public/dart/fuchsia_scenic_flutter/lib/src/child_view_connection.dart - topaz - Git at Google

 // Copyright 2018 The Fuchsia 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:ui';

 import 'package:fidl_fuchsia_math/fidl_async.dart';
 import 'package:fidl_fuchsia_ui_gfx/fidl_async.dart' show ImportToken;
 import 'package:fidl_fuchsia_ui_views/fidl_async.dart' show ViewHolderToken;
 import 'package:fidl_fuchsia_ui_viewsv1/fidl_async.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter/widgets.dart';
 import 'package:zircon/zircon.dart';

 import 'internal/_child_scene_layer.dart';
 import 'view_container.dart' as shared;
 import 'view_container_listener_impl.dart';

 typedef ChildViewConnectionCallback = void Function(
     ChildViewConnection connection);

 void _emptyConnectionCallback(ChildViewConnection c) {}

 /// A connection with a child view.
 ///
 /// Used with the [ChildView] widget to display a child view.
 class ChildViewConnection implements ViewContainerListenerDelegate {
   // TODO consider providing this API after MS-2293 is fixed
   // factory ChildViewConnection.launch(String url, Launcher launcher,
   //     {InterfaceRequest<ComponentController> controller,
   //     InterfaceRequest<ServiceProvider> childServices,
   //     ChildViewConnectionCallback onAvailable,
   //     ChildViewConnectionCallback onUnavailable}) {
   //   final Services services = Services();
   //   final LaunchInfo launchInfo =
   //       LaunchInfo(url: url, directoryRequest: services.request());
   //   try {
   //     launcher.createComponent(launchInfo, controller);
   //     return ChildViewConnection.connect(services,
   //         childServices: childServices,
   //         onAvailable: onAvailable,
   //         onUnavailable: onUnavailable);
   //   } finally {
   //     services.close();
   //   }
   // }

   // TODO consider providing this API after MS-2293 is fixed
   // factory ChildViewConnection.connect(Services services,
   //     {InterfaceRequest<ServiceProvider> childServices,
   //     ChildViewConnectionCallback onAvailable,
   //     ChildViewConnectionCallback onUnavailable}) {
   // final app.ViewProviderProxy viewProvider = new app.ViewProviderProxy();
   // services.connectToService(viewProvider.ctrl);
   // try {
   //   EventPairPair viewTokens = new EventPairPair();
   //   assert(viewTokens.status == ZX.OK);

   //   viewProvider.createView(viewTokens.second, childServices, null);
   //   return new ChildViewConnection.fromViewHolderToken(viewTokens.first,
   //       onAvailable: onAvailable, onUnavailable: onUnavailable);
   //   } finally {
   //     viewProvider.ctrl.close();
   //   }
   // }

   final ChildViewConnectionCallback _onAvailableCallback;
   final ChildViewConnectionCallback _onUnavailableCallback;
   ViewHolderToken _viewHolderToken;

   int _viewKey;
   ViewProperties _currentViewProperties;
   bool _available = false;

   VoidCallback _onViewInfoAvailable;

   SceneHost _sceneHost;
   int _attachments = 0;

   /// Constructs |ChildViewConnection| from a token.
   ChildViewConnection(ViewHolderToken viewHolderToken,
       {ChildViewConnectionCallback onAvailable,
       ChildViewConnectionCallback onUnavailable})
       : _onAvailableCallback = onAvailable ?? _emptyConnectionCallback,
         _onUnavailableCallback = onUnavailable ?? _emptyConnectionCallback,
         _viewHolderToken = viewHolderToken {
     assert(_viewHolderToken?.value != null);
   }

   /// Deprecated.
   ChildViewConnection.fromViewHolderToken(EventPair viewHolderToken,
       {ChildViewConnectionCallback onAvailable,
       ChildViewConnectionCallback onUnavailable})
       : this(ViewHolderToken(value: viewHolderToken),
             onAvailable: onAvailable, onUnavailable: onUnavailable);

