Related
I have a chatbot screen that I built with a listview and there is a strange behavior that I don't understand the origin of.
From time to time, some of the elements overlap each other, then if I scroll or change screen and come back they are back to normal. I can't seem to find the problem...
import 'package:async_redux/async_redux.dart';
import 'package:flutter/material.dart';
import '../../../app_theme.dart';
import '../../../data/models/models.dart';
import '../../../helpers.dart';
import 'action_message.dart';
import 'conversation_bar.dart';
import 'image_message.dart';
import 'text_message.dart';
import 'typing_indicator.dart';
class ConversationFlow extends StatelessWidget {
// Max number of messages to show
final int maxMessages = 50;
Widget _buildConversationMessage(BuildContext context, message, next) {
// Detects which message type to build as child
Widget child = Container();
if (message.text.isEmpty) {
return child;
}
if (message.attachment == null) {
child = TextMessage(message: message);
} else if (message.attachment.type == 'image') {
child = ImageMessage(message: message);
}
// General structure of each message
var topSpacing = App.size(15, context);
// Between same speaker messages
if (next != null && next.speaker == message.speaker) {
topSpacing = App.size(1.5, context);
}
// Last one from conversation
if (next == null) {
topSpacing = App.size(10, context);
}
return Row(
mainAxisAlignment: (message.speaker == 'coach') ? MainAxisAlignment.start : MainAxisAlignment.end,
children: [
Container(
constraints: BoxConstraints(
maxWidth: App.isLandscape(context)
? MediaQuery.of(context).size.width * 0.42
: MediaQuery.of(context).size.width * 0.7,
),
padding: EdgeInsets.symmetric(
vertical: App.size(8, context),
horizontal: App.size(10, context),
),
margin: EdgeInsets.only(
left: (message.speaker == 'coach') ? App.margin(context) : 0,
top: topSpacing,
right: (message.speaker == 'coach') ? 0 : App.margin(context),
),
decoration: BoxDecoration(
color: (message.speaker == 'coach') ? AppTheme.colorGrey[100] : AppTheme.colorAccent,
borderRadius: BorderRadius.circular(App.radius()),
),
child: child,
),
(message.speaker == 'coach' && message.action != null) ? ActionMessage(action: message.action) : Container(),
],
);
}
#override
Widget build(BuildContext context) {
return StoreConnector(
converter: (Store<AppState> store) => store.state.bot,
builder: (BuildContext context, Bot bot) {
int itemsCount = bot.conversation.isNotEmpty
? bot.conversation.length > maxMessages
? maxMessages
: bot.conversation.length + 2
: 1;
return Align(
alignment: Alignment.bottomCenter,
child: ListView.builder(
shrinkWrap: true,
reverse: true,
scrollDirection: Axis.vertical,
physics: BouncingScrollPhysics(),
itemCount: itemsCount,
itemBuilder: (BuildContext context, int index) {
if (index == 0) {
return ConversationBar();
}
// Typing indicator Row
if (index == 1) {
return bot.typing ? TypingIndicator() : Container();
}
// Correct Typing index shift
index = index - 2;
// Reduces opacity as conversation fades away like memories
double opacity = 1.0;
(index > maxMessages - 10) ? opacity = 1.0 - ((index - maxMessages + 10) * 0.1) : 0.0;
if (opacity < 0.0) {
opacity = 0.0;
} else if (opacity > 1.0) {
opacity = 1.0;
}
if (index < maxMessages) {
// Conversation bubbles
return Opacity(
opacity: opacity,
child: _buildConversationMessage(
context,
bot.conversation[index],
bot.conversation.asMap().containsKey(index + 1) ? bot.conversation[index + 1] : null,
),
);
}
return Container();
},
),
);
},
);
}
}
Any idea of what could cause this?
apply itemExtent: value into Listview.builder
Use readmore package if you have different size and wrap your text into ReadMoreText
ReadMoreText(
'your message',
trimLines: 2,
trimMode: TrimMode.Line,
trimCollapsedText: 'Read more',
trimExpandedText: 'Read less',
),
use trimLines for line of text you want to show
I want to figure out the position of scroll and depending on that results, I want to show some buttons.
This is my code of Scroll Widget.
