packages/webview_flutter/webview_flutter_wkwebview/example/lib/main.dart - mirrors/plugins - Git at Google

 // Copyright 2013 The Flutter Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 // ignore_for_file: public_member_api_docs

 import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
 import 'dart:typed_data';

 import 'package:flutter/material.dart';
 import 'package:path_provider/path_provider.dart';
 import 'package:webview_flutter_platform_interface/webview_flutter_platform_interface.dart';

 import 'navigation_decision.dart';
 import 'navigation_request.dart';
 import 'web_view.dart';

 void main() {
   runApp(const MaterialApp(home: _WebViewExample()));
 }

 const String kNavigationExamplePage = '''
 <!DOCTYPE html><html>
 <head><title>Navigation Delegate Example</title></head>
 <body>
 <p>
 The navigation delegate is set to block navigation to the youtube website.
 </p>
 <ul>
 <ul><a href="https://www.youtube.com/">https://www.youtube.com/</a></ul>
 <ul><a href="https://www.google.com/">https://www.google.com/</a></ul>
 </ul>
 </body>
 </html>
 ''';

 const String kTransparentBackgroundPage = '''
 <!DOCTYPE html>
 <html>
 <head>
   <title>Transparent background test</title>
 </head>
 <style type="text/css">
   body { background: transparent; margin: 0; padding: 0; }
   #container { position: relative; margin: 0; padding: 0; width: 100vw; height: 100vh; }
   #shape { background: #FF0000; width: 200px; height: 100%; margin: 0; padding: 0; position: absolute; top: 0; bottom: 0; left: calc(50% - 100px); }
   p { text-align: center; }
 </style>
 <body>
   <div id="container">
     <p>Transparent background test</p>
     <div id="shape"></div>
   </div>
 </body>
 </html>
 ''';

 const String kLocalFileExamplePage = '''
 <!DOCTYPE html>
 <html lang="en">
 <head>
 <title>Load file or HTML string example</title>
 </head>
 <body>

 <h1>Local demo page</h1>
 <p>
   This is an example page used to demonstrate how to load a local file or HTML
   string using the <a href="https://pub.dev/packages/webview_flutter">Flutter
   webview</a> plugin.
 </p>

 </body>
 </html>
 ''';

 class _WebViewExample extends StatefulWidget {
   const _WebViewExample({Key? key}) : super(key: key);

   @override
   _WebViewExampleState createState() => _WebViewExampleState();
 }

 class _WebViewExampleState extends State<_WebViewExample> {
   final Completer<WebViewController> _controller =
       Completer<WebViewController>();

   @override
   void initState() {
     super.initState();
   }

   @override
   Widget build(BuildContext context) {
     return Scaffold(
       backgroundColor: const Color(0xFF4CAF50),
       appBar: AppBar(
         title: const Text('Flutter WebView example'),
         // This drop down menu demonstrates that Flutter widgets can be shown over the web view.
         actions: <Widget>[
           _NavigationControls(_controller.future),
           _SampleMenu(_controller.future),
         ],
       ),
       body: WebView(
         initialUrl: 'https://flutter.dev/',
         onWebViewCreated: (WebViewController controller) {
           _controller.complete(controller);
         },
         javascriptChannels: _createJavascriptChannels(context),
         javascriptMode: JavascriptMode.unrestricted,
         navigationDelegate: (NavigationRequest request) {
           if (request.url.startsWith('https://www.youtube.com/')) {
             print('blocking navigation to $request}');
             return NavigationDecision.prevent;
           }
           print('allowing navigation to $request');
           return NavigationDecision.navigate;
         },
         backgroundColor: const Color(0x80000000),
       ),
       floatingActionButton: favoriteButton(),
     );
   }

   Widget favoriteButton() {
     return FutureBuilder<WebViewController>(
         future: _controller.future,
         builder: (BuildContext context,
             AsyncSnapshot<WebViewController> controller) {
           if (controller.hasData) {
             return FloatingActionButton(
               onPressed: () async {
                 final String url = (await controller.data!.currentUrl())!;
                 ScaffoldMessenger.of(context).showSnackBar(
                   SnackBar(content: Text('Favorited $url')),
                 );
               },
               child: const Icon(Icons.favorite),
             );
           }
           return Container();
         });
   }
 }

