Implement mix-blend-mode in GL renderer using shaders.

cc/output/gl_renderer.h

Index: cc/output/gl_renderer.h
diff --git a/cc/output/gl_renderer.h b/cc/output/gl_renderer.h
index 8e53d7023ee1a67d5df589f3dbcec0643178e5f3..1292eeec8952431f48c5087fd2cf1c328d99d873 100644
--- a/cc/output/gl_renderer.h
+++ b/cc/output/gl_renderer.h
@@ -42,6 +42,21 @@ class TextureMailboxDeleter;
 class GeometryBinding;
 class ScopedEnsureFramebufferAllocation;
 
+static const SkXfermode::Mode kDefaultBlendMode = SkXfermode::kSrcOver_Mode;
+static const SkXfermode::Mode kFirstBlendMode = SkXfermode::kScreen_Mode;
+static const SkXfermode::Mode kLastBlendMode = SkXfermode::kLuminosity_Mode;
+static const int kNumBlendModes = kLastBlendMode - kFirstBlendMode + 2;

[enne (OOO), 2014/10/16 01:41:25]

Would it make sense to add these to Skia?

[rosca, 2014/10/16 16:14:56]

Actually, we don't need coeff blend modes for shaders. I made kFirstBlendMode =
SkXfermode::kLastCoeffMode + 1 and kLastBlendMode = SkXfermode::kLastMode. Given
this, do you think we should add to kFirstBlendMode and kLastBlendMode to Skia?

+static inline int index_for_blend_mode(SkXfermode::Mode blend_mode) {
+  return (blend_mode < kFirstBlendMode || blend_mode > kLastBlendMode)
+             ? 0
+             : blend_mode - kFirstBlendMode + 1;
+}
+
+static_assert(
+    kDefaultBlendMode < kFirstBlendMode && kFirstBlendMode < kLastBlendMode,
+    "The order should be: kSrcOver_Mode, kFirstBlendMode, kLastBlendMode");
+static_assert(kNumBlendModes == 16, "There are 16 blend modes.");
+
 // Class that handles drawing of composited render layers using GL.
 class CC_EXPORT GLRenderer : public DirectRenderer {
  public:
@@ -153,7 +168,8 @@ class CC_EXPORT GLRenderer : public DirectRenderer {
   gfx::Rect GetBackdropBoundingBoxForRenderPassQuad(
       DrawingFrame* frame,
       const RenderPassDrawQuad* quad,
-      const gfx::Transform& contents_device_transform);
+      const gfx::Transform& contents_device_transform,
+      bool use_aa);
   scoped_ptr<ScopedResource> GetBackdropTexture(const gfx::Rect& bounding_rect);
 
   static bool ShouldApplyBackgroundFilters(DrawingFrame* frame,
@@ -166,7 +182,6 @@ class CC_EXPORT GLRenderer : public DirectRenderer {
       DrawingFrame* frame,
       const RenderPassDrawQuad* quad,
       const gfx::Transform& contents_device_transform_inverse,
-      ScopedResource* background_texture,
       skia::RefPtr<SkImage> backdrop_bitmap,
       const gfx::Rect& backdrop_bounding_rect);
 
@@ -328,22 +343,29 @@ class CC_EXPORT GLRenderer : public DirectRenderer {
 
   const TileCheckerboardProgram* GetTileCheckerboardProgram();
 
-  const RenderPassProgram* GetRenderPassProgram(
-      TexCoordPrecision precision);
+  const RenderPassProgram* GetRenderPassProgram(TexCoordPrecision precision,
+                                                SkXfermode::Mode blend_mode);
   const RenderPassProgramAA* GetRenderPassProgramAA(
-      TexCoordPrecision precision);
+      TexCoordPrecision precision,
+      SkXfermode::Mode blend_mode);
   const RenderPassMaskProgram* GetRenderPassMaskProgram(
-      TexCoordPrecision precision);
+      TexCoordPrecision precision,
+      SkXfermode::Mode blend_mode);
   const RenderPassMaskProgramAA* GetRenderPassMaskProgramAA(
-      TexCoordPrecision precision);
+      TexCoordPrecision precision,
+      SkXfermode::Mode blend_mode);
   const RenderPassColorMatrixProgram* GetRenderPassColorMatrixProgram(
-      TexCoordPrecision precision);
+      TexCoordPrecision precision,
+      SkXfermode::Mode blend_mode);
   const RenderPassColorMatrixProgramAA* GetRenderPassColorMatrixProgramAA(
-      TexCoordPrecision precision);
+      TexCoordPrecision precision,
+      SkXfermode::Mode blend_mode);
   const RenderPassMaskColorMatrixProgram* GetRenderPassMaskColorMatrixProgram(
-      TexCoordPrecision precision);
+      TexCoordPrecision precision,
+      SkXfermode::Mode blend_mode);
   const RenderPassMaskColorMatrixProgramAA*
-      GetRenderPassMaskColorMatrixProgramAA(TexCoordPrecision precision);
+  GetRenderPassMaskColorMatrixProgramAA(TexCoordPrecision precision,
+                                        SkXfermode::Mode blend_mode);
 
   const TextureProgram* GetTextureProgram(
       TexCoordPrecision precision);
@@ -388,18 +410,21 @@ class CC_EXPORT GLRenderer : public DirectRenderer {
       nonpremultiplied_texture_background_program_[NumTexCoordPrecisions];
   TextureProgram texture_io_surface_program_[NumTexCoordPrecisions];
 
-  RenderPassProgram render_pass_program_[NumTexCoordPrecisions];
-  RenderPassProgramAA render_pass_program_aa_[NumTexCoordPrecisions];
-  RenderPassMaskProgram render_pass_mask_program_[NumTexCoordPrecisions];
-  RenderPassMaskProgramAA render_pass_mask_program_aa_[NumTexCoordPrecisions];
+  RenderPassProgram render_pass_program_[NumTexCoordPrecisions][kNumBlendModes];
+  RenderPassProgramAA
+      render_pass_program_aa_[NumTexCoordPrecisions][kNumBlendModes];
+  RenderPassMaskProgram
+      render_pass_mask_program_[NumTexCoordPrecisions][kNumBlendModes];
+  RenderPassMaskProgramAA
+      render_pass_mask_program_aa_[NumTexCoordPrecisions][kNumBlendModes];
   RenderPassColorMatrixProgram
-      render_pass_color_matrix_program_[NumTexCoordPrecisions];
-  RenderPassColorMatrixProgramAA
-      render_pass_color_matrix_program_aa_[NumTexCoordPrecisions];
-  RenderPassMaskColorMatrixProgram
-      render_pass_mask_color_matrix_program_[NumTexCoordPrecisions];
-  RenderPassMaskColorMatrixProgramAA
-      render_pass_mask_color_matrix_program_aa_[NumTexCoordPrecisions];
+      render_pass_color_matrix_program_[NumTexCoordPrecisions][kNumBlendModes];
+  RenderPassColorMatrixProgramAA render_pass_color_matrix_program_aa_
+      [NumTexCoordPrecisions][kNumBlendModes];
+  RenderPassMaskColorMatrixProgram render_pass_mask_color_matrix_program_
+      [NumTexCoordPrecisions][kNumBlendModes];
+  RenderPassMaskColorMatrixProgramAA render_pass_mask_color_matrix_program_aa_
+      [NumTexCoordPrecisions][kNumBlendModes];
 
   VideoYUVProgram video_yuv_program_[NumTexCoordPrecisions];
   VideoYUVAProgram video_yuva_program_[NumTexCoordPrecisions];