   /// Deprecated.
   ChildViewConnection.fromImportToken(ImportToken viewHolderToken,
       {ChildViewConnectionCallback onAvailable,
       ChildViewConnectionCallback onUnavailable})
       : this(ViewHolderToken(value: viewHolderToken.value),
             onAvailable: onAvailable, onUnavailable: onUnavailable);

   bool get _attached => _attachments > 0;

   /// TODO add documnetation
   @override
   void onAvailable() {
     _available = true;
     if (_onViewInfoAvailable != null) {
       _onViewInfoAvailable();
     }
     _onAvailableCallback(this);
   }

   /// TODO add documentation
   @override
   void onUnavailable() {
     _available = false;
     _onUnavailableCallback(this);
   }

   /// Only call when the connection is available.
   void requestFocus() {
     if (_viewKey != null) {
       // TODO(SCN-1186): Use new mechanism to implement RequestFocus.
     }
   }

   // The number of render objects attached to this view. In between frames, we
   // might have more than one connected if we get added to a render object
   // before we get removed from the old render object. By the time we get around
   // to computing our layout, we must be back to just having one render object.
   /// TODO add documentation
   void sendSizeChangeHintHack(
       double widthChangeFactor, double heightChangeFactor) {
     assert(_attached);
     assert(_attachments == 1);
     if (_viewKey == null) {
       return;
     }

     if (shared.globalViewContainer == null) {
       return;
     }

     shared.globalViewContainer.sendSizeChangeHintHack(
         _viewKey, widthChangeFactor, heightChangeFactor);
   }

   void _addChildToViewHost() {
     if (shared.globalViewContainer == null) {
       return;
     }
     assert(_viewHolderToken.value.isValid);
     assert(_attached);
     assert(_viewKey == null);
     assert(!_available);
     assert(_sceneHost == null);

     final EventPairPair sceneTokens = EventPairPair();
     assert(sceneTokens.status == ZX.OK);

     // Analyzer doesn't know Handle must be dart:zircon's Handle
     _sceneHost = SceneHost(sceneTokens.first.passHandle());
     _viewKey = shared.nextGlobalViewKey();
     shared.globalViewContainer
         .addChild2(_viewKey, _viewHolderToken.value, sceneTokens.second);
     _viewHolderToken = ViewHolderToken(value: EventPair(null));
     assert(
         !ViewContainerListenerImpl.instance.containsConnectionForKey(_viewKey));
     ViewContainerListenerImpl.instance.addConnectionForKey(_viewKey, this);
   }

   void _attach() {
     assert(_attachments >= 0);
     ++_attachments;
     if (_viewKey == null) {
       _addChildToViewHost();
     }
   }

   ViewProperties _createViewProperties(
       double width,
       double height,
       double insetTop,
       double insetRight,
       double insetBottom,
       double insetLeft,
       bool focusable) {
     if (_currentViewProperties != null &&
         _currentViewProperties.viewLayout.size.width == width &&
         _currentViewProperties.viewLayout.size.height == height &&
         _currentViewProperties.viewLayout.inset.top == insetTop &&
         _currentViewProperties.viewLayout.inset.right == insetRight &&
         _currentViewProperties.viewLayout.inset.bottom == insetBottom &&
         _currentViewProperties.viewLayout.inset.left == insetLeft &&
         (_currentViewProperties.customFocusBehavior == null ||
                 _currentViewProperties.customFocusBehavior.allowFocus) ==
             focusable) {
       return null;
     }

