cc: Add analytic color conversion to shaders

cc/output/shader.cc

Index: cc/output/shader.cc
diff --git a/cc/output/shader.cc b/cc/output/shader.cc
index 3bd260f4a3deee18948fe883f19a62e9ef5b164d..8a398fd26cbdca450a680a941572f25f1757dd9b 100644
--- a/cc/output/shader.cc
+++ b/cc/output/shader.cc
@@ -449,6 +449,11 @@ void FragmentShader::Init(GLES2Interface* context,
       uniforms.push_back("color");
       break;
   }
+  if (color_conversion_mode_ == COLOR_CONVERSION_MODE_ANALYTIC) {
+    uniforms.push_back("color_src_to_dst_primary_matrix");
+    uniforms.push_back("color_src_to_linear_tr_fn");
+    uniforms.push_back("color_linear_to_dst_tr_fn");
+  }
 
   locations.resize(uniforms.size());
 
@@ -506,6 +511,11 @@ void FragmentShader::Init(GLES2Interface* context,
       color_location_ = locations[index++];
       break;
   }
+  if (color_conversion_mode_ == COLOR_CONVERSION_MODE_ANALYTIC) {
+    color_src_to_dst_primary_matrix_location_ = locations[index++];
+    color_src_to_linear_tr_fn_location_ = locations[index++];
+    color_linear_to_dst_tr_fn_location_ = locations[index++];
+  }
   DCHECK_EQ(index, locations.size());
 }
 
@@ -898,6 +908,30 @@ std::string FragmentShader::GetShaderSource() const {
       SRC("vec4 texColor = color;");
       break;
   }
+
+  // Apply color conversion
+  if (color_conversion_mode_ == COLOR_CONVERSION_MODE_ANALYTIC) {
+    HDR("uniform mat3 color_src_to_dst_primary_matrix;");
+    HDR("// Transfer function parameter uniforms. Parameters are based on");
+    HDR("// SkColorSpaceTransferFn (as fA at index 0 through fG at index 6).");
+    HDR("uniform float color_src_to_linear_tr_fn[7];");
+    HDR("uniform float color_linear_to_dst_tr_fn[7];");
+    HDR("float TransferFn(float x, float params[7]) {");
+    HDR("  x = clamp(x, 0.0, 1.0);");
+    HDR("  if (x < params[3])");
+    HDR("    return params[2]*x + params[5];");
+    HDR("  return pow(params[0] * x + params[1], params[6]) + params[4];");
+    HDR("}");
+    SRC("// Apply color conversion");
+    SRC("texColor.r = TransferFn(texColor.x, color_src_to_linear_tr_fn);");
+    SRC("texColor.g = TransferFn(texColor.y, color_src_to_linear_tr_fn);");
+    SRC("texColor.b = TransferFn(texColor.z, color_src_to_linear_tr_fn);");
+    SRC("texColor.rgb = color_src_to_dst_primary_matrix * texColor.rgb;");
+    SRC("texColor.r = TransferFn(texColor.x, color_linear_to_dst_tr_fn);");
+    SRC("texColor.g = TransferFn(texColor.y, color_linear_to_dst_tr_fn);");
+    SRC("texColor.b = TransferFn(texColor.z, color_linear_to_dst_tr_fn);");
+  }
+
   // Apply the color matrix to texColor.
   if (has_color_matrix_) {
     HDR("uniform mat4 colorMatrix;");