1 /*
2 * Copyright 2011 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 #include "SkBitmapCache.h"
9 #include "SkMutex.h"
10 #include "SkPixelRef.h"
11 #include "SkTraceEvent.h"
12
13 //#define SK_TRACE_PIXELREF_LIFETIME
14
15 #include "SkNextID.h"
16
ImageID()17 uint32_t SkNextID::ImageID() {
18 static uint32_t gID = 0;
19 uint32_t id;
20 // Loop in case our global wraps around, as we never want to return a 0.
21 do {
22 id = sk_atomic_fetch_add(&gID, 2u) + 2; // Never set the low bit.
23 } while (0 == id);
24 return id;
25 }
26
27 ///////////////////////////////////////////////////////////////////////////////
28
29 #ifdef SK_TRACE_PIXELREF_LIFETIME
30 static int32_t gInstCounter;
31 #endif
32
SkPixelRef(int width,int height,void * pixels,size_t rowBytes)33 SkPixelRef::SkPixelRef(int width, int height, void* pixels, size_t rowBytes)
34 : fWidth(width)
35 , fHeight(height)
36 , fPixels(pixels)
37 , fRowBytes(rowBytes)
38 #ifdef SK_BUILD_FOR_ANDROID_FRAMEWORK
39 , fStableID(SkNextID::ImageID())
40 #endif
41 {
42 #ifdef SK_TRACE_PIXELREF_LIFETIME
43 SkDebugf(" pixelref %d\n", sk_atomic_inc(&gInstCounter));
44 #endif
45
46 this->needsNewGenID();
47 fMutability = kMutable;
48 fAddedToCache.store(false);
49 }
50
~SkPixelRef()51 SkPixelRef::~SkPixelRef() {
52 #ifdef SK_TRACE_PIXELREF_LIFETIME
53 SkDebugf("~pixelref %d\n", sk_atomic_dec(&gInstCounter) - 1);
54 #endif
55 this->callGenIDChangeListeners();
56 }
57
58 // This is undefined if there are clients in-flight trying to use us
android_only_reset(int width,int height,size_t rowBytes)59 void SkPixelRef::android_only_reset(int width, int height, size_t rowBytes) {
60 fWidth = width;
61 fHeight = height;
62 fRowBytes = rowBytes;
63 // note: we do not change fPixels
64
65 // conservative, since its possible the "new" settings are the same as the old.
66 this->notifyPixelsChanged();
67 }
68
needsNewGenID()69 void SkPixelRef::needsNewGenID() {
70 fTaggedGenID.store(0);
71 SkASSERT(!this->genIDIsUnique()); // This method isn't threadsafe, so the assert should be fine.
72 }
73
getGenerationID() const74 uint32_t SkPixelRef::getGenerationID() const {
75 uint32_t id = fTaggedGenID.load();
76 if (0 == id) {
77 uint32_t next = SkNextID::ImageID() | 1u;
78 if (fTaggedGenID.compare_exchange(&id, next)) {
79 id = next; // There was no race or we won the race. fTaggedGenID is next now.
80 } else {
81 // We lost a race to set fTaggedGenID. compare_exchange() filled id with the winner.
82 }
83 // We can't quite SkASSERT(this->genIDIsUnique()). It could be non-unique
84 // if we got here via the else path (pretty unlikely, but possible).
85 }
86 return id & ~1u; // Mask off bottom unique bit.
87 }
88
addGenIDChangeListener(GenIDChangeListener * listener)89 void SkPixelRef::addGenIDChangeListener(GenIDChangeListener* listener) {
90 if (nullptr == listener || !this->genIDIsUnique()) {
91 // No point in tracking this if we're not going to call it.
92 delete listener;
93 return;
94 }
95 *fGenIDChangeListeners.append() = listener;
96 }
97
98 // we need to be called *before* the genID gets changed or zerod
callGenIDChangeListeners()99 void SkPixelRef::callGenIDChangeListeners() {
100 // We don't invalidate ourselves if we think another SkPixelRef is sharing our genID.
101 if (this->genIDIsUnique()) {
102 for (int i = 0; i < fGenIDChangeListeners.count(); i++) {
103 fGenIDChangeListeners[i]->onChange();
104 }
105
106 // TODO: SkAtomic could add "old_value = atomic.xchg(new_value)" to make this clearer.
107 if (fAddedToCache.load()) {
108 SkNotifyBitmapGenIDIsStale(this->getGenerationID());
109 fAddedToCache.store(false);
110 }
111 }
112 // Listeners get at most one shot, so whether these triggered or not, blow them away.
113 fGenIDChangeListeners.deleteAll();
114 }
115
notifyPixelsChanged()116 void SkPixelRef::notifyPixelsChanged() {
117 #ifdef SK_DEBUG
118 if (this->isImmutable()) {
119 SkDebugf("========== notifyPixelsChanged called on immutable pixelref");
120 }
121 #endif
122 this->callGenIDChangeListeners();
123 this->needsNewGenID();
124 this->onNotifyPixelsChanged();
125 }
126
setImmutable()127 void SkPixelRef::setImmutable() {
128 fMutability = kImmutable;
129 }
130
setImmutableWithID(uint32_t genID)131 void SkPixelRef::setImmutableWithID(uint32_t genID) {
132 /*
133 * We are forcing the genID to match an external value. The caller must ensure that this
134 * value does not conflict with other content.
135 *
136 * One use is to force this pixelref's id to match an SkImage's id
137 */
138 fMutability = kImmutable;
139 fTaggedGenID.store(genID);
140 }
141
setTemporarilyImmutable()142 void SkPixelRef::setTemporarilyImmutable() {
143 SkASSERT(fMutability != kImmutable);
144 fMutability = kTemporarilyImmutable;
145 }
146
restoreMutability()147 void SkPixelRef::restoreMutability() {
148 SkASSERT(fMutability != kImmutable);
149 fMutability = kMutable;
150 }
151
onNotifyPixelsChanged()152 void SkPixelRef::onNotifyPixelsChanged() { }
153