SkGrPixelRef.cpp revision f2703d83da3ab2ae18b45231fd4f11e16cce3184 
1
2/*
3 * Copyright 2010 Google Inc.
4 *
5 * Use of this source code is governed by a BSD-style license that can be
6 * found in the LICENSE file.
7 */
8
9
10
11#include "SkGrPixelRef.h"
12
13#include "GrContext.h"
14#include "GrTexture.h"
15#include "SkBitmapCache.h"
16#include "SkGr.h"
17#include "SkRect.h"
18
19// since we call lockPixels recursively on fBitmap, we need a distinct mutex,
20// to avoid deadlock with the default one provided by SkPixelRef.
21SK_DECLARE_STATIC_MUTEX(gROLockPixelsPixelRefMutex);
22
23SkROLockPixelsPixelRef::SkROLockPixelsPixelRef(const SkImageInfo& info)
24    : INHERITED(info, &gROLockPixelsPixelRefMutex) {}
25
26SkROLockPixelsPixelRef::~SkROLockPixelsPixelRef() {}
27
28bool SkROLockPixelsPixelRef::onNewLockPixels(LockRec* rec) {
29    fBitmap.reset();
30//    SkDebugf("---------- calling readpixels in support of lockpixels\n");
31    if (!this->onReadPixels(&fBitmap, NULL)) {
32        SkDebugf("SkROLockPixelsPixelRef::onLockPixels failed!\n");
33        return false;
34    }
35    fBitmap.lockPixels();
36    if (NULL == fBitmap.getPixels()) {
37        return false;
38    }
39
40    rec->fPixels = fBitmap.getPixels();
41    rec->fColorTable = NULL;
42    rec->fRowBytes = fBitmap.rowBytes();
43    return true;
44}
45
46void SkROLockPixelsPixelRef::onUnlockPixels() {
47    fBitmap.unlockPixels();
48}
49
50bool SkROLockPixelsPixelRef::onLockPixelsAreWritable() const {
51    return false;
52}
53
54///////////////////////////////////////////////////////////////////////////////
55
56static SkGrPixelRef* copy_to_new_texture_pixelref(GrTexture* texture, SkColorType dstCT,
57                                                  const SkIRect* subset) {
58    if (NULL == texture || kUnknown_SkColorType == dstCT) {
59        return NULL;
60    }
61    GrContext* context = texture->getContext();
62    if (NULL == context) {
63        return NULL;
64    }
65    GrSurfaceDesc desc;
66
67    SkIRect srcRect;
68
69    if (!subset) {
70        desc.fWidth  = texture->width();
71        desc.fHeight = texture->height();
72        srcRect = SkIRect::MakeWH(texture->width(), texture->height());
73    } else {
74        SkASSERT(SkIRect::MakeWH(texture->width(), texture->height()).contains(*subset));
75        // Create a new texture that is the size of subset.
76        desc.fWidth = subset->width();
77        desc.fHeight = subset->height();
78        srcRect = *subset;
79    }
80    desc.fFlags = kRenderTarget_GrSurfaceFlag | kNoStencil_GrSurfaceFlag;
81    desc.fConfig = SkImageInfo2GrPixelConfig(dstCT, kPremul_SkAlphaType);
82
83    GrTexture* dst = context->createUncachedTexture(desc, NULL, 0);
84    if (NULL == dst) {
85        return NULL;
86    }
87
88    // Blink is relying on the above copy being sent to GL immediately in the case when the source
89    // is a WebGL canvas backing store. We could have a TODO to remove this flush flag, but we have
90    // a larger TODO to remove SkGrPixelRef entirely.
