Implement Pango RenderText for Linux.

ui/gfx/render_text_linux.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_LINUX_H_
 #define UI_GFX_RENDER_TEXT_LINUX_H_
 #pragma once
 
+#include <pango/pango.h>
+
 #include "ui/gfx/render_text.h"
 
 namespace gfx {
 
 // RenderTextLinux is the Linux implementation of RenderText using Pango.
 class RenderTextLinux : public RenderText {
  public:
   RenderTextLinux();
   virtual ~RenderTextLinux();
 
-private:
+  // Overridden from RenderText:
+  virtual void SetText(const string16& text) OVERRIDE;
+  virtual void SetDisplayRect(const Rect&r) OVERRIDE;
+  virtual void ApplyStyleRange(StyleRange style_range) OVERRIDE;
+  virtual void ApplyDefaultStyle() OVERRIDE;
+  virtual base::i18n::TextDirection GetTextDirection() OVERRIDE;
+  virtual int GetStringWidth() OVERRIDE;
+  virtual void Draw(Canvas* canvas) OVERRIDE;
+  virtual SelectionModel FindCursorPosition(const Point& point) OVERRIDE;
+  virtual Rect GetCursorBounds(const SelectionModel& position,
+                               bool insert_mode) OVERRIDE;
+
+ protected:
+  // Overridden from RenderText:
+  virtual SelectionModel GetLeftSelectionModel(const SelectionModel& current,
+                                               BreakType break_type) OVERRIDE;
+  virtual SelectionModel GetRightSelectionModel(const SelectionModel& current,
+                                                BreakType break_type) OVERRIDE;
+  virtual size_t GetIndexOfPreviousGrapheme(size_t position) OVERRIDE;
+
+ private:
+  enum RelativeLogicalPosition {
+    PREVIOUS,
+    NEXT
+  };
+
+  // Get the SelectionModels corresponding to the left or right text ends.
+  // The returned value represents a cursor/caret position without a selection.
+  SelectionModel LeftEndSelectionModel();
+  SelectionModel RightEndSelectionModel();
+
+  // Returns the run that contains |position|. Return NULL if not found.
+  GSList* GetRunContainingPosition(size_t position) const;
+
+  // Given |utf16_index_of_current_grapheme|, returns the UTF8 or UTF16 index of
+  // next grapheme in the text if |pos| is NEXT, otherwise, returns the index of
+  // previous grapheme. Returns 0 if there is no previous grapheme, and returns
+  // the |text_| length if there is no next grapheme.

[msw, 2011/08/24 08:55:30]

See my other comment about handling this behavior at callsites.

+  size_t Utf8IndexOfAdjacentGrapheme(size_t utf16_index_of_current_grapheme,
+                                     RelativeLogicalPosition pos) const;
+  size_t Utf16IndexOfAdjacentGrapheme(size_t utf16_index_of_current_grapheme,
+                                      RelativeLogicalPosition pos) const;
+
+  // Given a |run|, returns the SelectionModel that contains the logical first
+  // or last caret position inside (not at a boundary of) the run.
+  // The returned value represents a cursor/caret position without a selection.
+  SelectionModel FirstSelectionModelInsideRun(const PangoItem* run) const;
+  SelectionModel LastSelectionModelInsideRun(const PangoItem* run) const;
+
+  // Get the selection model that visually left or right of |current| by one
+  // grapheme.
+  // The returned value represents a cursor/caret position without a selection.
+  SelectionModel LeftSelectionModel(const SelectionModel& current);
+  SelectionModel RightSelectionModel(const SelectionModel& current);
+
+  // Create, setup, and return pango layout and pango layout line if |layout_|
+  // is NULL. Otherwise, return the cached |layout_|.
+  PangoLayout* EnsureLayout();
+
+  // Unref |layout_| and |pango_line_|. Set them to NULL.
+  void ResetLayout();
+
+  // Setup pango attribute: foreground, background, font, strike.
+  void SetupPangoAttributes(PangoLayout* layout);
+
+  // Append one pango attribute |pango_attr| into pango attribute list |attrs|.
+  void AppendPangoAttribute(size_t start,
+                            size_t end,
+                            PangoAttribute* pango_attr,
+                            PangoAttrList* attrs);
+
+  // Returns |run|'s visually previous run.
+  GSList* GetPreviousRun(GSList* run) const;
+
+  // Returns the last run in |layout_line_|.
+  GSList* GetLastRun() const;
+
+  size_t Utf16IndexToUtf8Index(size_t index) const;
+  size_t Utf8IndexToUtf16Index(size_t index) const;
+
+  PangoLayout* layout_;
+
+  PangoLayoutLine* layout_line_;
+
   DISALLOW_COPY_AND_ASSIGN(RenderTextLinux);
 };
 
 }  // namespace gfx;
 
 #endif  // UI_GFX_RENDER_TEXT_LINUX_H_