Module input 

Pure input/gesture helpers (slop constants, input::VelocityTracker, the fling-decay math) re-exported for app authors and advanced widgets.

Structs

VelocityTracker

A ring of recent (time_ms, position) samples used to estimate the release velocity of a drag for flinging.

Constants

FLING_DECAY

Per-millisecond exponential fling decay factor (iOS “normal” deceleration): v(t) = v0 · FLING_DECAY.powf(t_ms).

FLING_STOP

Fling stop threshold, in px/s (~0.5 px/frame at 60 Hz): below this speed a fling is finished and the animation stops requesting frames.

MOUSE_SLOP

Mouse drag threshold (kept smaller than TOUCH_SLOP because a mouse is far more precise). Reserved for when events carry an input-kind flag; v1 widgets use TOUCH_SLOP uniformly.

TOUCH_SLOP

Touch drag threshold: how far a contact may move before a press becomes a drag/scroll (Flutter’s tap-vs-drag slop, 18 logical px).

VELOCITY_WINDOW_MS

Trailing window, in milliseconds, over which VelocityTracker estimates velocity — older samples are pruned.

WHEEL_LINE_PX

Logical pixels per wheel line — the constant a LineDelta wheel notch is multiplied by to get a pixel scroll amount (a sane cross-toolkit value).

Functions

fling_decay

Velocity of v0 after elapsed_ms of exponential fling decay.

fling_displacement

Closed-form displacement (in px) travelled by a fling of initial velocity v0 (px/s) over elapsed_ms milliseconds.