andrelsmoraes/bottom_sheet.dart

## bottom_sheet.dart
// 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/material.dart';
import 'package:flutter/widgets.dart';

import 'colors.dart';
import 'material.dart';
import 'material_localizations.dart';
import 'scaffold.dart';
import 'theme.dart';

const Duration _kBottomSheetDuration = const Duration(milliseconds: 200);
const double _kMinFlingVelocity = 700.0;
const double _kCloseProgressThreshold = 0.5;

/// 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, this.bottomInset);

  final double progress;
  final double bottomInset;

  @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 - bottomInset - childSize.height * progress);
  }

  @override
  bool shouldRelayout(_ModalBottomSheetLayout oldDelegate) {
    return progress != oldDelegate.progress || bottomInset != oldDelegate.bottomInset;
  }
}

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>> {
  @override
  Widget build(BuildContext context) {
    return new GestureDetector(
      onTap: widget.route.dismissOnTap ? () => Navigator.pop(context) : null,
      child: new AnimatedBuilder(
        animation: widget.route.animation,
        builder: (BuildContext context, Widget child) {
          double bottomInset = widget.route.resizeToAvoidBottomPadding
              ? MediaQuery.of(context).viewInsets.bottom : 0.0;
          return new ClipRect(
            child: new CustomSingleChildLayout(
              delegate: new _ModalBottomSheetLayout(widget.route.animation.value, bottomInset),
              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,
    this.barrierLabel,
    RouteSettings settings,
    this.resizeToAvoidBottomPadding,
    this.dismissOnTap,
  }) : super(settings: settings);

  final WidgetBuilder builder;
  final ThemeData theme;
  final bool resizeToAvoidBottomPadding;
  final bool dismissOnTap;

  @override
  Duration get transitionDuration => _kBottomSheetDuration;

  @override
  bool get barrierDismissible => true;

  @override
  final String barrierLabel;

  @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) {
    // By definition, the bottom sheet is aligned to the bottom of the page
    // and isn't exposed to the top padding of the MediaQuery.
    Widget bottomSheet = new MediaQuery.removePadding(
      context: context,
      removeTop: true,
      child: 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 [showBottomSheet] function or the
/// [ScaffoldState.showBottomSheet] method.
///
/// The `context` argument is used to look up the [Navigator] and [Theme] for
/// the bottom sheet. It is only used when the method is called. Its
/// corresponding widget can be safely removed from the tree before the bottom
/// sheet is closed.
///
/// 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].
///  * [showBottomSheet] and [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,
  bool dismissOnTap: true,
  bool resizeToAvoidBottomPadding : true,
}) {
  assert(context != null);
  assert(builder != null);
  return Navigator.push(context, new _ModalBottomSheetRoute<T>(
    builder: builder,
    theme: Theme.of(context, shadowThemeOnly: true),
    barrierLabel: MaterialLocalizations.of(context).modalBarrierDismissLabel,
    resizeToAvoidBottomPadding: resizeToAvoidBottomPadding,
    dismissOnTap: dismissOnTap,
  ));
}

/// Shows a persistent material design bottom sheet in the nearest [Scaffold].
///
/// 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. A [Scaffold] is required in the
/// given `context`; its [ScaffoldState.showBottomSheet] method is used to
/// actually show the bottom sheet.
///
/// A closely related widget is a modal bottom sheet, which 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.
///
/// Returns a controller that can be used to close and otherwise manipulate the
/// bottom sheet.
///
/// To rebuild the bottom sheet (e.g. if it is stateful), call
/// [PersistentBottomSheetController.setState] on the value returned from this
/// method.
///
/// The `context` argument is used to look up the [Scaffold] for the bottom
/// sheet. It is only used when the method is called. Its corresponding widget
/// can be safely removed from the tree before the bottom sheet is closed.
///
/// See also:
///
///  * [BottomSheet], which is the widget typically returned by the `builder`.
///  * [showModalBottomSheet], which can be used to display a modal bottom
///    sheet.
///  * [Scaffold.of], for information about how to obtain the [BuildContext].
///  * <https://material.google.com/components/bottom-sheets.html#bottom-sheets-persistent-bottom-sheets>
PersistentBottomSheetController<T> showBottomSheet<T>({
  @required BuildContext context,
  @required WidgetBuilder builder,
}) {
  assert(context != null);
  assert(builder != null);
  return Scaffold.of(context).showBottomSheet<T>(builder);
}
	// 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/material.dart';
	import 'package:flutter/widgets.dart';

	import 'colors.dart';
	import 'material.dart';
	import 'material_localizations.dart';
	import 'scaffold.dart';
	import 'theme.dart';

	const Duration _kBottomSheetDuration = const Duration(milliseconds: 200);
	const double _kMinFlingVelocity = 700.0;
	const double _kCloseProgressThreshold = 0.5;

