javascript - React Native - onTouchStart vs PanResponder for multiple touches per second - Stack Overflow

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I'm developing an app with React Native which has to respond to tap gestures as soon as possible because more than one tap event can be fired in a second. No need for double tap or move gestures, but need to take care of simultaneous taps. I've been testing with both onTouchStart and PanResponder | onPanResponderGrant and seen that:

• onTouchStart is fired twice when two taps are simultaneous, while onPanResponderGrant is called just once.
• onPanResponderMove is fired even when I have onMoveShouldSetPanResponder to false, and it's fired many times when two taps are simultaneous, or when there are several taps in a second.
• When several taps are done in a second, onTouchStart works fine, but onPanResponderGrant is fired less times.

Based on above reasons, I think that I'd better use onTouchStart.

Now the question is: Should I use onTouchStart even when React Native docs suggest to use the PanResponder for multi-touch gestures?

PanResponder reconciles several touches into a single gesture. It makes single-touch gestures resilient to extra touches, and can be used to recognize simple multi-touch gestures.

Or am I missing something of PanResponder?

Edit:

Also, gestureState.numberActiveTouches is always 1, event when two taps are simultaneous. I thought that this could do the trick.

I'm developing an app with React Native which has to respond to tap gestures as soon as possible because more than one tap event can be fired in a second. No need for double tap or move gestures, but need to take care of simultaneous taps. I've been testing with both onTouchStart and PanResponder | onPanResponderGrant and seen that:

• onTouchStart is fired twice when two taps are simultaneous, while onPanResponderGrant is called just once.
• onPanResponderMove is fired even when I have onMoveShouldSetPanResponder to false, and it's fired many times when two taps are simultaneous, or when there are several taps in a second.
• When several taps are done in a second, onTouchStart works fine, but onPanResponderGrant is fired less times.

Based on above reasons, I think that I'd better use onTouchStart.

Now the question is: Should I use onTouchStart even when React Native docs suggest to use the PanResponder for multi-touch gestures?

PanResponder reconciles several touches into a single gesture. It makes single-touch gestures resilient to extra touches, and can be used to recognize simple multi-touch gestures.

Or am I missing something of PanResponder?

Edit:

Also, gestureState.numberActiveTouches is always 1, event when two taps are simultaneous. I thought that this could do the trick.

• javascript
• react-native
• touch
• gesture

Share Improve this question Follow edited Aug 15, 2017 at 19:25 CommunityBot 111 silver badge asked Aug 3, 2017 at 16:27 ManoloManolo 26.4k2121 gold badges8989 silver badges134134 bronze badges 8

• Is this for a scroll view? – sooper Commented Aug 3, 2017 at 23:23
• 1 @sooper - No, it's for some drums. – Manolo Commented Aug 4, 2017 at 8:52
• Hi @Manolo , is my answer satisfying? please accept it if so, otherwise let us know what's missing :). (edit: ah my bad, the bounty is replacing the check icon I suppose) – Jeremie Commented Aug 16, 2017 at 13:00
• @Jeremie - Well, your answer is based on mon sense and makes sense, but what about multi-touch gestures? They won't be fired simultaneously. And why does not work with PanResponder? Is it just a not documented behaviour? – Manolo Commented Aug 16, 2017 at 18:27
• to detect multitouch, I suppose we must tolerate that user is not going to press 3 fingers at the exact same time, so the API leaves some delay for the user to make it happen. this explains why it get triggered a few times per second and not more. I'm not sure I understand your ment "multi touch gestures won't be fired simultaneously". sounds plicated to me, you expect the user pressing at the same time 2 different drums with multiple fingers? – Jeremie Commented Aug 17, 2017 at 19:24

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1 Answer 1

Sorted by: Reset to default 11 +50

From the definition of PanResponder, I understand that it's used to interpret a multi-touch gesture and render 1 action. Like I tap with 2 fingers on an image and I could get the image copied to the clipboard.

While it seems you want a different behaviour: I you tap with 2 fingers on 1 drum cymbal, you want to get 2 sounds. It's as if you were dividing your drum cymbals into an infinity of buttons, and whatever you do, for every tap, you'll get one separate sound.

Then you don't want to use PanResponder, because it's going to try to interpret a bunch of movements into a single sound, while you want every movement to generate a separate sound. And onTouchStart simply gets the job done. So you are probably doing the right thing with it!

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