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/*
* Copyright 2011 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "SkBitmapCache.h"
#include "SkMutex.h"
#include "SkPixelRef.h"
#include "SkTraceEvent.h"
//#define SK_TRACE_PIXELREF_LIFETIME
#include "SkNextID.h"
uint32_t SkNextID::ImageID() {
static uint32_t gID = 0;
uint32_t id;
// Loop in case our global wraps around, as we never want to return a 0.
do {
id = sk_atomic_fetch_add(&gID, 2u) + 2; // Never set the low bit.
} while (0 == id);
return id;
}
///////////////////////////////////////////////////////////////////////////////
#ifdef SK_TRACE_PIXELREF_LIFETIME
static int32_t gInstCounter;
#endif
SkPixelRef::SkPixelRef(int width, int height, void* pixels, size_t rowBytes)
: fWidth(width)
, fHeight(height)
, fPixels(pixels)
, fRowBytes(rowBytes)
#ifdef SK_BUILD_FOR_ANDROID_FRAMEWORK
, fStableID(SkNextID::ImageID())
#endif
{
#ifdef SK_TRACE_PIXELREF_LIFETIME
SkDebugf(" pixelref %d\n", sk_atomic_inc(&gInstCounter));
#endif
this->needsNewGenID();
fMutability = kMutable;
fAddedToCache.store(false);
}
SkPixelRef::~SkPixelRef() {
#ifdef SK_TRACE_PIXELREF_LIFETIME
SkDebugf("~pixelref %d\n", sk_atomic_dec(&gInstCounter) - 1);
#endif
this->callGenIDChangeListeners();
}
// This is undefined if there are clients in-flight trying to use us
void SkPixelRef::android_only_reset(int width, int height, size_t rowBytes) {
fWidth = width;
fHeight = height;
fRowBytes = rowBytes;
// note: we do not change fPixels
// conservative, since its possible the "new" settings are the same as the old.
this->notifyPixelsChanged();
}
void SkPixelRef::needsNewGenID() {
fTaggedGenID.store(0);
SkASSERT(!this->genIDIsUnique()); // This method isn't threadsafe, so the assert should be fine.
}
uint32_t SkPixelRef::getGenerationID() const {
uint32_t id = fTaggedGenID.load();
if (0 == id) {
uint32_t next = SkNextID::ImageID() | 1u;
if (fTaggedGenID.compare_exchange(&id, next)) {
id = next; // There was no race or we won the race. fTaggedGenID is next now.
} else {
// We lost a race to set fTaggedGenID. compare_exchange() filled id with the winner.
}
// We can't quite SkASSERT(this->genIDIsUnique()). It could be non-unique
// if we got here via the else path (pretty unlikely, but possible).
}
return id & ~1u; // Mask off bottom unique bit.
}
void SkPixelRef::addGenIDChangeListener(GenIDChangeListener* listener) {
if (nullptr == listener || !this->genIDIsUnique()) {
// No point in tracking this if we're not going to call it.
delete listener;
return;
}
*fGenIDChangeListeners.append() = listener;
}
// we need to be called *before* the genID gets changed or zerod
void SkPixelRef::callGenIDChangeListeners() {
// We don't invalidate ourselves if we think another SkPixelRef is sharing our genID.
if (this->genIDIsUnique()) {
for (int i = 0; i < fGenIDChangeListeners.count(); i++) {
fGenIDChangeListeners[i]->onChange();
}
// TODO: SkAtomic could add "old_value = atomic.xchg(new_value)" to make this clearer.
if (fAddedToCache.load()) {
SkNotifyBitmapGenIDIsStale(this->getGenerationID());
fAddedToCache.store(false);
}
}
// Listeners get at most one shot, so whether these triggered or not, blow them away.
fGenIDChangeListeners.deleteAll();
}
void SkPixelRef::notifyPixelsChanged() {
#ifdef SK_DEBUG
if (this->isImmutable()) {
SkDebugf("========== notifyPixelsChanged called on immutable pixelref");
}
#endif
this->callGenIDChangeListeners();
this->needsNewGenID();
}
void SkPixelRef::setImmutable() {
fMutability = kImmutable;
}
void SkPixelRef::setImmutableWithID(uint32_t genID) {
/*
* We are forcing the genID to match an external value. The caller must ensure that this
* value does not conflict with other content.
*
* One use is to force this pixelref's id to match an SkImage's id
*/
fMutability = kImmutable;
fTaggedGenID.store(genID);
}
void SkPixelRef::setTemporarilyImmutable() {
SkASSERT(fMutability != kImmutable);
fMutability = kTemporarilyImmutable;
}
void SkPixelRef::restoreMutability() {
SkASSERT(fMutability != kImmutable);
fMutability = kMutable;
}
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