Flutter. How to scan a barcode without UI - flutter

Question

How can you scan a 2D barcode using a flutter without the camera's UI? I don't need to see the camera preview. I just want to click on the "Scan" button, and the camera started looking for a barcode, but it did not display what the phone's camera sees in UI.

Answer 1

You could look into using the qr_code_scanner package (pub link). Instead of opening in a new view, it uses a custom view for the preview. You can then manipulate the view's dimensions to fit your needs. Note that making it invisible using Visibility or by giving its parent size 0 will disable the camera. Giving it (for example) a height of 1 pixel will still work.
Example code (run with version 0.4.0 of the qr_code_scanner package)
import 'package:flutter/material.dart';
import 'package:qr_code_scanner/qr_code_scanner.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: MyHomePage(title: 'QR scanner demo'),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
#override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
String result = '';
QRViewController controller;
bool isVisible = true;
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Container(
width: 200,
// 1 pixel, as a height 0 disables the view
height: isVisible ? 100 : 1,
child: QRView(
key: GlobalKey(),
onQRViewCreated: _onQRViewCreated,
),
),
Text(
'The barcode value was:',
),
Text(
'$result',
style: Theme.of(context).textTheme.headline4,
),
],
),
),
floatingActionButton: FloatingActionButton(
child: Icon(Icons.visibility),
onPressed: () {
setState(() {
isVisible = !isVisible;
});
},
),
);
}
void _onQRViewCreated(QRViewController controller) {
this.controller = controller;
controller.scannedDataStream.listen((scanData) {
setState(() {
result = scanData.code;
});
});
}
#override
void dispose() {
controller?.dispose();
super.dispose();
}
}
I found that one solution is to put the QRView inside a stack, s.t. it is hidden under another view