1/*
2 * Copyright 2008 The Android Open Source Project
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 SkPixelRef_DEFINED
9#define SkPixelRef_DEFINED
10
11#include "include/core/SkBitmap.h"
12#include "include/core/SkFilterQuality.h"
13#include "include/core/SkImageInfo.h"
14#include "include/core/SkPixmap.h"
15#include "include/core/SkRefCnt.h"
16#include "include/core/SkSize.h"
17#include "include/private/SkIDChangeListener.h"
18#include "include/private/SkMutex.h"
19#include "include/private/SkTDArray.h"
20
21#include <atomic>
22
23struct SkIRect;
24
25class GrTexture;
26class SkDiscardableMemory;
27
28/** \class SkPixelRef
29
30 This class is the smart container for pixel memory, and is used with SkBitmap.
31 This class can be shared/accessed between multiple threads.
32*/
33class SK_API SkPixelRef : public SkRefCnt {
34public:
35 SkPixelRef(int width, int height, void* addr, size_t rowBytes);
36 ~SkPixelRef() override;
37
38 SkISize dimensions() const { return {fWidth, fHeight}; }
39 int width() const { return fWidth; }
40 int height() const { return fHeight; }
41 void* pixels() const { return fPixels; }
42 size_t rowBytes() const { return fRowBytes; }
43
44 /** Returns a non-zero, unique value corresponding to the pixels in this
45 pixelref. Each time the pixels are changed (and notifyPixelsChanged is
46 called), a different generation ID will be returned.
47 */
48 uint32_t getGenerationID() const;
49
50 /**
51 * Call this if you have changed the contents of the pixels. This will in-
52 * turn cause a different generation ID value to be returned from
53 * getGenerationID().
54 */
55 void notifyPixelsChanged();
56
57 /** Returns true if this pixelref is marked as immutable, meaning that the
58 contents of its pixels will not change for the lifetime of the pixelref.
59 */
60 bool isImmutable() const { return fMutability != kMutable; }
61
62 /** Marks this pixelref is immutable, meaning that the contents of its
63 pixels will not change for the lifetime of the pixelref. This state can
64 be set on a pixelref, but it cannot be cleared once it is set.
65 */
66 void setImmutable();
67
68 // Register a listener that may be called the next time our generation ID changes.
69 //
70 // We'll only call the listener if we're confident that we are the only SkPixelRef with this
71 // generation ID. If our generation ID changes and we decide not to call the listener, we'll
72 // never call it: you must add a new listener for each generation ID change. We also won't call
73 // the listener when we're certain no one knows what our generation ID is.
74 //
75 // This can be used to invalidate caches keyed by SkPixelRef generation ID.
76 // Takes ownership of listener. Threadsafe.
77 void addGenIDChangeListener(sk_sp<SkIDChangeListener> listener);
78
79 // Call when this pixelref is part of the key to a resourcecache entry. This allows the cache
80 // to know automatically those entries can be purged when this pixelref is changed or deleted.
81 void notifyAddedToCache() {
82 fAddedToCache.store(true);
83 }
84
85 virtual SkDiscardableMemory* diagnostic_only_getDiscardable() const { return nullptr; }
86
87protected:
88 void android_only_reset(int width, int height, size_t rowBytes);
89
90private:
91 int fWidth;
92 int fHeight;
93 void* fPixels;
94 size_t fRowBytes;
95
96 // Bottom bit indicates the Gen ID is unique.
97 bool genIDIsUnique() const { return SkToBool(fTaggedGenID.load() & 1); }
98 mutable std::atomic<uint32_t> fTaggedGenID;
99
100 SkIDChangeListener::List fGenIDChangeListeners;
101
102 // Set true by caches when they cache content that's derived from the current pixels.
103 std::atomic<bool> fAddedToCache;
104
105 enum Mutability {
106 kMutable, // PixelRefs begin mutable.
107 kTemporarilyImmutable, // Considered immutable, but can revert to mutable.
108 kImmutable, // Once set to this state, it never leaves.
109 } fMutability : 8; // easily fits inside a byte
110
111 void needsNewGenID();
112 void callGenIDChangeListeners();
113
114 void setTemporarilyImmutable();
115 void restoreMutability();
116 friend class SkSurface_Raster; // For the two methods above.
117
118 void setImmutableWithID(uint32_t genID);
119 friend void SkBitmapCache_setImmutableWithID(SkPixelRef*, uint32_t);
120
121 typedef SkRefCnt INHERITED;
122};
123
124#endif
125