[flutter_markdown] MarkdownElementBuilder Fails to Support WidgetSpans in Text.rich #144383
Description
Steps to reproduce
- Set up a custom MarkdownElementBuilder
- Inside the
visitElementAfterWithContextfunction return aText.richwith aWidgetSpan
Expected results
The markdown library should support WidgetSpan inside Text.rich
Actual results
A error is thrown: type 'WidgetSpan' is not a subtype of type 'TextSpan' in type cast
Code sample
Code sample
import 'package:flutter/material.dart';
import 'package:flutter_markdown/flutter_markdown.dart';
import 'package:markdown/markdown.dart' as md;
void main() {
runApp(const MyApp());
}
class MyApp extends StatelessWidget {
const MyApp({super.key});
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
colorScheme: ColorScheme.fromSeed(seedColor: Colors.blue),
useMaterial3: true,
),
home: const MyHomePage(),
);
}
}
class MyHomePage extends StatelessWidget {
const MyHomePage({super.key});
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
backgroundColor: Theme.of(context).colorScheme.inversePrimary,
title: const Text('Markdown Demo'),
),
body: Markdown(
data: 'The terms foobar ...',
builders: <String, MarkdownElementBuilder>{
'sub': SubscriptBuilder(),
},
extensionSet: md.ExtensionSet(
<md.BlockSyntax>[],
<md.InlineSyntax>[SubscriptSyntax()],
),
),
);
}
}
class SubscriptBuilder extends MarkdownElementBuilder {
@override
Widget visitElementAfterWithContext(
BuildContext context,
md.Element element,
TextStyle? preferredStyle,
TextStyle? parentStyle,
) {
// This where the error happens
return Text.rich(WidgetSpan(
alignment: PlaceholderAlignment.middle,
child: Text(
element.textContent,
style: const TextStyle(color: Colors.red),
),
));
}
}
class SubscriptSyntax extends md.InlineSyntax {
SubscriptSyntax() : super(_pattern);
static const String _pattern = r'(foo)';
@override
bool onMatch(md.InlineParser parser, Match match) {
parser.addNode(md.Element.text('sub', match[1]!));
return true;
}
}Screenshots or Video
Screenshots / Video demonstration
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Logs
Logs
Performing hot restart...
Syncing files to device macOS...
Restarted application in 403ms.
======== Exception caught by widgets library =======================================================
The following _TypeError was thrown building KeyedSubtree-[GlobalKey#2c996]:
type 'WidgetSpan' is not a subtype of type 'TextSpan' in type cast
The relevant error-causing widget was:
Scaffold Scaffold:file:///Users/patrick/Code/markdown_demo/lib/main.dart:30:12
When the exception was thrown, this was the stack:
#0 MarkdownBuilder._mergeInlineChildren (package:flutter_markdown/src/builder.dart:727:38)
#1 MarkdownBuilder._addAnonymousBlockIfNeeded (package:flutter_markdown/src/builder.dart:689:42)
#2 MarkdownBuilder.visitElementAfter (package:flutter_markdown/src/builder.dart:373:7)
#3 Element.accept (package:markdown/src/ast.dart:53:15)
#4 MarkdownBuilder.build (package:flutter_markdown/src/builder.dart:193:12)
#5 _MarkdownWidgetState._parseMarkdown (package:flutter_markdown/src/widget.dart:360:25)
#6 _MarkdownWidgetState.didChangeDependencies (package:flutter_markdown/src/widget.dart:304:5)
#7 StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:5630:11)
#8 ComponentElement.mount (package:flutter/src/widgets/framework.dart:5457:5)
... Normal element mounting (25 frames)
#33 Element.inflateWidget (package:flutter/src/widgets/framework.dart:4336:16)
#34 MultiChildRenderObjectElement.inflateWidget (package:flutter/src/widgets/framework.dart:6896:36)
#35 MultiChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:6908:32)
... Normal element mounting (134 frames)
#169 Element.inflateWidget (package:flutter/src/widgets/framework.dart:4336:16)
#170 MultiChildRenderObjectElement.inflateWidget (package:flutter/src/widgets/framework.dart:6896:36)
#171 MultiChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:6908:32)
... Normal element mounting (178 frames)
