packages/flutter/lib/src/material/drawer.dart - external/github.com/flutter/flutter - Git at Google

 // Copyright 2015 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 'package:flutter/foundation.dart';
 import 'package:flutter/widgets.dart';

 import 'colors.dart';
 import 'list_tile.dart';
 import 'material.dart';

 // TODO(eseidel): Draw width should vary based on device size:
 // http://material.google.com/layout/structure.html#structure-side-nav

 // Mobile:
 // Width = Screen width − 56 dp
 // Maximum width: 320dp
 // Maximum width applies only when using a left nav. When using a right nav,
 // the panel can cover the full width of the screen.

 // Desktop/Tablet:
 // Maximum width for a left nav is 400dp.
 // The right nav can vary depending on content.

 const double _kWidth = 304.0;
 const double _kEdgeDragWidth = 20.0;
 const double _kMinFlingVelocity = 365.0;
 const Duration _kBaseSettleDuration = const Duration(milliseconds: 246);

 /// A material design panel that slides in horizontally from the edge of a
 /// [Scaffold] to show navigation links in an application.
 ///
 /// Drawers are typically used with the [Scaffold.drawer] property. The child of
 /// the drawer is usually a [ListView] whose first child is a [DrawerHeader]
 /// that displays status information about the current user. The remaining
 /// drawer children are often constructed with [ListTile]s, often concluding
 /// with an [AboutListTile].
 ///
 /// An open drawer can be closed by calling [Navigator.pop]. For example
 /// a drawer item might close the drawer when tapped:
 ///
 /// ```dart
 /// new ListTile(
 ///   leading: new Icon(Icons.change_history),
 ///   title: new Text('Change history'),
 ///   onTap: () {
 ///     // change app state...
 ///     Navigator.pop(context); // close the drawer
 ///   },
 /// );
 /// ```
 ///
 /// The [AppBar] automatically displays an appropriate [IconButton] to show the
 /// [Drawer] when a [Drawer] is available in the [Scaffold]. The [Scaffold]
 /// automatically handles the edge-swipe gesture to show the drawer.
 ///
 /// See also:
 ///
 ///  * [Scaffold.drawer], where one specifies a [Drawer] so that it can be
 ///    shown.
 ///  * [Scaffold.of], to obtain the current [ScaffoldState], which manages the
 ///    display and animation of the drawer.
 ///  * [ScaffoldState.openDrawer], which displays its [Drawer], if any.
 ///  * <https://material.google.com/patterns/navigation-drawer.html>
 class Drawer extends StatelessWidget {
   /// Creates a material design drawer.
   ///
   /// Typically used in the [Scaffold.drawer] property.
   const Drawer({
     Key key,
     this.elevation: 16.0,
     this.child
   }) : super(key: key);

   /// The z-coordinate at which to place this drawer. This controls the size of
   /// the shadow below the drawer.
   ///
   /// Defaults to 16, the appropriate elevation for drawers.
   final double elevation;

   /// The widget below this widget in the tree.
   ///
   /// Typically a [SliverList].
   final Widget child;

   @override
   Widget build(BuildContext context) {
     return new ConstrainedBox(
       constraints: const BoxConstraints.expand(width: _kWidth),
       child: new Material(
         elevation: elevation,
         child: child
       )
     );
   }
 }

 /// Provides interactive behavior for [Drawer] widgets.
 ///
 /// Rarely used directly. Drawer controllers are typically created automatically
 /// by [Scaffold] widgets.
 ///
 /// The draw controller provides the ability to open and close a drawer, either
 /// via an animation or via user interaction. When closed, the drawer collapses
 /// to a translucent gesture detector that can be used to listen for edge
 /// swipes.
 ///
 /// See also:
 ///
 ///  * [Drawer]
 ///  * [Scaffold.drawer]
 class DrawerController extends StatefulWidget {
   /// Creates a controller for a [Drawer].
   ///
   /// Rarely used directly.
   ///
   /// The [child] argument must not be null and is typically a [Drawer].
   const DrawerController({
     GlobalKey key,
     @required this.child
   }) : assert(child != null),
        super(key: key);

   /// The widget below this widget in the tree.
   ///
   /// Typically a [Drawer].
   final Widget child;

   @override
   DrawerControllerState createState() => new DrawerControllerState();
 }

 /// State for a [DrawerController].
 ///
 /// Typically used by a [Scaffold] to [open] and [close] the drawer.
 class DrawerControllerState extends State<DrawerController> with SingleTickerProviderStateMixin {
   @override
   void initState() {
     super.initState();
     _controller = new AnimationController(duration: _kBaseSettleDuration, vsync: this)
       ..addListener(_animationChanged)
       ..addStatusListener(_animationStatusChanged);
   }