Flexible(
child: Container(
constraints: BoxConstraints(
maxWidth: 730,
),
child: ListView.separated(
controller: _platformController,
scrollDirection: Axis.horizontal,
itemBuilder: (context, index) {
String platform = platformlistA[index].toLowerCase();
return InkWell(
onTap: () {
if (platformIndex !=
platformlistA.indexWhere(
(element) => element == platformlistA[index])) {
setState(() {
platformIndex = platformlistA.indexWhere(
(element) => element == platformlistA[index]);
});
} else {
setState(() {
platformIndex = -1;
});
}
},
child: Container(
alignment: Alignment.center,
height: 37,
width: platform != 'fortnite' ? 100 : 85,
padding: EdgeInsets.symmetric(
horizontal: 5,
),
child: WebsafeSvg.asset(
'assets/$platform.svg',
color: platformIndex ==
platformlistA.indexWhere(
(element) => element == platformlistA[index])
? Colors.black
: Color(0xffb7b7b7),
),
),
);
},
separatorBuilder: (context, index) {
return SizedBox(width: 7);
},
itemCount: platformlistA.length),
),
),
and this is the code getting the position of Scroll widget.
WidgetsBinding.instance!.addPostFrameCallback((timeStamp) {
setState(() {
if (_platformController.position.maxScrollExtent > 0) {
if (_platformController.position.atEdge) {
if (_platformController.position.pixels == 0) {
print('left edge');
// show -> button at right
} else {
print('right edge');
// show <- button at left
}
} else {
print('middle of the scroll');
// show <-, -> buttons at both side
}
} else {
print('not scrollable');
// do not show any button.
}
});
});
I used WidgetsBinding.instance!.addPostFrameCallback because, it shows error if I handle with controller before the build.
Eventually, this works functionally, but it is too slow since WidgetsBinding.instance!.addPostFrameCallback in build function continues to run. I cannot put it in initstate because if() phrase has to be called everytime when the size of web application changes.
Is there any faster way than this method??? Please help!!
Map<String, dynamic> toJson() => {
'name': name,
'email': email,
};
Try adding => front of toJson()
I have a GridView that contains draggable items. When an item is dragged to the top/bottom of the screen I want to scroll the GridView in that direction.
Currently I wrapped each draggable item in a Listener like so:
Listener(
child: _wrap(widget.children[i], i),
onPointerMove: (PointerMoveEvent event) {
if (event.position.dy >= MediaQuery.of(context).size.height - 100) {
// 120 is height of your draggable.
widget.scrollController.animateTo(
widget.scrollController.offset + 120,
curve: Curves.easeOut,
duration: const Duration(milliseconds: 200));
}if (event.position.dy <= kToolbarHeight + MediaQueryData.fromWindow(window).padding.top + 100) {
// 120 is height of your draggable.
widget.scrollController.animateTo(
widget.scrollController.offset - 120,
curve: Curves.easeOut,
duration: const Duration(milliseconds: 200));
}
}
)
It works, but the scroll is not smooth at all and looks kind of laggy.
I would need it to work on web too.
Does anyone have a better solution for this?
Here's how I'm solving it. Using TickerProviderStateMixin, you can obtain a Ticker that invokes a callback once per frame, where you can adjust the scroll offset by a small amount for a smooth scroll. I used a Stack to add dummy DragTargets to the top and bottom of the list area which control the tickers. I used two per edge, to allow different scrolling speeds. You could probably use a Listener to interpolate the speed using the cursor position if you want finer-grained control.
