Flutter:如何允许内容与SliverAppBar重叠? [英] Flutter : how Allow content to overlap SliverAppBar?
问题描述
在android中,我们使用 app:behavior_overlapTop = 64dp
来实现这一目标
我希望重叠的内容与上述GIF一样扑朔迷离
我的代码
class DetailsPage扩展了StatefulWidget {
@override
_DetailsPage createState() => _DetailsPage();
}
类_DetailsPage扩展了State< DetailsPage> {
@override
void initState(){
super.initState();
SystemChrome.setPreferredOrientations([
DeviceOrientation.portraitUp,
DeviceOrientation.portraitDown,
]);
_scrollController = ScrollController();
_scrollController.addListener(_scrollListener);
}
ScrollController _scrollController;
bool lastStatus = true;
_scrollListener(){
if(isShrink!= lastStatus){
setState((){
lastStatus = isShrink;
});
}
}
bool get isShrink {
return _scrollController.hasClients&
_scrollController.offset> (250-kToolbarHeight);
}
@override
void dispose(){
_scrollController.removeListener(_scrollListener);
super.dispose();
}
@override
小部件build(BuildContext context){
return Scaffold(
// backgroundColor:Colors.transparent,
body :NestedScrollView(
controller:_scrollController,
headerSliverBuilder:(BuildContext context,bool innerBoxIsScrolled){
return< Widget> [
SliverAppBar(
expandHeight:250.0,
浮动:false,
亮度:Brightness.light,
固定:true,
//高程:0.0,
// backgroundColor:AppColors.colorCreateTripOrange,
backgroundColor:Colors.white,
操作:< Widget> [
GestureDetector(
onTap:(){
Navigator.of(context).pop();
},
子级:Padding(
padding:const EdgeInsets.only(right: 20.0),
子级:Image.asset(
'assets / images / close.png',
宽度:25.0,
高度:25.0,
),
),
)
],
开头:Padding(
padding:const EdgeInsets.only(left:20.0,top:0),
child: IconButton(
iconSize:25,
icon:Image.asset(
'assets / images / back.png',
宽度:25,
高度:25,
),
颜色:Colors.black,
onPressed :(){
Navigator.of(context).pop();
},
)),
flexibleSpace:FlexibleSpaceBar(
centerTitle:false,
crashMode:CollapseMode.parallax,
title:Text(isShrink?罗马:,
样式:TextStyle(
颜色:isShrink?Colors.black:Colors.white,
fontFamily:'bin_bold',
fontSize:18.0,
)),
背景:Image.network(
https://media.istockphoto.com/photos/great-colosseum-rome-italy-picture-id692334500\",
适合:BoxFit.cover,
)),
),
];
},
正文:Container(
//填充:const EdgeInsets.only(左:20.0,右:20.0,上:40.0),
装饰:BoxDecoration(
颜色:AppColors.colorWhite,
borderRadius:BorderRadius.all(Radius.circular(20)),
),
子级:列(
子级:< Widget> [
Expanded(
child:Container(
padding:
const EdgeInsets.only(left:20.0,right:20.0,top:40.0)),
装饰:BoxDecoration (
color:AppColors.colorWhite,
borderRadius:BorderRadius.all(Radius.circular(20)),
),
child:ListView(
children:< ; Widget> [
Column(
crossAxisAlignment:CrossAxisAlignment.start,
子代:< Widget> [
填充(
填充:EdgeInsets.symmetric(水平:15.0),
子代:文本(
罗马,
样式: TextStyle(
color:Colors.black,
fontFamily:'bin_bold',
fontSize:25.0),
),
),
填充(
padding:EdgeInsets.only(top:20,left:15,right:15),
child:Row(
children:< Widget> [
Image.asset(
'assets / images / calender.png',
宽度:25.0,
高度:25.0,
),
填充(
填充:const EdgeInsets.only(左:10.0),
子级:文本(
2020年3月6日至12日,
样式:TextStyle(
fontFamily:'bin',
fontSize:18,
