1 /*
2 * Copyright 2013 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 "SkCachingPixelRef.h"
9 #include "SkScaledImageCache.h"
10
11
Install(SkImageGenerator * generator,SkBitmap * dst)12 bool SkCachingPixelRef::Install(SkImageGenerator* generator,
13 SkBitmap* dst) {
14 SkImageInfo info;
15 SkASSERT(generator != NULL);
16 SkASSERT(dst != NULL);
17 if ((NULL == generator)
18 || !(generator->getInfo(&info))
19 || !dst->setConfig(info, 0)) {
20 SkDELETE(generator);
21 return false;
22 }
23 SkAutoTUnref<SkCachingPixelRef> ref(SkNEW_ARGS(SkCachingPixelRef,
24 (info, generator, dst->rowBytes())));
25 dst->setPixelRef(ref);
26 return true;
27 }
28
SkCachingPixelRef(const SkImageInfo & info,SkImageGenerator * generator,size_t rowBytes)29 SkCachingPixelRef::SkCachingPixelRef(const SkImageInfo& info,
30 SkImageGenerator* generator,
31 size_t rowBytes)
32 : INHERITED(info)
33 , fImageGenerator(generator)
34 , fErrorInDecoding(false)
35 , fScaledCacheId(NULL)
36 , fRowBytes(rowBytes) {
37 SkASSERT(fImageGenerator != NULL);
38 }
~SkCachingPixelRef()39 SkCachingPixelRef::~SkCachingPixelRef() {
40 SkDELETE(fImageGenerator);
41 SkASSERT(NULL == fScaledCacheId);
42 // Assert always unlock before unref.
43 }
44
onLockPixels(SkColorTable **)45 void* SkCachingPixelRef::onLockPixels(SkColorTable**) {
46 const SkImageInfo& info = this->info();
47
48 if (fErrorInDecoding) {
49 return NULL; // don't try again.
50 }
51 SkBitmap bitmap;
52 SkASSERT(NULL == fScaledCacheId);
53 fScaledCacheId = SkScaledImageCache::FindAndLock(this->getGenerationID(),
54 info.fWidth,
55 info.fHeight,
56 &bitmap);
57 if (NULL == fScaledCacheId) {
58 // Cache has been purged, must re-decode.
59 if ((!bitmap.setConfig(info, fRowBytes)) || !bitmap.allocPixels()) {
60 fErrorInDecoding = true;
61 return NULL;
62 }
63 SkAutoLockPixels autoLockPixels(bitmap);
64 if (!fImageGenerator->getPixels(info, bitmap.getPixels(), fRowBytes)) {
65 fErrorInDecoding = true;
66 return NULL;
67 }
68 fScaledCacheId = SkScaledImageCache::AddAndLock(this->getGenerationID(),
69 info.fWidth,
70 info.fHeight,
71 bitmap);
72 SkASSERT(fScaledCacheId != NULL);
73 }
74
75 // Now bitmap should contain a concrete PixelRef of the decoded
76 // image.
77 SkAutoLockPixels autoLockPixels(bitmap);
78 void* pixels = bitmap.getPixels();
79 SkASSERT(pixels != NULL);
80 // At this point, the autoLockPixels will unlockPixels()
81 // to remove bitmap's lock on the pixels. We will then
82 // destroy bitmap. The *only* guarantee that this pointer
83 // remains valid is the guarantee made by
84 // SkScaledImageCache that it will not destroy the *other*
85 // bitmap (SkScaledImageCache::Rec.fBitmap) that holds a
86 // reference to the concrete PixelRef while this record is
87 // locked.
88 return pixels;
89 }
90
onUnlockPixels()91 void SkCachingPixelRef::onUnlockPixels() {
92 SkASSERT(fScaledCacheId != NULL);
93 SkScaledImageCache::Unlock( static_cast<SkScaledImageCache::ID*>(fScaledCacheId));
94 fScaledCacheId = NULL;
95 }
96