[Merged by Bors] - Implement the Overflow::Hidden
style property for UI
#3296
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Objective
This PR implements the
overflow
style property inbevy_ui
. When set toOverflow::Hidden
, the children of that node are clipped so that overflowing parts are not rendered. This is an important building block for UI widgets.Solution
Clipping is done on the CPU so that it does not break batching.
The clip regions update was implemented as a separate system for clarity, but it could be merged with the other UI systems to avoid doing an additional tree traversal. (I don't think it's important until we fix the layout performance issues though).
A scrolling list was added to the
ui_pipelined
example to showcaseOverflow::Hidden
. For the sake of simplicity, it can only be scrolled with a mouse.