// 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 'dart:async'; import 'package:flutter/foundation.dart'; import 'package:flutter/widgets.dart'; import 'colors.dart'; import 'material.dart'; import 'theme.dart'; const Duration _kBottomSheetDuration = const Duration(milliseconds: 200); const double _kMinFlingVelocity = 700.0; const double _kCloseProgressThreshold = 0.5; const Color _kTransparent = const Color(0x00000000); const Color _kBarrierColor = Colors.black54; /// A material design bottom sheet. /// /// There are two kinds of bottom sheets in material design: /// /// * _Persistent_. A persistent bottom sheet shows information that /// supplements the primary content of the app. A persistent bottom sheet /// remains visible even when the user interacts with other parts of the app. /// Persistent bottom sheets can be created and displayed with the /// [ScaffoldState.showBottomSheet] function. /// /// * _Modal_. A modal bottom sheet is an alternative to a menu or a dialog and /// prevents the user from interacting with the rest of the app. Modal bottom /// sheets can be created and displayed with the [showModalBottomSheet] /// function. /// /// The [BottomSheet] widget itself is rarely used directly. Instead, prefer to /// create a persistent bottom sheet with [ScaffoldState.showBottomSheet] and a modal /// bottom sheet with [showModalBottomSheet]. /// /// See also: /// /// * [ScaffoldState.showBottomSheet] /// * [showModalBottomSheet] /// * <https://material.google.com/components/bottom-sheets.html> class BottomSheet extends StatefulWidget { /// Creates a bottom sheet. /// /// Typically, bottom sheets are created implicitly by /// [ScaffoldState.showBottomSheet], for persistent bottom sheets, or by /// [showModalBottomSheet], for modal bottom sheets. const BottomSheet({ Key key, this.animationController, @required this.onClosing, @required this.builder }) : assert(onClosing != null), assert(builder != null), super(key: key); /// The animation that controls the bottom sheet's position. /// /// The BottomSheet widget will manipulate the position of this animation, it /// is not just a passive observer. final AnimationController animationController; /// Called when the bottom sheet begins to close. /// /// A bottom sheet might be be prevented from closing (e.g., by user /// interaction) even after this callback is called. For this reason, this /// callback might be call multiple times for a given bottom sheet. final VoidCallback onClosing; /// A builder for the contents of the sheet. /// /// The bottom sheet will wrap the widget produced by this builder in a /// [Material] widget. final WidgetBuilder builder; @override _BottomSheetState createState() => new _BottomSheetState(); /// Creates an animation controller suitable for controlling a [BottomSheet]. static AnimationController createAnimationController(TickerProvider vsync) { return new AnimationController( duration: _kBottomSheetDuration, debugLabel: 'BottomSheet', vsync: vsync, ); } } class _BottomSheetState extends State<BottomSheet> { final GlobalKey _childKey = new GlobalKey(debugLabel: 'BottomSheet child'); double get _childHeight { final RenderBox renderBox = _childKey.currentContext.findRenderObject(); return renderBox.size.height; } bool get _dismissUnderway => widget.animationController.status == AnimationStatus.reverse; void _handleDragUpdate(DragUpdateDetails details) { if (_dismissUnderway) return; widget.animationController.value -= details.primaryDelta / (_childHeight ?? details.primaryDelta); } void _handleDragEnd(DragEndDetails details) { if (_dismissUnderway) return; if (details.velocity.pixelsPerSecond.dy > _kMinFlingVelocity) { final double flingVelocity = -details.velocity.pixelsPerSecond.dy / _childHeight; if (widget.animationController.value > 0.0) widget.animationController.fling(velocity: flingVelocity); if (flingVelocity < 0.0) widget.onClosing(); } else if (widget.animationController.value < _kCloseProgressThreshold) { if (widget.animationController.value > 