Flutter ListView.builder - How to Jump to Certain Index Programmatically - user-interface

i have a screen that build using MaterialApp, DefaultTabController, Scaffold and TabBarView.
in this screen, i have body content that retreive a list of element from sqllite using StreamBuilder. i get exact 100 elements ("finite list") to be shown using ListView.
my question, using ListView.builder, How we can jump to certain index when this screen opened ?
my main screen:
...
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();
}
},
);
}
...
class MyDraggableScrollBar.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,
);
}
}
i have tried find other solutions but seems not working, for example indexed_list_view that only support infinite list
and it seems flutter still not have feature for this, see this issue
Any Idea ?

You can use https://pub.dev/packages/scrollable_positioned_list. You can pass the initial index to the widget.
ScrollablePositionedList.builder(
initialScrollIndex: 12, //you can pass the desired index here//
itemCount: 500,
itemBuilder: (context, index) => Text('Item $index'),
itemScrollController: itemScrollController,
itemPositionsListener: itemPositionsListener,
);

General Solution:
To store anything which can be represented as a number/string/list of strings, Flutter provides a powerful easy-to-use plugin which stores the values needed to be stored along with a key. So the next time you need you'll need to retrieve or even update that value all that you'll need is that key.
To get started, add the shared_preferences plugin to the pubspec.yaml file,
dependencies:
flutter:
sdk: flutter
shared_preferences: "<newest version>"
Run flutter pub get from the terminal or if your using IntelliJ just click on Packages get(You'll find it somewhere around the top-right corner of your screen while viewing the pubspec.yaml file)
Once the above command is successfully executed, import the below file in your main.dart or concerned file.
import 'package:shared_preferences/shared_preferences.dart';
Now just attach a ScrollController to your ListView.builder() widget and make sure that the final/last offset is stored along with a specific key using shared_preferences whenever the user leaves the app in any way and is set when the initState of your concerned widget is called.
In order to know to detect changes in the state of our app and to act with accordance to it, we'll be inheriting WidgetsBindingObserver to our class.
Steps to follow:
Extend the WidgetsBindingObserver class along with the State class of your StatefulWidget.
Define a async function resumeController() as a function member of the above class.
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;
});
Declare two variables one to store and pass the scrollcontroller and the other to store and use the instance of SharedPreferences.
ScrollController _scrollController;
SharedPreferences _sharedPreferences;
Call resumeController() and pass your class to the addObserver method of the instance object in WidgetsBinding class.
resumeController();
WidgetsBinding.instance.addObserver(this);
Simply paste this code in the class definition (outside other member functions)
#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);
}
Pass the ScrollController() to the concerned Scrollable.
Working Example:
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()),
),
),
),
);
}
}

Solution without knowing the size of your widgets
the Solution I found without knowing the size of your widget is displaying a reverse 'sublist' from the index to the end, then scroll to the top of your 'sublist' and reset the entire list. As it is a reverse list the item will be add at the top of the list and you will stay at your position (the index).
the problem is that you can't use a listView.builder because you will need to change the size of the list
example
class _ListViewIndexState extends State<ListViewIndex> {
ScrollController _scrollController;
List<Widget> _displayedList;
#override
void initState() {
super.initState();
_scrollController = ScrollController();
_displayedList = widget.items.sublist(0, widget.items.length - widget.index);
if (SchedulerBinding.instance.schedulerPhase == SchedulerPhase.persistentCallbacks) {
SchedulerBinding.instance.addPostFrameCallback((_) {
//here the sublist is already build
completeList();
});
}
}
completeList() {
//to go to the last item(in first position)
_scrollController.jumpTo(_scrollController.position.maxScrollExtent);
//reset the list to the full list
setState(() {
_displayedList = widget.items;
});
}
#override
Widget build(BuildContext context) {
return Stack(
children: <Widget>[
ListView(
controller: _scrollController,
reverse: true,
children: _displayedList,
),
]
);
}
}

The https://pub.dev/packages/indexed_list_view package could maybe help you out for this. Use something like this:
IndexedListView.builder(
controller: indexScrollController,
itemBuilder: itemBuilder
);
indexScrollController.jumpToIndex(10000);

