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Hackernoon logoIntroducing InAppWebView Plugin For Flutter by@lorenzo-pichilli

Introducing InAppWebView Plugin For Flutter

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@lorenzo-pichilliLorenzo Pichilli

Software Engineer focused on Web and Mobile Development. JavaScript, TypeScript & Flutter enthusiast

What is 

flutter_inappwebview
 ? It’s a Flutter plugin that allows you to incorporate WebView widgets into your Flutter app, to use headless WebViews, or to use In-App browsers.

So, what’s the difference between 

webview_flutter
 (Official flutter plugin) and 
flutter_webview_plugin
 ?

Compared to all other WebView plugins, it is feature-rich: a lot of events, methods, and options to control WebViews. Furthermore, they do not have good documentation about their API or, at least, it is not complete. Instead, every feature of 

flutter_inappwebview
 is almost all documented (just check the API Reference on pub.dev).

In this article, I’m going to present the main classes and some examples of the 

InAppWebView
 widget that people were asking about on the official flutter_inappwebview repository (issue section) and on StackOverflow.

Main Classes Overview

This is a list of the main classes that the plugin offers:

  • InAppWebView: Flutter Widget for adding an inline native WebView integrated into the flutter widget tree.
  • ContextMenu: This class represents the WebView context menu.
  • HeadlessInAppWebView: Class that represents a WebView in headless mode. It can be used to run a WebView in background without attaching an 
    InAppWebView
     to the widget tree.
  • InAppBrowser: In-App Browser using native WebView.
  • ChromeSafariBrowser: In-App Browser using Chrome Custom Tabs on Android / SFSafariViewController on iOS.
  • InAppLocalhostServer: This class allows you to create a simple server on 
    http://localhost:[port]/
    . The default 
    port
     value is 
    8080
    .
  • CookieManager: This class implements a singleton object (shared instance) which manages the cookies used by WebView instances.
  • HttpAuthCredentialDatabase: This class implements a singleton object (shared instance) that manages the shared HTTP auth credentials cache.
  • WebStorageManager: This class implements a singleton object (shared instance) which manages the web storage used by WebView instances.

In this article, I’m going to show in particular the 

InAppWebView
 widget, that is the most used/requested one.

InAppWebView is a Widget like any other!

Adding the 

InAppWebView
 widget into your app is very simple. It’s just a widget like any other Flutter widget: 
InAppWebView(initialUrl: 'https://github.com/flutter')
.

NOTE: To use it on iOS, you need to opt-in for the embedded views preview by adding a boolean property to the app's 

Info.plist
 file, with the key 
io.flutter.embedded_views_preview
 and the value 
YES
.

This widget has a set of initial attributes that you can use to initialize the WebView:

  • initialUrl: Initial URL that will be loaded;
  • initialOptions: Initial WebView options that will be used;
  • gestureRecognizers: specifies which gestures should be consumed by the WebView;
  • initialData: Initial InAppWebViewInitialData that will be loaded, such as an HTML string;
  • initialFile: Initial asset file that will be loaded (check the “Load a file inside assets folder” Section);
  • initialHeaders: Initial headers that will be used;
  • contextMenu: Context menu which contains custom menu items.

The list of all available WebView options is quite long, for example, you can enable/disable JavaScript using the 

javascriptEnabled
 option or enable/disable cache using the 
cacheEnabled
 option. The full list of all options is available here.

Use InAppWebViewController to control your WebView

Instead, to control the WebView, you have the

InAppWebViewController 
class. This controller is returned by the 
onWebViewCreated
 callback when the WebView is ready to be used.

Through it, you can control your WebView or access its properties, such as the current URL using 

getUrl
 method. Other methods, for example, are
loadUrl
 to load a new URL, 
postUrl
 to load a given URL with custom data using POST method, 
evaluateJavascript
 to evaluate JavaScript code into the WebView, and to get the result of the evaluation, 
takeScreenshot
 to take the screenshot (in PNG format) of the WebView’s visible viewport,
getCertificate
 to get the SSL certificate for the main top-level page or 
null
 if there is no certificate.

The full list of all methods you can use is quite long and available here.

