flutter_widget_from_html
flutter_widget_from_html copied to clipboard
daohoangson
PDF does't render on Android but it works fine on web.
Simply try this HTML with below piece of Code on Android and you will see a black page as result. But you will see the PDF as you run app on Flutter Web. Tried these two versions but result is same: fwfh_webview: ^0.15.3 fwfh_webview: ^0.15.6
This HTML works perfectly on web but it displays a back page on Android. I have attached the Code sample below.
class PageContentEmbed extends StatelessWidget {
final String htmlString;
const PageContentEmbed(this.htmlString, {Key? key}) : super(key: key);
@override
Widget build(BuildContext context) {
return HtmlWidget(
htmlString,
factoryBuilder: () => MyWidgetFactory(),
);
}
}
class MyWidgetFactory extends WidgetFactory with WebViewFactory {
// optional: override getter to configure how WebViews are built
@override
bool get webViewMediaPlaybackAlwaysAllow => true;
@override
String? get webViewUserAgent => 'My app';
}
###Attached screenshot of my web app where it works fine and same behaviour is expected on Android
###This is what I see on Android:
[✓] Flutter (Channel stable, 3.35.3, on macOS 26.0.1 25A362 darwin-arm64, locale en-PK) [244ms]
• Flutter version 3.35.3 on channel stable at /Users/niklas/Documents/sdks/3.35.3/flutter
• Upstream repository https://github.com/flutter/flutter.git
• Framework revision a402d9a437 (5 weeks ago), 2025-09-03 14:54:31 -0700
• Engine revision ddf47dd3ff
• Dart version 3.9.2
• DevTools version 2.48.0
• Feature flags: enable-web, enable-linux-desktop, enable-macos-desktop, enable-windows-desktop, enable-android, enable-ios, cli-animations, enable-lldb-debugging
[✓] Android toolchain - develop for Android devices (Android SDK version 36.1.0-rc1) [998ms]
• Android SDK at /Users/niklas/Library/Android/sdk
• Emulator version 35.3.11.0 (build_id 12836668) (CL:N/A)
• Platform android-36, build-tools 36.1.0-rc1
• ANDROID_HOME = /Users/niklas/Library/Android/sdk
• Java binary at: /Users/niklas/Library/Java/JavaVirtualMachines/corretto-17.0.14/Contents/Home/bin/java
This JDK is specified in your Flutter configuration.
To change the current JDK, run: `flutter config --jdk-dir="path/to/jdk"`.
• Java version OpenJDK Runtime Environment Corretto-17.0.14.7.1 (build 17.0.14+7-LTS)
• All Android licenses accepted.
[✓] Xcode - develop for iOS and macOS (Xcode 26.0.1) [942ms]
• Xcode at /Applications/Xcode.app/Contents/Developer
• Build 17A400
• CocoaPods version 1.16.2
[✓] Chrome - develop for the web [7ms]
• Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome
[✓] Android Studio (version 2024.2) [7ms]
• Android Studio at /Applications/Android Studio.app/Contents
• Flutter plugin can be installed from:
🔨 https://plugins.jetbrains.com/plugin/9212-flutter
• Dart plugin can be installed from:
🔨 https://plugins.jetbrains.com/plugin/6351-dart
• Java version OpenJDK Runtime Environment (build 21.0.4+-12422083-b607.1)
[✓] Connected device (3 available) [6.1s]
• V2249 (mobile) • 10FD8R02B40003D • android-arm64 • Android 15 (API 35)
• macOS (desktop) • macos • darwin-arm64 • macOS 26.0.1 25A362 darwin-arm64
• Chrome (web) • chrome • web-javascript • Google Chrome 141.0.7390.55
[✓] Network resources [974ms]
• All expected network resources are available.
• No issues found!
Because Android WebView doesn't support PDF directly. You have to use Google Docs viewer or something similar
<iframe class="bespokely-embed" src="https://docs.google.com/gview?embedded=true&url=https://dm6lfrfdj0fil.cloudfront.net/attachments/attachments/000/000/471/original/Markdown_Support.pdf" frameborder="0" onmousewheel="" style="background:transparent;"></iframe>
Tried it but no change and seeing an exception in the logs
I/flutter (27961): PageContentEmbed.build <iframe class="bespokely-embed" src="https://docs.google.com/gview?embedded=true&url=https://dm6lfrfdj0fil.cloudfront.net/attachments/attachments/000/000/471/original/Markdown_Support.pdf" frameborder="0" onmousewheel="" width="392.72727272727275" height="848.7272727272727" style="background:transparent;"></iframe>
======== Exception caught by services library ======================================================
The following assertion was thrown during a platform message callback:
Argument for dev.flutter.pigeon.webview_flutter_android.DownloadListener.onDownloadStart was null, expected non-null DownloadListener.
'package:webview_flutter_android/src/android_webkit.g.dart':
Failed assertion: line 3924 pos 18: 'arg_pigeon_instance != null'
When the exception was thrown, this was the stack:
#2 DownloadListener.pigeon_setUpMessageHandlers.<anonymous closure> (package:webview_flutter_android/src/android_webkit.g.dart:3924:18)
#3 BasicMessageChannel.setMessageHandler.<anonymous closure> (package:flutter/src/services/platform_channel.dart:259:49)
#4 _DefaultBinaryMessenger.setMessageHandler.<anonymous closure> (package:flutter/src/services/binding.dart:653:35)
#5 _invoke2 (dart:ui/hooks.dart:362:13)
#6 _ChannelCallbackRecord.invoke (dart:ui/channel_buffers.dart:45:5)
#7 _Channel._drainStep (dart:ui/channel_buffers.dart:229:31)
(elided 4 frames from class _AssertionError and dart:async)
====================================================================================================
======== Exception caught by services library ======================================================
The following assertion was thrown during a platform message callback:
Argument for dev.flutter.pigeon.webview_flutter_android.WebChromeClient.onProgressChanged was null, expected non-null WebChromeClient.
'package:webview_flutter_android/src/android_webkit.g.dart':
Failed assertion: line 4439 pos 18: 'arg_pigeon_instance != null'
When the exception was thrown, this was the stack:
#2 WebChromeClient.pigeon_setUpMessageHandlers.<anonymous closure> (package:webview_flutter_android/src/android_webkit.g.dart:4439:18)
#3 BasicMessageChannel.setMessageHandler.<anonymous closure> (package:flutter/src/services/platform_channel.dart:259:49)
#4 _DefaultBinaryMessenger.setMessageHandler.<anonymous closure> (package:flutter/src/services/binding.dart:653:35)
#5 _invoke2 (dart:ui/hooks.dart:362:13)
#6 _ChannelCallbackRecord.invoke (dart:ui/channel_buffers.dart:45:5)
#7 _Channel._drainStep (dart:ui/channel_buffers.dart:229:31)
(elided 4 frames from class _AssertionError and dart:async)