From 2b38440faa43048f5bc98bce0f0b2e5045d86620 Mon Sep 17 00:00:00 2001
From: Mouad Debbar <mdebbar@google.com>
Date: Wed, 14 Oct 2020 16:00:39 -0700
Subject: [PATCH 1/8] [web] Implement Link for web

---
 .../url_launcher_web/CHANGELOG.md             |   4 +
 .../url_launcher_web/lib/link.dart            | 282 ++++++++++++++++++
 .../lib/url_launcher_web.dart                 |   7 +
 .../url_launcher_web/pubspec.yaml             |   4 +-
 4 files changed, 295 insertions(+), 2 deletions(-)
 create mode 100644 packages/url_launcher/url_launcher_web/lib/link.dart

diff --git a/packages/url_launcher/url_launcher_web/CHANGELOG.md b/packages/url_launcher/url_launcher_web/CHANGELOG.md
index 456d458834bf..e7abd1301c88 100644
--- a/packages/url_launcher/url_launcher_web/CHANGELOG.md
+++ b/packages/url_launcher/url_launcher_web/CHANGELOG.md
@@ -1,3 +1,7 @@
+# 0.1.5
+
+- Added the web implementation of the Link widget.
+
 # 0.1.4+2
 
 - Move `lib/third_party` to `lib/src/third_party`.
diff --git a/packages/url_launcher/url_launcher_web/lib/link.dart b/packages/url_launcher/url_launcher_web/lib/link.dart
new file mode 100644
index 000000000000..9874d00e8741
--- /dev/null
+++ b/packages/url_launcher/url_launcher_web/lib/link.dart
@@ -0,0 +1,282 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'dart:async';
+import 'dart:html' as html;
+import 'dart:js_util';
+
+import 'package:flutter/foundation.dart';
+import 'package:flutter/gestures.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter/rendering.dart';
+import 'package:flutter/services.dart';
+
+import 'package:url_launcher_platform_interface/link.dart';
+
+typedef _ClickListener = void Function(html.MouseEvent);
+
+/// The unique identifier for the view type to be used for link platform views.
+const String viewType = '__url_launcher::link';
+
+/// The name of the property used to set the viewId on the DOM element.
+const String _viewIdProperty = '__url_launcher::link::viewId';
+
+/// Signature for a function that takes a unique [id] and creates an HTML element.
+typedef PlatformViewFactory = html.Element Function(int viewId);
+
+/// Factory that returns the link DOM element for each unique view id.
+PlatformViewFactory get linkViewFactory => _LinkViewController._viewFactory;
+
+/// The delegate for building the [Link] widget on the web.
+///
+/// It uses a platform view to render an anchor element in the DOM.
+class WebLinkDelegate extends StatefulWidget {
+  /// Creates a delegate for the given [link].
+  const WebLinkDelegate(this.link);
+
+  /// Information about the link built by the app.
+  final LinkInfo link;
+
+  @override
+  _WebLinkDelegateState createState() => _WebLinkDelegateState();
+}
+
+class _WebLinkDelegateState extends State<WebLinkDelegate> {
+  _LinkViewController _controller;
+
+  @override
+  void didUpdateWidget(WebLinkDelegate oldWidget) {
+    super.didUpdateWidget(oldWidget);
+    if (widget.link.uri != oldWidget.link.uri) {
+      _controller?._setUri(widget.link.uri);
+    }
+    if (widget.link.target != oldWidget.link.target) {
+      _controller?._setTarget(widget.link.target);
+    }
+  }
+
+  Future<void> _followLink() {
+    final Completer<void> completer = Completer<void>();
+    _LinkViewController._registerHitTest(
+      _controller,
+      onClick: (html.MouseEvent event) {
+        completer.complete(_onDomClick(event));
+      },
+    );
+    return completer.future;
+  }
+
+  Future<void> _onDomClick(html.MouseEvent event) {
+    if (!widget.link.uri.hasScheme) {
+      // A uri that doesn't have a scheme is an internal route name. In this
+      // case, we push it via Flutter's navigation system instead of letting the
+      // browser handle it.
+      event.preventDefault();
+      final String routeName = widget.link.uri.toString();
+      // TODO(mdebbar): how do we know if `isUsingRouter` should be true or false?
+      return pushRouteNameToFramework(routeName, isUsingRouter: false);
+    }
+
+    // External links will be handled by the browser, so we don't have to do
+    // anything.
+    return Future<void>.value(null);
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Stack(
+      children: <Widget>[
+        widget.link.builder(
+          context,
+          widget.link.isDisabled ? null : _followLink,
+        ),
+        Positioned.fill(
+          child: PlatformViewLink(
+            viewType: viewType,
+            onCreatePlatformView: _createController,
+            surfaceFactory:
+                (BuildContext context, PlatformViewController controller) {
+              return PlatformViewSurface(
+                controller: controller,
+                gestureRecognizers:
+                    Set<Factory<OneSequenceGestureRecognizer>>(),
+                hitTestBehavior: PlatformViewHitTestBehavior.transparent,
+              );
+            },
+          ),
+        ),
+      ],
+    );
+  }
+
+  _LinkViewController _createController(PlatformViewCreationParams params) {
+    _controller = _LinkViewController(params.id);
+    _controller._initialize().then((_) {
+      params.onPlatformViewCreated(params.id);
+    });
+    return _controller
+      .._setUri(widget.link.uri)
+      .._setTarget(widget.link.target);
+  }
+}
+
+/// Controls link views.
+class _LinkViewController extends PlatformViewController {
+  _LinkViewController(this.viewId) {
+    if (_instances.isEmpty) {
