skia/ext/lazy_pixel_ref.h

   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_