| 摘要 |
A method of setting a graphics container in a graphics device wherein a child application draws graphics within a parent application's graphics context. A parent application begins a graphics container, pushes the current state information to a container stack, and sets a new container transformation and a container clip region in the graphics context where the contained graphics will be displayed. The current world-to-device transformation is concatenated with the container transformation, and the current visible clip region is intersected with the container clip region for transforming the child graphics to the container. Further, an identifier is used to prevent the child from altering the container transformation set by the parent and from popping the container state stack. After the container is set by the parent application, the world and page transformations of the child application are set to default values and the clipping region is set to infinity. The child application draws graphics to the container without any knowledge that it is being contained. Further, the child is free to shrink the clipping that was set by the parent, but cannot expand it. When the container is ended by the parent, the graphics context is restored to the state prior to beginning the graphics container.
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