+      // This is the first controller being created, attach the global click
+      // listener.
+      _clickSubscribtion = html.window.onClick.listen(_onGlobalClick);
+    }
+    _instances[viewId] = this;
+  }
+
+  static Map<int, _LinkViewController> _instances =
+      <int, _LinkViewController>{};
+
+  static html.Element _viewFactory(int viewId) {
+    return _instances[viewId]?._element;
+  }
+
+  static int _hitTestedViewId;
+  static _ClickListener _hitTestedClickCallback;
+
+  static StreamSubscription _clickSubscribtion;
+
+  static void _onGlobalClick(html.MouseEvent event) {
+    final int viewId = _getViewIdFromTarget(event);
+    _instances[viewId]?._onDomClick(event);
+    // After the DOM click event has been received, clean up the hit test state
+    // so we can start fresh on the next click.
+    _unregisterHitTest();
+  }
+
+  /// Call this method to indicated that a hit test has been registered for the
+  /// given [controller].
+  ///
+  /// The [onClick] callback is invoked when the anchor element receives a
+  /// `click` from the browser.
+  static void _registerHitTest(
+    _LinkViewController controller, {
+    @required _ClickListener onClick,
+  }) {
+    _hitTestedViewId = controller.viewId;
+    _hitTestedClickCallback = onClick;
+  }
+
+  static void _unregisterHitTest() {
+    _hitTestedViewId = null;
+    _hitTestedClickCallback = null;
+  }
+
+  @override
+  final int viewId;
+
+  html.Element _element;
+  bool get _isInitialized => _element != null;
+
+  Future<void> _initialize() async {
+    _element = html.Element.tag('a');
+    setProperty(_element, _viewIdProperty, viewId);
+    _element.style
+      ..opacity = '0'
+      ..display = 'block'
+      ..cursor = 'unset';
+
+    final Map<String, dynamic> args = <String, dynamic>{
+      'id': viewId,
+      'viewType': viewType,
+    };
+    await SystemChannels.platform_views.invokeMethod<void>('create', args);
+  }
+
+  void _onDomClick(html.MouseEvent event) {
+    final bool isHitTested = _hitTestedViewId == viewId;
+    if (isHitTested) {
+      _hitTestedClickCallback(event);
+    } else {
+      // There was no hit test registered for this click. This means the click
+      // landed on the anchor element but not on the underlying widget. In this
+      // case, we prevent the browser from following the click.
+      event.preventDefault();
+    }
+  }
+
+  void _setUri(Uri uri) {
+    assert(_isInitialized);
+    if (uri == null) {
+      _element.removeAttribute('href');
+    } else {
+      _element.setAttribute('href', uri.toString());
+    }
+  }
+
+  void _setTarget(LinkTarget target) {
+    assert(_isInitialized);
+    _element.setAttribute('target', _getHtmlTarget(target));
+  }
+
+  String _getHtmlTarget(LinkTarget target) {
+    switch (target) {
+      case LinkTarget.defaultTarget:
+      case LinkTarget.self:
+        return '_self';
+      case LinkTarget.blank:
+        return '_blank';
+      default:
+        throw Exception('Unknown LinkTarget value $target.');
+    }
+  }
+
+  @override
+  Future<void> clearFocus() async {
+    // Currently this does nothing on Flutter Web.
+    // TODO(het): Implement this. See https://github.com/flutter/flutter/issues/39496
+  }
+
+  @override
+  Future<void> dispatchPointerEvent(PointerEvent event) async {
+    // We do not dispatch pointer events to HTML views because they may contain
+    // cross-origin iframes, which only accept user-generated events.
+  }
+
+  @override
+  Future<void> dispose() async {
+    if (_isInitialized) {
+      assert(_instances[viewId] == this);
+      _instances.remove(viewId);
+      if (_instances.isEmpty) {
+        await _clickSubscribtion.cancel();
+      }
+      // Asynchronously dispose this view.
+      await SystemChannels.platform_views.invokeMethod<void>('dispose', viewId);
+    }
+  }
+}
+
+int _getViewIdFromTarget(html.Event event) {
+  final html.Element linkElement = _getLinkElementFromTarget(event);
+  if (linkElement != null) {
+    return getProperty(linkElement, _viewIdProperty);
+  }
+  return null;
+}
+
+html.Element _getLinkElementFromTarget(html.Event event) {
+  final html.Element target = event.target;
+  if (_isLinkElement(target)) {
+    return target;
+  }
+  if (target.shadowRoot != null) {
+    final html.Element child = target.shadowRoot.lastChild;
+    if (_isLinkElement(child)) {
+      return child;
+    }
+  }
+  return null;
+}
+
+bool _isLinkElement(html.Element element) {
+  return element.tagName == 'A' && hasProperty(element, _viewIdProperty);
+}
diff --git a/packages/url_launcher/url_launcher_web/lib/url_launcher_web.dart b/packages/url_launcher/url_launcher_web/lib/url_launcher_web.dart
index 093e06a4d8ed..0c3c9d6afd67 100644
--- a/packages/url_launcher/url_launcher_web/lib/url_launcher_web.dart
+++ b/packages/url_launcher/url_launcher_web/lib/url_launcher_web.dart
@@ -4,10 +4,14 @@
 
 import 'dart:async';
 import 'dart:html' as html;
+// ignore: undefined_shown_name
+import 'dart:ui' as ui show platformViewRegistry;
 
 import 'package:flutter_web_plugins/flutter_web_plugins.dart';
 import 'package:meta/meta.dart';
+import 'package:url_launcher_platform_interface/link.dart';
 import 'package:url_launcher_platform_interface/url_launcher_platform_interface.dart';
+import 'package:url_launcher_web/link.dart';
 
 import 'src/third_party/platform_detect/browser.dart';
 
