selection start. If there is non-empty selection, the selection
-  // always starts visually at the leading edge of the selection_start. So, we
-  // do not need extra information for visual selection bounding.
+  // Logical selection start. If there is non-empty selection, if
+  // selection_start_ is less than selection_end_, the selection starts visually
+  // at the leading edge of the selection_start_. If selection_start_ is greater
+  // than selection_end_, the selection starts visually at the trailing edge of
+  // selection_start_'s previous grapheme. So, we do not need extra information
+  // for visual bounding.
   size_t selection_start_;
 
   // The logical cursor position that next character will be inserted into.
   // It is also the end of the selection.
   size_t selection_end_;
 
   // The following two fields are used to guide cursor visual position.
   // The index of the character that cursor is visually attached to.
   size_t caret_pos_;
   // The visual placement of the cursor, relative to its associated character.
@@ skipping 46 matching lines @@
 
   // Moves the cursor left or right. Cursor movement is visual, meaning that
   // left and right are relative to screen, not the directionality of the text.
   // If |select| is false, the selection start is moved to the same position.
   void MoveCursorLeft(BreakType break_type, bool select);
   void MoveCursorRight(BreakType break_type, bool select);
 
   // Set the selection_model_ to the value of |selection|.
   // The selection model components are modified if invalid.
   // Returns true if the cursor position or selection range changed.
+  // TODO(xji): need to check the cursor is set at grapheme boundary.
   bool MoveCursorTo(const SelectionModel& selection_model);
 
   // Move the cursor to the position associated with the clicked point.
   // If |select| is false, the selection start is moved to the same position.
   // Returns true if the cursor position or selection range changed.
   bool MoveCursorTo(const Point& point, bool select);
 
   size_t GetSelectionStart() const {
       return selection_model_.selection_start();
   }
   size_t MinOfSelection() const {
       return std::min(GetSelectionStart(), GetCursorPosition());
   }
   size_t MaxOfSelection() const {
       return std::max(GetSelectionStart(), GetCursorPosition());
   }
   bool EmptySelection() const {
       return GetSelectionStart() == GetCursorPosition();
   }
 
   // Returns true if the local point is over selected text.
   bool IsPointInSelection(const Point& point);
 
   // Selects no text, all text, or the word at the current cursor position.
   void ClearSelection();
   void SelectAll();
   void SelectWord();
 
   const ui::Range& GetCompositionRange() const;
-  void SetCompositionRange(const ui::Range& composition_range);
+  virtual void SetCompositionRange(const ui::Range& composition_range);
 
   // Apply |style_range| to the internal style model.
   virtual void ApplyStyleRange(StyleRange style_range);
 
   // Apply |default_style_| over the entire text range.
   virtual void ApplyDefaultStyle();
 
-  base::i18n::TextDirection GetTextDirection() const;
+  virtual base::i18n::TextDirection GetTextDirection();
 
   // Get the width of the entire string.
   virtual int GetStringWidth();
 
   virtual void Draw(Canvas* canvas);
 
   // Gets the SelectionModel from a visual point in local coordinates.
   virtual SelectionModel FindCursorPosition(const Point& point);
 
   // Get the visual bounds of a cursor at |selection|. These bounds typically
@@ skipping 67 matching lines @@
   // grapheme, or if there is no previous grapheme, leading the cursor position.
   // If |select| is false, the selection start is moved to the same position.
   void MoveCursorTo(size_t position, bool select);
 
   bool IsPositionAtWordSelectionBoundary(size_t pos);
 
   // Update the cached bounds and display offset to ensure that the current
   // cursor is within the visible display area.
   void UpdateCachedBoundsAndOffset();
 
+  // Returns the selection model of selection_start_.
+  // The returned value represents a cursor/caret position without a selection.
+  SelectionModel GetSelectionModelForSelectionStart();
+
   // Logical UTF-16 string data to be drawn.
   string16 text_;
 
   // Logical selection range and visual cursor position.
   SelectionModel selection_model_;
 
   // The cached cursor bounds; get these bounds with GetUpdatedCursorBounds.
   Rect cursor_bounds_;
 
   // The cursor visibility and insert mode.
@@ skipping 20 matching lines @@
   // The cached bounds and offset are invalidated by changes to the cursor,
   // selection, font, and other operations that adjust the visible text bounds.
   bool cached_bounds_and_offset_valid_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderText);
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_RENDER_TEXT_H_