I'll present another approach, which supports list lazy loading unlike #Shinbly 's method, and also support tiles in list to resize without recalculating the correct offset of the ListView nor saving any persistent information like "#Nephew of Stackoverflow" does.
The essential key to this approach is to utilize CustomScrollView, the CustomScrollView.center property.
Here's an example based on the example code from Flutter document (widgets.CustomScrollView.2):
class _MyStatefulWidgetState extends State<MyStatefulWidget> {
List<int> top = [];
List<int> bottom = [0];
List<int> test = List.generate(10, (i) => -5 + i);
bool positionSwitcher = true;
#override
Widget build(BuildContext context) {
positionSwitcher = !positionSwitcher;
final jumpIndex = positionSwitcher ? 1 : 9;
Key centerKey = ValueKey('bottom-sliver-list');
return Scaffold(
appBar: AppBar(
title: const Text('Press Jump!! to jump between'),
leading: IconButton(
icon: const Icon(Icons.add),
onPressed: () {
setState(() {
top.add(-top.length - 1);
bottom.add(bottom.length);
});
},
),
),
body: Column(
children: [
Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: [
RaisedButton(
child: Text('Jump!!'),
onPressed: () => setState(() {}),
),
Text(positionSwitcher ? 'At top' : 'At bottom'),
],
),
Expanded(
child: CustomScrollView(
center: centerKey,
slivers: <Widget>[
SliverList(
delegate: SliverChildBuilderDelegate(
(BuildContext context, int i) {
final index = jumpIndex - 1 - i;
return Container(
alignment: Alignment.center,
color: Colors.blue[200 + test[index] % 4 * 100],
height: 100 + test[index] % 4 * 20.0,
child: Text('Item: ${test[index]}'),
);
},
childCount: jumpIndex,
),
),
SliverList(
key: centerKey,
delegate: SliverChildBuilderDelegate(
(BuildContext context, int i) {
final index = i + jumpIndex;
return Container(
alignment: Alignment.center,
color: i == 0
? Colors.red
: Colors.blue[200 + test[index] % 4 * 100],
height: 100 + test[index] % 4 * 20.0,
child: Text('Item: ${test[index]}'),
);
},
childCount: test.length - jumpIndex,
),
),
],
),
)
],
),
);
}
}
Explanation:
We use single list as data source for both SliverList
During each rebuild, we use center key to reposition the second SliverList inside ViewPort
Carefully manage the conversion from SliverList index to data source list index
Notice how the scroll view build the first SliverList by passing an index starting from bottom of this SliverList (i.e. index 0 suggests last item in the first list sliver)
Give the CustomeScrollView a proper key to decide whether to "re-position" or not

Working Example:
import 'dart:math';
import 'package:flutter/material.dart';
import 'package:scroll_to_index/scroll_to_index.dart';
class ScrollToIndexDemo extends StatefulWidget {
const ScrollToIndexDemo({Key? key}) : super(key: key);
#override
_ScrollToIndexDemoState createState() => _ScrollToIndexDemoState();
}
class _ScrollToIndexDemoState extends State<ScrollToIndexDemo> {
late AutoScrollController controller = AutoScrollController();
var rng = Random();
ValueNotifier<int> scrollIndex = ValueNotifier(0);
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: ValueListenableBuilder(
valueListenable: scrollIndex,
builder: (context, index, child) {
return Text('Scroll Demo - $index');
},
),
),
body: ListView.builder(
itemCount: 100,
controller: controller,
itemBuilder: (context, index) {
return Padding(
padding: EdgeInsets.all(8),
child: AutoScrollTag(
key: ValueKey(index),
controller: controller,
index: index,
highlightColor: Colors.black.withOpacity(0.1),
child: Container(
padding: EdgeInsets.all(10),
alignment: Alignment.center,
color: Colors.grey[300],
height: 100,
child: Text(
'index: $index',
style: TextStyle(color: Colors.black),
),
),
),
);
},
),
floatingActionButton: FloatingActionButton(
onPressed: () async {
scrollIndex.value = rng.nextInt(100);
await controller.scrollToIndex(scrollIndex.value, preferPosition: AutoScrollPosition.begin);
},
tooltip: 'Increment',
child: Center(
child: Text(
'Next',
textAlign: TextAlign.center,
),
),
),
);
}
}

