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Commit 15ef622

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amirhamirh
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Initial (Android only) implementation of a WebView widget. (#752)
The focus of this CL is the overall widget/controller structure, and test plumbing. The API surface is just the bare minimum at this point (only loadUrl).
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‎packages/webview_flutter/android/src/main/AndroidManifest.xml‎

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<manifest xmlns:android="http://schemas.android.com/apk/res/android"
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package="io.flutter.plugins.webviewflutter">
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<uses-sdk android:minSdkVersion="20" android:targetSdkVersion="26"/>
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</manifest>

‎packages/webview_flutter/android/src/main/java/io/flutter/plugins/webviewflutter/FlutterWebView.java‎

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package io.flutter.plugins.webviewflutter;
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import static io.flutter.plugin.common.MethodChannel.MethodCallHandler;
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import static io.flutter.plugin.common.MethodChannel.Result;
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import android.content.Context;
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import android.view.View;
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import android.webkit.WebView;
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import io.flutter.plugin.common.BinaryMessenger;
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import io.flutter.plugin.common.MethodCall;
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import io.flutter.plugin.common.MethodChannel;
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import io.flutter.plugin.platform.PlatformView;
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public class FlutterWebView implements PlatformView, MethodCallHandler {
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private final WebView webView;
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private final MethodChannel methodChannel;
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FlutterWebView(Context context, BinaryMessenger messenger, int id) {
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webView = new WebView(context);
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methodChannel = new MethodChannel(messenger, "plugins.flutter.io/webview_" + id);
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methodChannel.setMethodCallHandler(this);
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}
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@Override
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public View getView() {
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return webView;
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}
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@Override
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public void onMethodCall(MethodCall methodCall, Result result) {
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switch (methodCall.method) {
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case "loadUrl":
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loadUrl(methodCall, result);
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break;
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default:
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result.notImplemented();
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}
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}
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private void loadUrl(MethodCall methodCall, Result result) {
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String url = (String) methodCall.arguments;
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webView.loadUrl(url);
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result.success(null);
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}
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@Override
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public void dispose() {}
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}

‎packages/webview_flutter/android/src/main/java/io/flutter/plugins/webviewflutter/WebViewFactory.java‎

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package io.flutter.plugins.webviewflutter;
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import android.content.Context;
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import io.flutter.plugin.common.BinaryMessenger;
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import io.flutter.plugin.common.StandardMessageCodec;
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import io.flutter.plugin.platform.PlatformView;
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import io.flutter.plugin.platform.PlatformViewFactory;
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public class WebViewFactory extends PlatformViewFactory {
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private final BinaryMessenger messenger;
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public WebViewFactory(BinaryMessenger messenger) {
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super(StandardMessageCodec.INSTANCE);
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this.messenger = messenger;
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}
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@Override
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public PlatformView create(Context context, int id, Object args) {
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return new FlutterWebView(context, messenger, id);
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}
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}

‎packages/webview_flutter/android/src/main/java/io/flutter/plugins/webviewflutter/WebviewFlutterPlugin.java‎

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package io.flutter.plugins.webviewflutter;
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import io.flutter.plugin.common.MethodCall;
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import io.flutter.plugin.common.MethodChannel;
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import io.flutter.plugin.common.MethodChannel.MethodCallHandler;
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import io.flutter.plugin.common.MethodChannel.Result;
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import io.flutter.plugin.common.PluginRegistry.Registrar;
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/** WebviewFlutterPlugin */
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public class WebviewFlutterPlugin implements MethodCallHandler {
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public class WebviewFlutterPlugin {
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/** Plugin registration. */
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public static void registerWith(Registrar registrar) {
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final MethodChannel channel = new MethodChannel(registrar.messenger(), "webview_flutter");
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channel.setMethodCallHandler(new WebviewFlutterPlugin());
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}
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@Override
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public void onMethodCall(MethodCall call, Result result) {
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if (call.method.equals("getPlatformVersion")) {
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result.success("Android " + android.os.Build.VERSION.RELEASE);
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} else {
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result.notImplemented();
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}
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registrar
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.platformViewRegistry()
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.registerViewFactory(
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"plugins.flutter.io/webview", new WebViewFactory(registrar.messenger()));
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}
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}

