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* Copyright 2008 The Android Open Source Project
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
#ifndef SkPixelRef_DEFINED
#define SkPixelRef_DEFINED
#include "include/core/SkRefCnt.h"
#include "include/core/SkSize.h"
#include "include/private/SkIDChangeListener.h"
#include "include/private/base/SkAPI.h"
#include "include/private/base/SkTo.h"
#include <atomic>
#include <cstddef>
#include <cstdint>
class SkDiscardableMemory;
/** \class SkPixelRef
This class is the smart container for pixel memory, and is used with SkBitmap.
This class can be shared/accessed between multiple threads.
class SK_API SkPixelRef : public SkRefCnt {
SkPixelRef(int width, int height, void* addr, size_t rowBytes);
~SkPixelRef() override;
SkISize dimensions() const { return {fWidth, fHeight}; }
int width() const { return fWidth; }
int height() const { return fHeight; }
void* pixels() const { return fPixels; }
size_t rowBytes() const { return fRowBytes; }
/** Returns a non-zero, unique value corresponding to the pixels in this
pixelref. Each time the pixels are changed (and notifyPixelsChanged is
called), a different generation ID will be returned.
uint32_t getGenerationID() const;
* Call this if you have changed the contents of the pixels. This will in-
* turn cause a different generation ID value to be returned from
* getGenerationID().
void notifyPixelsChanged();
/** Returns true if this pixelref is marked as immutable, meaning that the
contents of its pixels will not change for the lifetime of the pixelref.
bool isImmutable() const { return fMutability != kMutable; }
/** Marks this pixelref is immutable, meaning that the contents of its
pixels will not change for the lifetime of the pixelref. This state can
be set on a pixelref, but it cannot be cleared once it is set.
void setImmutable();
// Register a listener that may be called the next time our generation ID changes.
// We'll only call the listener if we're confident that we are the only SkPixelRef with this
// generation ID. If our generation ID changes and we decide not to call the listener, we'll
// never call it: you must add a new listener for each generation ID change. We also won't call
// the listener when we're certain no one knows what our generation ID is.
// This can be used to invalidate caches keyed by SkPixelRef generation ID.
// Takes ownership of listener. Threadsafe.
void addGenIDChangeListener(sk_sp<SkIDChangeListener> listener);
// Call when this pixelref is part of the key to a resourcecache entry. This allows the cache
// to know automatically those entries can be purged when this pixelref is changed or deleted.
void notifyAddedToCache() {;
virtual SkDiscardableMemory* diagnostic_only_getDiscardable() const { return nullptr; }
void android_only_reset(int width, int height, size_t rowBytes);
int fWidth;
int fHeight;
void* fPixels;
size_t fRowBytes;
// Bottom bit indicates the Gen ID is unique.
bool genIDIsUnique() const { return SkToBool(fTaggedGenID.load() & 1); }
mutable std::atomic<uint32_t> fTaggedGenID;
SkIDChangeListener::List fGenIDChangeListeners;
// Set true by caches when they cache content that's derived from the current pixels.
std::atomic<bool> fAddedToCache;
enum Mutability {
kMutable, // PixelRefs begin mutable.
kTemporarilyImmutable, // Considered immutable, but can revert to mutable.
kImmutable, // Once set to this state, it never leaves.
} fMutability : 8; // easily fits inside a byte
void needsNewGenID();
void callGenIDChangeListeners();
void setTemporarilyImmutable();
void restoreMutability();
friend class SkSurface_Raster; // For temporary immutable methods above.
void setImmutableWithID(uint32_t genID);
friend void SkBitmapCache_setImmutableWithID(SkPixelRef*, uint32_t);
using INHERITED = SkRefCnt;