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ui/gfx/pango_util.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_PANGO_UTIL_H_
 #define UI_GFX_PANGO_UTIL_H_
 #pragma once
 
+#include <cairo/cairo.h>
 #include <pango/pango.h>
+
 #include "base/i18n/rtl.h"
 #include "base/string16.h"
+#include "ui/base/ui_export.h"
+#include "third_party/skia/include/core/SkColor.h"
 
 // TODO(xji): move other pango related functions from gtk_util to here.
 
 namespace gfx {
 
 class Font;
+class Rect;
 
 // Setup pango layout |layout|, including set layout text as |text|, font
 // description based on |font|, width as |width| in PANGO_SCALE for RTL lcoale,
 // and set up whether auto-detect directionality, alignment, ellipsis, word
 // wrapping, resolution etc.
 void SetupPangoLayout(PangoLayout* layout,
                       const string16& text,
                       const gfx::Font& font,
                       int width,
                       base::i18n::TextDirection text_direction,
                       int flags);
+
+// A simple class to quickly do raw pango drawing.
+class UI_EXPORT PangoDrawString {

[Evan Stade, 2011/10/25 23:33:30]

seems weird to do

PangoDrawString draw(...);
draw.Draw(color);

why is this a class at all? why do you pass color into Draw instead of the
constructor? I see that it may be a class because you want that other class to
inherit from it, that said, it seems either the other class should use this one
(rather than inherit) or there should at least be some sort of easier way to
draw, i.e. a static function that creates the object and draws for you.

[Elliot Glaysher, 2011/10/26 21:06:57]

First, I agree this is weird.

The class is split at which drawing interface is used. This class all uses cairo
drawing and takes no gfx::Canvas objects, while the subclass specifically takes
a skia canvas and its methods use the additional mixed mode drawing.

I've uploaded a different version with one exported method for clients to use,
at the price of some code duplication.
Because in pango the the text (along with most other properties) is a property
of the PangoLayout while the color is part of the cairo pattern.

+ public:
+  PangoDrawString(cairo_t* cr,
+                  const string16& text,
+                  const gfx::Font& font,
+                  const gfx::Rect& bounds,
+                  const gfx::Rect& clip,
+                  int flags);
+  ~PangoDrawString();
+
+  void Draw(const SkColor& text_color);
+
+ protected:
+  // Draw an underline under the text using |cr|, which must already be
+  // initialized with the correct source.  |extra_edge_width| is added to the
+  // outer edge of the line.  Helper method for Draw() and DrawWithHalo().
+  void DrawUnderline(cairo_t* cr, double extra_edge_width);
+
+  const gfx::Rect& bounds_;
+  int flags_;
+  const gfx::Font& font_;
+
+  cairo_t* cr_;
+  PangoLayout* layout_;
+
+  int text_x_;
+  int text_y_;
+  int text_width_;
+  int text_height_;
+
+  base::i18n::TextDirection text_direction_;
+};
+
 }  // namespace gfx
 
 #endif  // UI_GFX_PANGO_UTIL_H_