     SizeF size = SizeF(width: width, height: height);
     InsetF inset = InsetF(
         top: insetTop, right: insetRight, bottom: insetBottom, left: insetLeft);
     ViewLayout viewLayout = ViewLayout(size: size, inset: inset);
     final customFocusBehavior = CustomFocusBehavior(allowFocus: focusable);
     return _currentViewProperties = ViewProperties(
       viewLayout: viewLayout,
       customFocusBehavior: customFocusBehavior,
     );
   }

   void _detach() {
     assert(_attached);
     --_attachments;
     scheduleMicrotask(_removeChildFromViewHostIfNeeded);
   }

   void _removeChildFromViewHost() {
     if (shared.globalViewContainer == null) {
       return;
     }
     assert(!_viewHolderToken.value.isValid);
     assert(!_attached);
     assert(_viewKey != null);
     assert(_sceneHost != null);
     assert(ViewContainerListenerImpl.instance.getConnectionForKey(_viewKey) ==
         this);
     final EventPairPair viewTokens = EventPairPair();
     assert(viewTokens.status == ZX.OK);
     ViewContainerListenerImpl.instance.removeConnectionForKey(_viewKey);
     _viewHolderToken = ViewHolderToken(value: viewTokens.first);
     shared.globalViewContainer.removeChild2(_viewKey, viewTokens.second);
     _viewKey = null;
     _available = false;
     _currentViewProperties = null;
     _sceneHost.dispose();
     _sceneHost = null;
   }

   void _removeChildFromViewHostIfNeeded() {
     assert(_attachments >= 0);
     if (_attachments == 0 && _viewKey != null) {
       _removeChildFromViewHost();
     }
   }

   void _setChildProperties(
     double width,
     double height,
     double insetTop,
     double insetRight,
     double insetBottom,
     double insetLeft,
     bool focusable,
   ) {
     assert(_attached);
     assert(_attachments == 1);
     assert(_viewKey != null);
     if (shared.globalViewContainer == null) {
       return;
     }
     ViewProperties viewProperties = _createViewProperties(
         width, height, insetTop, insetRight, insetBottom, insetLeft, focusable);
     if (viewProperties == null) {
       return;
     }
     shared.globalViewContainer.setChildProperties(_viewKey, viewProperties);
   }
 }

 /// TODO add documentation
 class RenderChildView extends RenderBox {
   ChildViewConnection _connection;

   bool _hitTestable;
   bool _focusable;
   TextPainter _debugErrorMessage;

   double _width;
   double _height;

   /// Creates a child view render object.
   RenderChildView({
     ChildViewConnection connection,
     bool hitTestable = true,
     bool focusable = true,
   })  : _connection = connection,
         _hitTestable = hitTestable,
         _focusable = focusable,
         assert(hitTestable != null);

   @override
   bool get alwaysNeedsCompositing => true;

   /// The child to display.
   ChildViewConnection get connection => _connection;
   set connection(ChildViewConnection value) {
     if (value == _connection) {
       return;
     }
     if (attached && _connection != null) {
       _connection._detach();
       assert(_connection._onViewInfoAvailable != null);
       _connection._onViewInfoAvailable = null;
     }
     _connection = value;
     if (attached && _connection != null) {
       _connection._attach();
       assert(_connection._onViewInfoAvailable == null);
       _connection._onViewInfoAvailable = markNeedsPaint;
     }
     if (_connection == null) {
       markNeedsPaint();
     } else {
       markNeedsLayout();
     }
   }

   /// Whether this child should be able to recieve focus events
   bool get focusable => _focusable;

   set focusable(bool value) {
     assert(value != null);
     if (value == _focusable) {
       return;
     }
     _focusable = value;
     if (_connection != null) {
       markNeedsPaint();
     }
   }

   /// Whether this child should be included during hit testing.
   bool get hitTestable => _hitTestable;

   set hitTestable(bool value) {
     assert(value != null);
     if (value == _hitTestable) {
       return;
     }
     _hitTestable = value;
     if (_connection != null) {
       markNeedsPaint();
     }
   }

   @override
   void attach(PipelineOwner owner) {
     super.attach(owner);
     if (_connection != null) {
       _connection._attach();
       assert(_connection._onViewInfoAvailable == null);
       _connection._onViewInfoAvailable = markNeedsPaint;
     }
   }

