packages/url_launcher/url_launcher_web/lib/src/link.dart - mirrors/packages - Git at Google

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

 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:flutter_web_plugins/flutter_web_plugins.dart' show urlStrategy;
 import 'package:url_launcher_platform_interface/link.dart';

 /// The unique identifier for the view type to be used for link platform views.
 const String linkViewType = '__url_launcher::link';

 /// The name of the property used to set the viewId on the DOM element.
 const String linkViewIdProperty = '__url_launcher::link::viewId';

 /// Signature for a function that takes a unique [id] and creates an HTML element.
 typedef HtmlViewFactory = html.Element Function(int viewId);

 /// Factory that returns the link DOM element for each unique view id.
 HtmlViewFactory 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, {super.key});

   /// Information about the link built by the app.
   final LinkInfo link;

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

 /// 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> {
   late 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() {
     LinkViewController.registerHitTest(_controller);
     return Future<void>.value();
   }

   @override
   Widget build(BuildContext context) {
     return Stack(
       fit: StackFit.passthrough,
       children: <Widget>[
         widget.link.builder(
           context,
           widget.link.isDisabled ? null : _followLink,
         ),
         Positioned.fill(
           child: PlatformViewLink(
             viewType: linkViewType,
             onCreatePlatformView: (PlatformViewCreationParams params) {
               _controller = LinkViewController.fromParams(params);
               return _controller
                 ..setUri(widget.link.uri)
                 ..setTarget(widget.link.target);
             },
             surfaceFactory:
                 (BuildContext context, PlatformViewController controller) {
               return PlatformViewSurface(
                 controller: controller,
                 gestureRecognizers: const <Factory<
                     OneSequenceGestureRecognizer>>{},
                 hitTestBehavior: PlatformViewHitTestBehavior.transparent,
               );
             },
           ),
         ),
       ],
     );
   }
 }

 /// Controls link views.
 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.
       _clickSubscription = html.window.onClick.listen(_onGlobalClick);
     }
     _instances[viewId] = this;
   }

   /// Creates and initializes a [LinkViewController] instance with the given
   /// platform view [params].
   factory LinkViewController.fromParams(
     PlatformViewCreationParams params,
   ) {
     final int viewId = params.id;
     final LinkViewController controller = LinkViewController(viewId);
     controller._initialize().then((_) {
       /// Because _initialize is async, it can happen that [LinkViewController.dispose]
       /// may get called before this `then` callback.
       /// Check that the `controller` that was created by this factory is not
       /// disposed before calling `onPlatformViewCreated`.
       if (_instances[viewId] == controller) {
         params.onPlatformViewCreated(viewId);
       }
     });
     return controller;
   }

   static final Map<int, LinkViewController> _instances =
       <int, LinkViewController>{};

   static html.Element _viewFactory(int viewId) {
     return _instances[viewId]!._element;
   }

   static int? _hitTestedViewId;

   static late StreamSubscription<html.MouseEvent> _clickSubscription;

   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 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) {
     _hitTestedViewId = controller.viewId;
   }

   /// Removes all information about previously registered hit tests.
   static void unregisterHitTest() {
     _hitTestedViewId = null;
   }

   @override
   final int viewId;

   late html.Element _element;

   Future<void> _initialize() async {
     _element = html.Element.tag('a');
     setProperty(_element, linkViewIdProperty, viewId);
     _element.style
       ..opacity = '0'
       ..display = 'block'
       ..width = '100%'
       ..height = '100%'
       ..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,
     };
     await SystemChannels.platform_views.invokeMethod<void>('create', args);
   }

   void _onDomClick(html.MouseEvent event) {
     final bool isHitTested = _hitTestedViewId == viewId;
     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 != null && _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(null, routeName);
   }

   Uri? _uri;

   /// Set the [Uri] value for this link.
   ///
   /// When Uri is null, the `href` attribute of the link is removed.
   void setUri(Uri? uri) {
     _uri = uri;
     if (uri == null) {
       _element.removeAttribute('href');
     } else {
       String href = uri.toString();
       // in case an internal uri is given, the url mus be properly encoded
       // using the currently used [UrlStrategy]
       if (!uri.hasScheme) {
         href = urlStrategy?.prepareExternalUrl(href) ?? href;
       }
       _element.setAttribute('href', href);
     }
   }

