I'm trying create a function to load images in Flutter (Dart) but not sure how to get this code working. I'm getting:
A value of type 'Future' can't be assigned to a variable of type 'Image'. Try changing the type of the variable, or casting the right-hand type to 'Image'.
import 'dart:typed_data';
import 'dart:ui' as ui;
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
home: MyHomePage(),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key}) : super(key: key);
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
ui.Image _backgroundImage;
Future<ui.Image> loadImage(imageString) async {
ByteData bd = await rootBundle.load(imageString);
// ByteData bd = await rootBundle.load("graphics/bar-1920×1080.jpg");
final Uint8List bytes = Uint8List.view(bd.buffer);
final ui.Codec codec = await ui.instantiateImageCodec(bytes);
final ui.Image image = (await codec.getNextFrame()).image;
return image;
// setState(() => imageStateVarible = image);
}
@override
Widget build(BuildContext context) {
setState( () => {
_backgroundImage = loadImage('imageNameString'); // <<== ISSUE: A value of type 'Future<Image>' can't be assigned to a variable of type 'Image'
});
return Scaffold(
body: Center(
child: Text('testing'),
),
);
}
}
Try this. Your problem is:
import 'dart:typed_data';
import 'dart:ui' as ui;
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
home: MyHomePage(),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key}) : super(key: key);
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
ui.Image _backgroundImage;
@override
void initState() {
super.initState();
_asyncInit();
}
Future<void> _asyncInit() async {
final image = await loadImage('imageNameString');
setState(() {
_backgroundImage = image;
});
}
Future<ui.Image> loadImage(imageString) async {
ByteData bd = await rootBundle.load(imageString);
// ByteData bd = await rootBundle.load("graphics/bar-1920×1080.jpg");
final Uint8List bytes = Uint8List.view(bd.buffer);
final ui.Codec codec = await ui.instantiateImageCodec(bytes);
final ui.Image image = (await codec.getNextFrame()).image;
return image;
// setState(() => imageStateVarible = image);
}
@override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: _backgroundImage != null ? YourWidget(_backgroundImage) : Text('you are loading that image'),
),
);
}
}
EDIT :
If you want an array of images:
import 'dart:typed_data';
import 'dart:ui' as ui;
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
home: MyHomePage(),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key}) : super(key: key);
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
List<ui.Image> _backgroundImages;
@override
void initState() {
super.initState();
_asyncInit();
}
Future<void> _asyncInit() async {
final imageNames = ['firstimage', 'secondimage', 'thirdimage'];
// NOTE by doing this, your images are loaded **simutanously** instead of **waiting for one to finish before starting the next**
final futures = [for (final name in imageNames) loadImage(name)];
final images = await Future.wait(futures);
setState(() {
_backgroundImages = images;
});
}
Future<ui.Image> loadImage(imageString) async {
ByteData bd = await rootBundle.load(imageString);
// ByteData bd = await rootBundle.load("graphics/bar-1920×1080.jpg");
final Uint8List bytes = Uint8List.view(bd.buffer);
final ui.Codec codec = await ui.instantiateImageCodec(bytes);
final ui.Image image = (await codec.getNextFrame()).image;
return image;
// setState(() => imageStateVarible = image);
}
@override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: _backgroundImages != null ? YourWidget(_backgroundImages) : Text('you are loading that image'),
),
);
}
}
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