颜色:AppColors.colorActivityGray),
),
)
] ,
),
),
Container(
宽度:double.infinity,
保证金:const EdgeInsets.only(
顶部:20.0,左侧: 20.0,右:30.0),
//填充:const EdgeInsets.only(左:20.0,右:20.0),
装饰:BoxDecoration(
颜色:AppColors.colorTripsGray,
borderRadius:BorderRadius.all(Radius.circular(20)) ,
边界:Border.all(color:AppColors.colorDivider),
),
子项:Column(
crossAxisAlignment:CrossAxisAlignment.start,
子项:<窗口小部件> [
填充(
填充:const EdgeInsets.only(
顶部:15.0,
底部:0.0,
左:20.0,
右: 20.0),
子级:文本(
Constants.region,
样式:TextStyle(
颜色:AppColors.colorLightBorderOrange,
fontFamily:'din',
fontSize:20),
),
),
填充(
填充:const EdgeInsets.only(
顶部:10.0,
底部:0.0,
左:20.0,
右: 20.0),
子级:Text(
Constants.firstName,
样式:TextStyle(
颜色:AppColors.colorCreateGreyTrans,
fontFamily:'din',
fontSize:20),
),
),
Padding(
padding:const EdgeInsets.only(
top: 10.0,下:0.0,左:0.0,右:00.0),
子级:Divider(),
),
填充(
padding:const EdgeInsets.only(
顶部:10.0,
底部:0.0,
左:20.0,
右:20.0),
子级:文本(
Constants.activities,
样式:TextStyle(
颜色:AppColors.colorLightBorderOrange,
fontFamily:'din',
fontSize:20),
),
),
填充(
填充:const EdgeInsets.only(
顶部:10.0,
底部:0.0,
左:20.0,
右:20.0),
子级:文本(
食品与饮料酒吧,必看景点,
样式:TextStyle(
颜色:AppColors.colorCreateGreyTrans,
fontFamily:'din',
fontSize:20),
),
),
填充(
填充:const EdgeInsets.only(
顶部:10.0,底部:0.0,左:0.0,右:00.0),
子级: Divider(),
),
填充(
padding:const EdgeInsets.only(
top:10.0,
bottom:0.0,
left:20.0 ,
右边:20.0),
孩子:文本(
Constants.noOfTravellers,
样式:TextStyle(
颜色:AppColors.colorLightBorderOrange,
fontFamily:'din',
fontSize:20),
),
),
填充(
填充:const EdgeInsets.only(
顶部:10.0,
底部:0.0,
左:20.0,
右:20.0),
儿童:Text(
2 Adults,1 kid,
样式:TextStyle (
color:AppColors.colorCreateGreyTrans,
fontFamily:'din',
fontSize:20),
),
),
填充(
padding:const EdgeInsets.only(
上:10.0,下:0.0,左:0.0,右:00.0),
子级:Divider(),
),
填充(
填充:const EdgeInsets.only(
顶部:10.0,
底部:0.0,
左:20.0,
右:20.0),
子代:文字(
Constants.email,
样式:TextStyle(
颜色:AppColors.colorLightBorderOrange,
fontFamily:'din',
fontSize:20),
),
),
填充(
填充:const EdgeInsets.only(
顶部:10.0,
底部:10.0,
左:20.0,
右: 20.0),
子级:Text(
kim.john12@gmail.com,
样式:TextStyle(
颜色:AppColors.colorCreateGreyTrans,
fontFamily:'din',
fontSize:20),
),
),
],
),
),
],
)
],
),
),
),
容器(
宽度:double.infinity,
保证金:const EdgeInsets.only(顶部:20.0),
填充:const EdgeInsets.all(10.0),
装饰:BoxDecoration(
颜色:AppColors.colorWhite,
borderRadius:BorderRadius.all(Radius.circular(40)),
border:Border.all(color:AppColors.colorDivider,width:2.0),
),
child:Center(
子级:Wrap(
子级:< Widget> [
MaterialButton(
padding:const EdgeInsets.symmetric(
水平:40,垂直:20),
textColor :Colors.black,
颜色:AppColors.colorWhite,
孩子:Text(
Constants.messageTripDesigner,
样式:TextStyle(
fontFamily:'din_bold',
fontSize:Constants.regionFontSize),
),
形状:RoundedRectangleBorder(
borderRadius:BorderRadius.circular(30.0),
侧面:BorderSide(
color :AppColors.colorLightBorderOrange,
width:2),
),
onPressed:(){
Navigator.of(context).pop();
},
)
],
),
),
)
],
),
),
),
);
}
}
类MySliverAppBar扩展了SliverPersistentHeaderDelegate {
最后的double ExpandedHeight;
MySliverAppBar({@ required this.expandedHeight});
