Allow client to force an SkImage snapshot to be unique (and uniquely own its backing store).

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"
@@ skipping 58 matching lines @@
 
 SkSurface* SkSurface_Gpu::onNewSurface(const SkImageInfo& info) {
     GrRenderTarget* rt = fDevice->accessRenderTarget();
     int sampleCount = rt->numColorSamples();
     // TODO: Make caller specify this (change virtual signature of onNewSurface).
     static const Budgeted kBudgeted = kNo_Budgeted;
     return SkSurface::NewRenderTarget(fDevice->context(), kBudgeted, info, sampleCount,
                                       &this->props());
 }
 
-SkImage* SkSurface_Gpu::onNewImageSnapshot(Budgeted budgeted) {
+SkImage* SkSurface_Gpu::onNewImageSnapshot(Budgeted budgeted, ForceCopyMode forceCopyMode) {
+    GrRenderTarget* rt = fDevice->accessRenderTarget();
+    SkASSERT(rt);
+    GrTexture* tex = rt->asTexture();
+    SkAutoTUnref<GrTexture> copy;
+    // TODO: Force a copy when the rt is an external resource.
+    if (kYes_ForceCopyMode == forceCopyMode || !tex) {
+        GrSurfaceDesc desc = fDevice->accessRenderTarget()->desc();
+        GrContext* ctx = fDevice->context();
+        desc.fFlags = desc.fFlags & !kRenderTarget_GrSurfaceFlag;

[brucedawson, 2016/02/25 01:27:26]

This line looks odd (/analyze flagged it as odd). Why is a logical not of an
enum value being done? Should this be ~ instead of !?

This works out to "& 0;"

The actual warning was:
    third_party\skia\include\gpu\grtypes.h(410) : warning C6323: Use of
arithmetic operator on Boolean type(s).
with a pointer back to this line of code.

[bsalomon, 2016/02/25 01:37:41]

d'oh. Yes, should be ~, will fix.

+        copy.reset(ctx->textureProvider()->createTexture(desc, kYes_Budgeted == budgeted));
+        if (!copy) {
+            return nullptr;
+        }
+        if (!ctx->copySurface(copy, rt)) {
+            return nullptr;
+        }
+        tex = copy;
+    }
     const SkImageInfo info = fDevice->imageInfo();
     SkImage* image = nullptr;
-    GrTexture* tex = fDevice->accessRenderTarget()->asTexture();
     if (tex) {
         image = new SkImage_Gpu(info.width(), info.height(), kNeedNewImageUniqueID,
                                 info.alphaType(), tex, budgeted);
     }
     return image;
 }
 
 // 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);
+    SkAutoTUnref<SkImage> image(this->refCachedImage(kNo_Budgeted, kNo_ForceUnique));
     SkASSERT(image);
     if (rt->asTexture() == as_IB(image)->getTexture()) {
         this->fDevice->replaceRenderTarget(SkSurface::kRetain_ContentChangeMode == mode);
         SkTextureImageApplyBudgetedDecision(image);
     } else if (kDiscard_ContentChangeMode == mode) {
         this->SkSurface_Gpu::onDiscard();
     }
 }
 
 void SkSurface_Gpu::onDiscard() {
@@ skipping 56 matching lines @@
     }
     SkAutoTUnref<SkGpuDevice> device(SkGpuDevice::Create(rt, props,
                                                          SkGpuDevice::kUninit_InitContents));
     if (!device) {
         return nullptr;
     }
     return new SkSurface_Gpu(device);
 }
 
 #endif