Is there a better way to check Left/Right Drag in #flutter?

Question

Is there a better way to check Left/Right Drag in #flutter. I have done it but somtime it works sometime it doesn't.

  new GestureDetector(
  onHorizontalDragEnd: (DragEndDetails details) {
      print("Drag Left - AddValue");

    setState((){
      _value++;
    });
    if (details.velocity.pixelsPerSecond.dx > -1000.0) {
      print("Drag Right - SubValue");

      setState((){
        _value--;
      });
    }
  },
  child: new Container(
    child:new Text("$_value"),
  ),
);

Answer 1

I would just use a Dismissible widget for this. It's pretty configurable.

Note: If you don't want to provide visual feedback on the swipe, you could use a Stack to put a transparent Dismissible on top of another widget.

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      home: new MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  State createState() => new MyHomePageState();
}

class MyHomePageState extends State<MyHomePage> {
  int _counter = 0;

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      body: new Dismissible(
        resizeDuration: null,
        onDismissed: (DismissDirection direction) {
          setState(() {
            _counter += direction == DismissDirection.endToStart ? 1 : -1;
          });
        },
        key: new ValueKey(_counter),
        child: new Center(
          child: new Text(
            '$_counter',
            style: Theme.of(context).textTheme.display4,
          ),
        ),
      ),
    );
  }
}