User interface 颤振ListView.builder-如何以编程方式跳转到特定索引
我有一个使用User interface 颤振ListView.builder-如何以编程方式跳转到特定索引,user-interface,scroll,flutter,dart,User Interface,Scroll,Flutter,Dart,我有一个使用MaterialApp、DefaultTabController、Scaffold和TabBarView构建的屏幕 在这个屏幕中,我的主体内容使用StreamBuilder从sqllite检索元素列表。我使用ListView获得精确的100个元素(“有限列表”) 我的问题是,使用ListView.builder,当这个屏幕打开时,我们如何跳转到特定的索引 我的主屏幕: ... ScrollController controller = ScrollController(); @o
MaterialApp
、DefaultTabController
、Scaffold
和TabBarView
构建的屏幕
在这个屏幕中,我的主体内容使用StreamBuilder
从sqllite检索元素列表。我使用ListView
获得精确的100个元素(“有限列表”)
我的问题是,使用ListView.builder
,当这个屏幕打开时,我们如何跳转到特定的索引
我的主屏幕:
...
ScrollController controller = ScrollController();
@override
Widget build(BuildContext context) {
return MaterialApp(
debugShowCheckedModeBanner : false,
home: DefaultTabController(
length: 3,
child: Scaffold(
appBar: AppBar(
backgroundColor: Pigment.fromString(UIData.primaryColor),
elevation: 0,
centerTitle: true,
title: Text(translations.text("quran").toUpperCase()),
bottom: TabBar(
tabs: [
Text("Tab1"),
Text("Tab2"),
Text("Tab3")
],
),
leading: Row(
crossAxisAlignment: CrossAxisAlignment.stretch,
children: <Widget>[
Expanded(
child: InkWell(
child: SizedBox(child: Image.asset("assets/images/home.png"), height: 10, width: 1,),
onTap: () => Navigator.of(context).pop(),
)
),
],
),
),
floatingActionButton: FloatingActionButton(
onPressed: _scrollToIndex,
tooltip: 'Testing Index Jump',
child: Text("GO"),
),
body:
TabBarView(
children: [
Stack(
children: <Widget>[
MyDraggableScrollBar.create(
scrollController: controller,
context: context,
heightScrollThumb: 25,
child: ListView(
controller: controller,
children: <Widget>[
Padding(
padding: EdgeInsets.fromLTRB(30, 15, 30, 8),
child: Container(
alignment: Alignment.center,
height: 30,
child: ClipRRect(
borderRadius: BorderRadius.circular(8),
child: TextField(
style: TextStyle(color: Colors.green),
decoration: new InputDecoration(
contentPadding: EdgeInsets.all(5),
border: InputBorder.none,
filled: true,
hintStyle: new TextStyle(color: Colors.green, fontSize: 14),
prefixIcon: Icon(FontAwesomeIcons.search,color: Colors.green,size: 17,),
hintText: translations.text("search-quran"),
fillColor: Colors.grey[300],
prefixStyle: TextStyle(color: Colors.green)
),
onChanged: (val) => quranBloc.searchSurah(val),
),
)
)
),
//surah list
streamBuilderQuranSurah(context)
],
)
) // MyDraggableScrollBar
],
),
Icon(Icons.directions_transit),
Icon(Icons.directions_bike),
],
)
)));
}
Widget streamBuilderQuranSurah(BuildContext ctx){
return StreamBuilder(
stream: quranBloc.chapterStream ,
builder: (BuildContext context, AsyncSnapshot<ChaptersModel> snapshot){
if(snapshot.hasData){
return ListView.builder(
controller: controller,
shrinkWrap: true,
physics: NeverScrollableScrollPhysics(),
itemCount:(snapshot.data.chapters?.length ?? 0),
itemBuilder: (BuildContext context, int index) {
var chapter =
snapshot.data.chapters?.elementAt(index);
return chapterDataCell(chapter);
},
);
}
else{
return SurahItemShimmer();
}
},
);
}
...
