On macOS a trackpad pinch-to-zoom is delivered as a rapid stream of
ctrl+wheel events. The zoomed image kept its 0.05s transform transition
during that stream, so each event restarted the in-flight transition
from its interpolated mid-point and the image lagged and flickered. This
is the same root cause as the #4451 pan flicker, which was fixed by
dropping the transition during the gesture for the pan and touch-pinch
paths; the wheel-zoom path was the only continuous gesture left with the
transition on.
Suppress the transition while a wheel-zoom gesture is streaming, cleared
on a short debounce since wheel has no explicit gesture-end event.
Discrete zoom (buttons, double-click, keyboard) keeps its smoothing.
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Huang Xin
8810aa6db0