How To Pass Information From one Screen to another Screen - flutter

Question

I wanted to Download a Image with its progress and message. I wanted to show it in a dialog. When ever I click Download Button the Image gets downloaded and the Container pops up, but it does not Show any value.
The below code uses Image_downloader package. Raised button downloads the image and display the Blank Container without any value;
import 'dart:async';
import 'dart:io';
import 'Download.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:image_downloader/image_downloader.dart';
void main() => runApp(HomePage());
class HomePage extends StatefulWidget {
#override
HomePageState createState() => HomePageState();
}
class HomePageState extends State<HomePage> {
String message = "";
String path = "";
int _progress = 0;
#override
void initState() {
super.initState();
ImageDownloader.callback(onProgressUpdate: (String imageId, int progress) {
setState(() {
_progress = progress;
});
});
}
#override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
appBar: AppBar(
title: const Text('Plugin example app'),
),
body: Center(
child: Column(
mainAxisSize: MainAxisSize.min,
children: <Widget>[
RaisedButton(
onPressed: () {
_downloadImage(
"https://images.unsplash.com/photo-1503023345310-bd7c1de61c7d?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&w=1000&q=80",
);
showDialog(
context: context,
builder: (_) => FunkyOverlay(progress: _progress, message: message,),
);
},
child: Text("default destination"),
),
],
),
),
),
);
}
Future<void> _downloadImage(String url,
{AndroidDestinationType destination, bool whenError = false}) async {
String fileName;
String path;
try {
String imageId;
if (whenError) {
imageId = await ImageDownloader.downloadImage(url).catchError((error) {
if (error is PlatformException) {
var path = "";
if (error.code == "404") {
print("Not Found Error.");
} else if (error.code == "unsupported_file") {
print("UnSupported FIle Error.");
path = error.details["unsupported_file_path"];
}
setState(() {
message = error.toString();
path = path;
});
}
print(error);
}).timeout(Duration(seconds: 10), onTimeout: () {
print("timeout");
});
} else {
if (destination == null) {
imageId = await ImageDownloader.downloadImage(url);
} else {
imageId = await ImageDownloader.downloadImage(
url,
destination: destination,
);
}
}
if (imageId == null) {
return;
}
fileName = await ImageDownloader.findName(imageId);
path = await ImageDownloader.findPath(imageId);
} on PlatformException catch (error) {
setState(() {
message = error.message;
});
return;
}
if (!mounted) return;
setState(() {
message = 'Image Downloaded';
});
}
}
This is the Pop up Container Part
import 'package:flutter/material.dart';
class FunkyOverlay extends StatefulWidget {
String message;
int progress;
FunkyOverlay({#required this.message, #required this.progress});
#override
State<StatefulWidget> createState() => FunkyOverlayState(message, progress);
}
class FunkyOverlayState extends State<FunkyOverlay>
with SingleTickerProviderStateMixin {
String message;
int progress;
FunkyOverlayState(this.message, this.progress);
AnimationController controller;
Animation<double> scaleAnimation;
#override
void initState() {
super.initState();
controller =
AnimationController(vsync: this, duration: Duration(milliseconds: 450));
scaleAnimation =
CurvedAnimation(parent: controller, curve: Curves.elasticInOut);
controller.addListener(() {
setState(() {});
});
controller.forward();
}
#override
Widget build(BuildContext context) {
return Center(
child: Material(
color: Colors.transparent,
child: ScaleTransition(
scale: scaleAnimation,
child: Container(
decoration: ShapeDecoration(
color: Colors.white,
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(15.0),
),
),
child: Padding(
padding: const EdgeInsets.all(50.0),
child: Column(
mainAxisSize: MainAxisSize.min,
children: <Widget>[
Text('Downloaded: $progress'),
Text(message)
],
),
),
),
),
),
);
}
}

