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 "ui/gfx/render_text.h"
 
+#include <pango/pango.h>
+
 namespace gfx {
 
 // RenderTextLinux is the Linux implementation of RenderText using Pango.
 class RenderTextLinux : public RenderText {
  public:
   RenderTextLinux();
   virtual ~RenderTextLinux();
 
-private:
+  virtual void SetText(const string16& text) OVERRIDE {
+    RenderText::SetText(text);

[msw, 2011/08/19 23:16:59]

All of these definitions are simple, but non-trivial; move them to the cc.

Also, you should remove spaces between the RenderText overrides and add a
comment above them that says: "// Overridden from RenderText:" (I just did the
same for my change)

[xji, 2011/08/22 23:57:28]

Done.

+    ResetLayout();
+  }
+
+  virtual void SetDisplayRect(const Rect&r) OVERRIDE {
+    RenderText::SetDisplayRect(r);
+    ResetLayout();
+  }
+
+  virtual void ApplyStyleRange(StyleRange style_range) OVERRIDE {
+    RenderText::ApplyStyleRange(style_range);
+    ResetLayout();
+  }
+
+  virtual void ApplyDefaultStyle() OVERRIDE {
+    RenderText::ApplyDefaultStyle();
+    ResetLayout();
+  }
+
+  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;
+
+ private:
+  enum CursorMovementDirection {
+    LEFT,
+    RIGHT
+  };
+
+  enum RelativeLogicalPosition {
+    PREVIOUS,
+    NEXT
+  };
+
+  virtual SelectionModel GetLeftSelectionModel(const SelectionModel& current,

[msw, 2011/08/19 23:16:59]

Also add "// Overridden from RenderText:" here and remove blank line 65.

[xji, 2011/08/22 23:57:28]

Done.

+                                               BreakType break_type) OVERRIDE;
+  virtual SelectionModel GetRightSelectionModel(const SelectionModel& current,
+                                                BreakType break_type) OVERRIDE;
+
+  virtual size_t GetIndexOfPreviousGrapheme(size_t position) OVERRIDE;
+
+  // Returns the SelectionModel for visual leftmost position in the line.

[msw, 2011/08/19 23:16:59]

There are going to be lots of opportunities for us to merge similar changes or
at least use the same signatures for functions like this and
RenderTextWin::Left/RightEndSelectionModel.

[xji, 2011/08/22 23:57:28]

Changed to the same names. But I can not declare them as "const" since they
depends on TextDirection() which needs ensure layout_.

I could  make TextDirection() to check the first strong character's
directionality (which I think is what pango does), but using pango_find_base_dir
might be more accurate.

[msw, 2011/08/23 08:01:01]

Sounds good.

+  // The returned value represents a cursor/caret position without a selection.
+  SelectionModel GetSelectionModelForVisualLeftmost() const;
+
+  // Returns the run that contains the caret_pos in |current|. Based on moving
+  // direction, set whether the (caret_pos, caret_placement) is at the boundary
+  // of the run. If moving right, the trailing edge of LTR run or the leading
+  // edge of RTL run is at boundary of run. If moving left, the leading edge of
+  // LTR run or the trailing edge of RTL run is at the boundary of run.
+  //
+  // This does not work if |current| is the visually rightmost END position,
+  // which is SelectionModel(text().length(), text().length(), LEADING).
+  // This END position does not belong to any run.

[msw, 2011/08/19 23:16:59]

Interesting, instead of using a caret at (text().length(), LEADING) I put it
leading/trailing the left-/right-most grapheme, which made things easier for me.

[xji, 2011/08/22 23:57:28]

I think you are right. I changed it to your way.

[msw, 2011/08/23 08:01:01]

:)

+  GSList* GetRunContainsCaretPos(const SelectionModel& current,

[msw, 2011/08/19 23:16:59]

Hopefully we'll be able to merge the signatures and uses of this with
RenderTextWin::GetRunContainingPosition.

[xji, 2011/08/22 23:57:28]

I changed the implementation as yours. But I am returning a GSList*. Unless I
have a local mapping of the single-linked list, return run's index is not
helping.

Also, I changed the usage (implementation of Left/RightSelectionModel) largely
based on yours. It simplified the code a lot.

[msw, 2011/08/23 08:01:01]

:) I'm so sorry about the GList, it's a tragedy.

+                                 CursorMovementDirection dir,
+                                 bool* at_boundary) const;
+
+  // Given |utf16_index_of_current_grapheme|, returns the UTF8 index of next
+  // graphame in the text if |pos| is NEXT, otherwise, returns the UTF8 index of
+  // previous grapheme.
+  size_t Utf8IndexOfAdjacentGrapheme(size_t utf16_index_of_current_grapheme,
+                                     RelativeLogicalPosition pos) const;
+
+  // Given |utf16_index_of_current_grapheme|, returns the UTF16 index of next
+  // graphame in the text if |pos| is NEXT, otherwise, returns the UTF16 index
+  // of previous grapheme.
+  size_t Utf16IndexOfAdjacentGrapheme(size_t utf16_index_of_current_grapheme,
+                                      RelativeLogicalPosition pos) const;
+
+  // Given a |run|, returns the SelectionModel that contains the logical first
+  // caret position inside (not at bounary of) the run.