   /// Set the [LinkTarget] value for this link.
   void setTarget(LinkTarget target) {
     _element.setAttribute('target', _getHtmlTarget(target));
   }

   String _getHtmlTarget(LinkTarget target) {
     switch (target) {
       case LinkTarget.defaultTarget:
       case LinkTarget.self:
         return '_self';
       case LinkTarget.blank:
         return '_blank';
     }
     // The enum comes from a different package, which could get a new value at
     // any time, so provide a fallback that ensures this won't break when used
     // with a version that contains new values. This is deliberately outside
     // the switch rather than a `default` so that the linter will flag the
     // switch as needing an update.
     return '_self';
   }

   @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 {
     assert(_instances[viewId] == this);
     _instances.remove(viewId);
     if (_instances.isEmpty) {
       await _clickSubscription.cancel();
     }
     await SystemChannels.platform_views.invokeMethod<void>('dispose', viewId);
   }
 }

 /// 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) {
     // TODO(stuartmorgan): Remove this ignore (and change to getProperty<int>)
     // once the templated version is available on stable. On master (2.8) this
     // is already not necessary.
     // ignore: return_of_invalid_type
     return getProperty(linkElement, linkViewIdProperty);
   }
   return null;
 }

 /// 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.EventTarget? target = event.target;
   if (target != null && target is html.Element) {
     if (isLinkElement(target)) {
       return target;
     }
     if (target.shadowRoot != null) {
       final html.Node? child = target.shadowRoot!.lastChild;
       if (child != null && child is html.Element && isLinkElement(child)) {
         return child;
       }
     }
   }
   return null;
 }

 /// Checks if the given [element] is a link that was created by
 /// [LinkViewController].
 bool isLinkElement(html.Element? element) {
   return element != null &&
       element.tagName == 'A' &&
       hasProperty(element, linkViewIdProperty);
 }
	// Copyright 2013 The Flutter Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	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:flutter_web_plugins/flutter_web_plugins.dart' show urlStrategy;
	import 'package:url_launcher_platform_interface/link.dart';

	/// The unique identifier for the view type to be used for link platform views.
	const String linkViewType = '__url_launcher::link';

	/// The name of the property used to set the viewId on the DOM element.
	const String linkViewIdProperty = '__url_launcher::link::viewId';

	/// Signature for a function that takes a unique [id] and creates an HTML element.
	typedef HtmlViewFactory = html.Element Function(int viewId);

	/// Factory that returns the link DOM element for each unique view id.
	HtmlViewFactory 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, {super.key});

	/// Information about the link built by the app.
	final LinkInfo link;

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

	/// 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> {
	late 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() {
	LinkViewController.registerHitTest(_controller);
	return Future<void>.value();
	}

	@override
	Widget build(BuildContext context) {
	return Stack(
	fit: StackFit.passthrough,
	children: <Widget>[
	widget.link.builder(
	context,
	widget.link.isDisabled ? null : _followLink,
	),
	Positioned.fill(
	child: PlatformViewLink(
	viewType: linkViewType,
	onCreatePlatformView: (PlatformViewCreationParams params) {
	_controller = LinkViewController.fromParams(params);
	return _controller
	..setUri(widget.link.uri)
	..setTarget(widget.link.target);
	},
	surfaceFactory:
	(BuildContext context, PlatformViewController controller) {
	return PlatformViewSurface(
	controller: controller,
	gestureRecognizers: const <Factory<
	OneSequenceGestureRecognizer>>{},
	hitTestBehavior: PlatformViewHitTestBehavior.transparent,
	);
	},
	),
	),
	],
	);
	}
	}

	/// Controls link views.
	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.
	_clickSubscription = html.window.onClick.listen(_onGlobalClick);
	}
	_instances[viewId] = this;
	}