InAppWebView Events

The 

InAppWebView
 widget offers a variety of events! Here’s a few of them:

  • onLoadStart: event fired when the WebView starts to load an URL;
  • onLoadStop: event fired when the WebView finishes loading an URL;
  • onLoadHttpError: event fired when the WebView main page receives an HTTP error;
  • onConsoleMessage: event fired when the WebView receives a JavaScript console message (such as 
    console.log
     , 
    console.error
     , etc.);
  • shouldOverrideUrlLoading: gives the host application a chance to take control when a URL is about to be loaded in the current WebView;
  • onDownloadStart: event fired when WebView recognizes a downloadable file;
  • onReceivedHttpAuthRequest: event fired when the WebView received an HTTP authentication request. The default behavior is to cancel the request;
  • onReceivedServerTrustAuthRequest: event fired when the WebView need to perform server trust authentication (certificate validation);
  • onPrint: event fired when 
    window.print()
     is called from JavaScript side;
  • onCreateWindow: event fired when the InAppWebView requests the host application to create a new window, for example when trying to open a link with 
    target="_blank"
     or when 
    window.open()
     is called by JavaScript side;

and many many more! I recommend checking the API Reference to get more details. As for the WebView options and methods, the full list of all WebView events is quite long and available here.

InAppWebView Simple Example

Here is a simple example that shows an InAppWebView widget, its current URL, and 3 buttons: one to go back, one to go forward, and another one to reload the current page.

This is the full code example:

import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter_inappwebview/flutter_inappwebview.dart';

Future main() async {
  WidgetsFlutterBinding.ensureInitialized();
  runApp(new MyApp());
}

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => new _MyAppState();
}

class _MyAppState extends State<MyApp> {

  InAppWebViewController _webViewController;
  String url = "";
  double progress = 0;

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: const Text('InAppWebView Example'),
        ),
        body: Container(
            child: Column(children: <Widget>[
              Container(
                padding: EdgeInsets.all(20.0),
                child: Text(
                    "CURRENT URL\n${(url.length > 50) ? url.substring(0, 50) + "..." : url}"),
              ),
              Container(
                  padding: EdgeInsets.all(10.0),
                  child: progress < 1.0
                      ? LinearProgressIndicator(value: progress)
                      : Container()),
              Expanded(
                child: Container(
                  margin: const EdgeInsets.all(10.0),
                  decoration:
                  BoxDecoration(border: Border.all(color: Colors.blueAccent)),
                  child: InAppWebView(
                    initialUrl: "https://flutter.dev/",
                    initialOptions: InAppWebViewGroupOptions(
                        crossPlatform: InAppWebViewOptions(
                          debuggingEnabled: true,
                        )
                    ),
                    onWebViewCreated: (InAppWebViewController controller) {
                      _webViewController = controller;
                    },
                    onLoadStart: (InAppWebViewController controller, String url) {
                      setState(() {
                        this.url = url;
                      });
                    },
                    onLoadStop: (InAppWebViewController controller, String url) async {
                      setState(() {
                        this.url = url;
                      });
                    },
                    onProgressChanged: (InAppWebViewController controller, int progress) {
                      setState(() {
                        this.progress = progress / 100;
                      });
                    },
                  ),
                ),
              ),
              ButtonBar(
                alignment: MainAxisAlignment.center,
                children: <Widget>[
                  RaisedButton(
                    child: Icon(Icons.arrow_back),
                    onPressed: () {
                      if (_webViewController != null) {
                        _webViewController.goBack();
                      }
                    },
                  ),
                  RaisedButton(
                    child: Icon(Icons.arrow_forward),
                    onPressed: () {
                      if (_webViewController != null) {
                        _webViewController.goForward();
                      }
                    },
                  ),
                  RaisedButton(
                    child: Icon(Icons.refresh),
                    onPressed: () {
                      if (_webViewController != null) {
                        _webViewController.reload();
                      }
                    },
                  ),
                ],
              ),
            ])),
      ),
    );
  }
}

JavaScript Handlers (Channels)

You can communicate with the JavaScript side and vice-versa.

To add a JavaScript handler, you can use

_webViewController.addJavaScriptHandler 
method, where you define the 
handlerName
 and a 
callback
 to be invoked when it is called by the JavaScript side. The 
callback
 can return data to be sent on the JavaScript side.

