Swap render target instead of creating a new gpu device for surface copy-on-write

src/gpu/SkGpuDevice.h

 
 /*
  * Copyright 2010 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkGpuDevice_DEFINED
 #define SkGpuDevice_DEFINED
@@ skipping 32 matching lines @@
     /**
      * New device that will create an offscreen renderTarget based on the ImageInfo and
      * sampleCount. The Budgeted param controls whether the device's backing store counts against
      * the resource cache budget. On failure, returns NULL.
      */
     static SkGpuDevice* Create(GrContext*, SkSurface::Budgeted, const SkImageInfo&,
                                int sampleCount, const SkSurfaceProps*, unsigned flags = 0);
 
     virtual ~SkGpuDevice();
 
+    /** Creates a render targetthat can be used as the render target of the device. */
+    static GrRenderTarget* CreateRenderTarget(GrContext* context, SkSurface::Budgeted budgeted,

[bsalomon, 2015/02/18 14:29:36]

Is it possible to just infer the parameters for the new RT from the old RT?
Maybe by making this method non-static? Or maybe have

GrRenderTarget* replaceRenderTarget(bool copyOldToNew);

that creates the new one (using budgeted status of the old one) and returns the
old one?

[Kimmo Kinnunen, 2015/02/18 14:42:54]

Yeah, this is just a refactoring. I did not hone it, since the problem you
address may be going away (the can be seen as "inferred") in:
https://chromiumcodereview.appspot.com/926843003/

+                                              const SkImageInfo& info, int sampleCount);
+
     SkGpuDevice* cloneDevice(const SkSurfaceProps& props) {
         SkBaseDevice* dev = this->onCreateCompatibleDevice(CreateInfo(this->imageInfo(),
                                                                       kGeneral_Usage,
                                                                       props.pixelGeometry()));
         return static_cast<SkGpuDevice*>(dev);
     }
 
     GrContext* context() const { return fRenderTarget->getContext(); }
 
     // set all pixels to 0
     void clearAll();
 
+    void swapRenderTarget(GrRenderTarget* newTarget);
+
     GrRenderTarget* accessRenderTarget() SK_OVERRIDE;
 
     SkImageInfo imageInfo() const SK_OVERRIDE {
         return fRenderTarget ? fRenderTarget->surfacePriv().info() : SkImageInfo::MakeUnknown();
     }
 
     const SkSurfaceProps& surfaceProps() const { return fSurfaceProps; }
 
     void drawPaint(const SkDraw&, const SkPaint& paint) SK_OVERRIDE;
     virtual void drawPoints(const SkDraw&, SkCanvas::PointMode mode, size_t count,
@@ skipping 124 matching lines @@
                          bool bicubic);
 
     bool drawDashLine(const SkPoint pts[2], const SkPaint& paint);
 
     static SkPicture::AccelData::Key ComputeAccelDataKey();
 
     typedef SkBaseDevice INHERITED;
 };
 
 #endif