You can use the flutter_scrollview_observer lib to implement your desired functionality without invasivity
Create and use instance of ScrollController normally.
ScrollController scrollController = ScrollController();
ListView _buildListView() {
return ListView.builder(
controller: scrollController,
...
);
}
Create an instance of ListObserverController pass it to ListViewObserver
ListObserverController observerController = ListObserverController(controller: scrollController);
ListViewObserver(
controller: observerController,
child: _buildListView(),
...
)
Now you can scroll to the specified index position
// Jump to the specified index position without animation.
observerController.jumpTo(index: 1)
// Jump to the specified index position with animation.
observerController.animateTo(
index: 1,
duration: const Duration(milliseconds: 250),
curve: Curves.ease,
);

Related

Flutter AnimatedList still janky?

I'm currently using an AnimatedList in my Flutter app and having problems with the way removed list items are animated out. The animation itself works as expected but once the removed item finishes animating, it just disappears causing the other widgets to jump into its place. I had expected the other items to transition into the place of the removed item ...
I tried wrapping my list items with a ScaleTransition but that didn't help - the other list items still do not react to the removed item until it has finished the animation.
This kind of defies the purpose of AnimatedList, right? Or did I do something wrong? The "Widget of the week" video about AnimatedList clearly shows that list items react to newly inserted items by changing their position ...
Here is my code:
#override
Widget build(BuildContext context) {
return AnimatedList(
padding: EdgeInsets.only(top: REGULAR_DIM,
bottom: REGULAR_DIM + kBottomNavigationBarHeight),
initialItemCount: data.length,
itemBuilder: (context, index, animation) {
return MyCustomWidget(
data: data[index],
animation: animation,
disabled: false
);
},
);
}
class MyCustomWidget extends AnimatedWidget {
final MyModel data;
final bool disabled;
MyCustomWidget({
#required this.data,
#required Animation<double> animation,
this.disabled = false
}) : super(listenable: animation);
Animation<double> get animation => listenable;
#override
Widget build(BuildContext context) {
final content = ... ;
return ScaleTransition(
scale: CurvedAnimation(
parent: animation,
curve: Interval(0, 0.25)
).drive(Tween(begin: 0, end: 1)),
child: FadeTransition(
opacity: animation,
child: SlideTransition(
position: animation.drive(
Tween(begin: Offset(-1, 0), end: Offset(0, 0))
.chain(CurveTween(curve: Curves.easeOutCubic))),
child: content,
),
),
);
}
}
And then somewhere in the MyCustomWidget I invoke this function:
void _remove(BuildContext context) async {
final animatedList = AnimatedList.of(context);
// obtain myModel asynchronously
myModel.removeData(data);
animatedList.removeItem(index, (context, animation) => MyCustomWidget(
data: data,
animation: animation,
disabled: true,
), duration: Duration(milliseconds: 350));
}
The key is to trigger two Transitions one SlideTranstion() and another SizeTransition to eliminate to jump when the item is removed
here is some sample code
import 'package:flutter/material.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
debugShowCheckedModeBanner: false,
home: Scaffold(
appBar: AppBar(title: Text('Update AnimatedList data')),
body: BodyWidget(),
),
);
}
}
class BodyWidget extends StatefulWidget {
#override
BodyWidgetState createState() {
return new BodyWidgetState();
}
}
class BodyWidgetState extends State<BodyWidget>
with SingleTickerProviderStateMixin {
// the GlobalKey is needed to animate the list
final GlobalKey<AnimatedListState> _listKey = GlobalKey(); // backing data
List<String> _data = ['Horse', 'Cow', 'Camel', 'Sheep', 'Goat'];
#override
Widget build(BuildContext context) {
return Column(
children: <Widget>[
SizedBox(
height: 400,
child: AnimatedList(
key: _listKey,
initialItemCount: _data.length,
itemBuilder: (context, index, animation) {
return _buildItem(
_data[index],
animation,
);
},
),
),
RaisedButton(
child: Text(
'Insert single item',
style: TextStyle(fontSize: 20),
),
onPressed: () {
_onButtonPress();
},
),
RaisedButton(
child: Text(
'Remove single item',
style: TextStyle(fontSize: 20),
),
onPressed: () {
_removeSingleItems();
},
),
],
);
}
Widget _buildItem(String item, Animation<double> animation, {direction: 0}) {
return (direction == 0)
? SizeTransition(
sizeFactor: animation,
child: Card(
color: Colors.amber,
child: ListTile(
title: Text(
item,
style: TextStyle(fontSize: 20),
),
),
),
)
: Stack(
children: [
SizeTransition(
sizeFactor: animation,
child: Card(
color: Colors.transparent,
child: ListTile(
title: Text(
item,
style: TextStyle(fontSize: 20),
),
),
),
),
Align(
alignment: Alignment.topCenter,
heightFactor: 0,
child: SlideTransition(
position: animation
.drive(Tween(begin: Offset(-1, 0), end: Offset(0, 0))),
child: Card(
color: Colors.red,
child: ListTile(
title: Text(
item,
style: TextStyle(fontSize: 20),
),
),
),
),
),
],
);
}
void _onButtonPress() {
_insertSingleItem();
}
void _insertSingleItem() {
String item = "Pig";
int insertIndex = 2;
_data.insert(insertIndex, item);
_listKey.currentState.insertItem(insertIndex);
}
void _removeSingleItems() {
int removeIndex = 2;
String removedItem = _data.removeAt(removeIndex);
// This builder is just so that the animation has something
// to work with before it disappears from view since the
// original has already been deleted.
AnimatedListRemovedItemBuilder builder = (context, animation) {
// A method to build the Card widget.
return _buildItem(removedItem, animation, direction: 1);
};
_listKey.currentState.removeItem(removeIndex, builder);
}
void _updateSingleItem() {
final newValue = 'I like sheep';
final index = 3;
setState(() {
_data[index] = newValue;
});
}
}
enter code here
You need to test the performance with the release version of your app.