‎packages/webview_flutter/example/lib/main.dart‎

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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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import 'dart:async';
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import 'package:flutter/material.dart';
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import 'package:flutter/services.dart';
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import 'package:webview_flutter/webview_flutter.dart';
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void main() => runApp(new MyApp());
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void main() => runApp(MaterialApp(home: new WebViewExample()));
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class MyApp extends StatefulWidget {
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class WebViewExample extends StatelessWidget {
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@override
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_MyAppState createState() => new _MyAppState();
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}
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class _MyAppState extends State<MyApp> {
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String _platformVersion = 'Unknown';
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@override
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void initState() {
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super.initState();
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initPlatformState();
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Widget build(BuildContext context) {
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return Scaffold(
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appBar: AppBar(
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title: const Text('Flutter WebView example'),
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// This drop down menu demonstrates that Flutter widgets can be shown over the web view.
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actions: <Widget>[const SampleMenu()],
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),
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body: WebView(
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onWebViewCreated: _onWebViewCreated,
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),
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);
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}
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// Platform messages are asynchronous, so we initialize in an async method.
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Future<void> initPlatformState() async {
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String platformVersion;
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// Platform messages may fail, so we use a try/catch PlatformException.
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try {
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platformVersion = await WebviewFlutter.platformVersion;
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} on PlatformException {
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platformVersion = 'Failed to get platform version.';
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}
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// If the widget was removed from the tree while the asynchronous platform
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// message was in flight, we want to discard the reply rather than calling
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// setState to update our non-existent appearance.
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if (!mounted) return;
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setState(() {
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_platformVersion = platformVersion;
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});
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void _onWebViewCreated(WebViewController controller) {
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controller.loadUrl('https://flutter.io');
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}
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}
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class SampleMenu extends StatelessWidget {
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const SampleMenu();
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@override
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Widget build(BuildContext context) {
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return new MaterialApp(
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home: new Scaffold(
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appBar: new AppBar(
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title: const Text('Plugin example app'),
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),
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body: new Center(
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child: new Text('Running on: $_platformVersion\n'),
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),
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),
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return PopupMenuButton<String>(
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onSelected: (String value) {
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Scaffold.of(context).showSnackBar(
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new SnackBar(content: new Text('You selected: $value')));
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},
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itemBuilder: (BuildContext context) => <PopupMenuItem<String>>[
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const PopupMenuItem<String>(
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value: 'Item 1',
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child: Text('Item 1'),
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),
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const PopupMenuItem<String>(
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value: 'Item 2',
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child: Text('Item 2'),
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),
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],
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);
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}
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}

‎packages/webview_flutter/lib/webview_flutter.dart‎

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import 'dart:async';
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import 'package:flutter/foundation.dart';
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import 'package:flutter/gestures.dart';
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import 'package:flutter/services.dart';
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import 'package:flutter/widgets.dart';
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class WebviewFlutter {
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static const MethodChannel _channel = MethodChannel('webview_flutter');
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typedef void WebViewCreatedCallback(WebViewController controller);
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static Future<String> get platformVersion async {
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final String version = await _channel.invokeMethod('getPlatformVersion');
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return version;
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/// A web view widget for showing html content.
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class WebView extends StatefulWidget {
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/// Creates a new web view.
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///
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/// The web view can be controlled using a `WebViewController` that is passed to the
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/// `onWebViewCreated` callback once the web view is created.
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///
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/// The `gestureRecognizers` parameter must not be null;
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const WebView({
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Key key,
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this.onWebViewCreated,
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this.gestureRecognizers = const <OneSequenceGestureRecognizer>[],
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}) : assert(gestureRecognizers != null),
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super(key: key);
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/// If not null invoked once the web view is created.
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final WebViewCreatedCallback onWebViewCreated;
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/// Which gestures should be consumed by the web view.
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///
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/// It is possible for other gesture recognizers to be competing with the web view on pointer
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/// events, e.g if the webview is inside a [ListView] the [ListView] will want to handle
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/// vertical drags. The web view will claim gestures that are recognized by any of the
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/// recognizers on this list.
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///
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/// When this list is empty, the web view will only handle pointer events for gestures that
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/// were not claimed by any other gesture recognizer.
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final List<OneSequenceGestureRecognizer> gestureRecognizers;
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@override
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State<StatefulWidget> createState() => _WebViewState();
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}
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class _WebViewState extends State<WebView> {
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@override
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Widget build(BuildContext context) {
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if (defaultTargetPlatform == TargetPlatform.android) {
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return new GestureDetector(
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// We prevent text selection by intercepting long press event.
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// This is a temporary workaround to prevent a native crash on a second
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// text selection.
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// TODO(amirh): remove this when the selection handles crash is resolved.
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// https://github.com/flutter/flutter/issues/21239
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onLongPress: () {},
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child: AndroidView(
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viewType: 'plugins.flutter.io/webview',
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onPlatformViewCreated: _onPlatformViewCreated,
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gestureRecognizers: widget.gestureRecognizers,
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// WebView content is not affected by the Android view's layout direction,
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// we explicitly set it here so that the widget doesn't require an ambient
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// directionality.
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layoutDirection: TextDirection.rtl,
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),
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);
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}
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return Text(
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'$defaultTargetPlatform is not yet supported by the webview_flutter plugin');
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}
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void _onPlatformViewCreated(int id) {
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if (widget.onWebViewCreated == null) {
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return;
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}
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widget.onWebViewCreated(new WebViewController._(id));
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}
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}
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/// Controls a [WebView].
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///
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/// A [WebViewController] instance can be obtained by setting the [WebView.onWebViewCreated]
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/// callback for a [WebView] widget.
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class WebViewController {
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WebViewController._(int id)
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: _channel = new MethodChannel('plugins.flutter.io/webview_$id');
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final MethodChannel _channel;
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/// Loads the specified URL.
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///
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/// `url` must not be null.
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///
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/// Throws an ArgumentError if `url` is not a valid URL string.
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Future<void> loadUrl(String url) async {
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assert(url != null);
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_validateUrlString(url);
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return _channel.invokeMethod('loadUrl', url);
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}
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}
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// Throws an ArgumentError if url is not a valid url string.
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void _validateUrlString(String url) {
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try {
106+
final Uri uri = Uri.parse(url);
107+
if (uri.scheme.isEmpty) {
108+
throw new ArgumentError('Missing scheme in URL string: "$url"');
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}
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} on FormatException catch (e) {
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throw new ArgumentError(e);
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}
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}

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