How do detect where a user tapped on my screen, with Flutter?

Question

I'd like to know the x/y coordinates of where a tap occurred on my screen. I found the GestureDetector, but it doesn't seem to tell me where exactly the tap took place.

Here's my code so far:

import 'package:flutter/material.dart';

void main() {
  runApp(new MyWidget());
}

class MyWidget extends StatelessWidget {

  @override
  Widget build(BuildContext context) {
    return new GestureDetector(
      onTap: () => print('tapped!')
    );
  }
}

Which does register a tap... but how do I found out where the tap started from?

Answer 1

Observe onTapDown and onTapUp, they provide more details for you to work with.

class MyWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new GestureDetector(
      onTap: () => print('tapped!'),
      onTapDown: (TapDownDetails details) => _onTapDown(details),
      onTapUp: (TapUpDetails details) => _onTapUp(details),
    );
  }

  _onTapDown(TapDownDetails details) {
    var x = details.globalPosition.dx;
    var y = details.globalPosition.dy;
    // or user the local position method to get the offset
    print(details.localPosition);
    print("tap down " + x.toString() + ", " + y.toString());
  }

  _onTapUp(TapUpDetails details) {
    var x = details.globalPosition.dx;
    var y = details.globalPosition.dy;
    // or user the local position method to get the offset
    print(details.localPosition);
    print("tap up " + x.toString() + ", " + y.toString());
  }
}