@override
窗口小部件构建(
BuildContext上下文,double收缩偏移量,布尔重叠内容){
return Stack(
fit:StackFit.expand,
溢出:Overflow.visible,
子级:[
Image.network(
https://images.pexels.com/photos/396547/pexels-photo-396547.jpeg? auto = compress& cs = tinysrgb& dpr = 1& w = 500,
fit:BoxFit.cover,
),
Center(
子级:Opacity(
不透明度:shrinkOffset / expandedHeight,
子元素:Text(
MySliverAppBar,
样式:TextStyle(
颜色:Colors.white,
fontWeight:FontWeight.w700 ,
fontSize:23,
),
),
),
),
],
);
}
@override
double get maxExtent => expandHeight;
@override
double get minExtent => kToolbarHeight;
@override
bool shouldRebuild(SliverPersistentHeaderDelegate oldDelegate)=>真正;
}
以下是我到目前为止尝试过的一些帖子
-
步骤
- 堆叠
DraggableScrollableSheet
和内的> AppBar
- 使用
DraggableScrollableNotification
更新标题高度和
AppBar
阴影。
在这里
import'package:flutter / material.dart ';
void main(){
runApp(MaterialApp(debugShowCheckedModeBanner:false,home:HomePage()));
}
类主页扩展StatefulWidget {
@override
State< StatefulWidget> createState()=> _HomePageState();
}
类_HomePageState扩展了State< HomePage>
和SingleTickerProviderStateMixin {
final ValueNotifier< double> headerNegativeOffset = ValueNotifier< double>(0);
final ValueNotifier< bool> appbarShadow = ValueNotifier< bool>(false);
最终双倍maxHeaderHeight = 250.0;
final double minHeaderHeight = 56.0;
final double bodyContentRatioMin = .8;
final double bodyContentRatioMax = 1.0;
///必须介于身体含量比率的最小值和最大值之间。
final double bodyContentRatioParallax = .9;
@override
void dispose(){
headerNegativeOffset.dispose();
appbarShadow.dispose();
super.dispose();
}
@override
窗口小部件build(BuildContext context){
return Scaffold(
//仅用于状态栏颜色
appBar: PreferredSize(
preferredSize:Size.fromHeight(0.0),
子对象:AppBar(
backgroundColor:Colors.pink,
高程:0.0,
),
),
正文:Stack(
子项:< Widget> [
Stack(子项:[
容器(
子项:ValueListenableBuilder< double>(
valueListenable:headerNegativeOffset,
生成器:(context,offset,child){
return Transform.translate(
offset:Offset(0,offset * -1),
child :SizedBox(
高度:maxHeaderHeight,
子级:容器(
颜色:Colors.pink,
),
),
);
})),
NotificationListener< DraggableScrollableNotification>(
onNotification:(通知){
if(notification.extent == bodyContentRatioMin){
appbarShadow.value = false ;;
headerNegativeOffset.value = 0;
}否则,如果(notification.extent == bodyContentRatioMax){
appbarShadow.value = true;
headerNegativeOffset.value =
maxHeaderHeight -minHeaderHeight;
}否则{
double newValue =(maxHeaderHeight-minHeaderHeight)-
((maxHeaderHeight-minHeaderHeight)*
((bodyContentRatioParallax-(notification.extent))/
(bodyContentRatioMax-
bodyContentRatioParallax)));
appbarShadow .value = false;
if(newValue> = maxHeaderHeight-minHeaderHeight){
appbarShadow.value = true;
newValue = maxHeaderHeight-minHeaderHeight;
}否则,如果(newValue< 0){
appbarShadow.value = false;
newValue = 0;
}
headerNegativeOffset.value = newValue;
}
返回true;
},
子项:Stack(
子项:< Widget> [
DraggableScrollableSheet(
initialChildSize:bodyContentRatioMin,
minChildSize:bodyContentRatioMin,
maxChildSize:bodyContentRatioMax,
builder:(BuildContext context,
