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Gecko:Layers: Difference between revisions
→Immediate Mode
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To enable an efficient immediate-mode implementation, we impose some constraints on the use of the layers API. First, define "mutation" as a call to any setter method on Layer, or a call to beginDraw or copyFrom on RenderedLayer, or a call to insertBefore or removeChild on ContainerLayer (when we add layer APIs, they may need to be added to this list). Then we impose the following rules: | To enable an efficient immediate-mode implementation, we impose some constraints on the use of the layers API. First, define "mutation" as a call to any setter method on Layer, or a call to beginDraw or copyFrom on RenderedLayer, or a call to insertBefore or removeChild on ContainerLayer (when we add layer APIs, they may need to be added to this list). Then we impose the following rules: | ||
# After calling RenderedLayer::beginDraw, you are not allowed to mutate any layer before or equal to the RenderedLayer in a pre-order traversal of the layer tree. | # After calling RenderedLayer::beginDraw, you are not allowed to mutate any layer before or equal to the RenderedLayer in a pre-order traversal of the layer tree (in this transaction). | ||
# The layer parameter to RenderedLayer::copyFrom must not be before this layer in a pre-order traversal of the layer tree. | # The layer parameter to RenderedLayer::copyFrom must not be before this layer in a pre-order traversal of the layer tree. | ||