@@ -43,6 +47,9 @@ class UrlLauncherPlugin extends UrlLauncherPlatform {
   /// Registers this class as the default instance of [UrlLauncherPlatform].
   static void registerWith(Registrar registrar) {
     UrlLauncherPlatform.instance = UrlLauncherPlugin();
+    linkDelegate = (LinkInfo linkInfo) => WebLinkDelegate(linkInfo);
+    // ignore: undefined_prefixed_name
+    ui.platformViewRegistry.registerViewFactory(viewType, linkViewFactory);
   }
 
   /// Opens the given [url] in the specified [webOnlyWindowName].
diff --git a/packages/url_launcher/url_launcher_web/pubspec.yaml b/packages/url_launcher/url_launcher_web/pubspec.yaml
index 957b25757036..7ae84cdfb07e 100644
--- a/packages/url_launcher/url_launcher_web/pubspec.yaml
+++ b/packages/url_launcher/url_launcher_web/pubspec.yaml
@@ -4,7 +4,7 @@ homepage: https://github.com/flutter/plugins/tree/master/packages/url_launcher/u
 # 0.1.y+z is compatible with 1.0.0, if you land a breaking change bump
 # the version to 2.0.0.
 # See more details: https://github.com/flutter/flutter/wiki/Package-migration-to-1.0.0
-version: 0.1.4+2
+version: 0.1.5
 
 flutter:
   plugin:
@@ -14,7 +14,7 @@ flutter:
         fileName: url_launcher_web.dart
 
 dependencies:
-  url_launcher_platform_interface: ^1.0.8
+  url_launcher_platform_interface: ^1.0.9
   flutter:
     sdk: flutter
   flutter_web_plugins:

From ea048e0ce9ccf4bf748905fb049f52d4af8554e0 Mon Sep 17 00:00:00 2001
From: Mouad Debbar <mdebbar@google.com>
Date: Thu, 15 Oct 2020 10:11:57 -0700
Subject: [PATCH 2/8] address comments

---
 .../url_launcher_web/lib/{ => src}/link.dart  | 95 +++++++++++--------
 .../lib/url_launcher_web.dart                 |  4 +-
 2 files changed, 57 insertions(+), 42 deletions(-)
 rename packages/url_launcher/url_launcher_web/lib/{ => src}/link.dart (71%)

diff --git a/packages/url_launcher/url_launcher_web/lib/link.dart b/packages/url_launcher/url_launcher_web/lib/src/link.dart
similarity index 71%
rename from packages/url_launcher/url_launcher_web/lib/link.dart
rename to packages/url_launcher/url_launcher_web/lib/src/link.dart
index 9874d00e8741..fefa7a8f216b 100644
--- a/packages/url_launcher/url_launcher_web/lib/link.dart
+++ b/packages/url_launcher/url_launcher_web/lib/src/link.dart
@@ -14,19 +14,20 @@ import 'package:flutter/services.dart';
 
 import 'package:url_launcher_platform_interface/link.dart';
 
-typedef _ClickListener = void Function(html.MouseEvent);
+/// Signature for a function that handles a mouse click event.
+typedef ClickListener = void Function(html.MouseEvent);
 
 /// The unique identifier for the view type to be used for link platform views.
-const String viewType = '__url_launcher::link';
+const String linkViewType = '__url_launcher::link';
 
 /// The name of the property used to set the viewId on the DOM element.
-const String _viewIdProperty = '__url_launcher::link::viewId';
+const String linkViewIdProperty = '__url_launcher::link::viewId';
 
 /// Signature for a function that takes a unique [id] and creates an HTML element.
-typedef PlatformViewFactory = html.Element Function(int viewId);
+typedef HtmlViewFactory = html.Element Function(int viewId);
 
 /// Factory that returns the link DOM element for each unique view id.
-PlatformViewFactory get linkViewFactory => _LinkViewController._viewFactory;
+HtmlViewFactory get linkViewFactory => LinkViewController._viewFactory;
 
 /// The delegate for building the [Link] widget on the web.
 ///
@@ -39,26 +40,30 @@ class WebLinkDelegate extends StatefulWidget {
   final LinkInfo link;
 
   @override
-  _WebLinkDelegateState createState() => _WebLinkDelegateState();
+  WebLinkDelegateState createState() => WebLinkDelegateState();
 }
 
-class _WebLinkDelegateState extends State<WebLinkDelegate> {
-  _LinkViewController _controller;
+/// The link delegate used on the web platform.
+///
+/// For external URIs, it lets the browser do its thing. For app route names, it
+/// pushes the route name to the framework.
+class WebLinkDelegateState extends State<WebLinkDelegate> {
+  LinkViewController _controller;
 
   @override
   void didUpdateWidget(WebLinkDelegate oldWidget) {
     super.didUpdateWidget(oldWidget);
     if (widget.link.uri != oldWidget.link.uri) {
-      _controller?._setUri(widget.link.uri);
+      _controller?.setUri(widget.link.uri);
     }
     if (widget.link.target != oldWidget.link.target) {
-      _controller?._setTarget(widget.link.target);
+      _controller?.setTarget(widget.link.target);
     }
   }
 
   Future<void> _followLink() {
     final Completer<void> completer = Completer<void>();
-    _LinkViewController._registerHitTest(
+    LinkViewController.registerHitTest(
       _controller,
       onClick: (html.MouseEvent event) {
         completer.complete(_onDomClick(event));
@@ -93,7 +98,7 @@ class _WebLinkDelegateState extends State<WebLinkDelegate> {
         ),
         Positioned.fill(
           child: PlatformViewLink(
-            viewType: viewType,
+            viewType: linkViewType,
             onCreatePlatformView: _createController,
             surfaceFactory:
                 (BuildContext context, PlatformViewController controller) {
@@ -110,20 +115,21 @@ class _WebLinkDelegateState extends State<WebLinkDelegate> {
     );
   }
 
