Created
June 11, 2020 15:53
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Flutter progress indicator full working example
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import 'package:flutter/material.dart'; | |
void main() { | |
runApp(MyApp()); | |
} | |
class MyApp extends StatelessWidget { | |
@override | |
Widget build(BuildContext context) { | |
return MaterialApp( | |
title: 'Flutter Demo', | |
theme: ThemeData( | |
primarySwatch: Colors.blue, | |
visualDensity: VisualDensity.adaptivePlatformDensity, | |
), | |
home: MyHomePage(title: 'Flutterclutter: Loading indicator'), | |
); | |
} | |
} | |
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; | |
Future _incrementCounter() async { | |
return Future.delayed(Duration(seconds: 2), () { | |
setState(() { | |
_counter++; | |
}); | |
}); | |
} | |
@override | |
Widget build(BuildContext context) { | |
return Scaffold( | |
appBar: AppBar( | |
title: Text(widget.title), | |
), | |
body: Center( | |
child: Text('Current counter is $_counter') | |
), | |
floatingActionButton: FloatingActionButton( | |
onPressed: () { | |
_onPressed(context); | |
}, | |
child: Icon(Icons.add), | |
), | |
); | |
} | |
void _onPressed(BuildContext context) async { | |
DialogBuilder(context).showLoadingIndicator('Calculating $_counter + 1'); | |
await _incrementCounter(); | |
DialogBuilder(context).hideOpenDialog(); | |
} | |
} | |
class DialogBuilder { | |
DialogBuilder(this.context); | |
final BuildContext context; | |
void showLoadingIndicator([String text]) { | |
showDialog( | |
context: context, | |
barrierDismissible: false, | |
builder: (BuildContext context) { | |
return WillPopScope( | |
onWillPop: () async => false, | |
child: AlertDialog( | |
shape: RoundedRectangleBorder( | |
borderRadius: BorderRadius.all(Radius.circular(8.0)) | |
), | |
backgroundColor: Colors.black87, | |
content: LoadingIndicator( | |
text: text | |
), | |
) | |
); | |
}, | |
); | |
} | |
void hideOpenDialog() { | |
Navigator.of(context).pop(); | |
} | |
} | |
class LoadingIndicator extends StatelessWidget{ | |
LoadingIndicator({this.text = ''}); | |
final String text; | |
@override | |
Widget build(BuildContext context) { | |
var displayedText = text; | |
return Container( | |
padding: EdgeInsets.all(16), | |
color: Colors.black87, | |
child: Column( | |
mainAxisAlignment: MainAxisAlignment.center, | |
mainAxisSize: MainAxisSize.min, | |
children: [ | |
_getLoadingIndicator(), | |
_getHeading(context), | |
_getText(displayedText) | |
] | |
) | |
); | |
} | |
Padding _getLoadingIndicator() { | |
return Padding( | |
child: Container( | |
child: CircularProgressIndicator( | |
strokeWidth: 3 | |
), | |
width: 32, | |
height: 32 | |
), | |
padding: EdgeInsets.only(bottom: 16) | |
); | |
} | |
Widget _getHeading(context) { | |
return | |
Padding( | |
child: Text( | |
'Please wait …', | |
style: TextStyle( | |
color: Colors.white, | |
fontSize: 16 | |
), | |
textAlign: TextAlign.center, | |
), | |
padding: EdgeInsets.only(bottom: 4) | |
); | |
} | |
Text _getText(String displayedText) { | |
return Text( | |
displayedText, | |
style: TextStyle( | |
color: Colors.white, | |
fontSize: 14 | |
), | |
textAlign: TextAlign.center, | |
); | |
} | |
} |
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Why is it that we pass the context here?