https://www.dartpad.dev/acb83fdbbbbb0fd765cd5afa414a8942
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(),
body: Stack(
children: [
ListView.separated(
controller: controller,
itemCount: 50,
itemBuilder: (context, index) {
return buildLongPressDraggable(index);
},
separatorBuilder: (context, index) {
return Divider();
},
),
Positioned(
top: 0, left: 0, right: 0, height: 25, child: buildEdgeScroller(-10)),
Positioned(
top: 25, left: 0, right: 0, height: 25, child: buildEdgeScroller(-5)),
Positioned(
bottom: 25, left: 0, right: 0, height: 25, child: buildEdgeScroller(5)),
Positioned(
bottom: 0, left: 0, right: 0, height: 25, child: buildEdgeScroller(10)),
],
),
);
}
Widget buildEdgeScroller(double offsetPerFrame) {
return DragTarget<int>(
builder: (context, candidateData, rejectedData) => Container(),
onWillAccept: (data) {
scrollTicker = this.createTicker((elapsed) {
if (!controller.hasClients) {
return;
}
final position = controller.position;
if ((offsetPerFrame < 0 && position.pixels <= position.minScrollExtent) ||
(offsetPerFrame > 0 && position.pixels >= position.maxScrollExtent)) {
scrollTicker.stop();
scrollTicker.dispose();
scrollTicker = null;
} else {
controller.jumpTo(controller.offset + offsetPerFrame);
}
});
scrollTicker.start();
return false;
},
onLeave: (data) {
scrollTicker?.stop();
scrollTicker?.dispose();
scrollTicker = null;
},
);
}
i am working on a project where i am using PageView.builder which basically scroll vertically. i am loading video list using PageView.builder where user can see the videos (one video at a time) i want to add load more functionality. currently i am fetching 10 videos at a time from the server and loading it in PageView.builder, when user reaches last video i.e 10th video i want to load more 10 videos from server. moreover i want to refresh the list by pulling it down if it's first video. below is the code which i am using. Does anyone know how to achieve the desired
function? thanks in advance.
Stack createListView(BuildContext context, AsyncSnapshot snapshot)
{
videoDataList =snapshot.data;
_videoListController.init(
_pageController,
videoDataList,
);
tkController.addListener(
() {
if (tkController.value == TikTokPagePositon.middle) {
_videoListController.currentPlayer.start();
} else {
_videoListController.currentPlayer.pause();
}
},
);
return Stack(
// index: currentPage == null ? 0 : 1,
children: <Widget>[
RefreshIndicator(
child: PageView.builder(
key: Key('home'),
controller: _pageController,
pageSnapping: true,
physics: ClampingScrollPhysics(),
scrollDirection: Axis.vertical,
itemCount: _videoListController.videoCount,
itemBuilder: (context, i) {
// Put together a video component
var data = videoDataList[i];
bool isF = SafeMap(favoriteMap)[i].boolean ?? false;
var player = _videoListController.playerOfIndex(i);
//Right button bar
Widget buttons = TikTokButtonColumn(
profilePic: Glob.ITEM_BASE_URL+data.user_profile,
isFavorite: isF,
videoModel: data,
onAvatar: () {
tkController.animateToPage(TikTokPagePositon.right);
},
onFavorite: () {
setState(() {
favoriteMap[i] = !isF;
});
// showAboutDialog(context: context);
},
onComment: () {
_getCommentData(data.post_id);
},
onShare: () {},
);
// video
Widget currentVideo = Center(
child: FijkView(
player: player,
color: Colors.black,
panelBuilder: (_, __, ___, ____, _____) => Container(),
),
);
currentVideo = TikTokVideoPage(
hidePauseIcon: player.state != FijkState.paused,
aspectRatio: 9 / 16.0,
key: Key(Glob.ITEM_BASE_URL+data.post_video + '$i'),
tag: Glob.ITEM_BASE_URL+data.post_video,
bottomPadding: hasBottomPadding ? 16.0 : 16.0,
userInfoWidget: VideoUserInfo(
viewers: data.post_view_count,
desc: data.post_description,
userName: data.user_name,
fullname: data.full_name,
bottomPadding: hasBottomPadding ? 16.0 : 50.0,
// onGoodGift: () => showDialog(
// context: context,
// builder: (_) => FreeGiftDialog(),
// ),
),
onSingleTap: () async {
if (player.state == FijkState.started) {
await player.pause();
} else {
await player.start();
}
setState(() {});
},
onAddFavorite: () {
setState(() {
favoriteMap[i] = true;
});
},
rightButtonColumn: buttons,
video: currentVideo,
);
return currentVideo;
},
),
onRefresh: _getData,
),
Opacity(
opacity: 1,
child: currentPage ?? Container(),
),
// Center(
// child: Text(_currentIndex.toString()),
// )
],
);
}
How can I realize items lazy loading for endless listview? I want to load more items by network when user scroll to the end of listview.
You can listen to a ScrollController.
ScrollController has some useful information, such as the scrolloffset and a list of ScrollPosition.
In your case the interesting part is in controller.position which is the currently visible ScrollPosition. Which represents a segment of the scrollable.