。。。
ScrollController=ScrollController();
@凌驾
小部件构建(构建上下文){
返回材料PP(
debugShowCheckedModeBanner:false,
主页:DefaultTabController(
长度:3,
孩子:脚手架(
appBar:appBar(
背景色:颜料.fromString(UIData.primaryColor),
海拔:0,
标题:对,
标题:Text(translations.Text(“古兰经”).toUpperCase()),
底部:选项卡栏(
选项卡:[
正文(“表1”),
文本(“表2”),
文本(“表3”)
],
),
领先:世界其他地区(
crossAxisAlignment:crossAxisAlignment.stretch,
儿童:[
扩大(
孩子:InkWell(
child:SizedBox(child:Image.asset(“assets/images/home.png”),高度:10,宽度:1,
onTap:()=>Navigator.of(context.pop(),
)
),
],
),
),
浮动操作按钮:浮动操作按钮(
按下时:\u滚动到索引,
工具提示:“正在测试索引跳转”,
儿童:文本(“GO”),
),
正文:
塔巴视图(
儿童:[
堆叠(
儿童:[
MyDragableScrollbar.create(
滚动控制器:控制器,
上下文:上下文,
身高:25,
子:ListView(
控制器:控制器,
儿童:[
填充物(
填充:从LTRB(30,15,30,8)开始的边缘设置,
子:容器(
对齐:对齐.center,
身高:30,
孩子:ClipRRect(
边界半径:边界半径。圆形(8),
孩子:TextField(
样式:TextStyle(颜色:Colors.green),
装饰:新的输入装饰(
contentPadding:EdgeInsets.all(5),
边框:InputBorder.none,
是的,
hintStyle:new TextStyle(颜色:Colors.green,字体大小:14),
前缀:图标(FontAwesomeIcons.search,颜色:Colors.green,大小:17,),
hintText:translations.text(“搜索古兰经”),
fillColor:颜色。灰色[300],
前缀样式:文本样式(颜色:Colors.green)
),
一旦更改:(val)=>quranBloc.searchSurah(val),
),
)
)
),
//苏拉名单
streamBuilderQuranSurah(上下文)
],
)
)//MyDragableScrollbar
],
),
图标(图标、方向和交通),
图标(图标、方向和自行车),
],
)
)));
}
小部件streamBuilderQuranSurah(BuildContext ctx){
返回流生成器(
溪流:quranBloc.chapterStream,
生成器:(BuildContext上下文,异步快照){
if(snapshot.hasData){
返回ListView.builder(
控制器:控制器,
收缩膜:对,
物理学:NeverscrollableScroll物理学(),
itemCount:(快照.数据.章节?.长度??0),
itemBuilder:(构建上下文,int索引){
风险值章节=
快照.data.chapters?.elementAt(索引);
返回第章数据单元(第章);
},
);
}
否则{
返回SURAHITEMSHIMER();
}
},
);
}
...
