Flutter’s GestureDetector is a powerful widget that allows you to recognize various types of user interactions with your app. With GestureDetector, you can detect taps, drags, scrolls, and many other user gestures.
To use GestureDetector, you first need to wrap it around the widget that you want to make interactive. For example, if you want to detect taps on an image, you can wrap GestureDetector around the Image widget like this:
GestureDetector(
onTap: () {
// Do something when the user taps the image
},
child: Image.asset('assets/my_image.png'),
);
In this example, we’ve specified an onTap callback that will be called whenever the user taps on the image. You can also specify other callbacks to detect other types of gestures, like onDoubleTap, onLongPress, onPanStart, onScaleUpdate, and many others.
One of the powerful features of GestureDetector is that it allows you to recognize complex gestures that involve multiple touch points. For example, you can detect a user pinch gesture (i.e. when the user uses two fingers to zoom in or out) using the onScaleUpdate callback:
GestureDetector(
onScaleUpdate: (ScaleUpdateDetails details) {
// Do something when the user pinches the widget
},
child: MyZoomableWidget(),
);
In this example, we’ve specified an onScaleUpdate callback that will be called whenever the user performs a pinch gesture on MyZoomableWidget.
Another, Flutter GestureDetector Example:
GestureDetector(
onTap: () {
setState(() {
clicked = !clicked; // here must need setState()
});
},
child: Center(child: clicked ? Text("First Text") : Text("Second Text")),
);Flutter GestureDetector Widget
tutorial source code example:
import 'package:flutter/material.dart';
import 'package:syncfusion_flutter_pdfviewer/pdfviewer.dart';
main() {
runApp(const MyApp());
}
class MyApp extends StatefulWidget {
const MyApp({Key? key}) : super(key: key);
@override
State<MyApp> createState() => _MyAppState();
}
class _MyAppState extends State<MyApp> {
@override
Widget build(BuildContext context) {
return const MaterialApp(
debugShowCheckedModeBanner: false,
home: Scaffold(body: HomePage()),
);
}
}
class HomePage extends StatefulWidget {
const HomePage({Key? key}) : super(key: key);
@override
State<HomePage> createState() => _HomePageState();
}
class _HomePageState extends State<HomePage> {
bool clicked = false;
@override
Widget build(BuildContext context) {
return GestureDetector(
onTap: () {
setState(() {
clicked = !clicked; // here must need setState()
});
},
child: Center(child: clicked ? Text("First Text") : Text("Second Text")),
);
}
}
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Overall, GestureDetector is a very flexible and powerful widget that can help you create highly interactive and engaging user interfaces in your Flutter app.