Flutter: How to put button on each image like (x) to cancel selected image

I am using multi_image_picker 4.6.1 in my application but I faced little problem. How to organize images on specific place on the page and put cancel button on each selected image so user can cancel or remove selected image one by one like in picture here. Thanks in advance
here is the code i am using
import 'package:flutter/material.dart';
import 'dart:async';
import 'package:multi_image_picker/multi_image_picker.dart';
void main() => runApp(new MyApp());
class MyApp extends StatefulWidget {
#override
_MyAppState createState() => new _MyAppState();
}
class _MyAppState extends State<MyApp> {
List<Asset> images = List<Asset>();
String _error = 'No Error Dectected';
#override
void initState() {
super.initState();
}
Widget buildGridView() {
return GridView.count(
crossAxisCount: 3,
children: List.generate(images.length, (index) {
Asset asset = images[index];
return AssetThumb(
asset: asset,
width: 300,
height: 300,
);
}),
);
}
Future<void> loadAssets() async {
List<Asset> resultList = List<Asset>();
String error = 'No Error Dectected';
try {
resultList = await MultiImagePicker.pickImages(
maxImages: 300,
enableCamera: true,
selectedAssets: images,
cupertinoOptions: CupertinoOptions(takePhotoIcon: "chat"),
materialOptions: MaterialOptions(
actionBarColor: "#abcdef",
actionBarTitle: "Example App",
allViewTitle: "All Photos",
useDetailsView: false,
selectCircleStrokeColor: "#000000",
),
);
} on Exception catch (e) {
error = e.toString();
}
// If the widget was removed from the tree while the asynchronous platform
// message was in flight, we want to discard the reply rather than calling
// setState to update our non-existent appearance.
if (!mounted) return;
setState(() {
images = resultList;
_error = error;
});
}
#override
Widget build(BuildContext context) {
return new MaterialApp(
home: new Scaffold(
appBar: new AppBar(
title: const Text('Plugin example app'),
),
body: Column(
children: <Widget>[
Center(child: Text('Error: $_error')),
RaisedButton(
child: Text("Pick images"),
onPressed: loadAssets,
),
Expanded(
child: buildGridView(),
)
],
),
),
);
}
}
Another way to fix using Stack
Stack(
children: <Widget>[
AssetThumb(
asset: asset,
width: 300,
height: 300,
),
Positioned(
right: -2,
top: -9,
child: IconButton(
icon: Icon(
Icons.cancel,
color: Colors.black.withOpacity(0.5),
size: 18,
),
onPressed: () => setState(() {
images.removeAt(index);
})))
],
);
You can try using Stack https://www.youtube.com/watch?v=liEGSeD3Zt8&vl=en
return Stack(
children: <Widget>[
AssetThumb(
asset: asset,
width: 300,
height: 300,
),
Positioned(
top: 0,
right: 0,
child: GestureDetector(
onTap: (){
print('delete image from List');
setState((){
print('set new state of images');
})
},
child: Icon(
Icons.delete,
),
),
),
],
);