 Set<JavascriptChannel> _createJavascriptChannels(BuildContext context) {
   return <JavascriptChannel>{
     JavascriptChannel(
         name: 'Snackbar',
         onMessageReceived: (JavascriptMessage message) {
           ScaffoldMessenger.of(context)
               .showSnackBar(SnackBar(content: Text(message.message)));
         }),
   };
 }

 enum _MenuOptions {
   showUserAgent,
   listCookies,
   clearCookies,
   addToCache,
   listCache,
   clearCache,
   navigationDelegate,
   loadFlutterAsset,
   loadLocalFile,
   loadHtmlString,
   doPostRequest,
   setCookie,
   transparentBackground,
 }

 class _SampleMenu extends StatelessWidget {
   const _SampleMenu(this.controller);

   final Future<WebViewController> controller;

   @override
   Widget build(BuildContext context) {
     return FutureBuilder<WebViewController>(
       future: controller,
       builder:
           (BuildContext context, AsyncSnapshot<WebViewController> controller) {
         return PopupMenuButton<_MenuOptions>(
           key: const ValueKey<String>('ShowPopupMenu'),
           onSelected: (_MenuOptions value) {
             switch (value) {
               case _MenuOptions.showUserAgent:
                 _onShowUserAgent(controller.data!, context);
                 break;
               case _MenuOptions.listCookies:
                 _onListCookies(controller.data!, context);
                 break;
               case _MenuOptions.clearCookies:
                 _onClearCookies(controller.data!, context);
                 break;
               case _MenuOptions.addToCache:
                 _onAddToCache(controller.data!, context);
                 break;
               case _MenuOptions.listCache:
                 _onListCache(controller.data!, context);
                 break;
               case _MenuOptions.clearCache:
                 _onClearCache(controller.data!, context);
                 break;
               case _MenuOptions.navigationDelegate:
                 _onNavigationDelegateExample(controller.data!, context);
                 break;
               case _MenuOptions.loadFlutterAsset:
                 _onLoadFlutterAssetExample(controller.data!, context);
                 break;
               case _MenuOptions.loadLocalFile:
                 _onLoadLocalFileExample(controller.data!, context);
                 break;
               case _MenuOptions.loadHtmlString:
                 _onLoadHtmlStringExample(controller.data!, context);
                 break;
               case _MenuOptions.doPostRequest:
                 _onDoPostRequest(controller.data!, context);
                 break;
               case _MenuOptions.setCookie:
                 _onSetCookie(controller.data!, context);
                 break;
               case _MenuOptions.transparentBackground:
                 _onTransparentBackground(controller.data!, context);
                 break;
             }
           },
           itemBuilder: (BuildContext context) => <PopupMenuItem<_MenuOptions>>[
             PopupMenuItem<_MenuOptions>(
               value: _MenuOptions.showUserAgent,
               enabled: controller.hasData,
               child: const Text('Show user agent'),
             ),
             const PopupMenuItem<_MenuOptions>(
               value: _MenuOptions.listCookies,
               child: Text('List cookies'),
             ),
             const PopupMenuItem<_MenuOptions>(
               value: _MenuOptions.clearCookies,
               child: Text('Clear cookies'),
             ),
             const PopupMenuItem<_MenuOptions>(
               value: _MenuOptions.addToCache,
               child: Text('Add to cache'),
             ),
             const PopupMenuItem<_MenuOptions>(
               value: _MenuOptions.listCache,
               child: Text('List cache'),
             ),
             const PopupMenuItem<_MenuOptions>(
               value: _MenuOptions.clearCache,
               child: Text('Clear cache'),
             ),
             const PopupMenuItem<_MenuOptions>(
               value: _MenuOptions.navigationDelegate,
               child: Text('Navigation Delegate example'),
             ),
             const PopupMenuItem<_MenuOptions>(
               value: _MenuOptions.loadFlutterAsset,
               child: Text('Load Flutter Asset'),
             ),
             const PopupMenuItem<_MenuOptions>(
               value: _MenuOptions.loadHtmlString,
               child: Text('Load HTML string'),
             ),
             const PopupMenuItem<_MenuOptions>(
               value: _MenuOptions.loadLocalFile,
               child: Text('Load local file'),
             ),
             const PopupMenuItem<_MenuOptions>(
               value: _MenuOptions.doPostRequest,
               child: Text('Post Request'),
             ),
             const PopupMenuItem<_MenuOptions>(
               value: _MenuOptions.setCookie,
               child: Text('Set Cookie'),
             ),
             const PopupMenuItem<_MenuOptions>(
               key: ValueKey<String>('ShowTransparentBackgroundExample'),
               value: _MenuOptions.transparentBackground,
               child: Text('Transparent background example'),
             ),
           ],
         );
       },
     );
   }

