Add API for GrContext to recommend rendertarget sample count

src/gpu/GrContext.cpp

 
 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #include "GrContext.h"
@@ skipping 1685 matching lines @@
     }
 
     return pr;
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 bool GrContext::isConfigRenderable(GrPixelConfig config, bool withMSAA) const {
     return fGpu->caps()->isConfigRenderable(config, withMSAA);
 }
 
+int GrContext::getRecommendedSampleCount(GrPixelConfig config, float) const {
+  if (this->isConfigRenderable(config, true)) {
+    if (fGpu->caps()->pathRenderingSupport()) {
+      return 4;

[bsalomon, 2014/03/06 14:02:43]

Should probably also check that 4 >= caps()->maxSampleCount().

I'm thinking that we may want to check the DPI and go to 16 samples on a typical
"desktop" display. Maybe if we're below 250 dpi? I'm sure what the right
threshold is but I think 4 samples will look bad on a standard monitor. (Maybe
in the future someone can do some experimentation and fine tune it and perhaps
figure out if it makes sense to have an 8 sample middle ground as well.)

+    }
+  }
+  return 0;
+}
+
 void GrContext::setupDrawBuffer() {
     SkASSERT(NULL == fDrawBuffer);
     SkASSERT(NULL == fDrawBufferVBAllocPool);
     SkASSERT(NULL == fDrawBufferIBAllocPool);
 
     fDrawBufferVBAllocPool =
         SkNEW_ARGS(GrVertexBufferAllocPool, (fGpu, false,
                                     DRAW_BUFFER_VBPOOL_BUFFER_SIZE,
                                     DRAW_BUFFER_VBPOOL_PREALLOC_BUFFERS));
     fDrawBufferIBAllocPool =
@@ skipping 73 matching lines @@
     }
     return path;
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 #if GR_CACHE_STATS
 void GrContext::printCacheStats() const {
     fTextureCache->printStats();
 }
 #endif