ScrollPosition contains informations about it's position inside the scrollable. Such as extentBefore and extentAfter. Or it's size, with extentInside.
Considering this, you could trigger a server call based on extentAfter which represents the remaining scroll space available.
Here's an basic example using what I said.
class MyHome extends StatefulWidget {
#override
_MyHomeState createState() => _MyHomeState();
}
class _MyHomeState extends State<MyHome> {
ScrollController controller;
List<String> items = List.generate(100, (index) => 'Hello $index');
#override
void initState() {
super.initState();
controller = ScrollController()..addListener(_scrollListener);
}
#override
void dispose() {
controller.removeListener(_scrollListener);
super.dispose();
}
#override
Widget build(BuildContext context) {
return Scaffold(
body: Scrollbar(
child: ListView.builder(
controller: controller,
itemBuilder: (context, index) {
return Text(items[index]);
},
itemCount: items.length,
),
),
);
}
void _scrollListener() {
print(controller.position.extentAfter);
if (controller.position.extentAfter < 500) {
setState(() {
items.addAll(List.generate(42, (index) => 'Inserted $index'));
});
}
}
}
You can clearly see that when reaching the end of the scroll, it scrollbar expends due to having loaded more items.
Thanks for Rémi Rousselet's approach, but it does not solve all the problem. Especially when the ListView has scrolled to the bottom, it still calls the scrollListener a couple of times. The improved approach is to combine Notification Listener with Remi's approach. Here is my solution:
bool _handleScrollNotification(ScrollNotification notification) {
if (notification is ScrollEndNotification) {
if (_controller.position.extentAfter == 0) {
loadMore();
}
}
return false;
}
#override
Widget build(BuildContext context) {
final Widget gridWithScrollNotification = NotificationListener<
ScrollNotification>(
onNotification: _handleScrollNotification,
child: GridView.count(
controller: _controller,
padding: EdgeInsets.all(4.0),
// Create a grid with 2 columns. If you change the scrollDirection to
// horizontal, this would produce 2 rows.
crossAxisCount: 2,
crossAxisSpacing: 2.0,
mainAxisSpacing: 2.0,
// Generate 100 Widgets that display their index in the List
children: _documents.map((doc) {
return GridPhotoItem(
doc: doc,
);
}).toList()));
return new Scaffold(
key: _scaffoldKey,
body: RefreshIndicator(
onRefresh: _handleRefresh, child: gridWithScrollNotification));
}
The solution use ScrollController and I saw comments mentioned about page.
I would like to share my finding about package incrementally_loading_listview
https://github.com/MaikuB/incrementally_loading_listview.
As packaged said : This could be used to load paginated data received from API requests.
Basically, when ListView build last item and that means user has scrolled down to the bottom.
Hope it can help someone who have similar questions.
For purpose of demo, I have changed example to let a page only include one item
and add an CircularProgressIndicator.
...
bool _loadingMore;
bool _hasMoreItems;
int _maxItems = 30;
int _numItemsPage = 1;
...
_hasMoreItems = items.length < _maxItems;
...
return IncrementallyLoadingListView(
hasMore: () => _hasMoreItems,
itemCount: () => items.length,
loadMore: () async {
// can shorten to "loadMore: _loadMoreItems" but this syntax is used to demonstrate that
// functions with parameters can also be invoked if needed
await _loadMoreItems();
},
onLoadMore: () {
setState(() {
_loadingMore = true;
});
},
onLoadMoreFinished: () {
setState(() {
_loadingMore = false;
});
},
loadMoreOffsetFromBottom: 0,
itemBuilder: (context, index) {
final item = items[index];
if ((_loadingMore ?? false) && index == items.length - 1) {
return Column(
children: <Widget>[
ItemCard(item: item),
Card(
child: Padding(
padding: const EdgeInsets.all(16.0),
child: Column(
children: <Widget>[
Row(
crossAxisAlignment:
CrossAxisAlignment.start,
children: <Widget>[
Container(
width: 60.0,
height: 60.0,
color: Colors.grey,
),
Padding(
padding: const EdgeInsets.fromLTRB(
8.0, 0.0, 0.0, 0.0),
child: Container(
color: Colors.grey,
child: Text(
item.name,
style: TextStyle(
color: Colors.transparent),
),
),
)
],
),
Padding(
padding: const EdgeInsets.fromLTRB(
0.0, 8.0, 0.0, 0.0),
child: Container(
color: Colors.grey,
child: Text(
item.message,
style: TextStyle(
color: Colors.transparent),
),
),
)
],
),
),
),
Center(child: CircularProgressIndicator())
],
);
}
return ItemCard(item: item);
},
);
full example https://github.com/MaikuB/incrementally_loading_listview/blob/master/example/lib/main.dart
Package use ListView index = last item and loadMoreOffsetFromBottom to detect when to load more.
