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Gecko:Overview: Difference between revisions
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Texture transfer is done by synchronizing texture objects across processes/threads using a couple TextureClient/TextureHost that wrap shared data and provide access to it on both sides. TextureHosts provide access to one or several TextureSource, which has the necessary API to actually composite the texture (TextureClient/Host being more about IPC synchronization than actual compositing. | Texture transfer is done by synchronizing texture objects across processes/threads using a couple TextureClient/TextureHost that wrap shared data and provide access to it on both sides. TextureHosts provide access to one or several TextureSource, which has the necessary API to actually composite the texture (TextureClient/Host being more about IPC synchronization than actual compositing. | ||
The logic behind texture transfer (as in | The logic behind texture transfer (as in single/double/triple buffering, texture tiling, etc) is operated by the CompositableClient and CompositableHost. | ||
It is important to understand the separation between layers and compositables. Compositables handle all the logic around texture transfer, while layers define the shape of the layer tree. a Compositable is created independently form a layer and attached to it on both side. While layers transactions can only originate forme the content thread, this separation make it possible for us to have separate compositable transactions between any thread and the compositor thread. We use the ImageBridge IPDL protocol to that end. The Idea of ImageBridge, is to create a Compositable that is manipulated on the ImageBridgeThread, and that can transfer/synchronize textures without using the content thread at all. This is very useful for smooth Video compositing: Video frames are decoded and passed into the ImageBridge with ever touching the content thread, which could be busy processing reflows or heavy javascript workloads. | It is important to understand the separation between layers and compositables. Compositables handle all the logic around texture transfer, while layers define the shape of the layer tree. a Compositable is created independently form a layer and attached to it on both side. While layers transactions can only originate forme the content thread, this separation make it possible for us to have separate compositable transactions between any thread and the compositor thread. We use the ImageBridge IPDL protocol to that end. The Idea of ImageBridge, is to create a Compositable that is manipulated on the ImageBridgeThread, and that can transfer/synchronize textures without using the content thread at all. This is very useful for smooth Video compositing: Video frames are decoded and passed into the ImageBridge with ever touching the content thread, which could be busy processing reflows or heavy javascript workloads. | ||