Adding a new SkSurface factory for generating surfaces from the scratch texture pool.

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 ae05ea8c04609369fcef5279b53fe4c4c630319f..50d6606145a644d9a69be50613555854cc4d6da6 100644
--- a/src/image/SkSurface_Gpu.cpp
+++ b/src/image/SkSurface_Gpu.cpp
@@ -14,7 +14,7 @@ class SkSurface_Gpu : public SkSurface_Base {
 public:
     SK_DECLARE_INST_COUNT(SkSurface_Gpu)
 
-    SkSurface_Gpu(GrRenderTarget*);
+    SkSurface_Gpu(GrRenderTarget*, bool cached);
     virtual ~SkSurface_Gpu();
 
     virtual SkCanvas* onNewCanvas() SK_OVERRIDE;
@@ -32,9 +32,9 @@ private:
 
 ///////////////////////////////////////////////////////////////////////////////
 
-SkSurface_Gpu::SkSurface_Gpu(GrRenderTarget* renderTarget)
+SkSurface_Gpu::SkSurface_Gpu(GrRenderTarget* renderTarget, bool cached)
         : INHERITED(renderTarget->width(), renderTarget->height()) {
-    fDevice = SkNEW_ARGS(SkGpuDevice, (renderTarget->getContext(), renderTarget));
+    fDevice = SkGpuDevice::Create(renderTarget, cached ? SkGpuDevice::kCached_Flag : 0);
 
     if (kRGB_565_GrPixelConfig != renderTarget->config()) {
         fDevice->clear(0x0);
@@ -95,7 +95,7 @@ SkSurface* SkSurface::NewRenderTargetDirect(GrRenderTarget* target) {
     if (NULL == target) {
         return NULL;
     }
-    return SkNEW_ARGS(SkSurface_Gpu, (target));
+    return SkNEW_ARGS(SkSurface_Gpu, (target, false));
 }
 
 SkSurface* SkSurface::NewRenderTarget(GrContext* ctx, const SkImageInfo& info, int sampleCount) {
@@ -117,5 +117,28 @@ SkSurface* SkSurface::NewRenderTarget(GrContext* ctx, const SkImageInfo& info, i
         return NULL;
     }
 
-    return SkNEW_ARGS(SkSurface_Gpu, (tex->asRenderTarget()));
+    return SkNEW_ARGS(SkSurface_Gpu, (tex->asRenderTarget(), false));
+}
+
+SkSurface* SkSurface::NewScratchRenderTarget(GrContext* ctx, const SkImageInfo& info, int sampleCount) {
+    if (NULL == ctx) {
+        return NULL;
+    }
+
+    SkBitmap::Config config = SkImageInfoToBitmapConfig(info);
+
+    GrTextureDesc desc;
+    desc.fFlags = kRenderTarget_GrTextureFlagBit | kCheckAllocation_GrTextureFlagBit;
+    desc.fWidth = info.fWidth;
+    desc.fHeight = info.fHeight;
+    desc.fConfig = SkBitmapConfig2GrPixelConfig(config);
+    desc.fSampleCnt = sampleCount;
+
+    SkAutoTUnref<GrTexture> tex(ctx->lockAndRefScratchTexture(desc, GrContext::kExact_ScratchTexMatch));
+
+    if (NULL == tex) {
+        return NULL;
+    }
+
+    return SkNEW_ARGS(SkSurface_Gpu, (tex->asRenderTarget(), true));
 }