Touch events don't bubble up when nesting TouchableHighlight components

I would expect unhandled touch events to bubble up to the parent when a given TouchableHighlight component doesn’t handle them. All the events currently stop at the direct container.

<TouchableHighlight onLongPress={this._onLongPress}>
     <TouchableHighlight onPress={this._onPress}>
           <Text>
               Press or LongPress me
           </Text>
     </TouchableHighlight>
</TouchableHighlight>

Is there a particular reason why we don’t allow the events to bubble up and enable the above scenario?

[brentvatne]

Somewhat related, check out this great talk by Andy Matuschak about the challenges of implementing a gesture system.

So this is what I think is going on: the touchable state is local to the touchable component, and touchable components are completely unaware of others and eager to become responder for any touch event that is given to it. Currently, there can only be one responder for any touch event. So when you touch the inner TouchableHighlight, it captures the touch which prevents the outer component from even having a chance to transition from the “not responder” state of its state machine. When you release the touch, it simply ends the gesture.

I wasn’t sure whether there was a good reason not to default to this, which seemed like the natural behavior to me.

My guess would be that it is a simple model that works most of the time. Maybe @vjeux can speak more to this.

If one were to write his own TouchableHighlight, he could override onStartShouldSetResponderCapture or onStartShouldSetResponder but would he be able to tell which events is coming (e.g. long press) in order to make the determination of whether there’s a handler for it and therefore whether to return true or false? I couldn’t find a way to do this.

I’m actually not sure that this approach would work and don’t have time at the moment to look into it 😦 Let me know if you find a solution to it.

[lacker]

This issue seems like it has been sufficiently answered, so I am going to close it.