-  _LinkViewController _createController(PlatformViewCreationParams params) {
-    _controller = _LinkViewController(params.id);
+  LinkViewController _createController(PlatformViewCreationParams params) {
+    _controller = LinkViewController(params.id);
     _controller._initialize().then((_) {
       params.onPlatformViewCreated(params.id);
     });
     return _controller
-      .._setUri(widget.link.uri)
-      .._setTarget(widget.link.target);
+      ..setUri(widget.link.uri)
+      ..setTarget(widget.link.target);
   }
 }
 
 /// Controls link views.
-class _LinkViewController extends PlatformViewController {
-  _LinkViewController(this.viewId) {
+class LinkViewController extends PlatformViewController {
+  /// Creates a [LinkViewController] instance with the unique [viewId].
+  LinkViewController(this.viewId) {
     if (_instances.isEmpty) {
       // This is the first controller being created, attach the global click
       // listener.
@@ -132,40 +138,41 @@ class _LinkViewController extends PlatformViewController {
     _instances[viewId] = this;
   }
 
-  static Map<int, _LinkViewController> _instances =
-      <int, _LinkViewController>{};
+  static Map<int, LinkViewController> _instances =
+      <int, LinkViewController>{};
 
   static html.Element _viewFactory(int viewId) {
     return _instances[viewId]?._element;
   }
 
   static int _hitTestedViewId;
-  static _ClickListener _hitTestedClickCallback;
+  static ClickListener _hitTestedClickCallback;
 
   static StreamSubscription _clickSubscribtion;
 
   static void _onGlobalClick(html.MouseEvent event) {
-    final int viewId = _getViewIdFromTarget(event);
+    final int viewId = getViewIdFromTarget(event);
     _instances[viewId]?._onDomClick(event);
     // After the DOM click event has been received, clean up the hit test state
     // so we can start fresh on the next click.
-    _unregisterHitTest();
+    unregisterHitTest();
   }
 
-  /// Call this method to indicated that a hit test has been registered for the
+  /// Call this method to indicate that a hit test has been registered for the
   /// given [controller].
   ///
   /// The [onClick] callback is invoked when the anchor element receives a
   /// `click` from the browser.
-  static void _registerHitTest(
-    _LinkViewController controller, {
-    @required _ClickListener onClick,
+  static void registerHitTest(
+    LinkViewController controller, {
+    @required ClickListener onClick,
   }) {
     _hitTestedViewId = controller.viewId;
     _hitTestedClickCallback = onClick;
   }
 
-  static void _unregisterHitTest() {
+  /// Removes all information about previously registered hit tests.
+  static void unregisterHitTest() {
     _hitTestedViewId = null;
     _hitTestedClickCallback = null;
   }
@@ -178,7 +185,7 @@ class _LinkViewController extends PlatformViewController {
 
   Future<void> _initialize() async {
     _element = html.Element.tag('a');
-    setProperty(_element, _viewIdProperty, viewId);
+    setProperty(_element, linkViewIdProperty, viewId);
     _element.style
       ..opacity = '0'
       ..display = 'block'
@@ -186,7 +193,7 @@ class _LinkViewController extends PlatformViewController {
 
     final Map<String, dynamic> args = <String, dynamic>{
       'id': viewId,
-      'viewType': viewType,
+      'viewType': linkViewType,
     };
     await SystemChannels.platform_views.invokeMethod<void>('create', args);
   }
@@ -203,7 +210,8 @@ class _LinkViewController extends PlatformViewController {
     }
   }
 
-  void _setUri(Uri uri) {
+  /// Set the [Uri] value for this link.
+  void setUri(Uri uri) {
     assert(_isInitialized);
     if (uri == null) {
       _element.removeAttribute('href');
@@ -212,7 +220,8 @@ class _LinkViewController extends PlatformViewController {
     }
   }
 
-  void _setTarget(LinkTarget target) {
+  /// Set the [LinkTarget] value for this link.
+  void setTarget(LinkTarget target) {
     assert(_isInitialized);
     _element.setAttribute('target', _getHtmlTarget(target));
   }
@@ -255,28 +264,34 @@ class _LinkViewController extends PlatformViewController {
   }
 }
 
-int _getViewIdFromTarget(html.Event event) {
-  final html.Element linkElement = _getLinkElementFromTarget(event);
+/// Finds the view id of the DOM element targeted by the [event].
+int getViewIdFromTarget(html.Event event) {
+  final html.Element linkElement = getLinkElementFromTarget(event);
   if (linkElement != null) {
-    return getProperty(linkElement, _viewIdProperty);
+    return getProperty(linkElement, linkViewIdProperty);
   }
   return null;
 }
 
-html.Element _getLinkElementFromTarget(html.Event event) {
+/// Finds the targeted DOM element by the [event].
+///
+/// It handles the case where the target element is inside a shadow DOM too.
+html.Element getLinkElementFromTarget(html.Event event) {
   final html.Element target = event.target;
-  if (_isLinkElement(target)) {
+  if (isLinkElement(target)) {
     return target;
   }
   if (target.shadowRoot != null) {
     final html.Element child = target.shadowRoot.lastChild;
-    if (_isLinkElement(child)) {
+    if (isLinkElement(child)) {
       return child;
     }
   }
   return null;
 }
 
