ui/gfx/image/cairo_cached_surface.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef UI_GFX_IMAGE_CAIRO_CACHED_SURFACE_H_
   6 #define UI_GFX_IMAGE_CAIRO_CACHED_SURFACE_H_
   7
   8 #include <vector>
   9
  10 #include "ui/base/ui_export.h"
  11
  12 typedef struct _GdkDisplay GdkDisplay;
  13 typedef struct _GdkPixbuf GdkPixbuf;
  14 typedef struct _GtkWidget GtkWidget;
  15 typedef struct _cairo cairo_t;
  16 typedef struct _cairo_surface cairo_surface_t;
  17
  18 namespace gfx {
  19
  20 // A helper class that takes a GdkPixbuf* and renders it to the screen. Unlike
  21 // gdk_cairo_set_source_pixbuf(), CairoCachedSurface assumes that the pixbuf is
  22 // immutable after UsePixbuf() is called and can be sent to the display server
  23 // once. From then on, that cached version is used so we don't upload the same
  24 // image each and every time we expose.
  25 //
  26 // Most cached surfaces are owned by the GtkThemeService, which associates
  27 // them with a certain XDisplay. Some users of surfaces (CustomDrawButtonBase,
  28 // for example) own their surfaces instead since they interact with the
  29 // ResourceBundle instead of the GtkThemeService.
  30 class UI_EXPORT CairoCachedSurface {
  31  public:
  32   CairoCachedSurface();
  33   ~CairoCachedSurface();
  34
  35   // Whether this CairoCachedSurface owns a GdkPixbuf.
  36   bool valid() const {
  37     return pixbuf_;
  38   }
  39
  40   // Delete all our data.
  41   void Reset();
  42
  43   // The dimensions of the underlying pixbuf/surface. (or -1 if invalid.)
  44   int Width() const;
  45   int Height() const;
  46
  47   // Sets the pixbuf that we pass to cairo. Calling UsePixbuf() only derefs the
  48   // current pixbuf and surface (if they exist). Actually transfering data to
  49   // the X server occurs at SetSource() time. Calling UsePixbuf() should only
  50   // be done once as it clears cached data from the X server.
  51   void UsePixbuf(GdkPixbuf* pixbuf);
  52
  53   // Sets our pixbuf as the active surface starting at (x, y), uploading it in
  54   // case we don't have an X backed surface cached.
  55   void SetSource(cairo_t* cr, GtkWidget* widget, int x, int y) const;
  56   void SetSource(cairo_t* cr, GdkDisplay* display, int x, int y) const;
  57
  58   // Performs a mask operation, using this surface as the alpha channel.
  59   void MaskSource(cairo_t* cr, GtkWidget* widget, int x, int y) const;
  60   void MaskSource(cairo_t* cr, GdkDisplay* display, int x, int y) const;
  61
  62   // Raw access to the pixbuf. May be NULL. Used for a few gdk operations
  63   // regarding window shaping.
  64   GdkPixbuf* pixbuf() { return pixbuf_; }
  65
  66  private:
  67   typedef std::vector<std::pair<GdkDisplay*, cairo_surface_t*> > SurfaceVector;
  68
  69   // Returns a surface . Caches results so only one copy of the image data
  70   // lives on the display server.
  71   cairo_surface_t* GetSurfaceFor(cairo_t* cr, GdkDisplay* display) const;
  72
  73   // The source pixbuf.
  74   GdkPixbuf* pixbuf_;
  75
  76   // Our list of cached surfaces. 99% of the time, this will only contain a
  77   // single entry. At most two. We need to get this right for multiple displays
  78   // to work correct, since each GdkDisplay is a different display server.
  79   mutable SurfaceVector surface_map_;
  80 };
  81
  82 }  // namespace gfx
  83
  84 #endif  // UI_GFX_IMAGE_CAIRO_CACHED_SURFACE_H_