   @override
   void debugFillProperties(DiagnosticPropertiesBuilder description) {
     super.debugFillProperties(description);
     description.add(
       DiagnosticsProperty<ChildViewConnection>(
         'connection',
         connection,
       ),
     );
   }

   @override
   void detach() {
     if (_connection != null) {
       _connection._detach();
       assert(_connection._onViewInfoAvailable != null);
       _connection._onViewInfoAvailable = null;
     }
     super.detach();
   }

   @override
   bool hitTestSelf(Offset position) => true;

   @override
   void paint(PaintingContext context, Offset offset) {
     assert(needsCompositing);
     if (_connection?._available == true) {
       context.addLayer(ChildSceneLayer(
         offset: offset,
         width: _width,
         height: _height,
         sceneHost: _connection._sceneHost,
         hitTestable: hitTestable,
       ));
     }
     assert(() {
       if (shared.globalViewContainer == null) {
         context.canvas
             .drawRect(offset & size, Paint()..color = Color(0xFF0000FF));
         _debugErrorMessage.paint(context.canvas, offset);
       }
       return true;
     }());
   }

   @override
   void performLayout() {
     size = constraints.biggest;

     // Ignore if we have no child view connection.
     if (_connection == null) {
       return;
     }

     if (_width != null && _height != null) {
       double deltaWidth = (_width - size.width).abs();
       double deltaHeight = (_height - size.height).abs();

       // Ignore insignificant changes in size that are likely rounding errors.
       if (deltaWidth < 0.0001 && deltaHeight < 0.0001) {
         return;
       }
     }

     _width = size.width;
     _height = size.height;
     _connection._setChildProperties(
         _width, _height, 0.0, 0.0, 0.0, 0.0, _focusable);
     assert(() {
       if (shared.globalViewContainer == null) {
         _debugErrorMessage ??= TextPainter(
             text: TextSpan(
                 text:
                     'Child views are supported only when running in Scenic.'));
         _debugErrorMessage.layout(minWidth: size.width, maxWidth: size.width);
       }
       return true;
     }());
   }
 }
	// Copyright 2018 The Fuchsia 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:ui';

	import 'package:fidl_fuchsia_math/fidl_async.dart';
	import 'package:fidl_fuchsia_ui_gfx/fidl_async.dart' show ImportToken;
	import 'package:fidl_fuchsia_ui_views/fidl_async.dart' show ViewHolderToken;
	import 'package:fidl_fuchsia_ui_viewsv1/fidl_async.dart';
	import 'package:flutter/rendering.dart';
	import 'package:flutter/widgets.dart';
	import 'package:zircon/zircon.dart';

	import 'internal/_child_scene_layer.dart';
	import 'view_container.dart' as shared;
	import 'view_container_listener_impl.dart';

	typedef ChildViewConnectionCallback = void Function(
	ChildViewConnection connection);

	void _emptyConnectionCallback(ChildViewConnection c) {}

	/// A connection with a child view.
	///
	/// Used with the [ChildView] widget to display a child view.
	class ChildViewConnection implements ViewContainerListenerDelegate {
	// TODO consider providing this API after MS-2293 is fixed
	// factory ChildViewConnection.launch(String url, Launcher launcher,
	// {InterfaceRequest<ComponentController> controller,
	// InterfaceRequest<ServiceProvider> childServices,
	// ChildViewConnectionCallback onAvailable,
	// ChildViewConnectionCallback onUnavailable}) {
	// final Services services = Services();
	// final LaunchInfo launchInfo =
	// LaunchInfo(url: url, directoryRequest: services.request());
	// try {
	// launcher.createComponent(launchInfo, controller);
	// return ChildViewConnection.connect(services,
	// childServices: childServices,
	// onAvailable: onAvailable,
	// onUnavailable: onUnavailable);
	// } finally {
	// services.close();
	// }
	// }