ScrollController scrollController){
return Stack(
children:< Widget> [
Container(
对齐方式:AlignmentDirectional.center,
填充:EdgeInsets.only(
左:16.0,右:16.0,顶部:16.0),
子级:Material(
type:MaterialType。画布,
颜色:Colors.white,
海拔:2.0,
borderRadius:BorderRadius.only(
top左:Radius.circular(24.0),
top右:Radius.circular(24.0),
),
子代:ListView.builder(
控制器:scrollController,
itemCount:200,
itemBuilder:(BuildContext context,int index){
return ListTile(title:Text('Item $指数'));
},
),
),
),
],
);
},
),
],
),
)
]),
位置(剩余
:0.0,
右边:0.0,
顶部:0.0,
子元素:ValueListenableBuilder< bool>(
valueListenable:appbarShadow,
builder:(context,value,child){
/// appbar的默认高度是56.0。您也可以
////使用自定义高度的自定义小部件
return AppBar(
backgroundColor:Colors.pink ,
标题:Text( Notes),
海拔:值?2.0:0.0,
);
}),
),
] ,
),
抽屉:Drawer(),
);
}
}
观看实时演示此处。
In android we are using
app:behavior_overlapTop="64dp"
to achieve thisI want overlap content same like above GIF in flutter
My code
class DetailsPage extends StatefulWidget { @override _DetailsPage createState() => _DetailsPage(); } class _DetailsPage extends State<DetailsPage> { @override void initState() { super.initState(); SystemChrome.setPreferredOrientations([ DeviceOrientation.portraitUp, DeviceOrientation.portraitDown, ]); _scrollController = ScrollController(); _scrollController.addListener(_scrollListener); } ScrollController _scrollController; bool lastStatus = true; _scrollListener() { if (isShrink != lastStatus) { setState(() { lastStatus = isShrink; }); } } bool get isShrink { return _scrollController.hasClients && _scrollController.offset > (250 - kToolbarHeight); } @override void dispose() { _scrollController.removeListener(_scrollListener); super.dispose(); } @override Widget build(BuildContext context) { return Scaffold( // backgroundColor: Colors.transparent, body: NestedScrollView( controller: _scrollController, headerSliverBuilder: (BuildContext context, bool innerBoxIsScrolled) { return <Widget>[ SliverAppBar( expandedHeight: 250.0, floating: false, brightness: Brightness.light, pinned: true, // elevation: 0.0, // backgroundColor: AppColors.colorCreateTripOrange, backgroundColor: Colors.white, actions: <Widget>[ GestureDetector( onTap: () { Navigator.of(context).pop(); }, child: Padding( padding: const EdgeInsets.only(right: 20.0), child: Image.asset( 'assets/images/close.png', width: 25.0, height: 25.0, ), ), ) ], leading: Padding( padding: const EdgeInsets.only(left: 20.0, top: 0), child: IconButton( iconSize: 25, icon: Image.asset( 'assets/images/back.png', width: 25, height: 25, ), color: Colors.black, onPressed: () { Navigator.of(context).pop(); }, )), flexibleSpace: FlexibleSpaceBar( centerTitle: false, collapseMode: CollapseMode.parallax, title: Text(isShrink ? "Rome" : "", style: TextStyle( color: isShrink ? Colors.black : Colors.white, fontFamily: 'bin_bold', fontSize: 18.0, )), background: Image.network( "https://media.istockphoto.com/photos/great-colosseum-rome-italy-picture-id692334500", fit: