1 /*
2  * Copyright 2013 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 SkCachingPixelRef_DEFINED
9 #define SkCachingPixelRef_DEFINED
10 
11 #include "SkBitmapCache.h"
12 #include "SkImageInfo.h"
13 #include "SkImageGenerator.h"
14 #include "SkPixelRef.h"
15 
16 class SkColorTable;
17 
18 /**
19  *  PixelRef which defers decoding until SkBitmap::lockPixels() is
20  *  called.  Caches the decoded images in the global
21  *  SkScaledImageCache.  When the pixels are unlocked, this cache may
22  *  or be destroyed before the next lock.  If so, onLockPixels will
23  *  attempt to re-decode.
24  *
25  *  Decoding is handled by the SkImageGenerator
26  */
27 class SkCachingPixelRef : public SkPixelRef {
28 public:
29     SK_DECLARE_INST_COUNT(SkCachingPixelRef)
30     /**
31      *  Takes ownership of SkImageGenerator.  If this method fails for
32      *  whatever reason, it will return false and immediatetely delete
33      *  the generator.  If it succeeds, it will modify destination
34      *  bitmap.
35      *
36      *  If Install fails or when the SkCachingPixelRef that is
37      *  installed into destination is destroyed, it will call
38      *  SkDELETE() on the generator.  Therefore, generator should be
39      *  allocated with SkNEW() or SkNEW_ARGS().
40      */
41     static bool Install(SkImageGenerator* gen, SkBitmap* dst);
42 
43 protected:
44     virtual ~SkCachingPixelRef();
45     bool onNewLockPixels(LockRec*) override;
46     void onUnlockPixels() override;
onLockPixelsAreWritable()47     bool onLockPixelsAreWritable() const override { return false; }
48 
onRefEncodedData()49     SkData* onRefEncodedData() override {
50         return fImageGenerator->refEncodedData();
51     }
52 
53 private:
54     SkImageGenerator* const fImageGenerator;
55     bool                    fErrorInDecoding;
56     const size_t            fRowBytes;
57 
58     SkBitmap                fLockedBitmap;
59 
60     SkCachingPixelRef(const SkImageInfo&, SkImageGenerator*, size_t rowBytes);
61 
62     typedef SkPixelRef INHERITED;
63 };
64 
65 #endif  // SkCachingPixelRef_DEFINED
66