flutter how to make Hero like animation between widgets on the same page

I have a button with a text, and when I pressed the button, a text widget with the same text is added to the same page.
I'd like to add Hero like animation between them.
I guess what I need is SlideTransition, but I don't know how to slide from one widget position to another widget position.
Is it possible to do? What widget (or class) should I look into?
Here's the code I want to do (but doesn't work since Hero doesn't work on the same page widgets):
import 'package:flutter/material.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
home: MyHomePage(),
);
}
}
class MyHomePage extends StatefulWidget {
#override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
List<String> text = [];
String buttonTag = "0";
#override
Widget build(BuildContext context) {
List<Widget> textWidgets = [];
for (int i = 0; i < text.length; ++i) {
textWidgets.add(
Padding(
padding: const EdgeInsets.all(8.0),
child: Hero(tag: "${i}", child: Text(text[i])),
)
);
}
return SafeArea(
child: Scaffold(
body: Center(
child: Column(
children: <Widget>[
RaisedButton(
child: Hero(
tag: buttonTag,
child: Text("abcde${text.length}")),
onPressed: () {
setState(() {
text.add("abcde${text.length}");
buttonTag = "${text.length}";
});
},
)
] + textWidgets,
),
),
),
);
}
}
Not exactly the answer to the question but instead of Hero (if it's possible) you can use AnimatedList to get the same result.
Code snippet
import 'package:flutter/material.dart';
import 'dart:math';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
home: MyHomePage(),
);
}
}
class MyHomePage extends StatefulWidget {
#override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
final GlobalKey<AnimatedListState> _listKey = GlobalKey<AnimatedListState>();
final List<Text> _textWidgets = [];
var rng = new Random();
_addItem() {
setState(() {
_listKey.currentState.insertItem(_textWidgets.length,
duration: const Duration(milliseconds: 500));
int id = rng.nextInt(100);
_textWidgets.add(Text('item $id'));
});
}
Widget _buildItem(
BuildContext context, Text item, Animation<double> animation) {
final offsetAnimation = Tween<Offset>(
begin: Offset(1.0, 0.0),
end: Offset(0.0, 0.0),
).animate(animation);
return SlideTransition(
position: offsetAnimation,
child: SizedBox(
height: 50.0,
child: Center(
child: item,
),
),
);
}
#override
Widget build(BuildContext context) {
return SafeArea(
child: Scaffold(
body: Column(
children: <Widget>[
RaisedButton(
child: Text("Add Item"),
onPressed: () {
setState(() {
_addItem();
});
},
),
Expanded(
child: AnimatedList(
key: _listKey,
initialItemCount: _textWidgets.length,
itemBuilder: (context, index, animation) {
return _buildItem(context, _textWidgets[index], animation);
},
),
),
],
),
),
);
}
}
I think it's possible by this llibrary which named: LocalHero
Implement your self
The AnimationController, Tween, AnimatedBuilder are key components.
This is a sample and code about this.
Don't use AnimatedController.animate in AnimatedBuilder builder.
evaluate is enough. Because the builder function is called every ticker frame.
Use AnimationController.animate as class member field.
class _AuthorizedState extends State<_Authorized> with SingleTickerProviderStateMixin {
late final _menuAC = AnimationController(vsync: this, duration: 200.ms);
late final isFilterOpen = ValueNotifier(false)..addListener(_handleFilterOpenChanged);
late final filterColor =
ColorTween(begin: context.color.primaryContainer, end: context.color.secondaryContainer)
.animate(_menuAC);
late final filterBorderRadius = Tween<double>(begin: 12, end: 0).animate(_menuAC);
void _handleFilterOpenChanged() {
print(isFilterOpen.value);
if (isFilterOpen.value) {
_menuAC.forward();
} else {
_menuAC.reverse();
}
}
#override
void dispose() {
_menuAC.dispose();
super.dispose();
}
#override
Widget build(BuildContext context) {
return AppScaffold(
child: LayoutBuilder(
builder: (context, cons) => Stack(
children: [
AnimatedBuilder(
animation: _menuAC,
builder: (context, child) {
return Positioned(
bottom: Tween(begin: 16.0, end: 0.0).evaluate(_menuAC),
right: Tween(begin: 16.0, end: 0.0).evaluate(_menuAC),
child: ClipRRect(
borderRadius: BorderRadius.only(
topLeft: const Radius.circular(12.0),
topRight: const Radius.circular(12.0),
bottomLeft:
Radius.circular(Tween<double>(begin: 12, end: 0).evaluate(_menuAC)),
bottomRight:
Radius.circular(Tween<double>(begin: 12, end: 0).evaluate(_menuAC)),
),
child: Container(
width: Tween(begin: 56.0, end: cons.maxWidth).evaluate(_menuAC),
height: Tween(begin: 56.0, end: min(cons.maxHeight * 0.7, 500.0))
.evaluate(_menuAC),
decoration: BoxDecoration(
color: filterColor.value,
),
child: child,
),
),
);
},
child: Material(
elevation: 24,
color: Colors.transparent,
child: InkWell(
onTap: () {
isFilterOpen.value = !isFilterOpen.value;
},
child: const Center(child: Icon(MdiIcons.filter)),
),
),
),
],
),
),
);
}
}