	/// Creates and initializes a [LinkViewController] instance with the given
	/// platform view [params].
	factory LinkViewController.fromParams(
	PlatformViewCreationParams params,
	) {
	final int viewId = params.id;
	final LinkViewController controller = LinkViewController(viewId);
	controller._initialize().then((_) {
	/// Because _initialize is async, it can happen that [LinkViewController.dispose]
	/// may get called before this `then` callback.
	/// Check that the `controller` that was created by this factory is not
	/// disposed before calling `onPlatformViewCreated`.
	if (_instances[viewId] == controller) {
	params.onPlatformViewCreated(viewId);
	}
	});
	return controller;
	}

	static final Map<int, LinkViewController> _instances =
	<int, LinkViewController>{};

	static html.Element _viewFactory(int viewId) {
	return _instances[viewId]!._element;
	}

	static int? _hitTestedViewId;

	static late StreamSubscription<html.MouseEvent> _clickSubscription;

	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 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) {
	_hitTestedViewId = controller.viewId;
	}

	/// Removes all information about previously registered hit tests.
	static void unregisterHitTest() {
	_hitTestedViewId = null;
	}

	@override
	final int viewId;

	late html.Element _element;

	Future<void> _initialize() async {
	_element = html.Element.tag('a');
	setProperty(_element, linkViewIdProperty, viewId);
	_element.style
	..opacity = '0'
	..display = 'block'
	..width = '100%'
	..height = '100%'
	..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,
	};
	await SystemChannels.platform_views.invokeMethod<void>('create', args);
	}

	void _onDomClick(html.MouseEvent event) {
	final bool isHitTested = _hitTestedViewId == viewId;
	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 != null && _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(null, routeName);
	}

	Uri? _uri;

	/// Set the [Uri] value for this link.
	///
	/// When Uri is null, the `href` attribute of the link is removed.
	void setUri(Uri? uri) {
	_uri = uri;
	if (uri == null) {
	_element.removeAttribute('href');
	} else {
	String href = uri.toString();
	// in case an internal uri is given, the url mus be properly encoded
	// using the currently used [UrlStrategy]
	if (!uri.hasScheme) {
	href = urlStrategy?.prepareExternalUrl(href) ?? href;
	}
	_element.setAttribute('href', href);
	}
	}

	/// Set the [LinkTarget] value for this link.
	void setTarget(LinkTarget target) {
	_element.setAttribute('target', _getHtmlTarget(target));
	}

	String _getHtmlTarget(LinkTarget target) {
	switch (target) {
	case LinkTarget.defaultTarget:
	case LinkTarget.self:
	return '_self';
	case LinkTarget.blank:
	return '_blank';
	}
	// The enum comes from a different package, which could get a new value at
	// any time, so provide a fallback that ensures this won't break when used
	// with a version that contains new values. This is deliberately outside
	// the switch rather than a `default` so that the linter will flag the
	// switch as needing an update.
	return '_self';
	}

	@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 {
	assert(_instances[viewId] == this);
	_instances.remove(viewId);
	if (_instances.isEmpty) {
	await _clickSubscription.cancel();
	}
	await SystemChannels.platform_views.invokeMethod<void>('dispose', viewId);
	}
	}

	/// 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) {
	// TODO(stuartmorgan): Remove this ignore (and change to getProperty<int>)
	// once the templated version is available on stable. On master (2.8) this
	// is already not necessary.
	// ignore: return_of_invalid_type
	return getProperty(linkElement, linkViewIdProperty);
	}
	return null;
	}

	/// 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.EventTarget? target = event.target;
	if (target != null && target is html.Element) {
	if (isLinkElement(target)) {
	return target;
	}
	if (target.shadowRoot != null) {
	final html.Node? child = target.shadowRoot!.lastChild;
	if (child != null && child is html.Element && isLinkElement(child)) {
	return child;
	}
	}
	}
	return null;
	}

	/// Checks if the given [element] is a link that was created by
	/// [LinkViewController].
	bool isLinkElement(html.Element? element) {
	return element != null &&
	element.tagName == 'A' &&
	hasProperty(element, linkViewIdProperty);
	}