Improve focus navigation performance by caching Screen.focus_chain between layout changes#6608
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RajanChavada wants to merge 1 commit into
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Improve focus navigation performance by caching Screen.focus_chain between layout changes#6608RajanChavada wants to merge 1 commit into
RajanChavada wants to merge 1 commit into
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…nges Recalculating the focus chain on every access traverses the entire DOM sorted by focus order, which is moderately expensive. Cache the result and clear it in the three places that make it stale: _on_layout (mount/unmount/ visibility/disabled changes), set_focus (root node depends on focused widget when _trap_focus is active), and trap_focus() (directly changes which node acts as root).
RajanChavada
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Addresses the acknowledged TODO at
screen.py:774:What this PR does
Screen.focus_chaintraverses the entire DOM on every call — sorting children by focus order, walking visibility, and checking disabled state. It's called on every Tab/Shift+Tab keypress and in several internal focus-management paths.This PR caches the result in
_focus_chain_cacheand clears it in the three places that make it stale:Screen._on_layoutdisplay: none), and disabled state changes — all of which post aLayoutmessageScreen.set_focusself.focusedwhen_trap_focusis activeDOMNode.trap_focus_trap_focus, changing which node acts as the traversal root — no layout message is posted_add_children(test-only helper that bypasses the mount pipeline) also clears the cache so existing tests stay green.Testing
test_focus.py,test_app_focus_blur.py,test_screens.py,test_screen_modes.py)test_features.pyunrelated to this change