[msw, 2011/08/19 23:16:59]

"not at *a* boundary" here and elsewhere

[xji, 2011/08/22 23:57:28]

Done.

+  // The returned value represents a cursor/caret position without a selection.
+  SelectionModel FirstSelectionModelInsideRun(const PangoItem* run) const;
+
+  // Given a |run|, returns the SelectionModel that contains the logical last
+  // caret position inside (not at bounary of) the run.
+  // The returned value represents a cursor/caret position without a selection.
+  SelectionModel LastSelectionModelInsideRun(const PangoItem* run) const;
+
+  // Given a |run|, returns the SelectionModel that contains the leftmost caret
+  // position inside (not at bounary of) the run.
+  // The returned value represents a cursor/caret position without a selection.
+  SelectionModel LeftmostSelectionModelInsideRun(const PangoItem* run) const;
+
+  // Given a |run|, returns the SelectionModel that contains the rightmost caret
+  // position inside (not at bounary of) the run.
+  // The returned value represents a cursor/caret position without a selection.
+  SelectionModel RightmostSelectionModelInsideRun(const PangoItem* run) const;
+
+  // when |sel| is the visually rightmost END position of line, set |adjacent|

[msw, 2011/08/19 23:16:59]

Wouldn't it be left-most for RTL text/UI?

[xji, 2011/08/22 23:57:28]

this handles the right (visual) end (NOT the logical END in HOME/END), which is
when text is LTR text. It is no longer needed.

+  // as the left or right (depends on |dir|) of |sel| and return true.
+  // Otherwise, return false.
+  // The value set in |adjacent| represnts a cursor/caret positin without a

[msw, 2011/08/19 23:16:59]

positi*o*n

[xji, 2011/08/22 23:57:28]

Done.

+  // selection.
+  bool GetVisuallyAdjacentCursorPositionForEnd(const SelectionModel& current,
+                                               CursorMovementDirection dir,
+                                               SelectionModel* adjacent) const;
+
+  // Get the selection model that visually left of |current| by one grapheme.
+  // The returned value represents a cursor/caret position without a selection.
+  SelectionModel GetLeftSelectionModelByGrapheme(
+      const SelectionModel& current) const;
+
+  // Get the selection model that visually right of |current| by one grapheme.
+  // The returned value represents a cursor/caret position without a selection.
+  SelectionModel GetRightSelectionModelByGrapheme(
+      const SelectionModel& current) const;
+
+  // Creates, setup, and returns pango layout and pango layout line if layout_

[msw, 2011/08/19 23:16:59]

"Create*, setup, and return*" to match the tense of 'setup'.

[xji, 2011/08/22 23:57:28]

Done.

+  // is NULL. Otherwise, return the cached layout_.
+  PangoLayout* EnsureLayout();
+
+  // Unref pango layout (layout_) and pango layout line (pango_line_). Set them

[msw, 2011/08/19 23:16:59]

Use vertical bars to indicate members, and you can omit the friendly name or the
member name, both is redundant.

[xji, 2011/08/22 23:57:28]

Done.
I thought we only use vertical bar for function parameter, but not data member.

[msw, 2011/08/23 08:01:01]

Hmm, you might be right; I'm still learning chromium style. Feel free to undo
that change.

[xji, 2011/08/23 23:52:52]

I checked with my co-worker, and seems there is no hard line on this. So, I will
leave it there (using | to mean I am talking about a variable).

+  // to NULL. nds_.

[msw, 2011/08/19 23:16:59]

what is " nds_."?

[xji, 2011/08/22 23:57:28]

must have done extra editing accidently. removed.

+  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 last run in Layout_line_.

[msw, 2011/08/19 23:16:59]

"*the* last run" and use bars and un-capitalize "|layout_line_|".

[xji, 2011/08/22 23:57:28]

Done.

+  GSList* GetLastRun() const;
+
+  size_t Utf16IndexToUtf8Index(const string16& text, size_t index) const;

[msw, 2011/08/19 23:16:59]

These two functions don't use any class members, and can be implemented as file
static functions local to the code file.

[xji, 2011/08/22 23:57:28]

Done.

+  size_t Utf8IndexToUtf16Index(const string16& text, size_t index) const;
+
+  // Adjust |bounds| for non insert mode.
+  void AdjustBoundsForNonInsertMode(const SelectionModel& selection,
+                                    const PangoRectangle& pos,
+                                    Rect* bounds) const;
+
+  PangoLayout* layout_;
+
+  PangoLayoutLine* layout_line_;
+
   DISALLOW_COPY_AND_ASSIGN(RenderTextLinux);
 };
 
 }  // namespace gfx;
 
 #endif  // UI_GFX_RENDER_TEXT_LINUX_H_