#349 Element.inflateWidget (package:flutter/src/widgets/framework.dart:4336:16)
#350 MultiChildRenderObjectElement.inflateWidget (package:flutter/src/widgets/framework.dart:6896:36)
#351 MultiChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:6908:32)
... Normal element mounting (514 frames)
#865 Element.inflateWidget (package:flutter/src/widgets/framework.dart:4336:16)
#866 Element.updateChild (package:flutter/src/widgets/framework.dart:3847:18)
#867 _RawViewElement._updateChild (package:flutter/src/widgets/view.dart:291:16)
#868 _RawViewElement.mount (package:flutter/src/widgets/view.dart:314:5)
... Normal element mounting (7 frames)
#875 Element.inflateWidget (package:flutter/src/widgets/framework.dart:4336:16)
#876 Element.updateChild (package:flutter/src/widgets/framework.dart:3847:18)
#877 RootElement._rebuild (package:flutter/src/widgets/binding.dart:1434:16)
#878 RootElement.mount (package:flutter/src/widgets/binding.dart:1403:5)
#879 RootWidget.attach.<anonymous closure> (package:flutter/src/widgets/binding.dart:1356:18)
#880 BuildOwner.buildScope (package:flutter/src/widgets/framework.dart:2845:19)
#881 RootWidget.attach (package:flutter/src/widgets/binding.dart:1355:13)
#882 WidgetsBinding.attachToBuildOwner (package:flutter/src/widgets/binding.dart:1092:27)
#883 WidgetsBinding.attachRootWidget (package:flutter/src/widgets/binding.dart:1074:5)
#884 WidgetsBinding.scheduleAttachRootWidget.<anonymous closure> (package:flutter/src/widgets/binding.dart:1060:7)
#888 _RawReceivePort._handleMessage (dart:isolate-patch/isolate_patch.dart:184:12)
(elided 3 frames from class _Timer and dart:async-patch)
====================================================================================================
======== Exception caught by widgets library =======================================================
The following _TypeError was thrown building KeyedSubtree-[GlobalKey#2c996]:
type 'WidgetSpan' is not a subtype of type 'TextSpan' in type cast
The relevant error-causing widget was:
Scaffold Scaffold:file:///Users/patrick/Code/markdown_demo/lib/main.dart:30:12
When the exception was thrown, this was the stack:
#0 MarkdownBuilder._mergeInlineChildren (package:flutter_markdown/src/builder.dart:727:38)
#1 MarkdownBuilder._addAnonymousBlockIfNeeded (package:flutter_markdown/src/builder.dart:689:42)
#2 MarkdownBuilder.visitElementAfter (package:flutter_markdown/src/builder.dart:373:7)
#3 Element.accept (package:markdown/src/ast.dart:53:15)
#4 MarkdownBuilder.build (package:flutter_markdown/src/builder.dart:193:12)
#5 _MarkdownWidgetState._parseMarkdown (package:flutter_markdown/src/widget.dart:360:25)
#6 _MarkdownWidgetState.didChangeDependencies (package:flutter_markdown/src/widget.dart:304:5)
#7 StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:5630:11)
#8 ComponentElement.mount (package:flutter/src/widgets/framework.dart:5457:5)
#9 Element.inflateWidget (package:flutter/src/widgets/framework.dart:4336:16)
#10 Element.updateChild (package:flutter/src/widgets/framework.dart:3841:20)
#11 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:5506:16)
#12 Element.rebuild (package:flutter/src/widgets/framework.dart:5197:7)
#13 StatelessElement.update (package:flutter/src/widgets/framework.dart:5557:5)
#14 Element.updateChild (package:flutter/src/widgets/framework.dart:3825:15)
#15 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:5506:16)
#16 Element.rebuild (package:flutter/src/widgets/framework.dart:5197:7)
#17 StatelessElement.update (package:flutter/src/widgets/framework.dart:5557:5)
#18 Element.updateChild (package:flutter/src/widgets/framework.dart:3825:15)
#19 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:5506:16)
#20 Element.rebuild (package:flutter/src/widgets/framework.dart:5197:7)
#21 ProxyElement.update (package:flutter/src/widgets/framework.dart:5810:5)
#22 Element.updateChild (package:flutter/src/widgets/framework.dart:3825:15)
