ui/gfx/canvas_paint_gtk.h

   1
   2 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
   3 // Use of this source code is governed by a BSD-style license that can be
   4 // found in the LICENSE file.
   5
   6 #ifndef UI_GFX_CANVAS_PAINT_LINUX_H_
   7 #define UI_GFX_CANVAS_PAINT_LINUX_H_
   8
   9 #include "base/logging.h"
  10 #include "skia/ext/platform_canvas.h"
  11 #include "ui/gfx/canvas.h"
  12 #include <gdk/gdk.h>
  13
  14 namespace gfx {
  15
  16 // A class designed to translate skia painting into a region in a GdkWindow.
  17 // On construction, it will set up a context for painting into, and on
  18 // destruction, it will commit it to the GdkWindow.
  19 // Note: The created context is always inialized to (0, 0, 0, 0).
  20 class UI_EXPORT CanvasSkiaPaint : public Canvas {
  21  public:
  22   // This constructor assumes the result is opaque.
  23   explicit CanvasSkiaPaint(GdkEventExpose* event);
  24   CanvasSkiaPaint(GdkEventExpose* event, bool opaque);
  25   virtual ~CanvasSkiaPaint();
  26
  27   // Sets whether the bitmap is composited in such a way that the alpha channel
  28   // is honored. This is only useful if you've enabled an RGBA colormap on the
  29   // widget. The default is false.
  30   void set_composite_alpha(bool composite_alpha) {
  31     composite_alpha_ = composite_alpha;
  32   }
  33
  34   // Returns true if the invalid region is empty. The caller should call this
  35   // function to determine if anything needs painting.
  36   bool is_empty() const {
  37     return gdk_region_empty(region_);
  38   }
  39
  40   GdkRectangle rectangle() const {
  41     GdkRectangle bounds;
  42     gdk_region_get_clipbox(region_, &bounds);
  43     return bounds;
  44   }
  45
  46  private:
  47   void Init(bool opaque);
  48
  49   cairo_t* context_;
  50   GdkWindow* window_;
  51   GdkRegion* region_;
  52   // See description above setter.
  53   bool composite_alpha_;
  54
  55   // Disallow copy and assign.
  56   CanvasSkiaPaint(const CanvasSkiaPaint&);
  57   CanvasSkiaPaint& operator=(const CanvasSkiaPaint&);
  58 };
  59
  60 }  // namespace gfx
  61
  62 #endif  // UI_GFX_CANVAS_PAINT_LINUX_H_