Created
July 28, 2021 12:09
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Expandable fab with flutter and material design
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| import 'dart:math' as math; | |
| import 'package:flutter/material.dart'; | |
| @immutable | |
| class ExpandableFab extends StatefulWidget { | |
| const ExpandableFab({ | |
| Key? key, | |
| this.initialOpen, | |
| this.spacing = 70, | |
| required this.children, | |
| }) : super(key: key); | |
| final double spacing; | |
| final bool? initialOpen; | |
| final List<Widget> children; | |
| @override | |
| _ExpandableFabState createState() => _ExpandableFabState(); | |
| } | |
| class _ExpandableFabState extends State<ExpandableFab> with SingleTickerProviderStateMixin { | |
| late final AnimationController _controller; | |
| late final Animation<double> _expandAnimation; | |
| bool _open = false; | |
| @override | |
| void initState() { | |
| super.initState(); | |
| _open = widget.initialOpen ?? false; | |
| _controller = AnimationController( | |
| value: _open ? 1.0 : 0.0, | |
| duration: const Duration(milliseconds: 250), | |
| vsync: this, | |
| ); | |
| _expandAnimation = CurvedAnimation( | |
| curve: Curves.fastOutSlowIn, | |
| reverseCurve: Curves.easeOutQuad, | |
| parent: _controller, | |
| ); | |
| } | |
| @override | |
| void dispose() { | |
| _controller.dispose(); | |
| super.dispose(); | |
| } | |
| void _toggle() { | |
| setState(() { | |
| _open = !_open; | |
| if (_open) { | |
| _controller.forward(); | |
| } else { | |
| _controller.reverse(); | |
| } | |
| }); | |
| } | |
| @override | |
| Widget build(BuildContext context) { | |
| return SizedBox.expand( | |
| child: Stack( | |
| alignment: Alignment.bottomRight, | |
| clipBehavior: Clip.none, | |
| children: [ | |
| _buildTapToCloseFab(), | |
| ..._buildExpandingActionButtons(), | |
| _buildTapToOpenFab(), | |
| ], | |
| ), | |
| ); | |
| } | |
| Widget _buildTapToCloseFab() { | |
| return SizedBox( | |
| width: 56.0, | |
| height: 56.0, | |
| child: Center( | |
| child: Material( | |
| shape: const CircleBorder(), | |
| clipBehavior: Clip.antiAlias, | |
| elevation: 4.0, | |
| child: InkWell( | |
| onTap: _toggle, | |
| child: Padding( | |
| padding: const EdgeInsets.all(8.0), | |
| child: Icon(Icons.close, color: Theme.of(context).primaryColor), | |
| ), | |
| ), | |
| ), | |
| ), | |
| ); | |
| } | |
| List<Widget> _buildExpandingActionButtons() { | |
| final children = <Widget>[]; | |
| final count = widget.children.length; | |
| for (var i = 0; i < count; i++) { | |
| children.add( | |
| _ExpandingActionButton( | |
| distance: widget.spacing * i + widget.spacing, | |
| progress: _expandAnimation, | |
| child: widget.children[i], | |
| ), | |
| ); | |
| } | |
| return children; | |
| } | |
| Widget _buildTapToOpenFab() { | |
| return IgnorePointer( | |
| ignoring: _open, | |
| child: AnimatedContainer( | |
| transformAlignment: Alignment.center, | |
| transform: Matrix4.diagonal3Values( | |
| _open ? 0.7 : 1.0, | |
| _open ? 0.7 : 1.0, | |
| 1.0, | |
| ), | |
| duration: const Duration(milliseconds: 250), | |
| curve: const Interval(0.0, 0.5, curve: Curves.easeOut), | |
| child: AnimatedOpacity( | |
| opacity: _open ? 0.0 : 1.0, | |
| curve: const Interval(0.25, 1.0, curve: Curves.easeInOut), | |
| duration: const Duration(milliseconds: 250), | |
| child: FloatingActionButton( | |
| onPressed: _toggle, | |
| child: const Icon(Icons.add), | |
| ), | |
| ), | |
| ), | |
| ); | |
| } | |
| } | |
| @immutable | |
| class _ExpandingActionButton extends StatelessWidget { | |
| _ExpandingActionButton({ | |
| Key? key, | |
| required this.distance, | |
| required this.progress, | |
| required this.child, | |
| }) : super(key: key); | |
| final double distance; | |
| final Animation<double> progress; | |
| final Widget child; | |
| @override | |
| Widget build(BuildContext context) { | |
| return AnimatedBuilder( | |
| animation: progress, | |
| builder: (context, child) { | |
| final offset = Offset.fromDirection( | |
| math.pi / 2, | |
| progress.value * distance, | |
| ); | |
| return Positioned( | |
| right: 4.0 + offset.dx, | |
| bottom: 4.0 + offset.dy, | |
| child: Transform.rotate( | |
| angle: (1.0 - progress.value) * math.pi / 2, | |
| child: child!, | |
| ), | |
| ); | |
| }, | |
| child: FadeTransition( | |
| opacity: progress, | |
| child: child, | |
| ), | |
| ); | |
| } | |
| } | |
| @immutable | |
| class ActionButton extends StatelessWidget { | |
| const ActionButton({ | |
| Key? key, | |
| this.onPressed, | |
| required this.icon, | |
| required this.label, | |
| }) : super(key: key); | |
| final VoidCallback? onPressed; | |
| final Icon icon; | |
| final String label; | |
| @override | |
| Widget build(BuildContext context) { | |
| final theme = Theme.of(context); | |
| return Container( | |
| decoration: BoxDecoration( | |
| color: theme.accentColor, | |
| border: Border(), | |
| borderRadius: BorderRadius.circular(32), | |
| ), | |
| padding: EdgeInsets.only(left: 12, top: 12, bottom: 12, right: 14), | |
| clipBehavior: Clip.antiAlias, | |
| child: InkWell( | |
| onTap: onPressed, | |
| child: Row( | |
| children: [ | |
| IconTheme(data: IconThemeData(color: Theme.of(context).colorScheme.onPrimary), child: icon), | |
| SizedBox(width: 8), | |
| Text(label, | |
| style: Theme.of(context).textTheme.bodyText2?.copyWith(color: Theme.of(context).colorScheme.onPrimary)), | |
| ], | |
| ), | |
| ), | |
| ); | |
| } | |
| } |
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