applib/menu_layer: keep a mid-pan reload off the finger-owned offset - #1895
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applib/menu_layer: keep a mid-pan reload off the finger-owned offset#1895Mearman wants to merge 1 commit into
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menu_layer_update_caches finishes by re-selecting the current row with MenuRowAlignNone, and prv_corrected_scroll_align promotes that to MenuRowAlignCenter on center-focused menus. A reload_data arriving mid-pan (timer, inbox, timeline update) therefore snaps the scroll offset to re-centre the selection under a finger that is still down -- and the next pan update computes from the gesture's base offset, jumping the content straight back. The code's own invariant says menu_layer_set_selected_index cannot be used mid-pan for exactly this reason. Keep the promotion, but not while a touch gesture owns the menu: the finger owns the offset until liftoff, when the carousel settles through prv_menu_touch_settle_to_center as before. Callers that genuinely want a re-centre pass MenuRowAlignCenter explicitly and are unaffected, and the button-path reconcile still promotes because no gesture is active when buttons are pressed. Co-Authored-By: Claude <noreply@anthropic.com> Signed-off-by: Joseph Mearman <joseph@mearman.co.uk>
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Draft — still validating on hardware.
The last one I could reliably reproduce while playing with touch: on a center-focused carousel (the launcher), a data refresh landing mid-drag made the list visibly jump — yank one way, snap straight back — and feel desynced from my finger for the rest of the gesture.
menu_layer_update_caches finishes by re-selecting the current row with MenuRowAlignNone, and prv_corrected_scroll_align promotes that to MenuRowAlignCenter on center-focused menus. A reload mid-pan (timer, inbox, timeline update) therefore snaps the offset to re-centre the selection under a finger that is still down — and the next pan update recomputes from the gesture's base offset, jumping the content straight back. The code's own invariant says menu_layer_set_selected_index cannot be used mid-pan for exactly this reason.
The fix keeps the promotion but not while a touch gesture owns the menu: the finger owns the offset until liftoff, when the carousel settles through prv_menu_touch_settle_to_center as before. Callers that genuinely want a re-centre pass MenuRowAlignCenter explicitly and are unaffected, and the button-path reconcile still promotes because no gesture is active when buttons are pressed.
Covered by test_menu_layer__dispatch_pan_reload_mid_gesture_keeps_offset; full unit suite green.