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Touch pan: momentum/inertia after a flick #248
Description
What are you trying to do?
Pan a long agent transcript (opencode) on a touchscreen. The view stops dead the moment the finger lifts, so covering a long session means repeated swipes, and it doesn't match the glide a touchpad or browser gives you. Everything else about the recognizer feels right on a ThinkPad Z16 Gen 2: 8px slop, axis lock, second-finger reject, and with #245 fixed the wheel is a consistent 3 rows per detent.
What would you like wmux to do?
After pointerup on a committed vertical pan, keep scrolling with the release velocity and decay to zero, through the same synthetic-wheel path. Cancel on a new pointerdown or any rejected gesture; vertical only. Decay/velocity cap as constants would be fine; a setting is optional.
What do you do today instead?
Repeated swipes; the wheel for long distances.
Worth noting the web terminal handler deliberately skipped momentum (its comment cites xterm.js#594), so this would be the first implementation. You said in #243 you'd hand-roll it if wanted; happy to test and tune builds on the device.
Activity
feat(terminal): momentum after a touch flick (#248)
amirlehmam commentedon Sep 29, 2026
Shipped in v2.14.0. A committed vertical pan that ends in a flick now glides and decays through the same synthetic-wheel path. Velocity is a least-squares fit over the last ~100 ms, with a pause of 80 ms or more before lift giving no fling. Min is 0.25 px/ms, cap 4 px/ms, and the time constant is 325 ms, frame-rate independent. A new pointerdown, a real wheel, hiding the pane or unmount all cancel it. All constants are in
src/renderer/utils/touch-fling.ts. I couldn't feel it without a touchscreen, so your Z16 is the real test: tell me what to tune.Mattheinrichs commentedon Oct 2, 2026
Fling feedback after real use on a ThinkPad Z16 Gen 2 (Windows 11, v2.17.1):
Feels great. Flicks glide and decay like a phone, the pause-before-lift rule works (a placement drag never flings), hard flicks stop in the right place, and a new touch or a wheel cancels instantly. No tuning request on the fling itself.
One adjacent thing, filed separately as #267: while dragging, pan speed tracks the app's rows-per-report multiplier, so at opencode's default
scroll_speed3 the content outruns the finger. That's the mirror of #245 and distinct from the fling, which I'd like to keep at its current distance.