0.0) widget.animationController.fling(velocity: -1.0); widget.onClosing(); } else { widget.animationController.forward(); } } @override Widget build(BuildContext context) { return new GestureDetector( onVerticalDragUpdate: _handleDragUpdate, onVerticalDragEnd: _handleDragEnd, child: new Material( key: _childKey, child: widget.builder(context) ) ); } } // PERSISTENT BOTTOM SHEETS // See scaffold.dart // MODAL BOTTOM SHEETS class _ModalBottomSheetLayout extends SingleChildLayoutDelegate { _ModalBottomSheetLayout(this.progress); final double progress; @override BoxConstraints getConstraintsForChild(BoxConstraints constraints) { return new BoxConstraints( minWidth: constraints.maxWidth, maxWidth: constraints.maxWidth, minHeight: 0.0, maxHeight: constraints.maxHeight * 9.0 / 16.0 ); } @override Offset getPositionForChild(Size size, Size childSize) { return new Offset(0.0, size.height - childSize.height * progress); } @override bool shouldRelayout(_ModalBottomSheetLayout oldDelegate) { return progress != oldDelegate.progress; } } class _ModalBottomSheet<T> extends StatefulWidget { const _ModalBottomSheet({ Key key, this.route }) : super(key: key); final _ModalBottomSheetRoute<T> route; @override _ModalBottomSheetState<T> createState() => new _ModalBottomSheetState<T>(); } class _ModalBottomSheetState<T> extends State<_ModalBottomSheet<T>> { void _navigatorPop() { Navigator.pop(context); } @override Widget build(BuildContext context) { return new GestureDetector( onTap: _navigatorPop, child: new AnimatedBuilder( animation: widget.route.animation, builder: (BuildContext context, Widget child) { return new ClipRect( child: new CustomSingleChildLayout( delegate: new _ModalBottomSheetLayout(widget.route.animation.value), child: new BottomSheet( animationController: widget.route._animationController, onClosing: () => Navigator.pop(context), builder: widget.route.builder ) ) ); } ) ); } } class _ModalBottomSheetRoute<T> extends PopupRoute<T> { _ModalBottomSheetRoute({ this.builder, this.theme, }); final WidgetBuilder builder; final ThemeData theme; @override Duration get transitionDuration => _kBottomSheetDuration; @override bool get barrierDismissible => true; @override Color get barrierColor => Colors.black54; AnimationController _animationController; @override AnimationController createAnimationController() { assert(_animationController == null); _animationController = BottomSheet.createAnimationController(navigator.overlay); return _animationController; } @override Widget buildPage(BuildContext context, Animation<double> animation, Animation<double> secondaryAnimation) { Widget bottomSheet = new _ModalBottomSheet<T>(route: this); if (theme != null) bottomSheet = new Theme(data: theme, child: bottomSheet); return bottomSheet; } } /// Shows a modal material design bottom sheet. /// /// A modal bottom sheet is an alternative to a menu or a dialog and prevents /// the user from interacting with the rest of the app. /// /// A closely related widget is a persistent bottom sheet, which shows /// information that supplements the primary content of the app without /// preventing the use from interacting with the app. Persistent bottom sheets /// can be created and displayed with the [ScaffoldState.showBottomSheet] function. /// /// Returns a `Future` that resolves to the value (if any) that was passed to /// [Navigator.pop] when the modal bottom sheet was closed. /// /// See also: /// /// * [BottomSheet], which is the widget normally returned by the function /// passed as the `builder` argument to [showModalBottomSheet]. /// * [ScaffoldState.showBottomSheet], for showing non-modal bottom sheets. /// * <https://material.google.com/components/bottom-sheets.html#bottom-sheets-modal-bottom-sheets> Future<T> showModalBottomSheet<T>({ @required BuildContext context, @required WidgetBuilder builder, }) { assert(context != null); assert(builder != null); return Navigator.push(context, new _ModalBottomSheetRoute<T>( builder: builder, theme: Theme.of(context, shadowThemeOnly: true), )); }