   Future<void> _onShowUserAgent(
       WebViewController controller, BuildContext context) async {
     // Send a message with the user agent string to the Snackbar JavaScript channel we registered
     // with the WebView.
     await controller.runJavascript(
         'Snackbar.postMessage("User Agent: " + navigator.userAgent);');
   }

   Future<void> _onListCookies(
       WebViewController controller, BuildContext context) async {
     final String cookies =
         await controller.runJavascriptReturningResult('document.cookie');
     ScaffoldMessenger.of(context).showSnackBar(SnackBar(
       content: Column(
         mainAxisAlignment: MainAxisAlignment.end,
         mainAxisSize: MainAxisSize.min,
         children: <Widget>[
           const Text('Cookies:'),
           _getCookieList(cookies),
         ],
       ),
     ));
   }

   Future<void> _onAddToCache(
       WebViewController controller, BuildContext context) async {
     await controller.runJavascript(
         'caches.open("test_caches_entry"); localStorage["test_localStorage"] = "dummy_entry";');
     ScaffoldMessenger.of(context).showSnackBar(const SnackBar(
       content: Text('Added a test entry to cache.'),
     ));
   }

   Future<void> _onListCache(
       WebViewController controller, BuildContext context) async {
     await controller.runJavascript('caches.keys()'
         '.then((cacheKeys) => JSON.stringify({"cacheKeys" : cacheKeys, "localStorage" : localStorage}))'
         '.then((caches) => Snackbar.postMessage(caches))');
   }

   Future<void> _onClearCache(
       WebViewController controller, BuildContext context) async {
     await controller.clearCache();
     ScaffoldMessenger.of(context).showSnackBar(const SnackBar(
       content: Text('Cache cleared.'),
     ));
   }

   Future<void> _onClearCookies(
       WebViewController controller, BuildContext context) async {
     final bool hadCookies = await WebView.platform.clearCookies();
     String message = 'There were cookies. Now, they are gone!';
     if (!hadCookies) {
       message = 'There are no cookies.';
     }
     ScaffoldMessenger.of(context).showSnackBar(SnackBar(
       content: Text(message),
     ));
   }

   Future<void> _onNavigationDelegateExample(
       WebViewController controller, BuildContext context) async {
     final String contentBase64 =
         base64Encode(const Utf8Encoder().convert(kNavigationExamplePage));
     await controller.loadUrl('data:text/html;base64,$contentBase64');
   }

   Future<void> _onLoadFlutterAssetExample(
       WebViewController controller, BuildContext context) async {
     await controller.loadFlutterAsset('assets/www/index.html');
   }

   Future<void> _onLoadLocalFileExample(
       WebViewController controller, BuildContext context) async {
     final String pathToIndex = await _prepareLocalFile();

     await controller.loadFile(pathToIndex);
   }

   Future<void> _onLoadHtmlStringExample(
       WebViewController controller, BuildContext context) async {
     await controller.loadHtmlString(kLocalFileExamplePage);
   }

   Future<void> _onDoPostRequest(
       WebViewController controller, BuildContext context) async {
     final WebViewRequest request = WebViewRequest(
       uri: Uri.parse('https://httpbin.org/post'),
       method: WebViewRequestMethod.post,
       headers: <String, String>{'foo': 'bar', 'Content-Type': 'text/plain'},
       body: Uint8List.fromList('Test Body'.codeUnits),
     );
     await controller.loadRequest(request);
   }

   Future<void> _onSetCookie(
       WebViewController controller, BuildContext context) async {
     await WebViewCookieManager.instance.setCookie(
       const WebViewCookie(
           name: 'foo', value: 'bar', domain: 'httpbin.org', path: '/anything'),
     );
     await controller.loadUrl('https://httpbin.org/anything');
   }

   Widget _getCookieList(String cookies) {
     if (cookies == null || cookies == '""') {
       return Container();
     }
     final List<String> cookieList = cookies.split(';');
     final Iterable<Text> cookieWidgets =
         cookieList.map((String cookie) => Text(cookie));
     return Column(
       mainAxisAlignment: MainAxisAlignment.end,
       mainAxisSize: MainAxisSize.min,
       children: cookieWidgets.toList(),
     );
   }