Instead, on the JavaScript side, to execute the callback handler and send data to Flutter, you need to use

window.flutter_inappwebview.callHandler(handlerName <String>, ...args)
 method, where 
handlerName
 is a string that represents the handler name that your calling and 
args
 are optional arguments that you can send to the Flutter side.

In order to call

window.flutter_inappwebview.callHandler(handlerName <String>, ...args)
 properly, you need to wait and listen to the JavaScript event 
flutterInAppWebViewPlatformReady
.

This event will be dispatched as soon as the platform (Android or iOS) is ready to handle the 

callHandler
 method.

Here is an example:

import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter_inappwebview/flutter_inappwebview.dart';

Future main() async {
  WidgetsFlutterBinding.ensureInitialized();
  runApp(new MyApp());
}

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => new _MyAppState();
}

class _MyAppState extends State<MyApp> {
  InAppWebViewController _webViewController;

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: const Text('InAppWebView Example'),
        ),
        body: Container(
            child: Column(children: <Widget>[
              Expanded(
                child:InAppWebView(
                    initialData: InAppWebViewInitialData(
                      data: """
<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8">
        <meta name="viewport" content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
    </head>
    <body>
        <h1>JavaScript Handlers (Channels) TEST</h1>
        <script>
            window.addEventListener("flutterInAppWebViewPlatformReady", function(event) {
                window.flutter_inappwebview.callHandler('handlerFoo')
                  .then(function(result) {
                    // print to the console the data coming
                    // from the Flutter side.
                    console.log(JSON.stringify(result));
                    
                    window.flutter_inappwebview
                      .callHandler('handlerFooWithArgs', 1, true, ['bar', 5], {foo: 'baz'}, result);
                });
            });
        </script>
    </body>
</html>
                      """
                    ),
                    initialOptions: InAppWebViewGroupOptions(
                        crossPlatform: InAppWebViewOptions(
                          debuggingEnabled: true,
                        )
                    ),
                    onWebViewCreated: (InAppWebViewController controller) {
                      _webViewController = controller;

                      _webViewController.addJavaScriptHandler(handlerName:'handlerFoo', callback: (args) {
                        // return data to JavaScript side!
                        return {
                          'bar': 'bar_value', 'baz': 'baz_value'
                        };
                      });

                      _webViewController.addJavaScriptHandler(handlerName: 'handlerFooWithArgs', callback: (args) {
                        print(args);
                        // it will print: [1, true, [bar, 5], {foo: baz}, {bar: bar_value, baz: baz_value}]
                      });
                    },
                    onConsoleMessage: (controller, consoleMessage) {
                      print(consoleMessage);
                      // it will print: {message: {"bar":"bar_value","baz":"baz_value"}, messageLevel: 1}
                    },
                ),
              ),
            ])),
      ),
    );
  }
}

WebRTC in InAppWebView

At this moment, WebRTC is supported only on Android, because, unfortunately, on iOS 

WKWebView
 doesn’t implement all the WebRTC API (you can follow this issue: #200).

I’m going to show an example using https://appr.tc/ to test WebRTC feature. It’s a video chat demo app based on WebRTC (https://github.com/webrtc/apprtc).

To request permissions about the camera and microphone, you can use the permission_handler plugin. Also, you need to set the WebView option 

mediaPlaybackRequiresUserGesture
 to 
false
 in order to autoplay HTML5 audio and video.

Furthermore, on Android, you need to implement the

androidOnPermissionRequest
 event (it’s an Android-specific event), that is an event fired when the WebView is requesting permission to access a specific resource (that is the Android native WebChromeClient.onPermissionRequest event).

In this case, this event is used to grant permissions for the WebRTC API. Also, you need to add these permissions in the 

AndroidManifest.xml
:

<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.RECORD_AUDIO" />
<uses-permission android:name="android.permission.MODIFY_AUDIO_SETTINGS" />
<uses-permission android:name="android.permission.VIDEO_CAPTURE" />
<uses-permission android:name="android.permission.AUDIO_CAPTURE" />

Here is the full code example:

import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter_inappwebview/flutter_inappwebview.dart';
import 'package:permission_handler/permission_handler.dart';