-bool _isLinkElement(html.Element element) {
-  return element.tagName == 'A' && hasProperty(element, _viewIdProperty);
+/// Checks if the given [element] is a link that was created by
+/// [LinkViewController].
+bool isLinkElement(html.Element element) {
+  return element.tagName == 'A' && hasProperty(element, linkViewIdProperty);
 }
diff --git a/packages/url_launcher/url_launcher_web/lib/url_launcher_web.dart b/packages/url_launcher/url_launcher_web/lib/url_launcher_web.dart
index 0c3c9d6afd67..76e15330d21b 100644
--- a/packages/url_launcher/url_launcher_web/lib/url_launcher_web.dart
+++ b/packages/url_launcher/url_launcher_web/lib/url_launcher_web.dart
@@ -11,8 +11,8 @@ import 'package:flutter_web_plugins/flutter_web_plugins.dart';
 import 'package:meta/meta.dart';
 import 'package:url_launcher_platform_interface/link.dart';
 import 'package:url_launcher_platform_interface/url_launcher_platform_interface.dart';
-import 'package:url_launcher_web/link.dart';
 
+import 'src/link.dart';
 import 'src/third_party/platform_detect/browser.dart';
 
 const _safariTargetTopSchemes = {
@@ -49,7 +49,7 @@ class UrlLauncherPlugin extends UrlLauncherPlatform {
     UrlLauncherPlatform.instance = UrlLauncherPlugin();
     linkDelegate = (LinkInfo linkInfo) => WebLinkDelegate(linkInfo);
     // ignore: undefined_prefixed_name
-    ui.platformViewRegistry.registerViewFactory(viewType, linkViewFactory);
+    ui.platformViewRegistry.registerViewFactory(linkViewType, linkViewFactory);
   }
 
   /// Opens the given [url] in the specified [webOnlyWindowName].

From d5ec9c5582a96d086dda342ec2313e92c9d21fbe Mon Sep 17 00:00:00 2001
From: Mouad Debbar <mdebbar@google.com>
Date: Thu, 15 Oct 2020 17:34:46 -0700
Subject: [PATCH 3/8] changes

---
 packages/url_launcher/url_launcher_web/lib/src/link.dart    | 6 ++----
 .../url_launcher/url_launcher_web/lib/url_launcher_web.dart | 4 +++-
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/packages/url_launcher/url_launcher_web/lib/src/link.dart b/packages/url_launcher/url_launcher_web/lib/src/link.dart
index fefa7a8f216b..05fde311012c 100644
--- a/packages/url_launcher/url_launcher_web/lib/src/link.dart
+++ b/packages/url_launcher/url_launcher_web/lib/src/link.dart
@@ -79,8 +79,7 @@ class WebLinkDelegateState extends State<WebLinkDelegate> {
       // browser handle it.
       event.preventDefault();
       final String routeName = widget.link.uri.toString();
-      // TODO(mdebbar): how do we know if `isUsingRouter` should be true or false?
-      return pushRouteNameToFramework(routeName, isUsingRouter: false);
+      return pushRouteNameToFramework(context, routeName);
     }
 
     // External links will be handled by the browser, so we don't have to do
@@ -138,8 +137,7 @@ class LinkViewController extends PlatformViewController {
     _instances[viewId] = this;
   }
 
-  static Map<int, LinkViewController> _instances =
-      <int, LinkViewController>{};
+  static Map<int, LinkViewController> _instances = <int, LinkViewController>{};
 
   static html.Element _viewFactory(int viewId) {
     return _instances[viewId]?._element;
diff --git a/packages/url_launcher/url_launcher_web/lib/url_launcher_web.dart b/packages/url_launcher/url_launcher_web/lib/url_launcher_web.dart
index 76e15330d21b..81d1418d9c25 100644
--- a/packages/url_launcher/url_launcher_web/lib/url_launcher_web.dart
+++ b/packages/url_launcher/url_launcher_web/lib/url_launcher_web.dart
@@ -47,11 +47,13 @@ class UrlLauncherPlugin extends UrlLauncherPlatform {
   /// Registers this class as the default instance of [UrlLauncherPlatform].
   static void registerWith(Registrar registrar) {
     UrlLauncherPlatform.instance = UrlLauncherPlugin();
-    linkDelegate = (LinkInfo linkInfo) => WebLinkDelegate(linkInfo);
     // ignore: undefined_prefixed_name
     ui.platformViewRegistry.registerViewFactory(linkViewType, linkViewFactory);
   }
 
+  @override
+  LinkDelegate linkDelegate = (LinkInfo linkInfo) => WebLinkDelegate(linkInfo);
+
   /// Opens the given [url] in the specified [webOnlyWindowName].
   ///
   /// Returns the newly created window.

From 082bbbdd429ce047b90c98e8a1c080db200d62ef Mon Sep 17 00:00:00 2001
From: Mouad Debbar <mdebbar@google.com>
Date: Sun, 18 Oct 2020 02:27:57 -0700
Subject: [PATCH 4/8] more changes

---
 .../url_launcher/url_launcher_web/lib/url_launcher_web.dart   | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/packages/url_launcher/url_launcher_web/lib/url_launcher_web.dart b/packages/url_launcher/url_launcher_web/lib/url_launcher_web.dart
index 81d1418d9c25..a51bf8cbfe4a 100644
--- a/packages/url_launcher/url_launcher_web/lib/url_launcher_web.dart
+++ b/packages/url_launcher/url_launcher_web/lib/url_launcher_web.dart
@@ -52,7 +52,9 @@ class UrlLauncherPlugin extends UrlLauncherPlatform {
   }
 
   @override
-  LinkDelegate linkDelegate = (LinkInfo linkInfo) => WebLinkDelegate(linkInfo);
+  LinkDelegate get linkDelegate {
+    return (LinkInfo linkInfo) => WebLinkDelegate(linkInfo);
+  }
 
