gfx/layers/ReadbackProcessor.h

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  21  * Contributor(s):
  22  *   Robert O'Callahan <robert@ocallahan.org>
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  37
  38 #ifndef GFX_READBACKPROCESSOR_H
  39 #define GFX_READBACKPROCESSOR_H
  40
  41 #include "ReadbackLayer.h"
  42 #include "ThebesLayerBuffer.h"
  43
  44 namespace mozilla {
  45 namespace layers {
  46
  47 class ReadbackProcessor {
  48 public:
  49   /**
  50    * Called by the container before processing any child layers. Call this
  51    * if any child layer might have changed in any way (other than content-only
  52    * changes to layers other than ColorLayers and ThebesLayers).
  53    *
  54    * This method recomputes the relationship between ReadbackLayers and
  55    * sibling layers, and dispatches changes to ReadbackLayers. Except that
  56    * if a ThebesLayer needs its contents sent to some ReadbackLayer, we'll
  57    * just record that internally and later the ThebesLayer should call
  58    * GetThebesLayerUpdates when it paints, to find out which rectangle needs
  59    * to be sent, and the ReadbackLayer it needs to be sent to.
  60    */
  61   void BuildUpdates(ContainerLayer* aContainer);
  62
  63   struct Update {
  64     /**
  65      * The layer a ThebesLayer should send its contents to.
  66      */
  67     ReadbackLayer* mLayer;
  68     /**
  69      * The rectangle of content that it should send, in the ThebesLayer's
  70      * coordinate system. This rectangle is guaranteed to be in the ThebesLayer's
  71      * visible region. Translate it to mLayer's coordinate system
  72      * by adding mLayer->GetBackgroundLayerOffset().
  73      */
  74     nsIntRect      mUpdateRect;
  75     /**
  76      * The sequence counter value to use when calling DoUpdate
  77      */
  78     PRUint64       mSequenceCounter;
  79   };
  80   /**
  81    * Appends any ReadbackLayers that need to be updated, and the rects that
  82    * need to be updated, to aUpdates. Only need to call this for ThebesLayers
  83    * that have been marked UsedForReadback().
  84    * Each Update's mLayer's mBackgroundLayer will have been set to aLayer.
  85    * If a ThebesLayer doesn't call GetThebesLayerUpdates, then all the
  86    * ReadbackLayers that needed data from that ThebesLayer will be marked
  87    * as having unknown backgrounds.
  88    * @param aUpdateRegion if non-null, this region is set to the union
  89    * of the mUpdateRects.
  90    */
  91   void GetThebesLayerUpdates(ThebesLayer* aLayer,
  92                              nsTArray<Update>* aUpdates,
  93                              nsIntRegion* aUpdateRegion = nsnull);
  94
  95   ~ReadbackProcessor();
  96
  97 protected:
  98   void BuildUpdatesForLayer(ReadbackLayer* aLayer);
  99
 100   nsTArray<Update> mAllUpdates;
 101 };
 102
 103 }
 104 }
 105 #endif /* GFX_READBACKPROCESSOR_H */