ExpandView Animation In Flutter :

expandview animation.dart
import 'package:flutter/material.dart'; class FilterView extends StatefulWidget { final bool expanded; final double expandedHeight; FilterView({ this.expanded = false, this.expandedHeight = 200.0, }); @override State<StatefulWidget> createState() => FilterViewState(); } class FilterViewState extends State<FilterView> with SingleTickerProviderStateMixin { AnimationController _controller; Animation<double> _animation; bool _expanded; @override void initState() { super.initState(); _controller = AnimationController(vsync: this, duration: const Duration(milliseconds: 200)); final CurvedAnimation curve = CurvedAnimation(parent: this._controller, curve: Curves.easeInCubic); _animation = Tween(begin: 34.0, end: this.widget.expandedHeight).animate(curve) ..addListener(() { setState(() {}); }); this._expanded = this.widget.expanded; if (this._expanded) { this._controller.forward(); } } @override void dispose() { super.dispose(); this._controller.dispose(); } @override Widget build(BuildContext context) { Widget _filterForm = Padding( padding: EdgeInsets.only(bottom: 46), child: ListView( children: <Widget>[ Wrap( children: <Widget>[], ), ], ), ); Widget _expandButton = Card( color: Theme.of(context).primaryColor, shape: RoundedRectangleBorder(borderRadius: BorderRadius.vertical(top: Radius.zero, bottom: Radius.circular(2))), margin: EdgeInsets.all(0), child: InkWell( child: Container( padding: EdgeInsets.only(bottom: 6, top: 3), child: Row( mainAxisAlignment: MainAxisAlignment.center, crossAxisAlignment: CrossAxisAlignment.center, children: <Widget>[ Text( '筛选', style: TextStyle(fontSize: 16, color: Colors.white), ), SizedBox(width: 10), Icon( this._expanded ? Icons.expand_less : Icons.menu, color: Colors.white, size: 25, ), ], ), ), onTap: () { this._expanded ? this._controller.reverse(from: this._animation.value) : this._controller.forward(); this.setState(() => this._expanded = !this._expanded); }, ), ); Widget _filterFormButton = Positioned( child: Row( mainAxisAlignment: MainAxisAlignment.end, children: <Widget>[ RaisedButton.icon( onPressed: () {}, color: Theme.of(context).backgroundColor, textTheme: ButtonTextTheme.primary, label: Text('重置'), icon: Icon(Icons.replay), ), SizedBox(width: 10), RaisedButton.icon( onPressed: () {}, color: Theme.of(context).primaryColor, textTheme: ButtonTextTheme.primary, label: const Text('查询'), icon: Icon(Icons.search), ) ], ), bottom: 0, right: 10, ); return SizedBox( width: MediaQuery.of(context).size.width, height: this._animation.value, child: Column( mainAxisAlignment: MainAxisAlignment.end, children: <Widget>[ Expanded( child: Container( child: Stack( children: <Widget>[ _filterForm, _filterFormButton, ], ), decoration: BoxDecoration( border: Border.all(color: Theme.of(context).primaryColor, width: 3), ), ), ), _expandButton, ], ), ); } }
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