   /// Opens the given [url] in the specified [webOnlyWindowName].
   ///

From b653731e146a40c2d83576d33e295a138891a99a Mon Sep 17 00:00:00 2001
From: Mouad Debbar <mdebbar@google.com>
Date: Tue, 20 Oct 2020 11:23:09 -0700
Subject: [PATCH 5/8] add test + remove layer piercing

---
 .../url_launcher_web/lib/src/link.dart        | 93 +++++++++----------
 .../url_launcher_web_integration.dart         | 88 ++++++++++++++++++
 2 files changed, 133 insertions(+), 48 deletions(-)

diff --git a/packages/url_launcher/url_launcher_web/lib/src/link.dart b/packages/url_launcher/url_launcher_web/lib/src/link.dart
index 05fde311012c..8fac399c9a4e 100644
--- a/packages/url_launcher/url_launcher_web/lib/src/link.dart
+++ b/packages/url_launcher/url_launcher_web/lib/src/link.dart
@@ -14,9 +14,6 @@ import 'package:flutter/services.dart';
 
 import 'package:url_launcher_platform_interface/link.dart';
 
-/// Signature for a function that handles a mouse click event.
-typedef ClickListener = void Function(html.MouseEvent);
-
 /// The unique identifier for the view type to be used for link platform views.
 const String linkViewType = '__url_launcher::link';
 
@@ -62,29 +59,8 @@ class WebLinkDelegateState extends State<WebLinkDelegate> {
   }
 
   Future<void> _followLink() {
-    final Completer<void> completer = Completer<void>();
-    LinkViewController.registerHitTest(
-      _controller,
-      onClick: (html.MouseEvent event) {
-        completer.complete(_onDomClick(event));
-      },
-    );
-    return completer.future;
-  }
-
-  Future<void> _onDomClick(html.MouseEvent event) {
-    if (!widget.link.uri.hasScheme) {
-      // A uri that doesn't have a scheme is an internal route name. In this
-      // case, we push it via Flutter's navigation system instead of letting the
-      // browser handle it.
-      event.preventDefault();
-      final String routeName = widget.link.uri.toString();
-      return pushRouteNameToFramework(context, routeName);
-    }
-
-    // External links will be handled by the browser, so we don't have to do
-    // anything.
-    return Future<void>.value(null);
+    LinkViewController.registerHitTest(_controller);
+    return Future<void>.value();
   }
 
   @override
@@ -98,7 +74,12 @@ class WebLinkDelegateState extends State<WebLinkDelegate> {
         Positioned.fill(
           child: PlatformViewLink(
             viewType: linkViewType,
-            onCreatePlatformView: _createController,
+            onCreatePlatformView: (PlatformViewCreationParams params) {
+              _controller = LinkViewController.fromParams(params, context);
+              return _controller
+                ..setUri(widget.link.uri)
+                ..setTarget(widget.link.target);
+            },
             surfaceFactory:
                 (BuildContext context, PlatformViewController controller) {
               return PlatformViewSurface(
@@ -113,22 +94,12 @@ class WebLinkDelegateState extends State<WebLinkDelegate> {
       ],
     );
   }
-
-  LinkViewController _createController(PlatformViewCreationParams params) {
-    _controller = LinkViewController(params.id);
-    _controller._initialize().then((_) {
-      params.onPlatformViewCreated(params.id);
-    });
-    return _controller
-      ..setUri(widget.link.uri)
-      ..setTarget(widget.link.target);
-  }
 }
 
 /// Controls link views.
 class LinkViewController extends PlatformViewController {
   /// Creates a [LinkViewController] instance with the unique [viewId].
-  LinkViewController(this.viewId) {
+  LinkViewController(this.viewId, this.context) {
     if (_instances.isEmpty) {
       // This is the first controller being created, attach the global click
       // listener.
@@ -137,6 +108,20 @@ class LinkViewController extends PlatformViewController {
     _instances[viewId] = this;
   }
 
+  /// Creates and initializes a [LinkViewController] instance with the given
+  /// platform view [params].
+  factory LinkViewController.fromParams(
+    PlatformViewCreationParams params,
+    BuildContext context,
+  ) {
+    final int viewId = params.id;
+    final LinkViewController controller = LinkViewController(viewId, context);
+    controller._initialize().then((_) {
+      params.onPlatformViewCreated(viewId);
+    });
+    return controller;
+  }
+
   static Map<int, LinkViewController> _instances = <int, LinkViewController>{};
 
   static html.Element _viewFactory(int viewId) {
@@ -144,7 +129,6 @@ class LinkViewController extends PlatformViewController {
   }
 
   static int _hitTestedViewId;
-  static ClickListener _hitTestedClickCallback;
 
   static StreamSubscription _clickSubscribtion;
 
@@ -161,23 +145,21 @@ class LinkViewController extends PlatformViewController {
   ///
   /// The [onClick] callback is invoked when the anchor element receives a
   /// `click` from the browser.
-  static void registerHitTest(
-    LinkViewController controller, {
-    @required ClickListener onClick,
-  }) {
+  static void registerHitTest(LinkViewController controller) {
     _hitTestedViewId = controller.viewId;
-    _hitTestedClickCallback = onClick;
   }
 
   /// Removes all information about previously registered hit tests.
   static void unregisterHitTest() {
     _hitTestedViewId = null;
-    _hitTestedClickCallback = null;
   }
 
   @override
   final int viewId;
 
+  /// The context of the [Link] widget that created this controller.
+  final BuildContext context;
+
   html.Element _element;
   bool get _isInitialized => _element != null;
 
