Closed
Description
Small but easy issue: docs for Image's loadingBuilder don't show the ImageChunkEvent param as optional. Docs just need to have the ? to show the implementation
Steps to Reproduce
- Execute
flutter runon the code sample
Expected results: Flutter logo loads
Actual results: Dart fails to compile
Code sample
import 'package:flutter/material.dart';
void main() {
runApp(
MaterialApp(
title: "Example",
home: Image.network(
// Flutter logo
"https://storage.googleapis.com/cms-storage-bucket/c823e53b3a1a7b0d36a9.png",
// Non-working code, copied directly from documentation
// Works if ImageChunkEvent is marked as optional with ?
loadingBuilder: (BuildContext context, Widget child, ImageChunkEvent loadingProgress) {
return Center(child: child);
},
),
),
);
}
Logs
lib/example.dart:9:25: Error: The argument type 'Center Function(BuildContext, Widget, ImageChunkEvent)' can't be assigned to the parameter type 'Widget Function(BuildContext, Widget, ImageChunkEvent?)?' because 'ImageChunkEvent?' is nullable and 'ImageChunkEvent' isn't.
- 'Center' is from 'package:flutter/src/widgets/basic.dart' ('/usr/local/Caskroom/flutter/3.0.5/flutter/packages/flutter/lib/src/widgets/basic.dart').
- 'BuildContext' is from 'package:flutter/src/widgets/framework.dart' ('/usr/local/Caskroom/flutter/3.0.5/flutter/packages/flutter/lib/src/widgets/framework.dart').
- 'Widget' is from 'package:flutter/src/widgets/framework.dart' ('/usr/local/Caskroom/flutter/3.0.5/flutter/packages/flutter/lib/src/widgets/framework.dart').
- 'ImageChunkEvent' is from 'package:flutter/src/painting/image_stream.dart' ('/usr/local/Caskroom/flutter/3.0.5/flutter/packages/flutter/lib/src/painting/image_stream.dart').
loadingBuilder: (BuildContext context, Widget child, ImageChunkEvent loadingProgress) {
^
error • The argument type 'Center Function(BuildContext, Widget, ImageChunkEvent)' can't be assigned to the parameter type 'Widget Function(BuildContext, Widget, ImageChunkEvent?)?' • lib/example.dart:13:25 • argument_type_not_assignable
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