   Future<void> _onTransparentBackground(
       WebViewController controller, BuildContext context) async {
     await controller.loadHtmlString(kTransparentBackgroundPage);
   }

   static Future<String> _prepareLocalFile() async {
     final String tmpDir = (await getTemporaryDirectory()).path;
     final File indexFile = File('$tmpDir/www/index.html');

     await Directory('$tmpDir/www').create(recursive: true);
     await indexFile.writeAsString(kLocalFileExamplePage);

     return indexFile.path;
   }
 }

 class _NavigationControls extends StatelessWidget {
   const _NavigationControls(this._webViewControllerFuture)
       : assert(_webViewControllerFuture != null);

   final Future<WebViewController> _webViewControllerFuture;

   @override
   Widget build(BuildContext context) {
     return FutureBuilder<WebViewController>(
       future: _webViewControllerFuture,
       builder:
           (BuildContext context, AsyncSnapshot<WebViewController> snapshot) {
         final bool webViewReady =
             snapshot.connectionState == ConnectionState.done;
         final WebViewController? controller = snapshot.data;

         return Row(
           children: <Widget>[
             IconButton(
               icon: const Icon(Icons.arrow_back_ios),
               onPressed: !webViewReady
                   ? null
                   : () async {
                       if (await controller!.canGoBack()) {
                         await controller.goBack();
                       } else {
                         ScaffoldMessenger.of(context).showSnackBar(
                           const SnackBar(content: Text('No back history item')),
                         );
                         return;
                       }
                     },
             ),
             IconButton(
               icon: const Icon(Icons.arrow_forward_ios),
               onPressed: !webViewReady
                   ? null
                   : () async {
                       if (await controller!.canGoForward()) {
                         await controller.goForward();
                       } else {
                         ScaffoldMessenger.of(context).showSnackBar(
                           const SnackBar(
                               content: Text('No forward history item')),
                         );
                         return;
                       }
                     },
             ),
             IconButton(
               icon: const Icon(Icons.replay),
               onPressed: !webViewReady
                   ? null
                   : () {
                       controller!.reload();
                     },
             ),
           ],
         );
       },
     );
   }
 }

 /// Callback type for handling messages sent from JavaScript running in a web view.
 typedef JavascriptMessageHandler = void Function(JavascriptMessage message);
	// Copyright 2013 The Flutter Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	// ignore_for_file: public_member_api_docs

	import 'dart:async';
	import 'dart:convert';
	import 'dart:io';
	import 'dart:typed_data';

	import 'package:flutter/material.dart';
	import 'package:path_provider/path_provider.dart';
	import 'package:webview_flutter_platform_interface/webview_flutter_platform_interface.dart';

	import 'navigation_decision.dart';
	import 'navigation_request.dart';
	import 'web_view.dart';

	void main() {
	runApp(const MaterialApp(home: _WebViewExample()));
	}

	const String kNavigationExamplePage = '''
	<!DOCTYPE html><html>
	<head><title>Navigation Delegate Example</title></head>
	<body>
	<p>
	The navigation delegate is set to block navigation to the youtube website.
	</p>
	<ul>
	<ul><a href="https://www.youtube.com/">https://www.youtube.com/</a></ul>
	<ul><a href="https://www.google.com/">https://www.google.com/</a></ul>
	</ul>
	</body>
	</html>
	''';

	const String kTransparentBackgroundPage = '''
	<!DOCTYPE html>
	<html>
	<head>
	<title>Transparent background test</title>
	</head>
	<style type="text/css">
	body { background: transparent; margin: 0; padding: 0; }
	#container { position: relative; margin: 0; padding: 0; width: 100vw; height: 100vh; }
	#shape { background: #FF0000; width: 200px; height: 100%; margin: 0; padding: 0; position: absolute; top: 0; bottom: 0; left: calc(50% - 100px); }
	p { text-align: center; }
	</style>
	<body>
	<div id="container">
	<p>Transparent background test</p>
	<div id="shape"></div>
	</div>
	</body>
	</html>
	''';

	const String kLocalFileExamplePage = '''
	<!DOCTYPE html>
	<html lang="en">
	<head>
	<title>Load file or HTML string example</title>
	</head>
	<body>

	<h1>Local demo page</h1>
	<p>
	This is an example page used to demonstrate how to load a local file or HTML
	string using the <a href="https://pub.dev/packages/webview_flutter">Flutter
	webview</a> plugin.
	</p>