@@ -198,19 +180,34 @@ class LinkViewController extends PlatformViewController {
 
   void _onDomClick(html.MouseEvent event) {
     final bool isHitTested = _hitTestedViewId == viewId;
-    if (isHitTested) {
-      _hitTestedClickCallback(event);
-    } else {
+    if (!isHitTested) {
       // There was no hit test registered for this click. This means the click
       // landed on the anchor element but not on the underlying widget. In this
       // case, we prevent the browser from following the click.
       event.preventDefault();
+      return;
+    }
+
+    if (_uri.hasScheme) {
+      // External links will be handled by the browser, so we don't have to do
+      // anything.
+      return;
     }
+
+    // A uri that doesn't have a scheme is an internal route name. In this
+    // case, we push it via Flutter's navigation system instead of letting the
+    // browser handle it.
+    event.preventDefault();
+    final String routeName = _uri.toString();
+    pushRouteNameToFramework(context, routeName);
   }
 
+  Uri _uri;
+
   /// Set the [Uri] value for this link.
   void setUri(Uri uri) {
     assert(_isInitialized);
+    _uri = uri;
     if (uri == null) {
       _element.removeAttribute('href');
     } else {
diff --git a/packages/url_launcher/url_launcher_web/test/test_driver/url_launcher_web_integration.dart b/packages/url_launcher/url_launcher_web/test/test_driver/url_launcher_web_integration.dart
index d0dd6e38ee46..4d103443deb9 100644
--- a/packages/url_launcher/url_launcher_web/test/test_driver/url_launcher_web_integration.dart
+++ b/packages/url_launcher/url_launcher_web/test/test_driver/url_launcher_web_integration.dart
@@ -3,8 +3,12 @@
 // found in the LICENSE file.
 
 import 'dart:html' as html;
+import 'dart:js_util';
+import 'package:flutter/widgets.dart';
 import 'package:flutter_test/flutter_test.dart';
+import 'package:url_launcher_platform_interface/link.dart';
 import 'package:url_launcher_web/url_launcher_web.dart';
+import 'package:url_launcher_web/src/link.dart';
 import 'package:mockito/mockito.dart';
 import 'package:integration_test/integration_test.dart';
 
@@ -228,4 +232,88 @@ void main() {
       });
     });
   });
+
+  group('link', () {
+    testWidgets('creates anchor with correct attributes',
+        (WidgetTester tester) async {
+      final Uri uri = Uri.parse('http://foobar/example?q=1');
+      await tester.pumpWidget(Directionality(
+        textDirection: TextDirection.ltr,
+        child: WebLinkDelegate(TestLinkInfo(
+          uri: uri,
+          target: LinkTarget.blank,
+          builder: (BuildContext context, FollowLink followLink) {
+            return Container(width: 100, height: 100);
+          },
+        )),
+      ));
+      // Platform view creation happens asynchronously.
+      await tester.pumpAndSettle();
+
+      final html.Element anchor = _findSingleAnchor();
+      expect(anchor.getAttribute('href'), uri.toString());
+      expect(anchor.getAttribute('target'), '_blank');
+
+      final Uri uri2 = Uri.parse('http://foobar2/example?q=2');
+      await tester.pumpWidget(Directionality(
+        textDirection: TextDirection.ltr,
+        child: WebLinkDelegate(TestLinkInfo(
+          uri: uri2,
+          target: LinkTarget.self,
+          builder: (BuildContext context, FollowLink followLink) {
+            return Container(width: 100, height: 100);
+          },
+        )),
+      ));
+      await tester.pumpAndSettle();
+
+      // Check that the same anchor has been updated.
+      expect(anchor.getAttribute('href'), uri2.toString());
+      expect(anchor.getAttribute('target'), '_self');
+    });
+  });
+}
+
+html.Element _findSingleAnchor() {
+  final List<html.Element> foundAnchors = <html.Element>[];
+  for (final html.Element anchor in html.document.querySelectorAll('a')) {
+    if (hasProperty(anchor, linkViewIdProperty)) {
+      foundAnchors.add(anchor);
+    }
+  }
+
+  // Search inside platform views with shadow roots as well.
+  for (final html.Element platformView
+      in html.document.querySelectorAll('flt-platform-view')) {
+    final html.ShadowRoot shadowRoot = platformView.shadowRoot;
+    if (shadowRoot != null) {
+      for (final html.Element anchor in shadowRoot.querySelectorAll('a')) {
+        if (hasProperty(anchor, linkViewIdProperty)) {
+          foundAnchors.add(anchor);
+        }
+      }
+    }
+  }
+
+  return foundAnchors.single;
+}
+
+class TestLinkInfo extends LinkInfo {
+  @override
+  final LinkWidgetBuilder builder;
+
+  @override
+  final Uri uri;
+
+  @override
+  final LinkTarget target;
+
+  @override
+  bool get isDisabled => uri == null;
+
+  TestLinkInfo({
+    @required this.uri,
+    @required this.target,
+    @required this.builder,
+  });
 }

From b6a51f78a70ed14eb7194040267bb0d28082097b Mon Sep 17 00:00:00 2001
From: Mouad Debbar <mdebbar@google.com>
Date: Tue, 20 Oct 2020 11:31:05 -0700
Subject: [PATCH 6/8] add rel attribute to all links

---
 packages/url_launcher/url_launcher_web/lib/src/link.dart | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/packages/url_launcher/url_launcher_web/lib/src/link.dart b/packages/url_launcher/url_launcher_web/lib/src/link.dart
index 8fac399c9a4e..06fd2c4d561b 100644
--- a/packages/url_launcher/url_launcher_web/lib/src/link.dart
+++ b/packages/url_launcher/url_launcher_web/lib/src/link.dart
@@ -171,6 +171,10 @@ class LinkViewController extends PlatformViewController {
       ..display = 'block'
       ..cursor = 'unset';
 
+    // This is recommended on MDN:
+    // - https://developer.mozilla.org/en-US/docs/Web/HTML/Element/a#attr-target
+    _element.setAttribute('rel', 'noreferrer noopener');
+
     final Map<String, dynamic> args = <String, dynamic>{
       'id': viewId,
       'viewType': linkViewType,