How to scroll or jump to position of PageView.builder or PageController in Flutter?

Issue: Unable to scroll to POSITION after loading the Pageviews using PageController *
like ViewPager scroll to specific page in Android
Widget _buildCarousel(BuildContext context, int selectedIndex) {
PageController controller = PageController(viewportFraction: 1, keepPage: true);
return Column(
mainAxisSize: MainAxisSize.min,
children: <Widget>[
SizedBox(
// you may want to use an aspect ratio here for tablet support
height: 400.0,
width: 240,
child: PageView.builder(
itemCount: assetImageList.length,
controller: controller,
itemBuilder: (BuildContext context, int itemIndex) {
return _buildCarouselItem(context, selectedIndex, itemIndex);
},
),
)
],
);
}
Finally found the answer. Just set the initialPage: mSelectedPosition attribute like:
child: PageView.builder(
itemCount: mTemplateModelList.length,
controller: PageController(initialPage: mSelectedPosition, keepPage: true, viewportFraction: 1),
itemBuilder: (BuildContext context, int itemIndex) {
return _buildCarouselItem(context, selectedIndex, itemIndex);
},
),
OR if you want to scroll the page after the button is clicked then, you can use jumpTo() method using PageController which is clearly mentioned below by another user: #android.
Currently there's 2 options to handle your request:
PageView.builder(
controller: _pageController,
itemCount: _list.length,
itemBuilder: (context, index) {
return GestureDetector(
onTap: () {
_pageController.jumpToPage(index); // for regular jump
_pageController.animateToPage(_position, curve: Curves.decelerate, duration: Duration(milliseconds: 300)); // for animated jump. Requires a curve and a duration
},
child: Container();
);
}
),
You can use jumpTo() method to scroll position for PageView.
I have create one changePageViewPostion() method in below example:
import 'package:flutter/material.dart';
class MyPageView extends StatefulWidget {
createState() {
return StateKeeper();
}
}
class StateKeeper extends State<MyPageView> {
PageController controller = PageController(viewportFraction: 1, keepPage: true);
var currentPageValue = 0.0;
var mItemCount = 10;
#override
void initState() {
// TODO: implement initState
super.initState();
controller.addListener(() {
setState(() {
currentPageValue = controller.page;
});
});
}
void changePageViewPostion(int whichPage) {
if(controller != null){
whichPage = whichPage + 1; // because position will start from 0
double jumpPosition = MediaQuery.of(context).size.width / 2;
double orgPosition = MediaQuery.of(context).size.width / 2;
for(int i=0; i<mItemCount; i++){
controller.jumpTo(jumpPosition);
if(i==whichPage){
break;
}
jumpPosition = jumpPosition + orgPosition;
}
}
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('PageView position change'),
),
body: PageView.builder(
controller: controller,
itemBuilder: (context, position) {
return Container(
color: position % 2 == 0 ? Colors.blue : Colors.pink,
child: Column(
children: <Widget>[
Center(
child: Text(
"Page " + (position + 1).toString(),
style: TextStyle(color: Colors.white, fontSize: 22.0),
),
),
Align(
alignment: FractionalOffset.bottomCenter,
child: Padding(padding: EdgeInsets.only(bottom: 20),
child: FloatingActionButton(
elevation: 0.0,
child: new Icon(Icons.check),
backgroundColor: new Color(0xFFE57373),
onPressed: (){
changePageViewPostion(5);
}
),),
),
],
),
);
},
itemCount: mItemCount,
)
);
}
}
We can get current position with controller as below:
controller.addListener(() {
setState(() {
currentPageValue = controller.page.toInt();
print((currentPageValue + 1).toString());
});
});
Hope it helps :)
If you just want to scroll to the next page using a button, you can simply use the following method.
//Create a PageController variable
late PageController _pageController;
//Initialize the variable in the init method.
#override
void initState() {
_pageController = PageController(
initialPage: _activePage, keepPage: true, viewportFraction: 1);
super.initState();
}
//Use this nextPage() method in the onPressed() method.
onPressed: () {
setState(() {
_activePage < 2
? _activePage++
: Navigator.pushReplacementNamed(
context, LoginScreen.id);
});
_pageController.nextPage(
duration: const Duration(milliseconds: 300),
curve: Curves.decelerate,
);
}