BoxFit.cover, )), ), ]; }, body: Container( // padding: const EdgeInsets.only(left: 20.0, right: 20.0, top: 40.0), decoration: BoxDecoration( color: AppColors.colorWhite, borderRadius: BorderRadius.all(Radius.circular(20)), ), child: Column( children: <Widget>[ Expanded( child: Container( padding: const EdgeInsets.only(left: 20.0, right: 20.0, top: 40.0), decoration: BoxDecoration( color: AppColors.colorWhite, borderRadius: BorderRadius.all(Radius.circular(20)), ), child: ListView( children: <Widget>[ Column( crossAxisAlignment: CrossAxisAlignment.start, children: <Widget>[ Padding( padding: EdgeInsets.symmetric(horizontal: 15.0), child: Text( "Rome", style: TextStyle( color: Colors.black, fontFamily: 'bin_bold', fontSize: 25.0), ), ), Padding( padding: EdgeInsets.only(top: 20, left: 15, right: 15), child: Row( children: <Widget>[ Image.asset( 'assets/images/calender.png', width: 25.0, height: 25.0, ), Padding( padding: const EdgeInsets.only(left: 10.0), child: Text( "March 6-12, 2020", style: TextStyle( fontFamily: 'bin', fontSize: 18, color: AppColors.colorActivityGray), ), ) ], ), ), Container( width: double.infinity, margin: const EdgeInsets.only( top: 20.0, left: 20.0, right: 30.0), // padding: const EdgeInsets.only(left: 20.0, right: 20.0), decoration: BoxDecoration( color: AppColors.colorTripsGray, borderRadius: BorderRadius.all(Radius.circular(20)), border: Border.all(color: AppColors.colorDivider), ), child: Column( crossAxisAlignment: CrossAxisAlignment.start, children: <Widget>[ Padding( padding: const EdgeInsets.only( top: 15.0, bottom: 0.0, left: 20.0, right: 20.0), child: Text( Constants.region, style: TextStyle( color: AppColors.colorLightBorderOrange, fontFamily: 'din', fontSize: 20), ), ), Padding( padding: const EdgeInsets.only( top: 10.0, bottom: 0.0, left: 20.0, right: 20.0), child: Text( Constants.firstName, style: TextStyle( color: AppColors.colorCreateGreyTrans, fontFamily: 'din', fontSize: 20), ), ), Padding( padding: const EdgeInsets.only( top: 10.0, bottom: 0.0, left: 0.0, right: 00.0), child: Divider(), ), Padding( padding: const EdgeInsets.only( top: 10.0, bottom: 0.0, left: 20.0, right: 20.0), child: Text( Constants.activities, style: TextStyle( color: AppColors.colorLightBorderOrange, fontFamily: 'din', fontSize: 20), ), ), Padding( padding: const EdgeInsets.only( top: 10.0, bottom: 0.0, left: 20.0, right: 20.0), child: Text( "Food & Bar, Must See Attractions", style: TextStyle( color: AppColors.colorCreateGreyTrans, fontFamily: 'din', fontSize: 20), ), ), Padding( padding: const EdgeInsets.only( top: 10.0, bottom: 0.0, left: 0.0, right: 00.0), child: Divider(), ), Padding( padding: const EdgeInsets.only( top: 10.0, bottom: 0.0, left: 20.0, right: 20.0), child: Text( Constants.noOfTravellers, style: TextStyle( color: AppColors.colorLightBorderOrange, fontFamily: 'din', fontSize: 20), ), ), Padding( padding: const EdgeInsets.only( top: 10.0, bottom: 0.0, left: 20.0, right: 20.0), child: Text( "2 Adults, 1 kid", style: TextStyle( color: AppColors.colorCreateGreyTrans, fontFamily: 'din', fontSize: 20), ), ), Padding( padding: const EdgeInsets.only( top: 10.0, bottom: 0.0, left: 0.0, right: 00.0), child: Divider(), ), Padding( padding: const EdgeInsets.only( top: 10.0, bottom: 0.0, left: 20.0, right: 20.0), child: Text( Constants.email, style: TextStyle( color: AppColors.colorLightBorderOrange, fontFamily: 'din', fontSize: 20), ), ), Padding( padding: const EdgeInsets.only( top: 10.0, bottom: 10.0, left: 20.0, right: 20.0), child: Text( "kim.john12@gmail.com", style: TextStyle( color: AppColors.colorCreateGreyTrans, fontFamily: 'din', fontSize: 20), ), ), ], ), ), ], ) ], ), ), ), Container( width: double.infinity, margin: const EdgeInsets.only(top: 20.0), padding: const EdgeInsets.all(10.0), decoration: BoxDecoration( color: AppColors.colorWhite, borderRadius: BorderRadius.all(Radius.circular(40)), border: Border.all(color: AppColors.colorDivider, width: 2.0), ), child: Center( child: Wrap( children: <Widget>[ MaterialButton( padding: const EdgeInsets.symmetric( horizontal: 40, vertical: 20), textColor: Colors.black, color: AppColors.colorWhite, child: Text( Constants.messageTripDesigner, style: TextStyle( fontFamily: 'din_bold', fontSize: Constants.regionFontSize), ), shape: RoundedRectangleBorder( borderRadius: BorderRadius.circular(30.0), side: BorderSide( color: AppColors.colorLightBorderOrange, width: 2), ), onPressed: () { Navigator.of(context).pop(); }, ) ], ), ), ) ], ), ), ), ); } } class MySliverAppBar extends SliverPersistentHeaderDelegate { final double expandedHeight; MySliverAppBar({@required this.expandedHeight}); @override Widget build( BuildContext context, double shrinkOffset, bool overlapsContent) { return Stack( fit: StackFit.expand, overflow: Overflow.visible, children: [ Image.network( "https://images.pexels.com/photos/396547/pexels-photo-396547.jpeg?auto=compress&cs=tinysrgb&dpr=1&w=500", fit: BoxFit.cover, ), Center( child: Opacity( opacity: shrinkOffset / expandedHeight, child: Text( "MySliverAppBar", style: TextStyle( color: Colors.white, fontWeight: FontWeight.w700, fontSize: 23, ), ), ), ), ], ); } @override double get maxExtent => expandedHeight; @override double get minExtent => kToolbarHeight; @override bool shouldRebuild(SliverPersistentHeaderDelegate oldDelegate) => true; }
Below are some post that i have tried so far
- https://github.com/flutter/flutter/issues/404
- Allow GridView to overlap SliverAppBar
- How to overlap SliverList on a SliverAppBar
- https://flutter.dev/docs/cookbook/lists/floating-app-bar
- https://medium.com/flutter-community/flutter-increase-the-power-of-your-appbar-sliverappbar-c4f67c4e076f
If need more information please do let me know. Thanks in advance. Your efforts will be appreciated.
解决方案You can make the App bar scrolling with overlapping content like flexible space by using any of the following combo depending upon your use case.
