flutter-Gesture Detector Widget with tap Example

main.dart

// this gist demonstrate the Flutter Gesture Detector Widget

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      debugShowCheckedModeBanner: false,
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

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

  void _incrementCounter() {
    setState(() {
      _counter++;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(
              'You have pushed the button this many times:',
            ),
            Text(
              '$_counter',
              style: Theme.of(context).textTheme.headline4,
            ),
            GestureDetector(
      onTap: () {
        setState(() {
          _counter++;
        });
      },
      child: Container(
        color: Colors.green,
        child: Center(
          child: Text(
            "Tap here to increase the counter",
          ),
        ),
      ),
    ),
            GestureDetector(
              onTap: () { setState((){ _counter--;});},
              child: Text("Tap to decrease <counter"),
            )
          ],
        ),
      )
    );
  }
}