	/// 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, this.bottomInset);

	final double progress;
	final double bottomInset;

	@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 - bottomInset - childSize.height * progress);
	}

	@override
	bool shouldRelayout(_ModalBottomSheetLayout oldDelegate) {
	return progress != oldDelegate.progress \|\| bottomInset != oldDelegate.bottomInset;
	}
	}

	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>> {
	@override
	Widget build(BuildContext context) {
	return new GestureDetector(
	onTap: widget.route.dismissOnTap ? () => Navigator.pop(context) : null,
	child: new AnimatedBuilder(
	animation: widget.route.animation,
	builder: (BuildContext context, Widget child) {
	double bottomInset = widget.route.resizeToAvoidBottomPadding
	? MediaQuery.of(context).viewInsets.bottom : 0.0;
	return new ClipRect(
	child: new CustomSingleChildLayout(
	delegate: new _ModalBottomSheetLayout(widget.route.animation.value, bottomInset),
	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,
	this.barrierLabel,
	RouteSettings settings,
	this.resizeToAvoidBottomPadding,
	this.dismissOnTap,
	}) : super(settings: settings);

	final WidgetBuilder builder;
	final ThemeData theme;
	final bool resizeToAvoidBottomPadding;
	final bool dismissOnTap;

	@override
	Duration get transitionDuration => _kBottomSheetDuration;

	@override
	bool get barrierDismissible => true;

	@override
	final String barrierLabel;

	@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) {
	// By definition, the bottom sheet is aligned to the bottom of the page
	// and isn't exposed to the top padding of the MediaQuery.
	Widget bottomSheet = new MediaQuery.removePadding(
	context: context,
	removeTop: true,
	child: 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 [showBottomSheet] function or the
	/// [ScaffoldState.showBottomSheet] method.
	///
	/// The `context` argument is used to look up the [Navigator] and [Theme] for
	/// the bottom sheet. It is only used when the method is called. Its
	/// corresponding widget can be safely removed from the tree before the bottom
	/// sheet is closed.
	///
	/// 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].
	/// * [showBottomSheet] and [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,
	bool dismissOnTap: true,
	bool resizeToAvoidBottomPadding : true,
	}) {
	assert(context != null);
	assert(builder != null);
	return Navigator.push(context, new _ModalBottomSheetRoute<T>(
	builder: builder,
	theme: Theme.of(context, shadowThemeOnly: true),
	barrierLabel: MaterialLocalizations.of(context).modalBarrierDismissLabel,
	resizeToAvoidBottomPadding: resizeToAvoidBottomPadding,
	dismissOnTap: dismissOnTap,
	));
	}

	/// Shows a persistent material design bottom sheet in the nearest [Scaffold].
	///
	/// 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. A [Scaffold] is required in the
	/// given `context`; its [ScaffoldState.showBottomSheet] method is used to
	/// actually show the bottom sheet.
	///
	/// A closely related widget is a modal bottom sheet, which 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.
	///
	/// Returns a controller that can be used to close and otherwise manipulate the
	/// bottom sheet.
	///
	/// To rebuild the bottom sheet (e.g. if it is stateful), call
	/// [PersistentBottomSheetController.setState] on the value returned from this
	/// method.
	///
	/// The `context` argument is used to look up the [Scaffold] for the bottom
	/// sheet. It is only used when the method is called. Its corresponding widget
	/// can be safely removed from the tree before the bottom sheet is closed.
	///
	/// See also:
	///
	/// * [BottomSheet], which is the widget typically returned by the `builder`.
	/// * [showModalBottomSheet], which can be used to display a modal bottom
	/// sheet.
	/// * [Scaffold.of], for information about how to obtain the [BuildContext].
	/// * <https://material.google.com/components/bottom-sheets.html#bottom-sheets-persistent-bottom-sheets>
	PersistentBottomSheetController<T> showBottomSheet<T>({
	@required BuildContext context,
	@required WidgetBuilder builder,
	}) {
	assert(context != null);
	assert(builder != null);
	return Scaffold.of(context).showBottomSheet<T>(builder);
	}