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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 SKIA_EXT_LAZY_PIXEL_REF_H_
      6 #define SKIA_EXT_LAZY_PIXEL_REF_H_
      7 
      8 #include "third_party/skia/include/core/SkPixelRef.h"
      9 #include "third_party/skia/include/core/SkRect.h"
     10 
     11 namespace skia {
     12 
     13 // This class extends SkPixelRef to facilitate lazy image decoding on the impl
     14 // thread.
     15 class SK_API LazyPixelRef : public SkPixelRef {
     16  public:
     17   explicit LazyPixelRef(const SkImageInfo& info);
     18   virtual ~LazyPixelRef();
     19 
     20   struct PrepareParams {
     21     // Clipping rect for this pixel ref.
     22     SkIRect clip_rect;
     23   };
     24 
     25   // Request the ImageDecodingStore to prepare image decoding for the
     26   // given clipping rect. Returns true is succeeded, or false otherwise.
     27   virtual bool PrepareToDecode(const PrepareParams& params) = 0;
     28 
     29   // Returns true if this pixel ref is already in the ImageDecodingStore's
     30   // cache, false otherwise. Much cheaper than PrepareToDecode().
     31   virtual bool MaybeDecoded() = 0;
     32 
     33   // Start decoding the image.
     34   virtual void Decode() = 0;
     35 };
     36 
     37 }  // namespace skia
     38 
     39 #endif  // SKIA_EXT_LAZY_PIXEL_REF_H_
     40