| // Copyright 2014 The Cobalt Authors. 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_RENDERER_BACKEND_GRAPHICS_CONTEXT_H_ |
| #define COBALT_RENDERER_BACKEND_GRAPHICS_CONTEXT_H_ |
| |
| #include <memory> |
| |
| #include "base/memory/ref_counted.h" |
| #include "cobalt/math/size.h" |
| #include "cobalt/renderer/backend/render_target.h" |
| #include "starboard/extension/graphics.h" |
| |
| namespace cobalt { |
| namespace renderer { |
| namespace backend { |
| |
| class GraphicsSystem; |
| |
| // The GraphicsContext captures the concept of a data channel to the GPU. |
| // The above definition implies that all graphics commands must eventually |
| // be issued through a graphics context. Platform-specific graphics context |
| // objects must be acquired from a platform's concrete GraphicsContext object |
| // and then issued to that directly. A graphics context will always be |
| // associated with a render target on which all rendering output will appear. |
| class GraphicsContext { |
| public: |
| explicit GraphicsContext(GraphicsSystem* system); |
| virtual ~GraphicsContext() {} |
| |
| GraphicsSystem* system() const { return system_; } |
| |
| // Creates an offscreen render target that can be targeted by a |
| // GraphicsContext::Frame. This might be used in unit tests where a |
| // display render target is not needed and we simply wish to render to an |
| // offscreen buffer and analyze the results offline. |
| // This method allows platforms to choose their most compatible format that |
| // can express RGBA. |
| virtual scoped_refptr<RenderTarget> CreateOffscreenRenderTarget( |
| const math::Size& dimensions) = 0; |
| |
| // Similar to CreateOffscreenRenderTarget, but this should be used when |
| // the target will be used with DownloadPixelDataAsRGBA. This render target |
| // is more compatible for reading. |
| virtual scoped_refptr<RenderTarget> CreateDownloadableOffscreenRenderTarget( |
| const math::Size& dimensions) { |
| return CreateOffscreenRenderTarget(dimensions); |
| } |
| |
| // Initializes any values that are needed in a debugging context. |
| virtual void InitializeDebugContext() {} |
| |
| // Saves render target pixels to CPU memory returned as a scoped_array. |
| // This function will wait for the pipeline to flush, so it is slow and should |
| // only be used in a debug context. One use case for the returned image |
| // memory is to encode it and serialize it as a PNG file for offline viewing. |
| // The dimensions of the returned memory can be found by examining the results |
| // of render_target->GetSize(). The pitch in pixels is equal to the width. |
| // The pixel format of the returned data is always RGBA8, in that order. |
| // Each pixel is 4 bytes. The output alpha format is always premultiplied |
| // alpha. |
| virtual std::unique_ptr<uint8_t[]> DownloadPixelDataAsRGBA( |
| const scoped_refptr<RenderTarget>& render_target) = 0; |
| |
| // Waits until all drawing is finished. |
| virtual void Finish() = 0; |
| |
| // Get the maximum time between rendered frames. This value can be dynamic |
| // and is queried periodically. This can be used to force the rasterizer to |
| // present a new frame even if nothing has changed visually. Due to the |
| // imprecision of thread scheduling, it may be necessary to specify a lower |
| // interval time to ensure frames aren't skipped when the throttling logic |
| // is executed a little too early. Return a negative number if frames should |
| // only be presented when something changes. |
| virtual float GetMaximumFrameIntervalInMilliseconds(); |
| |
| // Allow throttling of the frame rate. This is expressed in terms of |
| // milliseconds and can be a floating point number. Keep in mind that |
| // swapping frames may take some additional processing time, so it may be |
| // better to specify a lower delay. For example, '33' instead of '33.33' |
| // for 30 Hz refresh. If implemented, this takes precedence over the gyp |
| // variable 'cobalt_minimum_frame_time_in_milliseconds'. |
| // Note: Return a negative number if no value is specified by the platform. |
| virtual float GetMinimumFrameIntervalInMilliseconds(); |
| |
| // Get whether the renderer should support 360 degree video or not. |
| static bool IsMapToMeshEnabled(const GraphicsContext* graphics_context); |
| |
| private: |
| GraphicsSystem* system_; |
| |
| const CobaltExtensionGraphicsApi* graphics_extension_; |
| }; |
| |
| } // namespace backend |
| } // namespace renderer |
| } // namespace cobalt |
| |
| #endif // COBALT_RENDERER_BACKEND_GRAPHICS_CONTEXT_H_ |