Get “details” on DoubleTap on Flutter GestureDetector

1
votes

I'm developing and app where on double tap I need to perform some actions, but they require the position where that double tap was executed. That information is normally carried by the details in events like "onTapDown/Up".

Now, I know you can call both "onTapDown" and "doubleTap" on a GestureDetector, but if you have a child that takes the "onTap" gesture the "onTapDown" won't fire when a double tap occurs. In my case I have a WebView under the GestureDetector, so only "onDoubleTap" fires.

I've already commented in this request (https://github.com/flutter/flutter/issues/20000) to the Flutter team to add "details" to "onDoubleTap", but it looks like it is going to take a while.

In that same thread they suggest a couple of solutions that I have already tried. 1st using this code:

var lastTapDown = 0;

onTapDown: (details) {
  var now = DateTime.now().millisecondsSinceEpoch;
  if (now - lastTapDown < 200) {
    print("Double Tap!")
  }
  lastTapDown = now;
},

...

This first solutions works, but I can't use it as I need the "onTap" to be claimed by the WebView.

And the other using this plugin: https://github.com/tomwyr/positioned-tap-detector, which I did and it is great but it bumps into the same problem as me, "onTapDown" won't fire if you have a child that wins "onTap" on the arena.

So if anyone can help me get that positions it would be much appreciated. :)

Thanks.

1
flutterwebviewgesturedetector

1 Answers

1
votes

Available with version 1.22.0 (release date: 01/10/2020) you can get the details with onDoubleTapDown.

TapDownDetails _doubleTapDetails;

void _handleDoubleTapDown(TapDownDetails details) {
  _doubleTapDetails = details;
}

void _handleDoubleTap() {
  print('Double tap on position ${_doubleTapDetails.localPosition}'); 
}

@override
Widget build(BuildContext context) {
  return GestureDetector(
    /* ... */
    onDoubleTapDown: _handleDoubleTapDown,
    onDoubleTap: _handleDoubleTap,
  );
}