ListView
with Scroll notificationSliverList
with Scroll notificationDraggableScrollableSheet
with DraggableScrollableNotification
Well, Here I am going with the easiest one,
DraggableScrollableSheet
which allows to scroll and drag simultaneously to create the desired effect.Steps
- Stack the
DraggableScrollableSheet
and theAppBar
inside the body of the Scaffold - Use
DraggableScrollableNotification
to update the header height andAppBar
shadow.
Here you go
import 'package:flutter/material.dart'; void main() { runApp(MaterialApp(debugShowCheckedModeBanner: false, home: HomePage())); } class HomePage extends StatefulWidget { @override State<StatefulWidget> createState() => _HomePageState(); } class _HomePageState extends State<HomePage> with SingleTickerProviderStateMixin { final ValueNotifier<double> headerNegativeOffset = ValueNotifier<double>(0); final ValueNotifier<bool> appbarShadow = ValueNotifier<bool>(false); final double maxHeaderHeight = 250.0; final double minHeaderHeight = 56.0; final double bodyContentRatioMin = .8; final double bodyContentRatioMax = 1.0; ///must be between min and max values of body content ratio. final double bodyContentRatioParallax = .9; @override void dispose() { headerNegativeOffset.dispose(); appbarShadow.dispose(); super.dispose(); } @override Widget build(BuildContext context) { return Scaffold( //just for status bar color appBar: PreferredSize( preferredSize: Size.fromHeight(0.0), child: AppBar( backgroundColor: Colors.pink, elevation: 0.0, ), ), body: Stack( children: <Widget>[ Stack(children: [ Container( child: ValueListenableBuilder<double>( valueListenable: headerNegativeOffset, builder: (context, offset, child) { return Transform.translate( offset: Offset(0, offset * -1), child: SizedBox( height: maxHeaderHeight, child: Container( color: Colors.pink, ), ), ); })), NotificationListener<DraggableScrollableNotification>( onNotification: (notification) { if (notification.extent == bodyContentRatioMin) { appbarShadow.value = false; headerNegativeOffset.value = 0; } else if (notification.extent == bodyContentRatioMax) { appbarShadow.value = true; headerNegativeOffset.value = maxHeaderHeight - minHeaderHeight; } else { double newValue = (maxHeaderHeight - minHeaderHeight) - ((maxHeaderHeight - minHeaderHeight) * ((bodyContentRatioParallax - (notification.extent)) / (bodyContentRatioMax - bodyContentRatioParallax))); appbarShadow.value = false; if (newValue >= maxHeaderHeight - minHeaderHeight) { appbarShadow.value = true; newValue = maxHeaderHeight - minHeaderHeight; } else if (newValue < 0) { appbarShadow.value = false; newValue = 0; } headerNegativeOffset.value = newValue; } return true; }, child: Stack( children: <Widget>[ DraggableScrollableSheet( initialChildSize: bodyContentRatioMin, minChildSize: bodyContentRatioMin, maxChildSize: bodyContentRatioMax, builder: (BuildContext context, ScrollController scrollController) { return Stack( children: <Widget>[ Container( alignment: AlignmentDirectional.center, padding: EdgeInsets.only( left: 16.0, right: 16.0, top: 16.0), child: Material( type: MaterialType.canvas, color: Colors.white, elevation: 2.0, borderRadius: BorderRadius.only( topLeft: Radius.circular(24.0), topRight: Radius.circular(24.0), ), child: ListView.builder( controller: scrollController, itemCount: 200, itemBuilder: (BuildContext context, int index) { return ListTile(title: Text('Item $index')); }, ), ), ), ], ); }, ), ], ), ) ]), Positioned( left: 0.0, right: 0.0, top: 0.0, child: ValueListenableBuilder<bool>( valueListenable: appbarShadow, builder: (context, value, child) { ///default height of appbar is 56.0. You can also ///use a custom widget with custom height if you want. return AppBar( backgroundColor: Colors.pink, title: Text("Notes"), elevation: value ? 2.0 : 0.0, ); }), ), ], ), drawer: Drawer(), ); } }
See the live demo here.
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