Instead of infinite scrolling in a Listview.builder.
I want to be able to see x amount of items in my ListView and then going on to the next page should show the next x amount of items.
What I have so far is just a standard ListView.builder:
Listview.Builder(
itemCount: data.length
itemBuilder:(context, index){
return Card(
child: ListTile(
title: data[index]
)
);
}
)
You can use a PageController to control which page is visible in the view. In addition to being able to control the pixel offset of the content inside the PageView, a PageController also lets you control the offset in terms of pages, which are increments of the viewport size.
The PageController can also be used to control the PageController.initialPage, which determines which page is shown when the PageView is first constructed, and the PageController.viewportFraction, which determines the size of the pages as a fraction of the viewport size.
Refer to :
geeksforgeeks
Flutter Docs
Hope this helps. Happy Coding :)
Related
I have a problem with infinite scroll in flutter, I am loading six items per page and loading more as I scroll , this works perfectly with a smaller screen size but the problem comes in when I use an emulator with a larger screen size, when the screen size is larger then the first six items don't fill the screen hence I cannot scroll in order to load the other items.
Does anybody have an idea of how I can get around this?
Thanks
You can use ListView.builder. The ListView.builder constructor takes an IndexedWidgetBuilder, which builds the children on demand. This constructor is appropriate for list views with a large (or infinite) number of children because the builder is called only for those children that are actually visible.
return ListView.builder(
padding: const EdgeInsets.all(10.0),
itemBuilder: (context, i) {
if (i.isOdd) return const Divider();
final index = i ~/ 2;
if (index >= _listItems.length) {
_listItems.addAll(_newItems); //load more items here
}
return yourWidget(_listItems[index]);
},
);
This way no need to use scrollController. You can refer to this codelab for more info.
I have 2 rows in my screen, the first row is consist of dropdown button and elevation button and the second row is where the stream builder located, I used flexible so that the stream builder is scrollable. What I want is every time I scroll the stream builder I want the first row to follow the scroll not stay in the screen.
This is how my widget set:
Scaffold
-Column
-Row
-Dropdown button
-Elevated buton
-Flexible
-Streambuilder
-stack
-listview
Just like in facebook everytime you scroll down the "what's in your mind" controller disappers too, not floating like an app bar
Inside Listview add physics: NeverScrollableScrollPhysics()
//
Listview(
physics: NeverScrollableScrollPhysics(),
return .....;
)
//
Follow this pattern.
If you want that widget to disappear when you scroll, you need to wrap your Column in a SingleChildScrollView which you will need to wrap in a Flxible
Code:
Flexible(
child: SingleChildScrollView(
child: Column(
//your normal code insode Column
Depending on your code, you may also need to make the ListView not scroll (as suggested by Rafid):
Listview( physics: NeverScrollableScrollPhysics()
I would like the ReorderableListView not to take up the whole height which is given to it, but to be as tall as the item views that it contains.
I could make the list either flex and fill the whole height it is given, or put it in a SizedBox and have a fixed height.
I'd like to add an + Add list tile directly under the list items (similar to Google Keep on Android)
Thank you
You can try this:
Wrap your List with an Expanded widget.
Fetch the number of items in your list and return the Add List tile widget at the length-1 position of your list.
You can alter the size of your ListView in correlation to the number of items fetched from the list.
Expanded will help you alter the length dynamically.
eg:
Expanded(
child: new ListView.builder
(
itemCount: litems.length,
itemBuilder: (BuildContext ctxt, int Index) {
return new Text(litems[Index]);
if(length==length-1){
//**call your Add List tile widget here**
}
}
)
)
I have a listview . I want to go to a certain widget by it's corresponding index number.
I've tried with ScrollController, but it need offset value to jumpTo the index. But I want to jumpTo a widget by using its index number.
Please, help me to fix it
Thanks in advance.
Unfortunately, ListView has no built-in approach to a scrollToIndex() function. You’ll have to develop your own way to measure to that element’s offset for animateTo() or jumpTo(), or you can search through suggested solutions/plugins from other posts such as:
flutter ListView scroll to index not available
Flutter: Scrolling to a widget in ListView
(the general scrollToIndex issue is discussed at flutter/issues/12319 since 2017, but still with no current plans)
But there is a different kind of ListView that does support scrollToIndex:
ScrollablePositionedList
scrollable_positioned_list
dependency: flutter_widgets
You set it up exactly like ListView and works the same, except you now have access to a ItemScrollController that does:
jumpTo({index, alignment})
scrollTo({index, alignment, duration, curve})
Simplified example:
ItemScrollController _scrollController = ItemScrollController();
ScrollablePositionedList.builder(
itemScrollController: _scrollController,
itemCount: _myList.length,
itemBuilder: (context, index) {
return _myList[index];
},
)
_scrollController.scrollTo(index: 150, duration: Duration(seconds: 1));
(note that this library is developed by Google but not by the core Flutter team.)
I want to translate a widget vertically as the user drags. I tried implementing it using two options:
AnimationController
Value notifier.
So when I use the animation controller the scroll is not very smooth and the widget is being scroll after a delay even when the duration of the animation is 1 milliseconds.
When I implement it using value notifier it is much better but still not as smooth as the ListView scroll. Is there a better way to scroll\translate a widget on user drag?
I found a better solution for this. Although it can be achieved using Gesture detector but that is not as smooth. Flutter has another wonderful widget for this and that is DraggableScrollableSheet.
If you want container for a Scrollable list that responds to drag gestures by resizing the scrollable until a limit is reached, and then scrolling this is the widget you should be using.
DraggableScrollableSheet(
initialChildSize: .70,
minChildSize: .70,
builder: (BuildContext context, ScrollController scrollcontroller){
scrollcontroller.addListener((){
});
return Container(
child: ListView.builder(
controller: scrollcontroller,
itemCount: widget.songs.length,
itemBuilder: (BuildContext context, int index) {
return buildSongRow(widget.songs[index]);
})
);
})
The above list will be place at the 70 percent of the height of the screen initially. When you scroll up it drags the list up to the top and then the list scrolls as a normal listview. When you reach the top while scrolling, the list drags down to the initial position(70 percent of height).