add getTextureHandle to SkSurface

src/image/SkSurface_Gpu.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkSurface_Gpu.h"
 
 #include "SkCanvas.h"
 #include "SkGpuDevice.h"
 #include "SkImage_Base.h"
 #include "SkImage_Gpu.h"
 #include "SkImagePriv.h"
 #include "SkSurface_Base.h"
 
 #if SK_SUPPORT_GPU
 
 ///////////////////////////////////////////////////////////////////////////////
 SkSurface_Gpu::SkSurface_Gpu(SkGpuDevice* device)
     : INHERITED(device->width(), device->height(), &device->surfaceProps())
     , fDevice(SkRef(device)) {
 }
 
 SkSurface_Gpu::~SkSurface_Gpu() {
     fDevice->unref();
 }
 
+GrBackendObject SkSurface_Gpu::onGetTextureHandle(TextureHandleAccess access) {
+    GrRenderTarget* rt = fDevice->accessRenderTarget();
+    switch (access) {
+        case kFlushRead_TextureHandleAccess:
+            rt->prepareForExternalRead();   // todo: rename to prepareForExternalAccess()
+            break;
+        case kFlushWrite_TextureHandleAccess:
+            this->notifyContentWillChange(kRetain_ContentChangeMode);
+            rt->flushWrites();
+            break;
+        case kDiscardWrite_TextureHandleAccess:
+            this->notifyContentWillChange(kDiscard_ContentChangeMode);
+            rt->discard();
+            break;
+    }
+    return rt->asTexture()->getTextureHandle();
+}
+
 SkCanvas* SkSurface_Gpu::onNewCanvas() {
     SkCanvas::InitFlags flags = SkCanvas::kDefault_InitFlags;
     // When we think this works...
 //    flags |= SkCanvas::kConservativeRasterClip_InitFlag;
 
     return SkNEW_ARGS(SkCanvas, (fDevice, flags));
 }
 
 SkSurface* SkSurface_Gpu::onNewSurface(const SkImageInfo& info) {
     GrRenderTarget* rt = fDevice->accessRenderTarget();
@@ skipping 77 matching lines @@
     }
     SkAutoTUnref<SkGpuDevice> device(SkGpuDevice::Create(surface->asRenderTarget(), props,
                                                          SkGpuDevice::kUninit_InitContents));
     if (!device) {
         return NULL;
     }
     return SkNEW_ARGS(SkSurface_Gpu, (device));
 }
 
 #endif