	// TODO consider providing this API after MS-2293 is fixed
	// factory ChildViewConnection.connect(Services services,
	// {InterfaceRequest<ServiceProvider> childServices,
	// ChildViewConnectionCallback onAvailable,
	// ChildViewConnectionCallback onUnavailable}) {
	// final app.ViewProviderProxy viewProvider = new app.ViewProviderProxy();
	// services.connectToService(viewProvider.ctrl);
	// try {
	// EventPairPair viewTokens = new EventPairPair();
	// assert(viewTokens.status == ZX.OK);

	// viewProvider.createView(viewTokens.second, childServices, null);
	// return new ChildViewConnection.fromViewHolderToken(viewTokens.first,
	// onAvailable: onAvailable, onUnavailable: onUnavailable);
	// } finally {
	// viewProvider.ctrl.close();
	// }
	// }

	final ChildViewConnectionCallback _onAvailableCallback;
	final ChildViewConnectionCallback _onUnavailableCallback;
	ViewHolderToken _viewHolderToken;

	int _viewKey;
	ViewProperties _currentViewProperties;
	bool _available = false;

	VoidCallback _onViewInfoAvailable;

	SceneHost _sceneHost;
	int _attachments = 0;

	/// Constructs \|ChildViewConnection\| from a token.
	ChildViewConnection(ViewHolderToken viewHolderToken,
	{ChildViewConnectionCallback onAvailable,
	ChildViewConnectionCallback onUnavailable})
	: _onAvailableCallback = onAvailable ?? _emptyConnectionCallback,
	_onUnavailableCallback = onUnavailable ?? _emptyConnectionCallback,
	_viewHolderToken = viewHolderToken {
	assert(_viewHolderToken?.value != null);
	}

	/// Deprecated.
	ChildViewConnection.fromViewHolderToken(EventPair viewHolderToken,
	{ChildViewConnectionCallback onAvailable,
	ChildViewConnectionCallback onUnavailable})
	: this(ViewHolderToken(value: viewHolderToken),
	onAvailable: onAvailable, onUnavailable: onUnavailable);

	/// Deprecated.
	ChildViewConnection.fromImportToken(ImportToken viewHolderToken,
	{ChildViewConnectionCallback onAvailable,
	ChildViewConnectionCallback onUnavailable})
	: this(ViewHolderToken(value: viewHolderToken.value),
	onAvailable: onAvailable, onUnavailable: onUnavailable);

	bool get _attached => _attachments > 0;

	/// TODO add documnetation
	@override
	void onAvailable() {
	_available = true;
	if (_onViewInfoAvailable != null) {
	_onViewInfoAvailable();
	}
	_onAvailableCallback(this);
	}

	/// TODO add documentation
	@override
	void onUnavailable() {
	_available = false;
	_onUnavailableCallback(this);
	}

	/// Only call when the connection is available.
	void requestFocus() {
	if (_viewKey != null) {
	// TODO(SCN-1186): Use new mechanism to implement RequestFocus.
	}
	}

	// The number of render objects attached to this view. In between frames, we
	// might have more than one connected if we get added to a render object
	// before we get removed from the old render object. By the time we get around
	// to computing our layout, we must be back to just having one render object.
	/// TODO add documentation
	void sendSizeChangeHintHack(
	double widthChangeFactor, double heightChangeFactor) {
	assert(_attached);
	assert(_attachments == 1);
	if (_viewKey == null) {
	return;
	}

	if (shared.globalViewContainer == null) {
	return;
	}

	shared.globalViewContainer.sendSizeChangeHintHack(
	_viewKey, widthChangeFactor, heightChangeFactor);
	}

	void _addChildToViewHost() {
	if (shared.globalViewContainer == null) {
	return;
	}
	assert(_viewHolderToken.value.isValid);
	assert(_attached);
	assert(_viewKey == null);
	assert(!_available);
	assert(_sceneHost == null);

	final EventPairPair sceneTokens = EventPairPair();
	assert(sceneTokens.status == ZX.OK);