#23 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:5506:16)
#24 Element.rebuild (package:flutter/src/widgets/framework.dart:5197:7)
#25 ProxyElement.update (package:flutter/src/widgets/framework.dart:5810:5)
#26 Element.updateChild (package:flutter/src/widgets/framework.dart:3825:15)
#27 Element.updateChildren (package:flutter/src/widgets/framework.dart:3974:32)
#28 MultiChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:6921:17)
#29 Element.updateChild (package:flutter/src/widgets/framework.dart:3825:15)
#30 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:5506:16)
#31 Element.rebuild (package:flutter/src/widgets/framework.dart:5197:7)
#32 ProxyElement.update (package:flutter/src/widgets/framework.dart:5810:5)
#33 Element.updateChild (package:flutter/src/widgets/framework.dart:3825:15)
#34 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:5506:16)
#35 StatefulElement.performRebuild (package:flutter/src/widgets/framework.dart:5644:11)
#36 Element.rebuild (package:flutter/src/widgets/framework.dart:5197:7)
#37 StatefulElement.update (package:flutter/src/widgets/framework.dart:5667:5)
#38 Element.updateChild (package:flutter/src/widgets/framework.dart:3825:15)
#39 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:5506:16)
#40 StatefulElement.performRebuild (package:flutter/src/widgets/framework.dart:5644:11)
#41 Element.rebuild (package:flutter/src/widgets/framework.dart:5197:7)
#42 StatefulElement.update (package:flutter/src/widgets/framework.dart:5667:5)
#43 Element.updateChild (package:flutter/src/widgets/framework.dart:3825:15)
#44 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:5506:16)
#45 Element.rebuild (package:flutter/src/widgets/framework.dart:5197:7)
#46 ProxyElement.update (package:flutter/src/widgets/framework.dart:5810:5)
#47 Element.updateChild (package:flutter/src/widgets/framework.dart:3825:15)
#48 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:5506:16)
#49 StatefulElement.performRebuild (package:flutter/src/widgets/framework.dart:5644:11)
#50 Element.rebuild (package:flutter/src/widgets/framework.dart:5197:7)
#51 StatefulElement.update (package:flutter/src/widgets/framework.dart:5667:5)
#52 Element.updateChild (package:flutter/src/widgets/framework.dart:3825:15)
#53 SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:6768:14)
#54 Element.updateChild (package:flutter/src/widgets/framework.dart:3825:15)
#55 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:5506:16)
#56 Element.rebuild (package:flutter/src/widgets/framework.dart:5197:7)
#57 ProxyElement.update (package:flutter/src/widgets/framework.dart:5810:5)
#58 Element.updateChild (package:flutter/src/widgets/framework.dart:3825:15)
#59 SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:6768:14)
#60 Element.updateChild (package:flutter/src/widgets/framework.dart:3825:15)
#61 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:5506:16)
#62 StatefulElement.performRebuild (package:flutter/src/widgets/framework.dart:5644:11)
#63 Element.rebuild (package:flutter/src/widgets/framework.dart:5197:7)
#64 StatefulElement.update (package:flutter/src/widgets/framework.dart:5667:5)
#65 Element.updateChild (package:flutter/src/widgets/framework.dart:3825:15)
#66 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:5506:16)
#67 StatefulElement.performRebuild (package:flutter/src/widgets/framework.dart:5644:11)
#68 Element.rebuild (package:flutter/src/widgets/framework.dart:5197:7)
#69 StatefulElement.update (package:flutter/src/widgets/framework.dart:5667:5)
#70 Element.updateChild (package:flutter/src/widgets/framework.dart:3825:15)
#71 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:5506:16)
#72 Element.rebuild (package:flutter/src/widgets/framework.dart:5197:7)
#73 ProxyElement.update (package:flutter/src/widgets/framework.dart:5810:5)
#74 Element.updateChild (package:flutter/src/widgets/framework.dart:3825:15)
#75 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:5506:16)