   @override
   void dispose() {
     _historyEntry?.remove();
     _controller.dispose();
     super.dispose();
   }

   void _animationChanged() {
     setState(() {
       // The animation controller's state is our build state, and it changed already.
     });
   }

   LocalHistoryEntry _historyEntry;
   final FocusScopeNode _focusScopeNode = new FocusScopeNode();

   void _ensureHistoryEntry() {
     if (_historyEntry == null) {
       final ModalRoute<dynamic> route = ModalRoute.of(context);
       if (route != null) {
         _historyEntry = new LocalHistoryEntry(onRemove: _handleHistoryEntryRemoved);
         route.addLocalHistoryEntry(_historyEntry);
         FocusScope.of(context).setFirstFocus(_focusScopeNode);
       }
     }
   }

   void _animationStatusChanged(AnimationStatus status) {
     switch (status) {
       case AnimationStatus.forward:
         _ensureHistoryEntry();
         break;
       case AnimationStatus.reverse:
         _historyEntry?.remove();
         _historyEntry = null;
         break;
       case AnimationStatus.dismissed:
         break;
       case AnimationStatus.completed:
         break;
     }
   }

   void _handleHistoryEntryRemoved() {
     _historyEntry = null;
     close();
   }

   AnimationController _controller;

   void _handleDragDown(DragDownDetails details) {
     _controller.stop();
     _ensureHistoryEntry();
   }

   void _handleDragCancel() {
     if (_controller.isDismissed || _controller.isAnimating)
       return;
     if (_controller.value < 0.5) {
       close();
     } else {
       open();
     }
   }

   final GlobalKey _drawerKey = new GlobalKey();

   double get _width {
     final RenderBox box = _drawerKey.currentContext?.findRenderObject();
     if (box != null)
       return box.size.width;
     return _kWidth; // drawer not being shown currently
   }

   void _move(DragUpdateDetails details) {
     _controller.value += details.primaryDelta / _width;
   }

   void _settle(DragEndDetails details) {
     if (_controller.isDismissed)
       return;
     if (details.velocity.pixelsPerSecond.dx.abs() >= _kMinFlingVelocity) {
       _controller.fling(velocity: details.velocity.pixelsPerSecond.dx / _width);
     } else if (_controller.value < 0.5) {
       close();
     } else {
       open();
     }
   }

   /// Starts an animation to open the drawer.
   ///
   /// Typically called by [ScaffoldState.openDrawer].
   void open() {
     _controller.fling(velocity: 1.0);
   }

   /// Starts an animation to close the drawer.
   void close() {
     _controller.fling(velocity: -1.0);
   }

   final ColorTween _color = new ColorTween(begin: Colors.transparent, end: Colors.black54);
   final GlobalKey _gestureDetectorKey = new GlobalKey();

   Widget _buildDrawer(BuildContext context) {
     if (_controller.status == AnimationStatus.dismissed) {
       return new Align(
         alignment: FractionalOffset.centerLeft,
         child: new GestureDetector(
           key: _gestureDetectorKey,
           onHorizontalDragUpdate: _move,
           onHorizontalDragEnd: _settle,
           behavior: HitTestBehavior.translucent,
           excludeFromSemantics: true,
           child: new Container(width: _kEdgeDragWidth)
         ),
       );
     } else {
       return new GestureDetector(
         key: _gestureDetectorKey,
         onHorizontalDragDown: _handleDragDown,
         onHorizontalDragUpdate: _move,
         onHorizontalDragEnd: _settle,
         onHorizontalDragCancel: _handleDragCancel,
         excludeFromSemantics: true,
         child: new RepaintBoundary(
           child: new Stack(
             children: <Widget>[
               new BlockSemantics(
                 child: new GestureDetector(
                   // On Android, the back button is used to dismiss a modal.
                   excludeFromSemantics: defaultTargetPlatform == TargetPlatform.android,
                   onTap: close,
                   child: new Container(
                     color: _color.evaluate(_controller)
                   ),
                 ),
               ),
               new Align(
                 alignment: FractionalOffset.centerLeft,
                 child: new Align(
                   alignment: FractionalOffset.centerRight,
                   widthFactor: _controller.value,
                   child: new RepaintBoundary(
                     child: new FocusScope(
                       key: _drawerKey,
                       node: _focusScopeNode,
                       child: widget.child
                     ),
                   ),
                 ),
               ),
             ],
           ),
         ),
       );
     }
   }
   @override
   Widget build(BuildContext context) {
     return new ListTileTheme(
       style: ListTileStyle.drawer,
       child: _buildDrawer(context),
     );
   }
 }
	// Copyright 2015 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 'package:flutter/foundation.dart';
	import 'package:flutter/widgets.dart';

	import 'colors.dart';
	import 'list_tile.dart';
	import 'material.dart';

	// TODO(eseidel): Draw width should vary based on device size:
	// http://material.google.com/layout/structure.html#structure-side-nav

	// Mobile:
	// Width = Screen width − 56 dp
	// Maximum width: 320dp
	// Maximum width applies only when using a left nav. When using a right nav,
	// the panel can cover the full width of the screen.