类MyDragableScrollbar.dart:
import 'package:draggable_scrollbar/draggable_scrollbar.dart';
import 'package:flutter/material.dart';
class MyDraggableScrollBar {
static Widget create({
@required BuildContext context,
@required ScrollController scrollController,
@required double heightScrollThumb,
@required Widget child,
}) {
return DraggableScrollbar(
alwaysVisibleScrollThumb: true,
scrollbarTimeToFade: Duration(seconds: 3),
controller: scrollController,
heightScrollThumb: heightScrollThumb,
backgroundColor: Colors.green,
scrollThumbBuilder: (
Color backgroundColor,
Animation<double> thumbAnimation,
Animation<double> labelAnimation,
double height, {
Text labelText,
BoxConstraints labelConstraints,
}) {
return InkWell(
onTap: () {},
child: Container(
height: height,
width: 7,
color: backgroundColor,
),
);
},
child: child,
);
}
}
import'package:draggable_scrollbar/draggable_scrollbar.dart';
进口“包装:颤振/材料.省道”;
类MyDragableScrollbar{
静态小部件创建({
@所需的BuildContext上下文,
@所需的ScrollController ScrollController,
@所需的双倍高度,
@必需的小部件子项,
}) {
返回可拖动滚动条(
始终可见滚动拇指:是的,
滚动次数:持续时间(秒数:3),
控制器:滚动控制器,
heightScrollThumb:heightScrollThumb,
背景颜色:Colors.green,
scrollThumbBuilder:(
颜色背景颜色,
动画,动画,,
动画labelAnimation,
双高{
文本标签文本,
BoxConstraints labelConstraints,
}) {
回墨槽(
onTap:(){},
子:容器(
高度:高度,,
wid
dependencies:
flutter:
sdk: flutter
shared_preferences: "<newest version>"
import 'package:shared_preferences/shared_preferences.dart';
Future<void> resumeController() async{
_sharedPreferences = await SharedPreferences.getInstance().then((_sharedPreferences){
if(_sharedPreferences.getKeys().contains("scroll-offset-0")) _scrollController= ScrollController(initialScrollOffset:_sharedPreferences.getDouble("scroll-offset-0"));
else _sharedPreferences.setDouble("scroll-offset-0", 0);
setState((){});
return _sharedPreferences;
});
ScrollController _scrollController;
SharedPreferences _sharedPreferences;
resumeController();
WidgetsBinding.instance.addObserver(this);
@override
void dispose() {
WidgetsBinding.instance.removeObserver(this);
_scrollController.dispose();
super.dispose();
}
@override
void didChangeAppLifecycleState(AppLifecycleState state) {
if(state==AppLifecycleState.paused || state==AppLifecycleState.inactive || state==AppLifecycleState.suspending)
_sharedPreferences.setDouble("scroll-offset-0", _scrollController.offset);
super.didChangeAppLifecycleState(state);
}
class MyWidget extends StatefulWidget {
@override
_MyWidgetState createState() => _MyWidgetState();
}
class _MyWidgetState extends State<MyWidget> with WidgetsBindingObserver{
//[...]
ScrollController _scrollController;
SharedPreferences _sharedPreferences;
Future<void> resumeController() async{
_sharedPreferences = await SharedPreferences.getInstance().then((_sharedPreferences){
if(_sharedPreferences.getKeys().contains("scroll-offset-0")) _scrollController= ScrollController(initialScrollOffset:_sharedPreferences.getDouble("scroll-offset-0"));
else _sharedPreferences.setDouble("scroll-offset-0", 0);
setState((){});
return _sharedPreferences;
});
}
@override
void initState() {
resumeController();
WidgetsBinding.instance.addObserver(this);
super.initState();
}
@override
void dispose() {
WidgetsBinding.instance.removeObserver(this);
_scrollController.dispose();
super.dispose();
}
@override
void didChangeAppLifecycleState(AppLifecycleState state) {
if(state==AppLifecycleState.paused || state==AppLifecycleState.inactive || state==AppLifecycleState.suspending)
_sharedPreferences.setDouble("scroll-offset-0", _scrollController.offset);
super.didChangeAppLifecycleState(state);
}
@override
Widget build(BuildContext context) {
return MaterialApp(
debugShowCheckedModeBanner: false,
home: Scaffold(
appBar: AppBar(
title: Text("Smart Scroll View"),
),
body: ListView.builder(
itemCount: 50,
controller: _scrollController,
itemBuilder: (c,i)=>
Padding(
padding: EdgeInsets.symmetric(horizontal: 24,vertical: 16),
child: Text((i+1).toString()),
),
),
),
);
}
}
IndexedListView.builder(
controller: indexScrollController,
itemBuilder: itemBuilder
);
indexScrollController.jumpToIndex(10000);
ScrollablePositionedList.builder(
initialScrollIndex: 12, //you can pass the desired index here//
itemCount: 500,
itemBuilder: (context, index) => Text('Item $index'),
itemScrollController: itemScrollController,
itemPositionsListener: itemPositionsListener,
);