Implement support for mixed sampled render targets

include/gpu/GrRenderTarget.h

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrRenderTarget_DEFINED
 #define GrRenderTarget_DEFINED
 
@@ skipping 13 matching lines @@
 class GrRenderTarget : virtual public GrSurface {
 public:
     SK_DECLARE_INST_COUNT(GrRenderTarget)
 
     // GrSurface overrides
     GrRenderTarget* asRenderTarget() SK_OVERRIDE { return this; }
     const GrRenderTarget* asRenderTarget() const  SK_OVERRIDE { return this; }
 
     // GrRenderTarget
     /**
-     * @return true if the surface is multisampled, false otherwise
+     * @param requestedConfig

[Chris Dalton, 2015/03/14 02:51:30]

Oops, sorry. I didn't finish my previous comment and then forgot to get back to
it. We should also document the requestedConfig parameter in the comment, not
just list it. But since we may reconsider these enum names it can probably wait.

+     * @return true if the surface is multisampled in all of the buffers
+     *         specified by the sample config, false if any are non-MSAA
      */
-    bool isMultisampled() const { return 0 != fDesc.fSampleCnt; }
+    bool isMultisampled(GrSampleConfig requestedConfig = kUnified_GrSampleConfig) const {
+        return 0 != numSamples(requestedConfig);
+    }
 
     /**
-     * @return the number of samples-per-pixel or zero if non-MSAA.
+     * @return the number of samples-per-pixel or zero if any of the specified
+     *         buffers is non-MSAA.
      */
-    int numSamples() const { return fDesc.fSampleCnt; }
+    int numSamples(GrSampleConfig requestedConfig = kUnified_GrSampleConfig) const {
+        if (kStencil_GrSampleConfig == fSampleConfig &&
+            kUnified_GrSampleConfig == requestedConfig) {
+            return 0;
+        }
+        return fDesc.fSampleCnt;
+    }
+
+    /**
+     * @return sample config.
+     */
+    GrSampleConfig sampleConfig() {
+        return fSampleConfig;
+    }
 
     /**
      * Call to indicate the multisample contents were modified such that the
      * render target needs to be resolved before it can be used as texture. Gr
      * tracks this for its own drawing and thus this only needs to be called
      * when the render target has been modified outside of Gr. This has no
      * effect on wrapped backend render targets.
      *
      * @param rect  a rect bounding the area needing resolve. NULL indicates
      *              the whole RT needs resolving.
@@ skipping 35 matching lines @@
         kAutoResolves_ResolveType,
         kCantResolve_ResolveType,
     };
     virtual ResolveType getResolveType() const = 0;
 
     // Provides access to functions that aren't part of the public API.
     GrRenderTargetPriv renderTargetPriv();
     const GrRenderTargetPriv renderTargetPriv() const;
 
 protected:
-    GrRenderTarget(GrGpu* gpu, LifeCycle lifeCycle, const GrSurfaceDesc& desc)
+    GrRenderTarget(GrGpu* gpu, LifeCycle lifeCycle, const GrSurfaceDesc& desc,
+                   GrSampleConfig sampleConfig)
         : INHERITED(gpu, lifeCycle, desc)
+        , fSampleConfig(sampleConfig)
         , fStencilBuffer(NULL) {
         fResolveRect.setLargestInverted();
     }
 
     // override of GrResource
     void onAbandon() SK_OVERRIDE;
     void onRelease() SK_OVERRIDE;
 
 private:
     // Checked when this object is asked to attach a stencil buffer.
     virtual bool canAttemptStencilAttachment() const = 0;
 
     friend class GrRenderTargetPriv;
 
+    GrSampleConfig    fSampleConfig;
+
     GrStencilBuffer*  fStencilBuffer;
 
     SkIRect           fResolveRect;
 
     typedef GrSurface INHERITED;
 };
 
 #endif