	</body>
	</html>
	''';

	class _WebViewExample extends StatefulWidget {
	const _WebViewExample({Key? key}) : super(key: key);

	@override
	_WebViewExampleState createState() => _WebViewExampleState();
	}

	class _WebViewExampleState extends State<_WebViewExample> {
	final Completer<WebViewController> _controller =
	Completer<WebViewController>();

	@override
	void initState() {
	super.initState();
	}

	@override
	Widget build(BuildContext context) {
	return Scaffold(
	backgroundColor: const Color(0xFF4CAF50),
	appBar: AppBar(
	title: const Text('Flutter WebView example'),
	// This drop down menu demonstrates that Flutter widgets can be shown over the web view.
	actions: <Widget>[
	_NavigationControls(_controller.future),
	_SampleMenu(_controller.future),
	],
	),
	body: WebView(
	initialUrl: 'https://flutter.dev/',
	onWebViewCreated: (WebViewController controller) {
	_controller.complete(controller);
	},
	javascriptChannels: _createJavascriptChannels(context),
	javascriptMode: JavascriptMode.unrestricted,
	navigationDelegate: (NavigationRequest request) {
	if (request.url.startsWith('https://www.youtube.com/')) {
	print('blocking navigation to $request}');
	return NavigationDecision.prevent;
	}
	print('allowing navigation to $request');
	return NavigationDecision.navigate;
	},
	backgroundColor: const Color(0x80000000),
	),
	floatingActionButton: favoriteButton(),
	);
	}

	Widget favoriteButton() {
	return FutureBuilder<WebViewController>(
	future: _controller.future,
	builder: (BuildContext context,
	AsyncSnapshot<WebViewController> controller) {
	if (controller.hasData) {
	return FloatingActionButton(
	onPressed: () async {
	final String url = (await controller.data!.currentUrl())!;
	ScaffoldMessenger.of(context).showSnackBar(
	SnackBar(content: Text('Favorited $url')),
	);
	},
	child: const Icon(Icons.favorite),
	);
	}
	return Container();
	});
	}
	}

	Set<JavascriptChannel> _createJavascriptChannels(BuildContext context) {
	return <JavascriptChannel>{
	JavascriptChannel(
	name: 'Snackbar',
	onMessageReceived: (JavascriptMessage message) {
	ScaffoldMessenger.of(context)
	.showSnackBar(SnackBar(content: Text(message.message)));
	}),
	};
	}

	enum _MenuOptions {
	showUserAgent,
	listCookies,
	clearCookies,
	addToCache,
	listCache,
	clearCache,
	navigationDelegate,
	loadFlutterAsset,
	loadLocalFile,
	loadHtmlString,
	doPostRequest,
	setCookie,
	transparentBackground,
	}

	class _SampleMenu extends StatelessWidget {
	const _SampleMenu(this.controller);

	final Future<WebViewController> controller;