How to make copyable Text Widget in Flutter?

When long tab on Text widget, a tooltip show up with 'copy'. When click on the 'copy' the text content should copy to system clipboard.
The following will copy the text on long tap, but does not show up 'copy', so user will not know, the content is copied to the clipboard.
class CopyableText extends StatelessWidget {
final String data;
final TextStyle style;
final TextAlign textAlign;
final TextDirection textDirection;
final bool softWrap;
final TextOverflow overflow;
final double textScaleFactor;
final int maxLines;
CopyableText(
this.data, {
this.style,
this.textAlign,
this.textDirection,
this.softWrap,
this.overflow,
this.textScaleFactor,
this.maxLines,
});
#override
Widget build(BuildContext context) {
return new GestureDetector(
child: new Text(data,
style: style,
textAlign: textAlign,
textDirection: textDirection,
softWrap: softWrap,
overflow: overflow,
textScaleFactor: textScaleFactor,
maxLines: maxLines),
onLongPress: () {
Clipboard.setData(new ClipboardData(text: data));
},
);
}
}
Since Flutter 1.9 you can use
SelectableText("Lorem ipsum...")
When text is selected the "Copy" context button will appear.
You can use a SnackBar to notify the user about the copy.
Here is a relevant code:
String _copy = "Copy Me";
#override
Widget build(BuildContext context) {
final key = new GlobalKey<ScaffoldState>();
return new Scaffold(
key: key,
appBar: new AppBar(
title: new Text("Copy"),
centerTitle: true,
),
body:
new Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
new GestureDetector(
child: new Text(_copy),
onLongPress: () {
Clipboard.setData(new ClipboardData(text: _copy));
key.currentState.showSnackBar(
new SnackBar(content: new Text("Copied to Clipboard"),));
},
),
new TextField(
decoration: new InputDecoration(hintText: "Paste Here")),
]),
);
}
EDIT
I was working on something and I did the followin, so I thought of revisiting this answer:
import "package:flutter/material.dart";
import 'package:flutter/services.dart';
void main() {
runApp(new MaterialApp(home: new MyApp(),
));
}
class MyApp extends StatefulWidget {
#override
_MyAppState createState() => new _MyAppState();
}
class _MyAppState extends State<MyApp> with TickerProviderStateMixin {
String _copy = "Copy Me";
#override
Widget build(BuildContext context) {
final key = new GlobalKey<ScaffoldState>();
return new Scaffold(
key: key,
appBar: new AppBar(
title: new Text("Copy"),
centerTitle: true,
),
body:
new Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
new GestureDetector(
child: new CustomToolTip(text: "My Copyable Text"),
onTap: () {
},
),
new TextField(
decoration: new InputDecoration(hintText: "Paste Here")),
]),
);
}
}
class CustomToolTip extends StatelessWidget {
String text;
CustomToolTip({this.text});
#override
Widget build(BuildContext context) {
return new GestureDetector(
child: new Tooltip(preferBelow: false,
message: "Copy", child: new Text(text)),
onTap: () {
Clipboard.setData(new ClipboardData(text: text));
},
);
}
}
There is also list of properties it in SelectableText to enable option copy, paste, selectAll, cut
child: Center(
child: SelectableText('Hello Flutter Developer',
cursorColor: Colors.red,
showCursor: true,