Future main() async {
  WidgetsFlutterBinding.ensureInitialized();

  await Permission.camera.request();
  await Permission.microphone.request();

  runApp(MyApp());
}

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => new _MyAppState();
}

class _MyAppState extends State<MyApp> {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        home: InAppWebViewPage()
    );
  }
}

class InAppWebViewPage extends StatefulWidget {
  @override
  _InAppWebViewPageState createState() => new _InAppWebViewPageState();
}

class _InAppWebViewPageState extends State<InAppWebViewPage> {
  InAppWebViewController _webViewController;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
            title: Text("InAppWebView")
        ),
        body: Container(
            child: Column(children: <Widget>[
              Expanded(
                child: Container(
                  child: InAppWebView(
                      initialUrl: "https://appr.tc/r/704328056",
                      initialOptions: InAppWebViewGroupOptions(
                        crossPlatform: InAppWebViewOptions(
                          mediaPlaybackRequiresUserGesture: false,
                          debuggingEnabled: true,
                        ),
                      ),
                      onWebViewCreated: (InAppWebViewController controller) {
                        _webViewController = controller;
                      },
                      androidOnPermissionRequest: (InAppWebViewController controller, String origin, List<String> resources) async {
                        return PermissionRequestResponse(resources: resources, action: PermissionRequestResponseAction.GRANT);
                      }
                  ),
                ),
              ),
            ]))
    );
  }
}

How to enable download files in InAppWebView

InAppWebView
 can recognize downloadable files in both Android and iOS platforms. To be able to recognize downloadable files, you need to set the 
useOnDownloadStart: true
 option, and then you can listen to the 
onDownloadStart
 event.

On Android you need to add write permission inside your

AndroidManifest.xml
 file:

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

Then, you need to ask permission using the permission_handler plugin. Instead, to effectively download your file, you can use the flutter_downloader plugin.

Here is a complete example using http://ovh.net/files/ (in particular, the http://ovh.net/files/1Mio.dat as URL) to test the download:

import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter_inappwebview/flutter_inappwebview.dart';
import 'package:flutter_downloader/flutter_downloader.dart';
import 'package:path_provider/path_provider.dart';
import 'package:permission_handler/permission_handler.dart';

Future main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await FlutterDownloader.initialize(
      debug: true // optional: set false to disable printing logs to console
  );
  await Permission.storage.request();
  runApp(MyApp());
}

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => new _MyAppState();
}

class _MyAppState extends State<MyApp> {
  InAppWebViewController _webViewController;

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: const Text('InAppWebView Example'),
        ),
        body: Container(
            child: Column(children: <Widget>[
              Expanded(
                  child: InAppWebView(
                    initialUrl: "http://ovh.net/files/1Mio.dat",
                    initialOptions: InAppWebViewGroupOptions(
                      crossPlatform: InAppWebViewOptions(
                          debuggingEnabled: true,
                          useOnDownloadStart: true
                      ),
                    ),
                    onWebViewCreated: (InAppWebViewController controller) {
                      _webViewController = controller;
                    },
                    onDownloadStart: (controller, url) async {
                      print("onDownloadStart $url");
                      final taskId = await FlutterDownloader.enqueue(
                        url: url,
                        savedDir: (await getExternalStorageDirectory()).path,
                        showNotification: true, // show download progress in status bar (for Android)
                        openFileFromNotification: true, // click on notification to open downloaded file (for Android)
                      );
                    },
                  ))
            ])),
      ),
    );
  }
}

As you can see, I’m using also the path_provider plugin to get the folder where I want to save the file.

Allow Self-signed SSL Certificates

To allow self-signed SSL certificates, you can use the

onReceivedServerTrustAuthRequest 
event and simply return to proceed with the request:

onReceivedServerTrustAuthRequest: (controller, challenge) async {
  return ServerTrustAuthResponse(action: ServerTrustAuthResponseAction.PROCEED);
},

How to manage popup windows opened with target=”_blank” or “window.open”

To manage popup windows when a user clicks on a link with

target="_blank" 
or through JavaScript code using 
window.open
 , you can use the 
onCreateWindow
 event. On Android, to be able to allow this event, you need to set the 
supportMultipleWindows
 option to 
true
 .

Also, in order to be able to allow the usage of JavaScript, you need to set the 

javaScriptCanOpenWindowsAutomatically
 to 
true
.

If you want to manage these requests, you should return 

true
 from this event, otherwise, the default implementation of this event does nothing and hence returns 
false
 .

