22 Pinch-to-Pan Coupling. 22 of 95.
22/GESTURE PHYSICS/22 of 95
Pinch-to-Pan Coupling
Two fingers can mean zoom or pan — the interface must choose.
Best experienced with a pointer.
The problem
Two fingers moving together still change scale when the user only meant to pan, so the canvas drifts and zooms at once.
The solution
Finger spread change drives zoom; parallel translation drives pan.
Experiment
Play with the values
12px
1
0.01
How it works
- Two contacts are tracked together.
- A change in the distance between them is the zoom signal.
- Movement of their centroid is the pan signal.
- Spread is compared with a threshold so a small wobble does not zoom.
- The gesture is routed to pan or zoom from those two measurements, and both can happen together when each is real.
Seen in
Maps
Two-finger slide pans the map; spreading fingers zooms instead.
Photo galleries
Parallel two-finger drag pans a zoomed image without accidental scale.
Design tools
Canvas pan and pinch-zoom share two fingers without fighting.
PDF readers
Reading pan stays stable until the fingers clearly change distance.