	@override
	Widget build(BuildContext context) {
	return FutureBuilder<WebViewController>(
	future: controller,
	builder:
	(BuildContext context, AsyncSnapshot<WebViewController> controller) {
	return PopupMenuButton<_MenuOptions>(
	key: const ValueKey<String>('ShowPopupMenu'),
	onSelected: (_MenuOptions value) {
	switch (value) {
	case _MenuOptions.showUserAgent:
	_onShowUserAgent(controller.data!, context);
	break;
	case _MenuOptions.listCookies:
	_onListCookies(controller.data!, context);
	break;
	case _MenuOptions.clearCookies:
	_onClearCookies(controller.data!, context);
	break;
	case _MenuOptions.addToCache:
	_onAddToCache(controller.data!, context);
	break;
	case _MenuOptions.listCache:
	_onListCache(controller.data!, context);
	break;
	case _MenuOptions.clearCache:
	_onClearCache(controller.data!, context);
	break;
	case _MenuOptions.navigationDelegate:
	_onNavigationDelegateExample(controller.data!, context);
	break;
	case _MenuOptions.loadFlutterAsset:
	_onLoadFlutterAssetExample(controller.data!, context);
	break;
	case _MenuOptions.loadLocalFile:
	_onLoadLocalFileExample(controller.data!, context);
	break;
	case _MenuOptions.loadHtmlString:
	_onLoadHtmlStringExample(controller.data!, context);
	break;
	case _MenuOptions.doPostRequest:
	_onDoPostRequest(controller.data!, context);
	break;
	case _MenuOptions.setCookie:
	_onSetCookie(controller.data!, context);
	break;
	case _MenuOptions.transparentBackground:
	_onTransparentBackground(controller.data!, context);
	break;
	}
	},
	itemBuilder: (BuildContext context) => <PopupMenuItem<_MenuOptions>>[
	PopupMenuItem<_MenuOptions>(
	value: _MenuOptions.showUserAgent,
	enabled: controller.hasData,
	child: const Text('Show user agent'),
	),
	const PopupMenuItem<_MenuOptions>(
	value: _MenuOptions.listCookies,
	child: Text('List cookies'),
	),
	const PopupMenuItem<_MenuOptions>(
	value: _MenuOptions.clearCookies,
	child: Text('Clear cookies'),
	),
	const PopupMenuItem<_MenuOptions>(
	value: _MenuOptions.addToCache,
	child: Text('Add to cache'),
	),
	const PopupMenuItem<_MenuOptions>(
	value: _MenuOptions.listCache,
	child: Text('List cache'),
	),
	const PopupMenuItem<_MenuOptions>(
	value: _MenuOptions.clearCache,
	child: Text('Clear cache'),
	),
	const PopupMenuItem<_MenuOptions>(
	value: _MenuOptions.navigationDelegate,
	child: Text('Navigation Delegate example'),
	),
	const PopupMenuItem<_MenuOptions>(
	value: _MenuOptions.loadFlutterAsset,
	child: Text('Load Flutter Asset'),
	),
	const PopupMenuItem<_MenuOptions>(
	value: _MenuOptions.loadHtmlString,
	child: Text('Load HTML string'),
	),
	const PopupMenuItem<_MenuOptions>(
	value: _MenuOptions.loadLocalFile,
	child: Text('Load local file'),
	),
	const PopupMenuItem<_MenuOptions>(
	value: _MenuOptions.doPostRequest,
	child: Text('Post Request'),
	),
	const PopupMenuItem<_MenuOptions>(
	value: _MenuOptions.setCookie,
	child: Text('Set Cookie'),
	),
	const PopupMenuItem<_MenuOptions>(
	key: ValueKey<String>('ShowTransparentBackgroundExample'),
	value: _MenuOptions.transparentBackground,
	child: Text('Transparent background example'),
	),
	],
	);
	},
	);
	}

	Future<void> _onShowUserAgent(
	WebViewController controller, BuildContext context) async {
	// Send a message with the user agent string to the Snackbar JavaScript channel we registered
	// with the WebView.
	await controller.runJavascript(
	'Snackbar.postMessage("User Agent: " + navigator.userAgent);');
	}

	Future<void> _onListCookies(
	WebViewController controller, BuildContext context) async {
	final String cookies =
	await controller.runJavascriptReturningResult('document.cookie');
	ScaffoldMessenger.of(context).showSnackBar(SnackBar(
	content: Column(
	mainAxisAlignment: MainAxisAlignment.end,
	mainAxisSize: MainAxisSize.min,
	children: <Widget>[
	const Text('Cookies:'),
	_getCookieList(cookies),
	],
	),
	));
	}

	Future<void> _onAddToCache(
	WebViewController controller, BuildContext context) async {
	await controller.runJavascript(
	'caches.open("test_caches_entry"); localStorage["test_localStorage"] = "dummy_entry";');
	ScaffoldMessenger.of(context).showSnackBar(const SnackBar(
	content: Text('Added a test entry to cache.'),
	));
	}

	Future<void> _onListCache(
	WebViewController controller, BuildContext context) async {
	await controller.runJavascript('caches.keys()'
	'.then((cacheKeys) => JSON.stringify({"cacheKeys" : cacheKeys, "localStorage" : localStorage}))'
	'.then((caches) => Snackbar.postMessage(caches))');
	}

	Future<void> _onClearCache(
	WebViewController controller, BuildContext context) async {
	await controller.clearCache();
	ScaffoldMessenger.of(context).showSnackBar(const SnackBar(
	content: Text('Cache cleared.'),
	));
	}

	Future<void> _onClearCookies(
	WebViewController controller, BuildContext context) async {
	final bool hadCookies = await WebView.platform.clearCookies();
	String message = 'There were cookies. Now, they are gone!';
	if (!hadCookies) {
	message = 'There are no cookies.';
	}
	ScaffoldMessenger.of(context).showSnackBar(SnackBar(
	content: Text(message),
	));
	}

