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 SetCompositionRange(const ui::Range& composition_range) 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.
+  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

[msw, 2011/08/29 20:38:05]

remove "that " or change it to "that is".

[xji, 2011/08/30 00:39:41]

Done.

+  // 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_|.

[msw, 2011/08/29 20:38:05]

Can you rephrase this comment? You're not returning layout_line_.

[xji, 2011/08/30 00:39:41]

Done.

+  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;

[msw, 2011/08/29 20:38:05]

Do you think it's worth warning that this function is O(n) on the runs since
it's using GSList? It might not be necessary since it's private and I'm sure
there are more important efficiency gains we could make.

[xji, 2011/08/30 00:39:41]

added a comment.

+
+  // Returns the last run in |layout_line_|.

[msw, 2011/08/29 20:38:05]

Same question about an O(n) warning here.

[xji, 2011/08/30 00:39:41]

Done.

+  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_