| 摘要 |
A framework for performing graphics animation and compositing operations has a layer tree for interfacing with the application and a render tree for interfacing with a render engine. Layers in the layer tree can be content, windows, views, video, images, text, media, or any other type of object for a user interface of an application. The application commits change to the state of the layers of the layer tree. The application does not need to include explicit code for animating the changes to the layers. Instead, an animation is determined for animating the change in state. In determining the animation, the framework can define a set of predetermined animations based on motion, visibility, and transition. The determined animation is explicitly applied to the affected layers in the render tree. A render engine renders from the render tree into a frame buffer for display on the computer system. Those portions of the render tree that have changed relative to prior versions can be tracked to improve resource management.
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