toolbarOptions: ToolbarOptions(
copy: true,
selectAll: true,
cut: false,
paste: false
),
style: Theme.of(context).textTheme.body2)
),
SelectableText widget
const SelectableText(
this.data, {
Key key,
this.focusNode,
this.style,
this.strutStyle,
this.textAlign,
this.textDirection,
this.showCursor = false,
this.autofocus = false,
ToolbarOptions toolbarOptions,
this.maxLines,
this.cursorWidth = 2.0,
this.cursorRadius,
this.cursorColor,
this.dragStartBehavior = DragStartBehavior.start,
this.enableInteractiveSelection = true,
this.onTap,
this.scrollPhysics,
this.textWidthBasis,
})
SelectableText(
"Copy me",
onTap: () {
// you can show toast to the user, like "Copied"
},
)
If you want to have different styling for text, use
SelectableText.rich(
TextSpan(
children: [
TextSpan(text: "Copy me", style: TextStyle(color: Colors.red)),
TextSpan(text: " and leave me"),
],
),
)
I use Clipboard.setData inside function.
...
child: RaisedButton(
onPressed: (){
Clipboard.setData(ClipboardData(text: "$textcopy"));
},
disabledColor: Colors.blue[400],
child: Text("Copy", style: TextStyle(color: Colors.white),),
),
I created a helper class CopiableText to accomplish my job. Just copy the class from below and put it in your code.
Helper class
copiable_text_widget.dart
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
class CopiableText extends StatelessWidget {
final String text;
final String copyMessage;
final Widget child;
CopiableText(this.text, {this.copyMessage, this.child});
#override
Widget build(BuildContext context) {
return Container(
width: double.infinity,
child: InkWell(
onTap: () {
Scaffold.of(context).showSnackBar(SnackBar(
content: Text(this.copyMessage ?? 'Copied to clipboard'),
));
Clipboard.setData(new ClipboardData(text: this.text));
},
child: Align(
alignment: Alignment.centerLeft,
child: Padding(
padding: const EdgeInsets.symmetric(vertical: 8, horizontal: 2),
child: this.child ??
Text(
this.text,
style: TextStyle(color: Color(0xFF1E272E), fontSize: 14),
),
),
),
),
);
}
}
Use it in different ways
import 'package:chaincargo_courier/ui/widgets/copiable_text_widget.dart';
import 'package:flutter/material.dart';
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Container(
child: Column(
children: [
// Just straightforward, click to copy
CopiableText('You are awesome'),
// Give a custom confirmation message
CopiableText(
'Asia, Nepal, Biratnagar',
copyMessage: 'Address copied to clipboard',
),
// Set custom child
CopiableText(
'Stunning view of mount everest',
copyMessage: 'Caption copied to clipboard',
child: Column(
children: [
Image.network(
'https://cdn.pixabay.com/photo/2010/11/29/mount-everest-413_960_720.jpg',
errorBuilder: (BuildContext context, Object exception,
StackTrace stackTrace) {
return Text('Cannot load picture');
},
),
Text('Stunning view of mount everest')
],
),
),
],
),
);
}
}
Just use SelectableText
SelectableText(
iosInfo.identifierForVendor.toString(),
),
Support Links and Copy&Paste
If you want to support both Links and Copy&Paste, use the SelectableLinkify widget.
This widget is part of the flutter_linkify package.
SelectableLinkify(
text: "Made by https://cretezy.com\n\nMail: example#gmail.com",
);

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