Implement SkBaseDevice snapshot support

src/image/SkSurface_Gpu.cpp

Index: src/image/SkSurface_Gpu.cpp
diff --git a/src/image/SkSurface_Gpu.cpp b/src/image/SkSurface_Gpu.cpp
index b94e4e30bd07f7a097a94a151a06b9558329476b..ea6e0899eebabd2e87c934babb500e7b3ac11d11 100644
--- a/src/image/SkSurface_Gpu.cpp
+++ b/src/image/SkSurface_Gpu.cpp
@@ -20,12 +20,23 @@
 SkSurface_Gpu::SkSurface_Gpu(SkGpuDevice* device)
     : INHERITED(device->width(), device->height(), &device->surfaceProps())
     , fDevice(SkRef(device)) {
+    fDevice->setSurface(this);
+    fGenerationID = 0;
 }
 
 SkSurface_Gpu::~SkSurface_Gpu() {
+    // In case the device outlives this instance, make sure device does not try to access this.
+    fDevice->setSurface(NULL);
     fDevice->unref();
 }
 
+uint32_t SkSurface_Gpu::generationID() {
+    if (0 == fGenerationID) {
+        fGenerationID = this->newGenerationID();
+    }
+    return fGenerationID;
+}
+
 SkCanvas* SkSurface_Gpu::onNewCanvas() {
     SkCanvas::InitFlags flags = SkCanvas::kDefault_InitFlags;
     // When we think this works...
@@ -35,8 +46,7 @@ SkCanvas* SkSurface_Gpu::onNewCanvas() {
 }
 
 SkSurface* SkSurface_Gpu::onNewSurface(const SkImageInfo& info) {
-    GrRenderTarget* rt = fDevice->accessRenderTarget();
-    int sampleCount = rt->numSamples();
+    int sampleCount = fDevice->getBackendSampleCnt();
     // TODO: Make caller specify this (change virtual signature of onNewSurface).
     static const Budgeted kBudgeted = kNo_Budgeted;
     return SkSurface::NewRenderTarget(fDevice->context(), kBudgeted, info, sampleCount,
@@ -44,39 +54,11 @@ SkSurface* SkSurface_Gpu::onNewSurface(const SkImageInfo& info) {
 }
 
 SkImage* SkSurface_Gpu::onNewImageSnapshot(Budgeted budgeted) {
-    const int sampleCount = fDevice->accessRenderTarget()->numSamples();
-    SkImage* image = SkNewImageFromBitmapTexture(fDevice->accessBitmap(false), sampleCount,
-                                                 budgeted);
-    if (image) {
-        as_IB(image)->initWithProps(this->props());
-    }
-    return image;
-}
-
-void SkSurface_Gpu::onDraw(SkCanvas* canvas, SkScalar x, SkScalar y,
-                              const SkPaint* paint) {
-    canvas->drawBitmap(fDevice->accessBitmap(false), x, y, paint);
-}
-
-// Create a new render target and, if necessary, copy the contents of the old
-// render target into it. Note that this flushes the SkGpuDevice but
-// doesn't force an OpenGL flush.
-void SkSurface_Gpu::onCopyOnWrite(ContentChangeMode mode) {
-    GrRenderTarget* rt = fDevice->accessRenderTarget();
-    // are we sharing our render target with the image? Note this call should never create a new
-    // image because onCopyOnWrite is only called when there is a cached image.
-    SkImage* image = this->getCachedImage(kNo_Budgeted);
-    SkASSERT(image);
-    if (rt->asTexture() == SkTextureImageGetTexture(image)) {
-        this->fDevice->replaceRenderTarget(SkSurface::kRetain_ContentChangeMode == mode);
-        SkTextureImageApplyBudgetedDecision(image);
-    } else if (kDiscard_ContentChangeMode == mode) {
-        this->SkSurface_Gpu::onDiscard();
-    }
+    return fDevice->newImageSnapshot(&this->props(), budgeted);
 }
 
-void SkSurface_Gpu::onDiscard() {
-    fDevice->accessRenderTarget()->discard();
+bool SkSurface_Gpu::isBackendBudgeted() const {
+    return fDevice->isBackendBudgeted();
 }
 
 ///////////////////////////////////////////////////////////////////////////////