问InAppWebView插件中谷歌地图中的问题

EN

<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>

 void requestPermission() async {
    Map<Permission, PermissionStatus> statuses =
        await [Permission.location].request();
  }

InAppWebView(
       ...
        androidOnGeolocationPermissionsShowPrompt:
            (InAppWebViewController controller, String origin) async {
          bool result = await showDialog<bool>(
            context: context,
            barrierDismissible: false, // user must tap button!
            builder: (BuildContext context) {
              return AlertDialog(
                title: Text('Allow access location $origin'),
                content: SingleChildScrollView(
                  child: ListBody(
                    children: <Widget>[
                      Text('Allow access location $origin'),
                    ],
                  ),
                ),
                actions: <Widget>[
                  TextButton(
                    child: Text('Allow'),
                    onPressed: () {
                      Navigator.of(context).pop(true);
                    },
                  ),
                  TextButton(
                    child: Text('Denied'),
                    onPressed: () {
                      Navigator.of(context).pop(false);
                    },
                  ),
                ],
              );
            },
          );
          if (result) {
            return Future.value(GeolocationPermissionShowPromptResponse(
                origin: origin, allow: true, retain: true));
          } else {
            return Future.value(GeolocationPermissionShowPromptResponse(
                origin: origin, allow: false, retain: false));
          }
        },

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

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Isolate Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: InAppWebViewExampleScreen(),
    );
  }
}

class InAppWebViewExampleScreen extends StatefulWidget {
  @override
  _InAppWebViewExampleScreenState createState() =>
      new _InAppWebViewExampleScreenState();
}

class _InAppWebViewExampleScreenState extends State<InAppWebViewExampleScreen> {
  InAppWebViewController webView;
  ContextMenu contextMenu;
  String url = "";
  double progress = 0;
  CookieManager _cookieManager = CookieManager.instance();

  void requestPermission() async {
    Map<Permission, PermissionStatus> statuses =
        await [Permission.location].request();
  }

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

    requestPermission();

    contextMenu = ContextMenu(
        menuItems: [
          ContextMenuItem(
              androidId: 1,
              iosId: "1",
              title: "Special",
              action: () async {
                print("Menu item Special clicked!");
                print(await webView.getSelectedText());
                await webView.clearFocus();
              })
        ],
        options: ContextMenuOptions(hideDefaultSystemContextMenuItems: true),
        onCreateContextMenu: (hitTestResult) async {
          print("onCreateContextMenu");
          print(hitTestResult.extra);
          print(await webView.getSelectedText());
        },
        onHideContextMenu: () {
          print("onHideContextMenu");
        },
        onContextMenuActionItemClicked: (contextMenuItemClicked) async {
          var id = (Platform.isAndroid)
              ? contextMenuItemClicked.androidId
              : contextMenuItemClicked.iosId;
          print("onContextMenuActionItemClicked: " +
              id.toString() +
              " " +
              contextMenuItemClicked.title);
        });
  }

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

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(title: Text("InAppWebView")),
        //drawer: myDrawer(context: context),
        body: SafeArea(
            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(
                // contextMenu: contextMenu,
                initialUrl: "https://www.google.co.in/maps/",
                // initialFile: "assets/index.html",
                initialHeaders: {},
                initialOptions: InAppWebViewGroupOptions(
                    crossPlatform: InAppWebViewOptions(
                      debuggingEnabled: true,
                      useShouldOverrideUrlLoading: true,
                    ),
                    android: AndroidInAppWebViewOptions(
                        //useHybridComposition: true
                        )),
                androidOnGeolocationPermissionsShowPrompt:
                    (InAppWebViewController controller, String origin) async {
                  bool result = await showDialog<bool>(
                    context: context,
                    barrierDismissible: false, // user must tap button!
                    builder: (BuildContext context) {
                      return AlertDialog(
                        title: Text('Allow access location $origin'),
                        content: SingleChildScrollView(
                          child: ListBody(
                            children: <Widget>[
                              Text('Allow access location $origin'),
                            ],
                          ),
                        ),
                        actions: <Widget>[
                          TextButton(
                            child: Text('Allow'),
                            onPressed: () {
                              Navigator.of(context).pop(true);
                            },
                          ),
                          TextButton(
                            child: Text('Denied'),
                            onPressed: () {
                              Navigator.of(context).pop(false);
                            },
                          ),
                        ],
                      );
                    },
                  );
                  if (result) {
                    return Future.value(GeolocationPermissionShowPromptResponse(
                        origin: origin, allow: true, retain: true));
                  } else {
                    return Future.value(GeolocationPermissionShowPromptResponse(
                        origin: origin, allow: false, retain: false));
                  }
                },
                onWebViewCreated: (InAppWebViewController controller) {
                  webView = controller;
                  print("onWebViewCreated");
                },
                onLoadStart: (InAppWebViewController controller, String url) {
                  print("onLoadStart $url");
                  setState(() {
                    this.url = url;
                  });
                },
                shouldOverrideUrlLoading:
                    (controller, shouldOverrideUrlLoadingRequest) async {
                  var url = shouldOverrideUrlLoadingRequest.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;
                },
                onLoadStop:
                    (InAppWebViewController controller, String url) async {
                  print("onLoadStop $url");
                  setState(() {
                    this.url = url;
                  });
                },
                onProgressChanged:
                    (InAppWebViewController controller, int progress) {
                  setState(() {
                    this.progress = progress / 100;
                  });
                },
                onUpdateVisitedHistory: (InAppWebViewController controller,
                    String url, bool androidIsReload) {
                  print("onUpdateVisitedHistory $url");
                  setState(() {
                    this.url = url;
                  });
                },
                onConsoleMessage: (controller, consoleMessage) {
                  print(consoleMessage);
                },
              ),
            ),
          ),
          ButtonBar(
            alignment: MainAxisAlignment.center,
            children: <Widget>[
              RaisedButton(
                child: Icon(Icons.arrow_back),
                onPressed: () {
                  if (webView != null) {
                    webView.goBack();
                  }
                },
              ),
              RaisedButton(
                child: Icon(Icons.arrow_forward),
                onPressed: () {
                  if (webView != null) {
                    webView.goForward();
                  }
                },
              ),
              RaisedButton(
                child: Icon(Icons.refresh),
                onPressed: () {
                  if (webView != null) {
                    webView.reload();
                  }
                },
              ),
            ],
          ),
        ])));
  }
}