20 Gesture Intent Threshold. 20 of 95.
20/GESTURE PHYSICS/20 of 95
Gesture Intent Threshold
The handler waits for proof before claiming the pointer.
Best experienced with a pointer.
The problem
Nested scroll and drag fight over the first few pixels, so a slight nudge steals the wrong gesture.
The solution
A movement threshold distinguishes tap and scroll from deliberate drag or pan intent.
Experiment
Play with the values
10px
Direction bias
How it works
- Pointer down on a child is ambiguous: it might be a tap, a scroll, or a drag.
- Movement is accumulated before any handler claims the gesture.
- That distance is compared with a slop threshold.
- Past the threshold, the handler either claims the gesture or yields it.
- A claimed drag captures the pointer; a yielded gesture is left for scroll.
Seen in
Carousel in a page
Vertical page scroll yields only after horizontal intent exceeds slop.
Map inside sheet
Sheet drag and map pan wait for clear direction before capturing.
Draggable list rows
Reorder handles ignore accidental micro-moves that should scroll the list.
Bottom sheets
Content scroll and sheet dismiss share the pointer until intent is proven.