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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_MANAGER_H_
      6 #define CONTENT_BROWSER_RENDERER_HOST_BACKING_STORE_MANAGER_H_
      7 
      8 #include <vector>
      9 
     10 #include "base/basictypes.h"
     11 #include "base/callback_forward.h"
     12 #include "base/process/process.h"
     13 #include "ui/gfx/rect.h"
     14 #include "ui/gfx/size.h"
     15 #include "ui/surface/transport_dib.h"
     16 
     17 namespace content {
     18 class BackingStore;
     19 class RenderWidgetHost;
     20 
     21 // This class manages backing stores in the browsr. Every RenderWidgetHost is
     22 // associated with a backing store which it requests from this class.  The
     23 // hosts don't maintain any references to the backing stores.  These backing
     24 // stores are maintained in a cache which can be trimmed as needed.
     25 class BackingStoreManager {
     26  public:
     27   // Returns a backing store which matches the desired dimensions.
     28   //
     29   // backing_store_rect
     30   //   The desired backing store dimensions.
     31   // Returns a pointer to the backing store on success, NULL on failure.
     32   static BackingStore* GetBackingStore(RenderWidgetHost* host,
     33                                        const gfx::Size& desired_size);
     34 
     35   // Makes a backing store which is fully ready for consumption, i.e. the
     36   // bitmap from the renderer has been copied into the backing store.
     37   //
     38   // backing_store_size
     39   //   The desired backing store dimensions, in DIPs.
     40   // bitmap_section
     41   //   The bitmap section from the renderer.
     42   // bitmap_rect
     43   //   The rect to be painted into the backing store, in DIPs.
     44   // scale_factor
     45   //   The device scale factor the backing store is expected to be at.
     46   //   If the backing store's device scale factor doesn't match, it will need
     47   //   to scale |bitmap| at paint time. This will only be out of sync with the
     48   //   backing store scale factor for a few frames, right after device scale
     49   //   changes.
     50   // needs_full_paint
     51   //   Set if we need to send out a request to paint the view
     52   //   to the renderer.
     53   static void PrepareBackingStore(
     54       RenderWidgetHost* host,
     55       const gfx::Size& backing_store_size,
     56       TransportDIB::Id bitmap,
     57       const gfx::Rect& bitmap_rect,
     58       const std::vector<gfx::Rect>& copy_rects,
     59       float scale_factor,
     60       const base::Closure& completion_callback,
     61       bool* needs_full_paint,
     62       bool* scheduled_completion_callback);
     63 
     64   // Returns a matching backing store for the host.
     65   // Returns NULL if we fail to find one.
     66   static BackingStore* Lookup(RenderWidgetHost* host);
     67 
     68   // Removes the backing store for the host.
     69   static void RemoveBackingStore(RenderWidgetHost* host);
     70 
     71   // Removes all backing stores.
     72   static void RemoveAllBackingStores();
     73 
     74   // Current size in bytes of the backing store cache.
     75   static size_t MemorySize();
     76 
     77  private:
     78   // Not intended for instantiation.
     79   BackingStoreManager() {}
     80 
     81   DISALLOW_COPY_AND_ASSIGN(BackingStoreManager);
     82 };
     83 
     84 }  // namespace content
     85 
     86 #endif  // CONTENT_BROWSER_RENDERER_HOST_BACKING_STORE_MANAGER_H_
     87