Use MSAA in GPU rasterization if Skia suggests it

cc/resources/resource_provider.cc

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/resources/resource_provider.h"
 
 #include <algorithm>
 #include <limits>
 
 #include "base/containers/hash_tables.h"
@@ skipping 43 matching lines @@
   scoped_ptr<GLuint[]> ids_;
   size_t next_id_index_;
 };
 
 namespace {
 
 // Measured in seconds.
 const double kSoftwareUploadTickRate = 0.000250;
 const double kTextureUploadTickRate = 0.004;
 
+// Display density in dots per inch at scale factor 1.0.
+const float kDisplayDensityScaleFactor = 160.0f;
+
 GLenum TextureToStorageFormat(ResourceFormat format) {
   GLenum storage_format = GL_RGBA8_OES;
   switch (format) {
     case RGBA_8888:
       break;
     case BGRA_8888:
       storage_format = GL_BGRA8_EXT;
       break;
     case RGBA_4444:
     case LUMINANCE_8:
@@ skipping 331 matching lines @@
 ResourceProvider::DirectRasterBuffer::~DirectRasterBuffer() {}
 
 SkCanvas* ResourceProvider::DirectRasterBuffer::DoLockForWrite() {
   if (!surface_)
     surface_ = CreateSurface();
   surface_generation_id_ = surface_ ? surface_->generationID() : 0u;
   return surface_ ? surface_->getCanvas() : NULL;
 }
 
 bool ResourceProvider::DirectRasterBuffer::DoUnlockForWrite() {
-  // generationID returns a non-zero, unique value corresponding to the content
-  // of surface. Hence, a change since DoLockForWrite was called means the
-  // surface has changed.
-  return surface_ ? surface_generation_id_ != surface_->generationID() : false;
+  if (surface_) {
+    // generationID returns a non-zero, unique value corresponding to the
+    // content of surface. Hence, a change since DoLockForWrite was called
+    // means the surface has changed.
+    if (surface_generation_id_ != surface_->generationID()) {
+      // Flush any pending or deferred work canvas or device might have. This
+      // also resolves the potential MSAA.
+      surface_->getCanvas()->flush();
+      return true;
+    }
+  }
+  return false;
 }
 
 skia::RefPtr<SkSurface> ResourceProvider::DirectRasterBuffer::CreateSurface() {
   skia::RefPtr<SkSurface> surface;
   switch (resource()->type) {
     case GLTexture: {
       DCHECK(resource()->gl_id);
       class GrContext* gr_context = resource_provider()->GrContext();
       if (gr_context) {
         GrBackendTextureDesc desc;
         desc.fFlags = kRenderTarget_GrBackendTextureFlag;
         desc.fWidth = resource()->size.width();
         desc.fHeight = resource()->size.height();
         desc.fConfig = ToGrPixelConfig(resource()->format);
         desc.fOrigin = kTopLeft_GrSurfaceOrigin;
         desc.fTextureHandle = resource()->gl_id;
+        desc.fSampleCnt = resource_provider()->num_gpu_rasterization_samples(
+            resource()->format);
         skia::RefPtr<GrTexture> gr_texture =
             skia::AdoptRef(gr_context->wrapBackendTexture(desc));
         surface = skia::AdoptRef(
             SkSurface::NewRenderTargetDirect(gr_texture->asRenderTarget()));
       }
       break;
     }
     case Bitmap: {
       DCHECK(resource()->pixels);
       DCHECK_EQ(RGBA_8888, resource()->format);
@@ skipping 144 matching lines @@
 
 ResourceProvider::~ResourceProvider() {
   while (!children_.empty())
     DestroyChildInternal(children_.begin(), ForShutdown);
   while (!resources_.empty())
     DeleteResourceInternal(resources_.begin(), ForShutdown);
 
   CleanUpGLIfNeeded();
 }
 
+unsigned ResourceProvider::num_gpu_rasterization_samples(
+    ResourceFormat format) const {
+  const float dpi =
+      kDisplayDensityScaleFactor * output_surface_->SurfaceScaleFactor();

[Kimmo Kinnunen, 2014/03/06 07:16:51]

Not entirely sure if this call is thread-safe. Is it?

+  return GrContext()->getRecommendedSampleCount(ToGrPixelConfig(format), dpi);
+}
+
 bool ResourceProvider::InUseByConsumer(ResourceId id) {
   Resource* resource = GetResource(id);
   return resource->lock_for_read_count > 0 || resource->exported_count > 0 ||
          resource->lost;
 }
 
 bool ResourceProvider::IsLost(ResourceId id) {
   Resource* resource = GetResource(id);
   return resource->lost;
 }
@@ skipping 1572 matching lines @@
   ContextProvider* context_provider = output_surface_->context_provider();
   return context_provider ? context_provider->ContextGL() : NULL;
 }
 
 class GrContext* ResourceProvider::GrContext() const {
   ContextProvider* context_provider = output_surface_->context_provider();
   return context_provider ? context_provider->GrContext() : NULL;
 }
 
 }  // namespace cc