Answer 1

You can copy paste run full code below
You can use StreamBuilder to receive progress from onProgressUpdate
class HomePageState extends State<HomePage> {
...
#override
void initState() {
super.initState();
_events = new StreamController<int>.broadcast();;
_events.add(0);
ImageDownloader.callback(onProgressUpdate: (String imageId, int progress) {
setState(() {
print("progress $progress");
_progress = progress;
_events.add(progress);
});
return StreamBuilder<int>(
stream: _events.stream,
builder: (BuildContext context, AsyncSnapshot<int> snapshot) {
return Center(
...
children: <Widget>[
Text('Downloaded: ${snapshot.data.toString()}'),
Text(message)
working demo
full code
import 'package:flutter/material.dart';
import 'dart:async';
import 'dart:io';
import 'package:flutter/services.dart';
import 'package:image_downloader/image_downloader.dart';
void main() => runApp(MaterialApp(home: HomePage()));
class HomePage extends StatefulWidget {
#override
HomePageState createState() => HomePageState();
}
StreamController<int> _events;
class HomePageState extends State<HomePage> {
String message = "";
String path = "";
int _progress = 0;
#override
void initState() {
super.initState();
_events = new StreamController<int>.broadcast();
;
_events.add(0);
ImageDownloader.callback(onProgressUpdate: (String imageId, int progress) {
setState(() {
print("progress $progress");
_progress = progress;
_events.add(progress);
if (progress == 100) {
Navigator.pop(context);
}
});
});
}
#override
void dispose() {
// TODO: implement dispose
_events.close();
super.dispose();
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: const Text('Plugin example app'),
),
body: Center(
child: Column(
mainAxisSize: MainAxisSize.min,
children: <Widget>[
RaisedButton(
onPressed: () {
_events.add(0);
_downloadImage(
"https://images.unsplash.com/photo-1503023345310-bd7c1de61c7d?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&w=1000&q=80",
);
showDialog(
context: context,
builder: (_) => FunkyOverlay(
progress: _progress,
message: message,
),
);
},
child: Text("default destination"),
),
],
),
),
);
}
Future<void> _downloadImage(String url,
{AndroidDestinationType destination, bool whenError = false}) async {
String fileName;
String path;
try {
String imageId;
if (whenError) {
imageId = await ImageDownloader.downloadImage(url).catchError((error) {
if (error is PlatformException) {
var path = "";
if (error.code == "404") {
print("Not Found Error.");
} else if (error.code == "unsupported_file") {
print("UnSupported FIle Error.");
path = error.details["unsupported_file_path"];
}
setState(() {
message = error.toString();
path = path;
});
}
print(error);
}).timeout(Duration(seconds: 10), onTimeout: () {
print("timeout");
});
} else {
if (destination == null) {
imageId = await ImageDownloader.downloadImage(url);
} else {
imageId = await ImageDownloader.downloadImage(
url,
destination: destination,
);
}
}
if (imageId == null) {
print("imageId is null");
return;
}
fileName = await ImageDownloader.findName(imageId);
path = await ImageDownloader.findPath(imageId);
} on PlatformException catch (error) {
setState(() {
message = error.message;
});
return;
}
if (!mounted) return;
setState(() {
message = 'Image Downloaded';
});
}
}
class FunkyOverlay extends StatefulWidget {
String message;
int progress;
FunkyOverlay({#required this.message, #required this.progress});
#override
State<StatefulWidget> createState() => FunkyOverlayState(message, progress);
}
class FunkyOverlayState extends State<FunkyOverlay>
with SingleTickerProviderStateMixin {
String message;
int progress;
FunkyOverlayState(this.message, this.progress);
AnimationController controller;
Animation<double> scaleAnimation;
#override
void initState() {
super.initState();
controller =
AnimationController(vsync: this, duration: Duration(milliseconds: 450));
scaleAnimation =
CurvedAnimation(parent: controller, curve: Curves.elasticInOut);
controller.addListener(() {
setState(() {});
});
controller.forward();
}
#override
Widget build(BuildContext context) {
print("StreamBuilder build");
return StreamBuilder<int>(
stream: _events.stream,
builder: (BuildContext context, AsyncSnapshot<int> snapshot) {
print("snapshot.data ${snapshot.data.toString()}");
return Center(
child: Material(
color: Colors.transparent,
child: ScaleTransition(
scale: scaleAnimation,
child: Container(
decoration: ShapeDecoration(
color: Colors.white,
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(15.0),
),
),
child: Padding(
padding: const EdgeInsets.all(50.0),
child: Column(
mainAxisSize: MainAxisSize.min,
children: <Widget>[
Text('Downloaded: ${snapshot.data.toString()}'),
Text(message)
],
),
),
),
),
),
);
});
}
}