	// Desktop/Tablet:
	// Maximum width for a left nav is 400dp.
	// The right nav can vary depending on content.

	const double _kWidth = 304.0;
	const double _kEdgeDragWidth = 20.0;
	const double _kMinFlingVelocity = 365.0;
	const Duration _kBaseSettleDuration = const Duration(milliseconds: 246);

	/// A material design panel that slides in horizontally from the edge of a
	/// [Scaffold] to show navigation links in an application.
	///
	/// Drawers are typically used with the [Scaffold.drawer] property. The child of
	/// the drawer is usually a [ListView] whose first child is a [DrawerHeader]
	/// that displays status information about the current user. The remaining
	/// drawer children are often constructed with [ListTile]s, often concluding
	/// with an [AboutListTile].
	///
	/// An open drawer can be closed by calling [Navigator.pop]. For example
	/// a drawer item might close the drawer when tapped:
	///
	/// ```dart
	/// new ListTile(
	/// leading: new Icon(Icons.change_history),
	/// title: new Text('Change history'),
	/// onTap: () {
	/// // change app state...
	/// Navigator.pop(context); // close the drawer
	/// },
	/// );
	/// ```
	///
	/// The [AppBar] automatically displays an appropriate [IconButton] to show the
	/// [Drawer] when a [Drawer] is available in the [Scaffold]. The [Scaffold]
	/// automatically handles the edge-swipe gesture to show the drawer.
	///
	/// See also:
	///
	/// * [Scaffold.drawer], where one specifies a [Drawer] so that it can be
	/// shown.
	/// * [Scaffold.of], to obtain the current [ScaffoldState], which manages the
	/// display and animation of the drawer.
	/// * [ScaffoldState.openDrawer], which displays its [Drawer], if any.
	/// * <https://material.google.com/patterns/navigation-drawer.html>
	class Drawer extends StatelessWidget {
	/// Creates a material design drawer.
	///
	/// Typically used in the [Scaffold.drawer] property.
	const Drawer({
	Key key,
	this.elevation: 16.0,
	this.child
	}) : super(key: key);

	/// The z-coordinate at which to place this drawer. This controls the size of
	/// the shadow below the drawer.
	///
	/// Defaults to 16, the appropriate elevation for drawers.
	final double elevation;

	/// The widget below this widget in the tree.
	///
	/// Typically a [SliverList].
	final Widget child;

	@override
	Widget build(BuildContext context) {
	return new ConstrainedBox(
	constraints: const BoxConstraints.expand(width: _kWidth),
	child: new Material(
	elevation: elevation,
	child: child
	)
	);
	}
	}

	/// Provides interactive behavior for [Drawer] widgets.
	///
	/// Rarely used directly. Drawer controllers are typically created automatically
	/// by [Scaffold] widgets.
	///
	/// The draw controller provides the ability to open and close a drawer, either
	/// via an animation or via user interaction. When closed, the drawer collapses
	/// to a translucent gesture detector that can be used to listen for edge
	/// swipes.
	///
	/// See also:
	///
	/// * [Drawer]
	/// * [Scaffold.drawer]
	class DrawerController extends StatefulWidget {
	/// Creates a controller for a [Drawer].
	///
	/// Rarely used directly.
	///
	/// The [child] argument must not be null and is typically a [Drawer].
	const DrawerController({
	GlobalKey key,
	@required this.child
	}) : assert(child != null),
	super(key: key);

	/// The widget below this widget in the tree.
	///
	/// Typically a [Drawer].
	final Widget child;

	@override
	DrawerControllerState createState() => new DrawerControllerState();
	}

	/// State for a [DrawerController].
	///
	/// Typically used by a [Scaffold] to [open] and [close] the drawer.
	class DrawerControllerState extends State<DrawerController> with SingleTickerProviderStateMixin {
	@override
	void initState() {
	super.initState();
	_controller = new AnimationController(duration: _kBaseSettleDuration, vsync: this)
	..addListener(_animationChanged)
	..addStatusListener(_animationStatusChanged);
	}

