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      1 /*
      2  * Copyright 2012 Google Inc.
      3  *
      4  * Use of this source code is governed by a BSD-style license that can be
      5  * found in the LICENSE file.
      6  */
      7 
      8 #ifndef SkLazyPixelRef_DEFINED
      9 #define SkLazyPixelRef_DEFINED
     10 
     11 #include "SkBitmapFactory.h"
     12 #include "SkImage.h"
     13 #include "SkPixelRef.h"
     14 #include "SkFlattenable.h"
     15 
     16 class SkColorTable;
     17 class SkData;
     18 class SkImageCache;
     19 
     20 #ifdef SK_DEBUG
     21     #define LAZY_CACHE_STATS 1
     22 #elif !defined(LAZY_CACHE_STATS)
     23     #define LAZY_CACHE_STATS 0
     24 #endif
     25 
     26 /**
     27  *  PixelRef which defers decoding until SkBitmap::lockPixels() is called.
     28  */
     29 class SkLazyPixelRef : public SkPixelRef {
     30 
     31 public:
     32     /**
     33      *  Create a new SkLazyPixelRef.
     34      *  @param SkData Encoded data representing the pixels.
     35      *  @param DecodeProc Called to decode the pixels when needed. Must be non-NULL.
     36      *  @param SkImageCache Object that handles allocating and freeing the pixel memory, as needed.
     37      *         Must not be NULL.
     38      */
     39     SkLazyPixelRef(SkData*, SkBitmapFactory::DecodeProc, SkImageCache*);
     40 
     41     virtual ~SkLazyPixelRef();
     42 
     43 #ifdef SK_DEBUG
     44     intptr_t getCacheId() const { return fCacheId; }
     45 #endif
     46 
     47 #if LAZY_CACHE_STATS
     48     static int32_t GetCacheHits() { return gCacheHits; }
     49     static int32_t GetCacheMisses() { return gCacheMisses; }
     50     static void ResetCacheStats() { gCacheHits = gCacheMisses = 0; }
     51 #endif
     52 
     53     // No need to flatten this object. When flattening an SkBitmap, SkOrderedWriteBuffer will check
     54     // the encoded data and write that instead.
     55     // Future implementations of SkFlattenableWriteBuffer will need to special case for
     56     // onRefEncodedData as well.
     57     SK_DECLARE_UNFLATTENABLE_OBJECT()
     58 
     59 protected:
     60     virtual void* onLockPixels(SkColorTable**) SK_OVERRIDE;
     61     virtual void onUnlockPixels() SK_OVERRIDE;
     62     virtual bool onLockPixelsAreWritable() const SK_OVERRIDE { return false; }
     63     virtual SkData* onRefEncodedData() SK_OVERRIDE;
     64 
     65 private:
     66     bool                        fErrorInDecoding;
     67     SkData*                     fData;
     68     SkBitmapFactory::DecodeProc fDecodeProc;
     69     SkImageCache*               fImageCache;
     70     intptr_t                    fCacheId;
     71     size_t                      fRowBytes;
     72 
     73 #if LAZY_CACHE_STATS
     74     static int32_t              gCacheHits;
     75     static int32_t              gCacheMisses;
     76 #endif
     77 
     78     typedef SkPixelRef INHERITED;
     79 };
     80 
     81 #endif  // SkLazyPixelRef_DEFINED
     82