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      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 CONTENT_BROWSER_RENDERER_HOST_BACKING_STORE_H_
      6 #define CONTENT_BROWSER_RENDERER_HOST_BACKING_STORE_H_
      7 
      8 #include <vector>
      9 
     10 #include "base/basictypes.h"
     11 #include "base/callback_forward.h"
     12 #include "content/common/content_export.h"
     13 #include "ui/gfx/size.h"
     14 #include "ui/gfx/vector2d.h"
     15 #include "ui/surface/transport_dib.h"
     16 
     17 class RenderProcessHost;
     18 
     19 namespace gfx {
     20 class Rect;
     21 }
     22 
     23 namespace skia {
     24 class PlatformBitmap;
     25 }
     26 
     27 namespace content {
     28 class RenderProcessHost;
     29 class RenderWidgetHost;
     30 
     31 // Represents a backing store for the pixels in a RenderWidgetHost.
     32 class CONTENT_EXPORT BackingStore {
     33  public:
     34   virtual ~BackingStore();
     35 
     36   RenderWidgetHost* render_widget_host() const {
     37     return render_widget_host_;
     38   }
     39   const gfx::Size& size() { return size_; }
     40 
     41   // The number of bytes that this backing store consumes. The default
     42   // implementation just assumes there's 32 bits per pixel over the current
     43   // size of the screen. Implementations may override this if they have more
     44   // information about the color depth.
     45   virtual size_t MemorySize();
     46 
     47   // Paints the bitmap from the renderer onto the backing store. bitmap_rect
     48   // gives the location of bitmap, and copy_rects specifies the subregion(s) of
     49   // the backingstore to be painted from the bitmap. All coordinates are in
     50   // DIPs. |scale_factor| contains the expected device scale factor of the
     51   // backing store.
     52   //
     53   // PaintToBackingStore does not need to guarantee that this has happened by
     54   // the time it returns, in which case it will set |scheduled_callback| to
     55   // true and will call |callback| when completed.
     56   virtual void PaintToBackingStore(
     57       RenderProcessHost* process,
     58       TransportDIB::Id bitmap,
     59       const gfx::Rect& bitmap_rect,
     60       const std::vector<gfx::Rect>& copy_rects,
     61       float scale_factor,
     62       const base::Closure& completion_callback,
     63       bool* scheduled_completion_callback) = 0;
     64 
     65   // Extracts the gives subset of the backing store and copies it to the given
     66   // PlatformCanvas. The PlatformCanvas should not be initialized. This function
     67   // will call initialize() with the correct size. The return value indicates
     68   // success.
     69   virtual bool CopyFromBackingStore(const gfx::Rect& rect,
     70                                     skia::PlatformBitmap* output) = 0;
     71 
     72   // Scrolls the contents of clip_rect in the backing store by |delta| (but
     73   // |delta|.x() and |delta|.y() cannot both be non-zero).
     74   virtual void ScrollBackingStore(const gfx::Vector2d& delta,
     75                                   const gfx::Rect& clip_rect,
     76                                   const gfx::Size& view_size) = 0;
     77  protected:
     78   // Can only be constructed via subclasses.
     79   BackingStore(RenderWidgetHost* widget, const gfx::Size& size);
     80 
     81  private:
     82   // The owner of this backing store.
     83   RenderWidgetHost* render_widget_host_;
     84 
     85   // The size of the backing store.
     86   gfx::Size size_;
     87 
     88   DISALLOW_COPY_AND_ASSIGN(BackingStore);
     89 };
     90 
     91 }  // namespace content
     92 
     93 #endif  // CONTENT_BROWSER_RENDERER_HOST_BACKING_STORE_H_
     94