	@override
	void dispose() {
	_historyEntry?.remove();
	_controller.dispose();
	super.dispose();
	}

	void _animationChanged() {
	setState(() {
	// The animation controller's state is our build state, and it changed already.
	});
	}

	LocalHistoryEntry _historyEntry;
	final FocusScopeNode _focusScopeNode = new FocusScopeNode();

	void _ensureHistoryEntry() {
	if (_historyEntry == null) {
	final ModalRoute<dynamic> route = ModalRoute.of(context);
	if (route != null) {
	_historyEntry = new LocalHistoryEntry(onRemove: _handleHistoryEntryRemoved);
	route.addLocalHistoryEntry(_historyEntry);
	FocusScope.of(context).setFirstFocus(_focusScopeNode);
	}
	}
	}

	void _animationStatusChanged(AnimationStatus status) {
	switch (status) {
	case AnimationStatus.forward:
	_ensureHistoryEntry();
	break;
	case AnimationStatus.reverse:
	_historyEntry?.remove();
	_historyEntry = null;
	break;
	case AnimationStatus.dismissed:
	break;
	case AnimationStatus.completed:
	break;
	}
	}

	void _handleHistoryEntryRemoved() {
	_historyEntry = null;
	close();
	}

	AnimationController _controller;

	void _handleDragDown(DragDownDetails details) {
	_controller.stop();
	_ensureHistoryEntry();
	}

	void _handleDragCancel() {
	if (_controller.isDismissed \|\| _controller.isAnimating)
	return;
	if (_controller.value < 0.5) {
	close();
	} else {
	open();
	}
	}

	final GlobalKey _drawerKey = new GlobalKey();

	double get _width {
	final RenderBox box = _drawerKey.currentContext?.findRenderObject();
	if (box != null)
	return box.size.width;
	return _kWidth; // drawer not being shown currently
	}

	void _move(DragUpdateDetails details) {
	_controller.value += details.primaryDelta / _width;
	}

	void _settle(DragEndDetails details) {
	if (_controller.isDismissed)
	return;
	if (details.velocity.pixelsPerSecond.dx.abs() >= _kMinFlingVelocity) {
	_controller.fling(velocity: details.velocity.pixelsPerSecond.dx / _width);
	} else if (_controller.value < 0.5) {
	close();
	} else {
	open();
	}
	}

	/// Starts an animation to open the drawer.
	///
	/// Typically called by [ScaffoldState.openDrawer].
	void open() {
	_controller.fling(velocity: 1.0);
	}

	/// Starts an animation to close the drawer.
	void close() {
	_controller.fling(velocity: -1.0);
	}

	final ColorTween _color = new ColorTween(begin: Colors.transparent, end: Colors.black54);
	final GlobalKey _gestureDetectorKey = new GlobalKey();

	Widget _buildDrawer(BuildContext context) {
	if (_controller.status == AnimationStatus.dismissed) {
	return new Align(
	alignment: FractionalOffset.centerLeft,
	child: new GestureDetector(
	key: _gestureDetectorKey,
	onHorizontalDragUpdate: _move,
	onHorizontalDragEnd: _settle,
	behavior: HitTestBehavior.translucent,
	excludeFromSemantics: true,
	child: new Container(width: _kEdgeDragWidth)
	),
	);
	} else {
	return new GestureDetector(
	key: _gestureDetectorKey,
	onHorizontalDragDown: _handleDragDown,
	onHorizontalDragUpdate: _move,
	onHorizontalDragEnd: _settle,
	onHorizontalDragCancel: _handleDragCancel,
	excludeFromSemantics: true,
	child: new RepaintBoundary(
	child: new Stack(
	children: <Widget>[
	new BlockSemantics(
	child: new GestureDetector(
	// On Android, the back button is used to dismiss a modal.
	excludeFromSemantics: defaultTargetPlatform == TargetPlatform.android,
	onTap: close,
	child: new Container(
	color: _color.evaluate(_controller)
	),
	),
	),
	new Align(
	alignment: FractionalOffset.centerLeft,
	child: new Align(
	alignment: FractionalOffset.centerRight,
	widthFactor: _controller.value,
	child: new RepaintBoundary(
	child: new FocusScope(
	key: _drawerKey,
	node: _focusScopeNode,
	child: widget.child
	),
	),
	),
	),
	],
	),
	),
	);
	}
	}
	@override
	Widget build(BuildContext context) {
	return new ListTileTheme(
	style: ListTileStyle.drawer,
	child: _buildDrawer(context),
	);
	}
	}