itemBuilder: (itemBuilderContext, index) {
if (!_loadingMore &&
index ==
widget.itemCount() -
widget.loadMoreOffsetFromBottom -
1 &&
widget.hasMore()) {
_loadingMore = true;
_loadingMoreSubject.add(true);
}
here is my solution for find end of listView
_scrollController.addListener(scrollListenerMilli);
if (_scrollController.position.pixels == _scrollController.position.maxScrollExtent) {
getMoreData();
}
If you want to load more data when 1/2 or 3/4 of a list view size, then use this way.
if (_scrollController.position.pixels == (_scrollController.position.maxScrollExtent * .75)) {//.5
getMoreData();
}
Additional -> Make sure you called getMore API only one time when reaching to the bottom. You can solve this in many ways, This is one of the ways to solve this by boolean variable.
bool loadMore = false;
if (_scrollController.position.pixels == _scrollController.position.maxScrollExtent && !loadMore) {
loadMore = true;
getMoreData().then(() => loadMore = false);
}
here is my approach which is inspired by answers above,
NotificationListener(onNotification: _onScrollNotification, child: GridView.builder())
bool _onScrollNotification(ScrollNotification notification) {
if (notification is ScrollEndNotification) {
final before = notification.metrics.extentBefore;
final max = notification.metrics.maxScrollExtent;
if (before == max) {
// load next page
// code here will be called only if scrolled to the very bottom
}
}
return false;
}
Use lazy_load_scrollview: 1.0.0 package that use same concept behind the scenes that panda world answered here. The package make it easier to implement.
The solutions posted don't solve the issue if you want to achieve lazy loading in up AND down direction. The scrolling would jump here, see this thread.
If you want to do lazy loading in up and down direction, the library bidirectional_listview could help.
Example (Source):
static const double kItemHeight = 30.0;
BidirectionalScrollController controller;
double oldScrollPosition = 0.0;
#override
void initState() {
super.initState();
for (int i = -10; i <= 10; i++) {
items[i] = "Item " + i.toString();
}
controller = new BidirectionalScrollController()
..addListener(_scrollListener);
}
#override
void dispose() {
controller.removeListener(_scrollListener);
super.dispose();
}
#override
void build() {
// ...
List<int> keys = items.keys.toList();
keys.sort();
return new BidirectionalListView.builder(
controller: controller,
physics: AlwaysScrollableScrollPhysics(),
itemBuilder: (context, index) {
return Container(
child: Text(items[index]),
height: kItemHeight,
},
itemCount: keys.first,
negativeItemCount: keys.last.abs(),
);
// ...
