PanResponder is not working when there are multiple touches

[faisalil]

Hey,

I am trying to implement a pinch gesture and I am trying to use PanResponder for that. However, looks like there is a bug, when I have a single touch, I get all events (start, move, end) and it working well. However, when I do a 2 figures, i only get a start event a directly after a terminated event. Any pointers to what might be going wrong?

Faisal

[allthetime]

I've implemented zooming with PanResponder without issue.

The supplied argument gestureState is relatively useless for this case as it doesn't return useful data (except for the number of touches)

You have to use evt.touchHistory.touchBank which is an array of all the touches.

I'll just show you the shell of my PanResponder creator (removed all specifics)

this._panResponder = PanResponder.create({
  onStartShouldSetPanResponder: (evt, gestureState) => true,
  onStartShouldSetPanResponderCapture: (evt, gestureState) => true,
  onMoveShouldSetPanResponder: (evt, gestureState) => true,
  onMoveShouldSetPanResponderCapture: (evt, gestureState) => true,

  onPanResponderGrant: (evt, gestureState) => {
 // do stuff on start
  },
  onPanResponderMove: (evt, gestureState) => {
 // do stuff on move
//
//   THIS IS WHERE YOU USE evt.touchHistory.touchBank
//
  },
  onPanResponderTerminationRequest: (evt, gestureState) => true,
  onPanResponderRelease: (evt, gestureState) => {
  },
  onPanResponderTerminate: (evt, gestureState) => {
  },
  onShouldBlockNativeResponder: (evt, gestureState) => {
    return true;
  },
});

[mkonicek]

@facebook-github-bot answered

[facebook-github-bot]

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[slorber]

@allthetime what's the difference between touchBank and evt.nativeEvent.touches ?

Also, for me it's not working very well because when I put a 2nd finger on the element, no more onPanResponderMove event is triggered unfortunatly. Any idea?

I'm trying to implement solution of https://stackoverflow.com/a/37449923/82609

[mileung]

Seems like touches and multiple touches can only act on one element. I have two elements and each should have their own PanResponder, but when I have multiple touches, only the first onPanResponderMove gets called.

[uditalias]

@faisalil is your PanResponder inside a Modal?