91    context->copySurface(dst->asRenderTarget(), texture, srcRect, SkIPoint::Make(0,0),
92                         GrContext::kFlushWrites_PixelOp);
93
94    SkImageInfo info = SkImageInfo::Make(desc.fWidth, desc.fHeight, dstCT, kPremul_SkAlphaType);
95    SkGrPixelRef* pixelRef = SkNEW_ARGS(SkGrPixelRef, (info, dst));
96    SkSafeUnref(dst);
97    return pixelRef;
98}
99
100///////////////////////////////////////////////////////////////////////////////
101
102SkGrPixelRef::SkGrPixelRef(const SkImageInfo& info, GrSurface* surface) : INHERITED(info) {
103    // For surfaces that are both textures and render targets, the texture owns the
104    // render target but not vice versa. So we ref the texture to keep both alive for
105    // the lifetime of this pixel ref.
106    fSurface = SkSafeRef(surface->asTexture());
107    if (NULL == fSurface) {
108        fSurface = SkSafeRef(surface);
109    }
110
111    if (fSurface) {
112        SkASSERT(info.width() <= fSurface->width());
113        SkASSERT(info.height() <= fSurface->height());
114    }
115}
116
117SkGrPixelRef::~SkGrPixelRef() {
118    SkSafeUnref(fSurface);
119}
120
121GrTexture* SkGrPixelRef::getTexture() {
122    if (fSurface) {
123        return fSurface->asTexture();
124    }
125    return NULL;
126}
127
128SkPixelRef* SkGrPixelRef::deepCopy(SkColorType dstCT, const SkIRect* subset) {
129    if (NULL == fSurface) {
130        return NULL;
131    }
132
133    // Note that when copying a render-target-backed pixel ref, we
134    // return a texture-backed pixel ref instead.  This is because
135    // render-target pixel refs are usually created in conjunction with
136    // a GrTexture owned elsewhere (e.g., SkGpuDevice), and cannot live
137    // independently of that texture.  Texture-backed pixel refs, on the other
138    // hand, own their GrTextures, and are thus self-contained.
139    return copy_to_new_texture_pixelref(fSurface->asTexture(), dstCT, subset);
140}
141
142static bool tryAllocBitmapPixels(SkBitmap* bitmap) {
143    SkBitmap::Allocator* allocator = SkBitmapCache::GetAllocator();
144    if (NULL != allocator) {
145        return allocator->allocPixelRef(bitmap, 0);
146    } else {
147        // DiscardableMemory is not available, fallback to default allocator
148        return bitmap->tryAllocPixels();
149    }
150}
151
152bool SkGrPixelRef::onReadPixels(SkBitmap* dst, const SkIRect* subset) {
153    if (NULL == fSurface || fSurface->wasDestroyed()) {
154        return false;
155    }
156
157    SkIRect bounds;
158    if (subset) {
159        bounds = *subset;
160    } else {
161        bounds = SkIRect::MakeWH(this->info().width(), this->info().height());
162    }
163
164    //Check the cache
165    if(!SkBitmapCache::Find(this->getGenerationID(), bounds, dst)) {
166        //Cache miss
167
168        SkBitmap cachedBitmap;
169        cachedBitmap.setInfo(this->info().makeWH(bounds.width(), bounds.height()));
170
171        // If we can't alloc the pixels, then fail
172        if (!tryAllocBitmapPixels(&cachedBitmap)) {
173            return false;
174        }
175
176        // Try to read the pixels from the surface
177        void* buffer = cachedBitmap.getPixels();
178        bool readPixelsOk = fSurface->readPixels(bounds.fLeft, bounds.fTop,
179                                bounds.width(), bounds.height(),
180                                kSkia8888_GrPixelConfig,
181                                buffer, cachedBitmap.rowBytes());
182
183        if (!readPixelsOk) {
184            return false;
185        }
186
187        // If we are here, pixels were read correctly from the surface.
188        cachedBitmap.setImmutable();
189        //Add to the cache
190        SkBitmapCache::Add(this->getGenerationID(), bounds, cachedBitmap);
191
192        dst->swap(cachedBitmap);
193    }
194
195    return true;
196
197}
198