}
// Reload new items in up and down direction and update scroll boundaries
void _scrollListener() {
bool scrollingDown = oldScrollPosition < controller.position.pixels;
List<int> keys = items.keys.toList();
keys.sort();
int negativeItemCount = keys.first.abs();
int itemCount = keys.last;
double positiveReloadBorder = (itemCount * kItemHeight - 3 * kItemHeight);
double negativeReloadBorder =
(-(negativeItemCount * kItemHeight - 3 * kItemHeight));
// reload items
bool rebuildNecessary = false;
if (scrollingDown && controller.position.pixels > positiveReloadBorder)
{
for (int i = itemCount + 1; i <= itemCount + 20; i++) {
items[i] = "Item " + i.toString();
}
rebuildNecessary = true;
} else if (!scrollingDown &&
controller.position.pixels < negativeReloadBorder) {
for (int i = -negativeItemCount - 20; i < -negativeItemCount; i++) {
items[i] = "Item " + i.toString();
}
rebuildNecessary = true;
}
// set new scroll boundaries
try {
BidirectionalScrollPosition pos = controller.position;
pos.setMinMaxExtent(
-negativeItemCount * kItemHeight, itemCount * kItemHeight);
} catch (error) {
print(error.toString());
}
if (rebuildNecessary) {
setState(({});
}
oldScrollPosition = controller.position.pixels;
}
I hope that this helps a few people :-)
The accepted answer is correct but you can also do as follows,
Timer _timer;
Widget chatMessages() {
_timer = new Timer(const Duration(milliseconds: 300), () {
_scrollController.animateTo(
_scrollController.position.maxScrollExtent,
curve: Curves.easeOut,
duration: const Duration(milliseconds: 300),
);
});
return StreamBuilder(
stream: chats,
builder: (context, snapshot) {
return snapshot.hasData
? ListView.builder(
// physics: NeverScrollableScrollPhysics(),
controller: _scrollController,
shrinkWrap: true,
reverse: false,
itemCount: snapshot.data.documents.length,
itemBuilder: (context, index) {
return MessageTile(
message: snapshot.data.documents[index].data["message"],
sendByMe: widget.sendByid ==
snapshot.data.documents[index].data["sendBy"],
);
})
: Container();
},
);
}
There is also this package, taking away the boilerplate: https://pub.dev/packages/lazy_load_scrollview
There is a much simpler solution than working with Scroll Controllers and Notifications. Just use the built in lazy loading feature of ListView Builders:
I suggest (and tested) to just wrap two FutureBuilders within each other and let them handle everything for you. Alternatively, the outer FutureBuilder can be replaced by loading the values in the initState.
Create FutureBuilder to retrieve the most compact version of your data. Best a url or an id of the data items to be displayed
Create a ListView.builder, which according to the flutter doc Flutter Lists Codebook, already takes care of the lazy loading part
The standard ListView constructor works well for small lists. To work with lists that contain a large number of items, it’s best to
use the ListView.builder constructor.
In contrast to the default ListView constructor, which requires creating all items at once, the ListView.builder() constructor
creates items as they’re scrolled onto the screen.
Within the ListView builder, add another FutureBuilder, which fetches the individual content.
You're done
Have a look at this example code.
#override
Widget build(BuildContext context) {
return FutureBuilder(
future: <get a short list of ids to fetch from the web>,
builder: (BuildContext context, AsyncSnapshot<List<int>> snapshot) {
if (snapshot.hasData) {
return Expanded(
child: ListView.builder(
itemCount: snapshot.data!.length,
itemBuilder: (BuildContext context, final int index) {
final int recordId = snapshot.data![index];
return FutureBuilder(
future: <get the record content from the web>,
builder: (BuildContext context,
AsyncSnapshot<Issue?> snapshot) {
if (snapshot.hasData) {
final Record? record = snapshot.data;
if (issue != null) {
return ListTile(
isThreeLine: true,
horizontalTitleGap: 0,
title: <build record widget>,
);
}
}
return ListTile(
isThreeLine: true,
horizontalTitleGap: 0,
title: const Text("Loading data..."));
});
}),
);
}
return const Text("Loading data...",
style: TextStyle(color: Colors.orange));
});
Let me know what you think. Performance was great when I've tried it, I'm wondering what you experienced with this. Sure, this needs some clean up, I know :D
This is an old question and the current answer is to use the ListView.builder method.
Same is true for the GridView.builder, please refer to the example below.
GridView.builder(
// ask GridView to cache and avoid redundant callings of Futures
cacheExtent: 100,
shrinkWrap: true,
itemCount: c.thumbnails.length,
// Define this as you like
gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
crossAxisCount: 3,
mainAxisSpacing: 0.0,
crossAxisSpacing: 0.0,
childAspectRatio: 1.0,
),
itemBuilder: (BuildContext context, int index) {
return FutureBuilder<Image>(builder: (ctx, snap) {
if (!snap.hasData) {
return const SizedBox.expand(); // show nothing
}
if (snap.hasError) {
return Text('An error occured ${snap.error}');
}
return snap.data!;
},
future: <YOUR THUMBNAIL FUTURE>,
);
}
);
You can handle it by knowing the current page and the last page
By using listview builder
itemBuilder: (context, index) {
if(list.length - 1 == index && currentPage! < lastPage!){
currentPage = currentPage! + 1;
/// Call your api here to update the list
return Progress();
}
return ///element widget here.
},