	// Analyzer doesn't know Handle must be dart:zircon's Handle
	_sceneHost = SceneHost(sceneTokens.first.passHandle());
	_viewKey = shared.nextGlobalViewKey();
	shared.globalViewContainer
	.addChild2(_viewKey, _viewHolderToken.value, sceneTokens.second);
	_viewHolderToken = ViewHolderToken(value: EventPair(null));
	assert(
	!ViewContainerListenerImpl.instance.containsConnectionForKey(_viewKey));
	ViewContainerListenerImpl.instance.addConnectionForKey(_viewKey, this);
	}

	void _attach() {
	assert(_attachments >= 0);
	++_attachments;
	if (_viewKey == null) {
	_addChildToViewHost();
	}
	}

	ViewProperties _createViewProperties(
	double width,
	double height,
	double insetTop,
	double insetRight,
	double insetBottom,
	double insetLeft,
	bool focusable) {
	if (_currentViewProperties != null &&
	_currentViewProperties.viewLayout.size.width == width &&
	_currentViewProperties.viewLayout.size.height == height &&
	_currentViewProperties.viewLayout.inset.top == insetTop &&
	_currentViewProperties.viewLayout.inset.right == insetRight &&
	_currentViewProperties.viewLayout.inset.bottom == insetBottom &&
	_currentViewProperties.viewLayout.inset.left == insetLeft &&
	(_currentViewProperties.customFocusBehavior == null \|\|
	_currentViewProperties.customFocusBehavior.allowFocus) ==
	focusable) {
	return null;
	}

	SizeF size = SizeF(width: width, height: height);
	InsetF inset = InsetF(
	top: insetTop, right: insetRight, bottom: insetBottom, left: insetLeft);
	ViewLayout viewLayout = ViewLayout(size: size, inset: inset);
	final customFocusBehavior = CustomFocusBehavior(allowFocus: focusable);
	return _currentViewProperties = ViewProperties(
	viewLayout: viewLayout,
	customFocusBehavior: customFocusBehavior,
	);
	}

	void _detach() {
	assert(_attached);
	--_attachments;
	scheduleMicrotask(_removeChildFromViewHostIfNeeded);
	}

	void _removeChildFromViewHost() {
	if (shared.globalViewContainer == null) {
	return;
	}
	assert(!_viewHolderToken.value.isValid);
	assert(!_attached);
	assert(_viewKey != null);
	assert(_sceneHost != null);
	assert(ViewContainerListenerImpl.instance.getConnectionForKey(_viewKey) ==
	this);
	final EventPairPair viewTokens = EventPairPair();
	assert(viewTokens.status == ZX.OK);
	ViewContainerListenerImpl.instance.removeConnectionForKey(_viewKey);
	_viewHolderToken = ViewHolderToken(value: viewTokens.first);
	shared.globalViewContainer.removeChild2(_viewKey, viewTokens.second);
	_viewKey = null;
	_available = false;
	_currentViewProperties = null;
	_sceneHost.dispose();
	_sceneHost = null;
	}

	void _removeChildFromViewHostIfNeeded() {
	assert(_attachments >= 0);
	if (_attachments == 0 && _viewKey != null) {
	_removeChildFromViewHost();
	}
	}

	void _setChildProperties(
	double width,
	double height,
	double insetTop,
	double insetRight,
	double insetBottom,
	double insetLeft,
	bool focusable,
	) {
	assert(_attached);
	assert(_attachments == 1);
	assert(_viewKey != null);
	if (shared.globalViewContainer == null) {
	return;
	}
	ViewProperties viewProperties = _createViewProperties(
	width, height, insetTop, insetRight, insetBottom, insetLeft, focusable);
	if (viewProperties == null) {
	return;
	}
	shared.globalViewContainer.setChildProperties(_viewKey, viewProperties);
	}
	}

	/// TODO add documentation
	class RenderChildView extends RenderBox {
	ChildViewConnection _connection;

	bool _hitTestable;
	bool _focusable;
	TextPainter _debugErrorMessage;

	double _width;
	double _height;