From 78cd34d004e84efe30d99c6c833d58a14347f9b9 Mon Sep 17 00:00:00 2001
From: Mouad Debbar <mdebbar@google.com>
Date: Tue, 20 Oct 2020 11:38:21 -0700
Subject: [PATCH 7/8] remove incorrect comment

---
 packages/url_launcher/url_launcher_web/lib/src/link.dart | 1 -
 1 file changed, 1 deletion(-)

diff --git a/packages/url_launcher/url_launcher_web/lib/src/link.dart b/packages/url_launcher/url_launcher_web/lib/src/link.dart
index 06fd2c4d561b..d4cbbe270b99 100644
--- a/packages/url_launcher/url_launcher_web/lib/src/link.dart
+++ b/packages/url_launcher/url_launcher_web/lib/src/link.dart
@@ -257,7 +257,6 @@ class LinkViewController extends PlatformViewController {
       if (_instances.isEmpty) {
         await _clickSubscribtion.cancel();
       }
-      // Asynchronously dispose this view.
       await SystemChannels.platform_views.invokeMethod<void>('dispose', viewId);
     }
   }

From 471353dabc4ca8313507cdb48043ae6460f9303c Mon Sep 17 00:00:00 2001
From: Mouad Debbar <mdebbar@google.com>
Date: Tue, 20 Oct 2020 14:32:51 -0700
Subject: [PATCH 8/8] type + analysis options

---
 .../url_launcher_web/analysis_options.yaml             | 10 ++++++++++
 .../url_launcher/url_launcher_web/lib/src/link.dart    |  6 +++---
 .../url_launcher_web/lib/url_launcher_web.dart         |  1 -
 script/incremental_build.sh                            |  1 +
 4 files changed, 14 insertions(+), 4 deletions(-)
 create mode 100644 packages/url_launcher/url_launcher_web/analysis_options.yaml

diff --git a/packages/url_launcher/url_launcher_web/analysis_options.yaml b/packages/url_launcher/url_launcher_web/analysis_options.yaml
new file mode 100644
index 000000000000..443b16551ec9
--- /dev/null
+++ b/packages/url_launcher/url_launcher_web/analysis_options.yaml
@@ -0,0 +1,10 @@
+# This is a temporary file to allow us to unblock the flutter/plugins repo CI.
+# It disables some of lints that were disabled inline. Disabling lints inline
+# is no longer possible, so this file is required.
+# TODO(ditman) https://github.com/flutter/flutter/issues/55000 (clean this up)
+
+include: ../../../analysis_options.yaml
+
+analyzer:
+  errors:
+    undefined_prefixed_name: ignore
diff --git a/packages/url_launcher/url_launcher_web/lib/src/link.dart b/packages/url_launcher/url_launcher_web/lib/src/link.dart
index d4cbbe270b99..e8a6d68348bb 100644
--- a/packages/url_launcher/url_launcher_web/lib/src/link.dart
+++ b/packages/url_launcher/url_launcher_web/lib/src/link.dart
@@ -103,7 +103,7 @@ class LinkViewController extends PlatformViewController {
     if (_instances.isEmpty) {
       // This is the first controller being created, attach the global click
       // listener.
-      _clickSubscribtion = html.window.onClick.listen(_onGlobalClick);
+      _clickSubscription = html.window.onClick.listen(_onGlobalClick);
     }
     _instances[viewId] = this;
   }
@@ -130,7 +130,7 @@ class LinkViewController extends PlatformViewController {
 
   static int _hitTestedViewId;
 
-  static StreamSubscription _clickSubscribtion;
+  static StreamSubscription _clickSubscription;
 
   static void _onGlobalClick(html.MouseEvent event) {
     final int viewId = getViewIdFromTarget(event);
@@ -255,7 +255,7 @@ class LinkViewController extends PlatformViewController {
       assert(_instances[viewId] == this);
       _instances.remove(viewId);
       if (_instances.isEmpty) {
-        await _clickSubscribtion.cancel();
+        await _clickSubscription.cancel();
       }
       await SystemChannels.platform_views.invokeMethod<void>('dispose', viewId);
     }
diff --git a/packages/url_launcher/url_launcher_web/lib/url_launcher_web.dart b/packages/url_launcher/url_launcher_web/lib/url_launcher_web.dart
index a51bf8cbfe4a..e7367b3a2f6d 100644
--- a/packages/url_launcher/url_launcher_web/lib/url_launcher_web.dart
+++ b/packages/url_launcher/url_launcher_web/lib/url_launcher_web.dart
@@ -47,7 +47,6 @@ class UrlLauncherPlugin extends UrlLauncherPlatform {
   /// Registers this class as the default instance of [UrlLauncherPlatform].
   static void registerWith(Registrar registrar) {
     UrlLauncherPlatform.instance = UrlLauncherPlugin();
-    // ignore: undefined_prefixed_name
     ui.platformViewRegistry.registerViewFactory(linkViewType, linkViewFactory);
   }
 
diff --git a/script/incremental_build.sh b/script/incremental_build.sh
index 30c166b4c666..8e9cf34b1cda 100755
--- a/script/incremental_build.sh
+++ b/script/incremental_build.sh
@@ -24,6 +24,7 @@ CUSTOM_ANALYSIS_PLUGINS=(
   "camera"
   "video_player/video_player_web"
   "google_maps_flutter/google_maps_flutter_web"
+  "url_launcher/url_launcher_web"
 )
 # Comma-separated string of the list above
 readonly CUSTOM_FLAG=$(IFS=, ; echo "${CUSTOM_ANALYSIS_PLUGINS[*]}")