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

cc/output/gl_renderer.h

 // Copyright 2010 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.
 
 #ifndef CC_OUTPUT_GL_RENDERER_H_
 #define CC_OUTPUT_GL_RENDERER_H_
 
 #include "base/cancelable_callback.h"
 #include "cc/base/cc_export.h"
 #include "cc/base/scoped_ptr_deque.h"
@@ skipping 24 matching lines @@
 class GLRendererShaderTest;
 class OutputSurface;
 class PictureDrawQuad;
 class ScopedResource;
 class StreamVideoDrawQuad;
 class TextureDrawQuad;
 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;

[Erik Dahlström (inactive), 2014/10/14 13:56:07]

why not use SkXfermode::kLastMode?

[rosca, 2014/10/15 15:33:55]

I thought kLastMode might not necessarily refer to a color blend mode. However,
I doubt they will ever change, so I can use it.

+static const int kNumBlendModes = kLastBlendMode - kFirstBlendMode + 2;

[Erik Dahlström (inactive), 2014/10/14 13:56:07]

Deserves a comment to explain the +2.

[rosca, 2014/10/15 15:33:55]

I will, thanks.

+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:
   class ScopedUseGrContext;
 
   static scoped_ptr<GLRenderer> Create(
       RendererClient* client,
       const LayerTreeSettings* settings,
       OutputSurface* output_surface,
       ResourceProvider* resource_provider,
@@ skipping 266 matching lines @@
       TexCoordPrecision precision, SamplerType sampler);
   const TileProgramSwizzle* GetTileProgramSwizzle(
       TexCoordPrecision precision, SamplerType sampler);
   const TileProgramSwizzleOpaque* GetTileProgramSwizzleOpaque(
       TexCoordPrecision precision, SamplerType sampler);
   const TileProgramSwizzleAA* GetTileProgramSwizzleAA(
       TexCoordPrecision precision, SamplerType sampler);
 
   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);
   const NonPremultipliedTextureProgram* GetNonPremultipliedTextureProgram(
       TexCoordPrecision precision);
   const TextureBackgroundProgram* GetTextureBackgroundProgram(
       TexCoordPrecision precision);
   const NonPremultipliedTextureBackgroundProgram*
       GetNonPremultipliedTextureBackgroundProgram(TexCoordPrecision precision);
   const TextureProgram* GetTextureIOSurfaceProgram(
@@ skipping 24 matching lines @@
   TileCheckerboardProgram tile_checkerboard_program_;
 
   TextureProgram texture_program_[NumTexCoordPrecisions];
   NonPremultipliedTextureProgram
       nonpremultiplied_texture_program_[NumTexCoordPrecisions];
   TextureBackgroundProgram texture_background_program_[NumTexCoordPrecisions];
   NonPremultipliedTextureBackgroundProgram
       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];
   VideoStreamTextureProgram
       video_stream_texture_program_[NumTexCoordPrecisions];
 
   DebugBorderProgram debug_border_program_;
   SolidColorProgram solid_color_program_;
   SolidColorProgramAA solid_color_program_aa_;
 
@@ skipping 42 matching lines @@
 #if DEBUG_GL_CALLS && !defined(NDEBUG)
 #define GLC(context, x)                                                        \
   (x, GLRenderer::DebugGLCall(&* context, #x, __FILE__, __LINE__))
 #else
 #define GLC(context, x) (x)
 #endif
 
 }  // namespace cc
 
 #endif  // CC_OUTPUT_GL_RENDERER_H_