	/// Creates a child view render object.
	RenderChildView({
	ChildViewConnection connection,
	bool hitTestable = true,
	bool focusable = true,
	}) : _connection = connection,
	_hitTestable = hitTestable,
	_focusable = focusable,
	assert(hitTestable != null);

	@override
	bool get alwaysNeedsCompositing => true;

	/// The child to display.
	ChildViewConnection get connection => _connection;
	set connection(ChildViewConnection value) {
	if (value == _connection) {
	return;
	}
	if (attached && _connection != null) {
	_connection._detach();
	assert(_connection._onViewInfoAvailable != null);
	_connection._onViewInfoAvailable = null;
	}
	_connection = value;
	if (attached && _connection != null) {
	_connection._attach();
	assert(_connection._onViewInfoAvailable == null);
	_connection._onViewInfoAvailable = markNeedsPaint;
	}
	if (_connection == null) {
	markNeedsPaint();
	} else {
	markNeedsLayout();
	}
	}

	/// Whether this child should be able to recieve focus events
	bool get focusable => _focusable;

	set focusable(bool value) {
	assert(value != null);
	if (value == _focusable) {
	return;
	}
	_focusable = value;
	if (_connection != null) {
	markNeedsPaint();
	}
	}

	/// Whether this child should be included during hit testing.
	bool get hitTestable => _hitTestable;

	set hitTestable(bool value) {
	assert(value != null);
	if (value == _hitTestable) {
	return;
	}
	_hitTestable = value;
	if (_connection != null) {
	markNeedsPaint();
	}
	}

	@override
	void attach(PipelineOwner owner) {
	super.attach(owner);
	if (_connection != null) {
	_connection._attach();
	assert(_connection._onViewInfoAvailable == null);
	_connection._onViewInfoAvailable = markNeedsPaint;
	}
	}

	@override
	void debugFillProperties(DiagnosticPropertiesBuilder description) {
	super.debugFillProperties(description);
	description.add(
	DiagnosticsProperty<ChildViewConnection>(
	'connection',
	connection,
	),
	);
	}

	@override
	void detach() {
	if (_connection != null) {
	_connection._detach();
	assert(_connection._onViewInfoAvailable != null);
	_connection._onViewInfoAvailable = null;
	}
	super.detach();
	}

	@override
	bool hitTestSelf(Offset position) => true;

	@override
	void paint(PaintingContext context, Offset offset) {
	assert(needsCompositing);
	if (_connection?._available == true) {
	context.addLayer(ChildSceneLayer(
	offset: offset,
	width: _width,
	height: _height,
	sceneHost: _connection._sceneHost,
	hitTestable: hitTestable,
	));
	}
	assert(() {
	if (shared.globalViewContainer == null) {
	context.canvas
	.drawRect(offset & size, Paint()..color = Color(0xFF0000FF));
	_debugErrorMessage.paint(context.canvas, offset);
	}
	return true;
	}());
	}

	@override
	void performLayout() {
	size = constraints.biggest;

	// Ignore if we have no child view connection.
	if (_connection == null) {
	return;
	}

	if (_width != null && _height != null) {
	double deltaWidth = (_width - size.width).abs();
	double deltaHeight = (_height - size.height).abs();

	// Ignore insignificant changes in size that are likely rounding errors.
	if (deltaWidth < 0.0001 && deltaHeight < 0.0001) {
	return;
	}
	}

	_width = size.width;
	_height = size.height;
	_connection._setChildProperties(
	_width, _height, 0.0, 0.0, 0.0, 0.0, _focusable);
	assert(() {
	if (shared.globalViewContainer == null) {
	_debugErrorMessage ??= TextPainter(
	text: TextSpan(
	text:
	'Child views are supported only when running in Scenic.'));
	_debugErrorMessage.layout(minWidth: size.width, maxWidth: size.width);
	}
	return true;
	}());
	}
	}