#76 Element.rebuild (package:flutter/src/widgets/framework.dart:5197:7)
#77 ProxyElement.update (package:flutter/src/widgets/framework.dart:5810:5)
#78 Element.updateChild (package:flutter/src/widgets/framework.dart:3825:15)
#79 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:5506:16)
#80 Element.rebuild (package:flutter/src/widgets/framework.dart:5197:7)
#81 ProxyElement.update (package:flutter/src/widgets/framework.dart:5810:5)
#82 Element.updateChild (package:flutter/src/widgets/framework.dart:3825:15)
#83 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:5506:16)
#84 StatefulElement.performRebuild (package:flutter/src/widgets/framework.dart:5644:11)
#85 Element.rebuild (package:flutter/src/widgets/framework.dart:5197:7)
#86 StatefulElement.update (package:flutter/src/widgets/framework.dart:5667:5)
#87 Element.updateChild (package:flutter/src/widgets/framework.dart:3825:15)
#88 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:5506:16)
#89 Element.rebuild (package:flutter/src/widgets/framework.dart:5197:7)
#90 ProxyElement.update (package:flutter/src/widgets/framework.dart:5810:5)
#91 Element.updateChild (package:flutter/src/widgets/framework.dart:3825:15)
#92 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:5506:16)
#93 StatefulElement.performRebuild (package:flutter/src/widgets/framework.dart:5644:11)
#94 Element.rebuild (package:flutter/src/widgets/framework.dart:5197:7)
#95 StatefulElement.update (package:flutter/src/widgets/framework.dart:5667:5)
#96 Element.updateChild (package:flutter/src/widgets/framework.dart:3825:15)
#97 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:5506:16)
#98 Element.rebuild (package:flutter/src/widgets/framework.dart:5197:7)
#99 BuildOwner.buildScope (package:flutter/src/widgets/framework.dart:2905:19)
#100 WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:993:21)
#101 RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:443:5)
#102 SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:1387:15)
#103 SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:1312:9)
#104 SchedulerBinding.scheduleWarmUpFrame.<anonymous closure> (package:flutter/src/scheduler/binding.dart:1035:7)
#108 _RawReceivePort._handleMessage (dart:isolate-patch/isolate_patch.dart:184:12)
(elided 3 frames from class _Timer and dart:async-patch)
====================================================================================================Flutter Doctor output
Doctor output
[✓] Flutter (Channel beta, 3.20.0-1.2.pre, on macOS 14.3.1 23D60 darwin-arm64, locale en-US)
• Flutter version 3.20.0-1.2.pre on channel beta at /Users/patrick/Development/flutter
• Upstream repository https://github.com/flutter/flutter.git
• Framework revision 1751123cde (7 days ago), 2024-02-21 22:06:22 -0800
• Engine revision 299e852cb9
• Dart version 3.4.0 (build 3.4.0-99.1.beta)
• DevTools version 2.31.0
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Run `path/to/sdkmanager --install "cmdline-tools;latest"`
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Run `flutter doctor --android-licenses` to accept the SDK licenses.
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• Build 15C500b
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• Java version OpenJDK Runtime Environment (build 17.0.7+0-17.0.7b1000.6-10550314)
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• VS Code at /Applications/Visual Studio Code.app/Contents
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[✓] Connected device (5 available)
• macOS (desktop) • macos • darwin-arm64 • macOS 14.3.1 23D60 darwin-arm64
• Mac Designed for iPad (desktop) • mac-designed-for-ipad • darwin • macOS 14.3.1 23D60 darwin-arm64
• Chrome (web) • chrome • web-javascript • Google Chrome 122.0.6261.94
! Error: Browsing on the local area network for Patrick’s Apple Watch. Ensure the device is unlocked and discoverable via Bluetooth. (code -27)
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