Fix GPURendererPixelTest.SolidColorBlend viz_unittest

Bug: 953284
Change-Id: Ic638c1ddfbc9dc8d05b30c480ff4b946ee3fb177
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1687557
Commit-Queue: Peng Huang <penghuang@chromium.org>
Reviewed-by: Jonathan Backer <backer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#675725}

components/viz/service/display/renderer_pixeltest.cc

@@ -1075,9 +1075,7 @@ TYPED_TEST(RendererPixelTest, PremultipliedTextureWithBackground) {
       cc::FuzzyPixelOffByOneComparator(true)));
 }
 
-// TODO(backer): Blending is not correct for SkiaRenderer
-// (https://crbug.com/953284)
-TYPED_TEST(GPURendererPixelTest, DISABLED_SolidColorBlend) {
+TYPED_TEST(GPURendererPixelTest, SolidColorBlend) {
   gfx::Rect rect(this->device_viewport_size_);
 
   int id = 1;
@@ -2381,7 +2379,7 @@ TYPED_TEST(RendererPixelTest, EnlargedRenderPassTexture) {
 
   EXPECT_TRUE(this->RunPixelTest(
       &pass_list, base::FilePath(FILE_PATH_LITERAL("blue_yellow.png")),
-      cc::ExactPixelComparator(true)));
+      cc::FuzzyPixelOffByOneComparator(true)));
 }
 
 TYPED_TEST(RendererPixelTest, EnlargedRenderPassTextureWithAntiAliasing) {
@@ -4080,7 +4078,7 @@ TYPED_TEST(RendererPixelTestWithFlippedOutputSurface, ExplicitFlipTest) {
   // right-side up result regardless (i.e., NOT blue_yellow_flipped.png).
   EXPECT_TRUE(this->RunPixelTest(
       &pass_list, base::FilePath(FILE_PATH_LITERAL("blue_yellow.png")),
-      cc::ExactPixelComparator(true)));
+      cc::FuzzyPixelOffByOneComparator(true)));
 }
 
 TYPED_TEST(RendererPixelTestWithFlippedOutputSurface, CheckChildPassUnflipped) {
@@ -4511,22 +4509,10 @@ TYPED_TEST(RendererPixelTest, RoundedCornerOnRenderPass) {
   pass_list.push_back(std::move(child_pass));
   pass_list.push_back(std::move(root_pass));
 
-  if (std::is_same<TypeParam, GLRenderer>() ||
-      std::is_same<TypeParam, cc::GLRendererWithExpandedViewport>()) {
-    // GL Renderer should have an exact match as that is the reference point.
-    EXPECT_TRUE(this->RunPixelTest(
-        &pass_list,
-        base::FilePath(FILE_PATH_LITERAL("rounded_corner_render_pass.png")),
-        cc::ExactPixelComparator(true)));
-  } else {
-    // Software/skia renderer uses skia rrect to create rounded corner clip.
-    // This results in a different corner path due to a different anti aliasing
-    // approach than the fragment shader in gl renderer.
-    EXPECT_TRUE(this->RunPixelTest(
-        &pass_list,
-        base::FilePath(FILE_PATH_LITERAL("rounded_corner_render_pass.png")),
-        cc::FuzzyPixelComparator(true, 0.6f, 0.f, 255.f, 255, 0)));
-  }
+  base::FilePath path(FILE_PATH_LITERAL("rounded_corner_render_pass_.png"));
+  path = path.InsertBeforeExtensionASCII(this->renderer_type());
+  EXPECT_TRUE(this->RunPixelTest(&pass_list, path,
+                                 cc::FuzzyPixelOffByOneComparator(true)));
 }
 
 TYPED_TEST(RendererPixelTest, RoundedCornerMultiRadii) {

components/viz/service/display_embedder/skia_output_device.h

@@ -86,6 +86,7 @@ class SkiaOutputDevice {
   virtual void DiscardBackbuffer();
 
   bool need_swap_semaphore() const { return need_swap_semaphore_; }
+  bool is_emulated_rgbx() const { return is_emulated_rgbx_; }
 
  protected:
   // Begin paint the back buffer.
@@ -113,6 +114,9 @@ class SkiaOutputDevice {
   base::Optional<BufferPresentedCallback> feedback_;
   base::Optional<gpu::SwapBuffersCompleteParams> params_;
 
+  // RGBX format is emulated with RGBA.
+  bool is_emulated_rgbx_ = false;
+
   DISALLOW_COPY_AND_ASSIGN(SkiaOutputDevice);
 };
 

components/viz/service/display_embedder/skia_output_device_offscreen.cc

@@ -45,8 +45,9 @@ void SkiaOutputDeviceOffscreen::Reshape(const gfx::Size& size,
       nullptr /* surfaceProps */);
   DCHECK(!!sk_surface_);
 
-  // Initialize alpha channel to opaque.
   if (!has_alpha_) {
+    is_emulated_rgbx_ = true;
+    // Initialize alpha channel to opaque.
     auto* canvas = sk_surface_->getCanvas();
     canvas->clear(SkColorSetARGB(255, 0, 0, 0));
   }

components/viz/service/display_embedder/skia_output_device_offscreen.h

@@ -40,6 +40,7 @@ class SkiaOutputDeviceOffscreen : public SkiaOutputDevice {
   GrContext* const gr_context_;
   const bool has_alpha_;
   sk_sp<SkSurface> sk_surface_;
+  bool supports_rgbx_ = true;
 
  private:
   SkImageInfo image_info_;

components/viz/service/display_embedder/skia_output_surface_impl_on_gpu.cc

@@ -851,6 +851,23 @@ void SkiaOutputSurfaceImplOnGpu::CopyOutput(
   auto* surface =
       from_fbo0 ? output_sk_surface() : offscreen_surfaces_[id].surface();
 
+  // If a platform doesn't support RGBX_8888 format, we will use RGBA_8888
+  // instead. In this case, we need discard alpha channel (modify the alpha
+  // value to 0xff, but keep other channel not changed).
+  bool need_discard_alpha = from_fbo0 && (output_device_->is_emulated_rgbx());
+  if (need_discard_alpha) {
+    base::Optional<gpu::raster::GrShaderCache::ScopedCacheUse> cache_use;
+    if (dependency_->GetGrShaderCache()) {
+      cache_use.emplace(dependency_->GetGrShaderCache(),
+                        gpu::kInProcessCommandBufferClientId);
+    }
+    SkPaint paint;
+    paint.setColor(SK_ColorBLACK);
+    paint.setBlendMode(SkBlendMode::kDstATop);
+    surface->getCanvas()->drawPaint(paint);
+    surface->flush();
+  }
+
   if (!is_using_vulkan() && !features::IsUsingSkiaForGLReadback()) {
     // Lazy initialize GLRendererCopier.
     if (!copier_) {
@@ -889,6 +906,7 @@ void SkiaOutputSurfaceImplOnGpu::CopyOutput(
       gl_id = texture_mapper.value().client_id();
       internal_format = GL_RGBA;
     }
+
     gfx::Size surface_size(surface->width(), surface->height());
     ScopedUseContextProvider use_context_provider(this, gl_id);
     copier_->CopyFromTextureOrFramebuffer(std::move(request), geometry,