The 

CreateWindowRequest
 represents the navigation request which contains a 
windowId
 that can be used to create, for example, a new
InAppWebView
 instance. This 
windowId
 is used by the native code to map the request and the WebView to be used to manage that request.

Also, 

CreateWindowRequest
 contains the 
url
 of the request (on Android, if the popup is opened using JavaScript with 
window.open
 , it will be
null
), but if you need to maintain the Window JavaScript object reference (created using 
window.open
 method), for example, to call
window.close 
method, then you should create the new WebView with the 
windowId
, without using the 
url
 .

Here is a simple example that shows an 

AlertDialog
 when the user clicks on the link:

import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter_inappwebview/flutter_inappwebview.dart';

Future main() async {
  WidgetsFlutterBinding.ensureInitialized();
  runApp(new MyApp());
}

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => new _MyAppState();
}

class _MyAppState extends State<MyApp> {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        home: InAppWebViewPage()
    );
  }
}

class InAppWebViewPage extends StatefulWidget {
  @override
  _InAppWebViewPageState createState() => new _InAppWebViewPageState();
}

class _InAppWebViewPageState extends State<InAppWebViewPage> {
  InAppWebViewController _webViewController;
  InAppWebViewController _webViewPopupController;

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

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

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: const Text('InAppWebView Example'),
        ),
        body: SafeArea(
          child: Container(
              child: InAppWebView(
                initialData: InAppWebViewInitialData(
                    data: """
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Flutter InAppWebView</title>
</head>
<body>
  <a style="margin: 50px; background: #333; color: #fff; font-weight: bold; font-size: 20px; padding: 15px; display: block;"
    href="https://github.com/flutter"
    target="_blank">
    Click here to open https://github.com/flutter in a popup!
  </a>
</body>
</html>
"""
                ),
                initialOptions: InAppWebViewGroupOptions(
                    crossPlatform: InAppWebViewOptions(
                      debuggingEnabled: true,
                      // set this to true if you are using window.open to open a new window with JavaScript
                      javaScriptCanOpenWindowsAutomatically: true
                    ),
                    android: AndroidInAppWebViewOptions(
                      // on Android you need to set supportMultipleWindows to true,
                      // otherwise the onCreateWindow event won't be called
                      supportMultipleWindows: true
                    )
                ),
                onWebViewCreated: (InAppWebViewController controller) {
                  _webViewController = controller;
                },
                onCreateWindow: (controller, createWindowRequest) async {

                  print("onCreateWindow");

                  showDialog(
                    context: context,
                    builder: (context) {
                      return AlertDialog(
                        content: Container(
                          width: MediaQuery.of(context).size.width,
                          height: 400,
                          child: InAppWebView(
                            // Setting the windowId property is important here!
                            windowId: createWindowRequest.windowId,
                            initialOptions: InAppWebViewGroupOptions(
                                crossPlatform: InAppWebViewOptions(
                                    debuggingEnabled: true,
                                ),
                            ),
                            onWebViewCreated: (InAppWebViewController controller) {
                              _webViewPopupController = controller;
                            },
                            onLoadStart: (InAppWebViewController controller, String url) {
                              print("onLoadStart popup $url");
                            },
                            onLoadStop: (InAppWebViewController controller, String url) {
                              print("onLoadStop popup $url");
                            },
                          ),
                        ),
                      );
                    },
                  );

                  return true;
                },
              ),
            ),
          ),
      ),
    );
  }
}

Manage platform URLs such as whatsapp:, fb:, tel:, mailto:, etc.

Generally, a WebView knows nothing on how to manage

whatsapp:
,
tel: 
or
fb:
 protocol/scheme. To capture the requests made with these custom protocols/schemes, you can use the 
shouldOverrideUrlLoading
 event (you need to enable it with 
useShouldOverrideUrlLoading: true
 option).

