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