| // Copyright 2014 Google Inc. All Rights Reserved. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| #ifndef COBALT_RENDER_TREE_BRUSH_VISITOR_H_ |
| #define COBALT_RENDER_TREE_BRUSH_VISITOR_H_ |
| |
| namespace cobalt { |
| namespace render_tree { |
| |
| class LinearGradientBrush; |
| class RadialGradientBrush; |
| class SolidColorBrush; |
| |
| // Type-safe branching on a class hierarchy of render tree brushes, |
| // implemented after a classical GoF pattern (see |
| // http://en.wikipedia.org/wiki/Visitor_pattern#Java_example). |
| // |
| // Usage example: |
| // |
| // class ShaderFactory : public BrushVisitor { |
| // SkShader* shader() { |
| // return shader_; |
| // } |
| // |
| // void Visit(SolidColorBrush* solid_color_brush) OVERRIDE { |
| // shader_ = new SkColorShader(...); |
| // } |
| // |
| // void Visit(LinearGradientBrush* linear_gradient_brush) OVERRIDE { |
| // shader_ = new SkGradientShader(...); |
| // } |
| // |
| // void Visit(RadialGradientBrush* radial_gradient_brush) OVERRIDE { |
| // shader_ = new SkGradientShader(...); |
| // } |
| // }; |
| // |
| // ShaderFactory shader_factory; |
| // render_tree_rect->background_brush().Accept(&shader_factory); |
| // paint.setShader(shader_factory.shader()); |
| // |
| class BrushVisitor { |
| public: |
| virtual void Visit(const SolidColorBrush* solid_color_brush) = 0; |
| virtual void Visit(const LinearGradientBrush* linear_gradient_brush) = 0; |
| virtual void Visit(const RadialGradientBrush* radial_gradient_brush) = 0; |
| |
| protected: |
| ~BrushVisitor() {} |
| }; |
| |
| } // namespace render_tree |
| } // namespace cobalt |
| |
| #endif // COBALT_RENDER_TREE_BRUSH_VISITOR_H_ |