Implement Pango RenderText for Linux.

ui/gfx/render_text.h

Index: ui/gfx/render_text.h
===================================================================
--- ui/gfx/render_text.h	(revision 97884)
+++ ui/gfx/render_text.h	(working copy)
@@ -121,9 +121,12 @@
  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.
@@ -176,7 +179,7 @@
   // edits take place, and doesn't necessarily correspond to
   // SelectionModel::caret_pos.
   size_t GetCursorPosition() const;
-  void SetCursorPosition(const size_t position);
+  void SetCursorPosition(size_t position);
 
   void SetCaretPlacement(SelectionModel::CaretPlacement placement) {
       selection_model_.set_caret_placement(placement);
@@ -226,7 +229,7 @@
   // 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();
@@ -274,13 +277,18 @@
   virtual SelectionModel GetRightSelectionModel(const SelectionModel& current,
                                                 BreakType break_type);
 
-  // Get the logical index of the grapheme preceeding the argument |position|.
+  // Get the logical index of the grapheme preceding the argument |position|.
   virtual size_t GetIndexOfPreviousGrapheme(size_t position);
 
   // Apply composition style (underline) to composition range and selection
   // style (foreground) to selection range.
   void ApplyCompositionAndSelectionStyles(StyleRanges* style_ranges) const;
 
+  // Convert points from the text space to the view space and back.
+  // Handles the display area, display offset, and the application LTR/RTL mode.
+  Point ToTextPoint(const Point& point);
+  Point ToViewPoint(const Point& point);
+
  private:
   friend class RenderTextTest;
 
@@ -292,12 +300,22 @@
   // Clear out |style_ranges_|.
   void ClearStyleRanges();
 
+  // Set the cursor to |position|, with the caret trailing the previous
+  // 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_. This should be called only
+  // when selection is not empty, i.e. selection_end_ != selection_start_.

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

I would hope that this function does something reasonable when the selection is
empty... You should remove this comment constraintor enforce it as a DCHECK in
the function body.

[xji, 2011/08/25 03:15:19]

changed the implementation to return selection_model_ when selection is empty.

+  // The returned value represents a cursor/caret position without a selection.
+  SelectionModel GetSelectionModelForSelectionStart();
+
   // Logical UTF-16 string data to be drawn.
   string16 text_;