This way you can cancel the request made for the WebView and, instead, open the App, for example, using the 

url_launcher
 plugin:

initialOptions: InAppWebViewGroupOptions(
  crossPlatform: InAppWebViewOptions(
      debuggingEnabled: true,
      useShouldOverrideUrlLoading: true
  ),
),
shouldOverrideUrlLoading: (controller, request) async {
  var url = request.url;
  var uri = Uri.parse(url);

  if (!["http", "https", "file",
    "chrome", "data", "javascript",
    "about"].contains(uri.scheme)) {
    if (await canLaunch(url)) {
      // Launch the App
      await launch(
        url,
      );
      // and cancel the request
      return ShouldOverrideUrlLoadingAction.CANCEL;
    }
  }

  return ShouldOverrideUrlLoadingAction.ALLOW;
},

Manage WebView Cookies

To manage WebView cookies, you can use the 

CookieManager
 class, which implements a singleton object (shared instance). On Android, it is implemented using the CookieManager class. On iOS, it is implemented using the WKHTTPCookieStore class.

Here is an example of how to set a cookie:

CookieManager _cookieManager = CookieManager.instance();

final expiresDate =
    DateTime.now().add(Duration(days: 3)).millisecondsSinceEpoch;
_cookieManager.setCookie(
  url: "https://flutter.dev/",
  name: "session",
  value: "54th5hfdcfg34",
  domain: ".flutter.dev",
  expiresDate: expiresDate,
  isSecure: true,
);

Custom context menus

You can customize WebView’s context menu adding custom menu items, and/or hiding the default system menu items. For each custom menu item, you can declare a callback 

action
 to be invoked when the user clicks on it. As an example, I will add a custom menu item named 
Special
 and I will define a callback action that shows a JavaScript 
window.alert
 to the user with the text selected.

Here is the full code example:

import 'dart:async';
import 'dart:io';
import 'package:flutter/material.dart';
import 'package:flutter_inappwebview/flutter_inappwebview.dart';

Future main() async {
  WidgetsFlutterBinding.ensureInitialized();
  runApp(MyApp());
}

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => new _MyAppState();
}

class _MyAppState extends State<MyApp> {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        home: InAppWebViewPage()
    );
  }
}

class InAppWebViewPage extends StatefulWidget {
  @override
  _InAppWebViewPageState createState() => new _InAppWebViewPageState();
}

class _InAppWebViewPageState extends State<InAppWebViewPage> {
  InAppWebViewController _webViewController;
  ContextMenu contextMenu;

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

    contextMenu = ContextMenu(
        menuItems: [
          ContextMenuItem(androidId: 1, iosId: "1", title: "Special", action: () async {
            print("Menu item Special clicked!");
            var selectedText = await _webViewController.getSelectedText();
            await _webViewController.clearFocus();
            await _webViewController.evaluateJavascript(source: "window.alert('You have selected: $selectedText')");
          })
        ],
        options: ContextMenuOptions(
            hideDefaultSystemContextMenuItems: false
        ),
        onCreateContextMenu: (hitTestResult) async {
          print("onCreateContextMenu");
          print(hitTestResult.extra);
          print(await _webViewController.getSelectedText());
        },
        onHideContextMenu: () {
          print("onHideContextMenu");
        },
        onContextMenuActionItemClicked: (contextMenuItemClicked) async {
          var id = (Platform.isAndroid) ? contextMenuItemClicked.androidId : contextMenuItemClicked.iosId;
          print("onContextMenuActionItemClicked: " + id.toString() + " " + contextMenuItemClicked.title);
        }
    );
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
            title: Text("InAppWebView")
        ),
        body: Container(
            child: Column(children: <Widget>[
              Expanded(
                child: Container(
                  child: InAppWebView(
                      initialUrl: "https://github.com/flutter",
                      contextMenu: contextMenu,
                      initialOptions: InAppWebViewGroupOptions(
                        crossPlatform: InAppWebViewOptions(
                          debuggingEnabled: true,
                        ),
                      ),
                      onWebViewCreated: (InAppWebViewController controller) {
                        _webViewController = controller;
                      },
                  ),
                ),
              ),
            ]))
    );
  }
}

Conclusion

In this article, I made a little introduction to the

flutter_inappwebview
plugin, in particular, about the InAppWebView widget. The plugin is in continuous development (at the time of this writing, the latest release is 
4.0.0+4
) and I recommend you check out the API Reference to find out all the features. For any new feature request/bug fix, you can use the issue section of the repository.

The next article will be on how to implement a Full-Featured Browser using this plugin.

That’s all for today! I hope it has opened new use cases for your Flutter apps.

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