	Future<void> _onNavigationDelegateExample(
	WebViewController controller, BuildContext context) async {
	final String contentBase64 =
	base64Encode(const Utf8Encoder().convert(kNavigationExamplePage));
	await controller.loadUrl('data:text/html;base64,$contentBase64');
	}

	Future<void> _onLoadFlutterAssetExample(
	WebViewController controller, BuildContext context) async {
	await controller.loadFlutterAsset('assets/www/index.html');
	}

	Future<void> _onLoadLocalFileExample(
	WebViewController controller, BuildContext context) async {
	final String pathToIndex = await _prepareLocalFile();

	await controller.loadFile(pathToIndex);
	}

	Future<void> _onLoadHtmlStringExample(
	WebViewController controller, BuildContext context) async {
	await controller.loadHtmlString(kLocalFileExamplePage);
	}

	Future<void> _onDoPostRequest(
	WebViewController controller, BuildContext context) async {
	final WebViewRequest request = WebViewRequest(
	uri: Uri.parse('https://httpbin.org/post'),
	method: WebViewRequestMethod.post,
	headers: <String, String>{'foo': 'bar', 'Content-Type': 'text/plain'},
	body: Uint8List.fromList('Test Body'.codeUnits),
	);
	await controller.loadRequest(request);
	}

	Future<void> _onSetCookie(
	WebViewController controller, BuildContext context) async {
	await WebViewCookieManager.instance.setCookie(
	const WebViewCookie(
	name: 'foo', value: 'bar', domain: 'httpbin.org', path: '/anything'),
	);
	await controller.loadUrl('https://httpbin.org/anything');
	}

	Widget _getCookieList(String cookies) {
	if (cookies == null \|\| cookies == '""') {
	return Container();
	}
	final List<String> cookieList = cookies.split(';');
	final Iterable<Text> cookieWidgets =
	cookieList.map((String cookie) => Text(cookie));
	return Column(
	mainAxisAlignment: MainAxisAlignment.end,
	mainAxisSize: MainAxisSize.min,
	children: cookieWidgets.toList(),
	);
	}

	Future<void> _onTransparentBackground(
	WebViewController controller, BuildContext context) async {
	await controller.loadHtmlString(kTransparentBackgroundPage);
	}

	static Future<String> _prepareLocalFile() async {
	final String tmpDir = (await getTemporaryDirectory()).path;
	final File indexFile = File('$tmpDir/www/index.html');

	await Directory('$tmpDir/www').create(recursive: true);
	await indexFile.writeAsString(kLocalFileExamplePage);

	return indexFile.path;
	}
	}

	class _NavigationControls extends StatelessWidget {
	const _NavigationControls(this._webViewControllerFuture)
	: assert(_webViewControllerFuture != null);

	final Future<WebViewController> _webViewControllerFuture;

	@override
	Widget build(BuildContext context) {
	return FutureBuilder<WebViewController>(
	future: _webViewControllerFuture,
	builder:
	(BuildContext context, AsyncSnapshot<WebViewController> snapshot) {
	final bool webViewReady =
	snapshot.connectionState == ConnectionState.done;
	final WebViewController? controller = snapshot.data;

	return Row(
	children: <Widget>[
	IconButton(
	icon: const Icon(Icons.arrow_back_ios),
	onPressed: !webViewReady
	? null
	: () async {
	if (await controller!.canGoBack()) {
	await controller.goBack();
	} else {
	ScaffoldMessenger.of(context).showSnackBar(
	const SnackBar(content: Text('No back history item')),
	);
	return;
	}
	},
	),
	IconButton(
	icon: const Icon(Icons.arrow_forward_ios),
	onPressed: !webViewReady
	? null
	: () async {
	if (await controller!.canGoForward()) {
	await controller.goForward();
	} else {
	ScaffoldMessenger.of(context).showSnackBar(
	const SnackBar(
	content: Text('No forward history item')),
	);
	return;
	}
	},
	),
	IconButton(
	icon: const Icon(Icons.replay),
	onPressed: !webViewReady
	? null
	: () {
	controller!.reload();
	},
	),
	],
	);
	},
	);
	}
	}

	/// Callback type for handling messages sent from JavaScript running in a web view.
	typedef JavascriptMessageHandler = void Function(JavascriptMessage message);