Skip to content

Instantly share code, notes, and snippets.

Embed
What would you like to do?
Modal Bottom Sheet with Input Fields fix for Flutter (Fix issue with overlap with keyboard and fix for tapping to dismiss)
// 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';
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,
this.barrierColor: Colors.black54,
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;
final Color barrierColor;
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,
}) {
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);
}
@ROTGP
Copy link

ROTGP commented Jul 12, 2018

@slightfoot would you mind providing a short example of how to implement this?

@rodydavis
Copy link

rodydavis commented Nov 15, 2018

Need to set the resize to true so it doesn't throw errors in the rest of the app.

// 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';

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 ?? false)
                      ? 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,
    this.barrierColor: Colors.black54,
    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;

  final Color barrierColor;

  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,
}) {
  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);
}

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment