Flutter web.
When we scroll by dragging the mouse, parent scrolls even when child listview is under cursor. But while scrolling with mouse wheel or double finger swipe gesture on touchpads, the scroll behavior is different. The parent stops scrolling and child starts scrolling when child listview comes under cursor.
gif of example
You can try the following code.
var _container = Container(
height: 200,
color: Colors.blue,
margin: EdgeInsets.symmetric(vertical: 10),
);
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(title: Text("ListView")),
body: Padding(
padding: const EdgeInsets.all(40.0),
child: ListView( // parent ListView
children: <Widget>[
_container,
_container,
Container(
height: 200, // give it a fixed height constraint
color: Colors.teal,
// child ListView
child: ListView.builder(itemBuilder: (_, i) => ListTile(title: Text("Item ${i}"))),
),
_container,
_container,
_container,
],
),
),
);
}
What I want is for the mousewheel scroll to behave like dragging. How can I get that?
Related
I have a SingleChildScrollView and inside it I have a list with some cards, that you can remove ou add more. I need to fix an add button at the bottom of the screen, when the card list is not scrollable yet, but when the card list increase size and the scrollview is able to scroll now (to see all the content), the button must follow the list and not keep fixed at the bottom anymore.
For now, what I did to solve this, was check the scroll view every time that a card is added ou removed, if I checked that the screen is now scrollable or not scrollable I change some properties of my build widget:
SingleChildScrollView(
controller: _scrollController,
physics: AlwaysScrollableScrollPhysics(),
child: Container(
height: isNotScrollable
? _pageSize - (_appBarSize + _notifySize)
: null,
padding: const EdgeInsets.symmetric(
horizontal: Constraints.paddingNormal),
child: Column(
.....
and after the list render I create the button like this
isNotScrollable
? Expanded(
child: Container(),
)
: Container(),
CVButton(
color: Palette.white,
Basically, my idea is: if the screen is not scrollable yet (the list content fits in the screen size) I will set a height to the container inside scrollview and add a Expanded() widget before the add button (so the button will stay in the bottom of the container), but if the screen is scrollable (the list content not fits inside the screen size) so I remove the container height and the Expanded widget, then the button will follow the list now as normally.
I don't know if this is the better way to deal with that, I want to know if there is some way to do this without this 'dinamic' way that I am doing, only with fixed widgets and not changing the widget according to the state of the scrollview.
An example when the list becomes scrollable and the button will keep at list bottom
Here the list is not scrollable yet but the button must be at the screen bottom and not list bottom
(I dont wanna use bottomNavBar)
Anyone has any idea how I can solve this?
I have a solution for this. check the code bellow. I added some buttons to add or remove cards. The main trick is to use constraints like minHeight.
import 'package:flutter/material.dart';
class BottomButton extends StatefulWidget {
#override
_BottomButtonState createState() => _BottomButtonState();
}
class _BottomButtonState extends State<BottomButton> {
List<Widget> cards = [];
#override
Widget build(BuildContext context) {
var appBar2 = AppBar(
actions: [
IconButton(
icon: Icon(Icons.add),
onPressed: () {
_addCard();
}),
IconButton(
icon: Icon(Icons.remove),
onPressed: () {
_removeCard();
}),
],
);
return Scaffold(
appBar: appBar2,
body: Container(
height: MediaQuery.of(context).size.height -
(MediaQuery.of(context).padding.top + appBar2.preferredSize.height),
alignment: Alignment.topCenter,
child: ListView(
primary: true,
children: [
Container(
constraints: BoxConstraints(
minHeight: MediaQuery.of(context).size.height -
(MediaQuery.of(context).padding.top +
appBar2.preferredSize.height),
),
alignment: Alignment.topCenter,
child: Column(
mainAxisSize: MainAxisSize.max,
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: [
Container(
constraints: BoxConstraints(
minHeight: MediaQuery.of(context).size.height -
(MediaQuery.of(context).padding.top +
appBar2.preferredSize.height +
50),
),
alignment: Alignment.topCenter,
child: Column(
mainAxisSize: MainAxisSize.max,
mainAxisAlignment: MainAxisAlignment.start,
children: cards,
),
),
ElevatedButton(
child: Text('this is a button'),
onPressed: () {},
),
],
),
)
],
),
),
);
}
void _addCard() {
Widget card = Card(
child: Container(
height: 100,
color: Colors.red,
padding: EdgeInsets.all(2),
),
);
setState(() {
cards.add(card);
});
}
void _removeCard() {
setState(() {
cards.removeLast();
});
}
}
I am trying to display a ListView Horizontal n times in Stack or Row. But in the end all the ListViews are piled up instead shows one by one from top to bottom.
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text("Prueba para trabajar en el proyecto"),
),
body: Stack(
children: <Widget>[
_crearLista(),
_crearLista(),
_crearLista(),
_crearLista(),
_crearLista(),
//_crearLoading(),
],
),
);
}
Widget _crearLista() {
return Container(
child: Column(
crossAxisAlignment: CrossAxisAlignment.center,
children: <Widget>[
Flexible(
child: Container(
width: MediaQuery.of(context).size.width,
height: MediaQuery.of(context).size.height * 0.25,
decoration: BoxDecoration(),
child: ListView.builder(
scrollDirection: Axis.horizontal,
itemCount: _listaNumeros.length,
itemBuilder: (BuildContext context, int index) {
//return image
},
controller: _scrollController,
),
),
)
],
),
);
}
Any suggestions? please. I want to show all the LsitViews.
A Stack widget puts its children above each other (overlapped or piled up) at the left top corner of the stack by default. Unless you position each child using a Positioned or Align widget. To have all the children one below the other (starting from top of the screen towards bottom), you need to use a Column instead of Stack.
Stack children behave like layers, one covers second, etc.
If you want one child exactly below another, there is ListView and Column
I'm trying to create a 2x2 grid for displaying some info in cards. Disclaimer: I'm totally new to Dart and Flutter, so expect a lot of ignorance on the topic here.
These cards should have a fixed size, have an image, display some text... and be positioned from left to right, from top to bottom.
First, I tried to use the Flex widget, but it seems to only work horizontally or vertically. Therefore, my only solution was to use two Flexes, but only showing the second when the amount of elements is higher than 2 (which would only use one row).
Then, I tried using GridView, but it doesn't work in any possible way. It doesn't matter which example from the Internet I copy and paste to begin testing: they just won't show up in the screen unless they're the only thing that is shown in the app, with no other widget whatsoever. I still don't understand why that happens.
This is my current code:
First widgets in "home_page.dart":
return Scaffold(
appBar: AppBar(
// Here we take the value from the MyHomePage object that was created by
// the App.build method, and use it to set our appbar title.
title: Text(widget.title),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.start,
children: <Widget>[
Padding(padding: EdgeInsets.only(top: 30)),
Text(
'App test',
style: TextStyle(fontSize: 24),
),
EventsList(key: new Key('test')),
],
),
),
floatingActionButton: FloatingActionButton(
onPressed: _incrementCounter,
tooltip: 'Increment',
child: Icon(Icons.add),
), // This trailing comma makes auto-formatting nicer for build methods.
);
The "EventList" part is a widget that should represent the grid functionality I explained before. This class gets some info from a service (which currently just sends some hardcoded info from a Future), and paints the given widgets ("Card" items, basically) into the EventList view:
class _EventsListState extends State<EventsList> {
#override
Widget build(BuildContext context) {
return FutureBuilder<List<Event>>(
future: new EventsService().getEventsForCoords(),
builder: (context, AsyncSnapshot<List<Event>> snapshot) {
if (snapshot.hasData) {
return Padding(
padding: EdgeInsets.only(left: 20, right: 20),
child: Flex(
direction: Axis.horizontal,
verticalDirection: VerticalDirection.down,
mainAxisAlignment: MainAxisAlignment.center,
children: generateProximityEventCards(snapshot.data),
));
} else {
return CircularProgressIndicator();
}
});
}
List<Card> generateProximityEventCards(List<Event> eventList) {
// Load Events from API
print(eventList);
// Render each card
return eventList.map((Event ev) {
return Card(
child: Padding(
padding: EdgeInsets.only(bottom: 15),
child: Column(
children: <Widget>[
Image(
fit: BoxFit.cover,
image: ev.imageUrl,
height: 100,
width: 150,
),
Padding(
child: Text(ev.name),
padding: EdgeInsets.only(left: 10, right: 10),
),
Padding(
child: Text(ev.address),
padding: EdgeInsets.only(left: 10, right: 10),
),
],
),
));
}).toList();
}
}
This is how it currently looks:
As I said before, I understand that the Flex widget can't really get that 2x2 grid look that I'm looking for, which would be something like this (done with Paint):
So, some questions:
How can I get a grid like that working? Have in mind that I want to have more stuff below that, so it cannot be an "infinite" grid, nor a full window grid.
Is it possible to perform some scrolling to the right in the container of that grid? So in case there are more than 4 elements, I can get to the other ones just scrolling with the finger to the right.
As you can see in the first image, the second example is bigger than the first. How to limit the Card's size?
Thank you a lot for your help!
The reason the gridview was not working is because you need to set the shrinkWrap property of theGridView to true, to make it take up as little space as possible. (by default, scrollable widgets like gridview and listview take up as much vertical space as possible, which gives you an error if you put that inside a column widget)
Try using the scrollable GridView.count widget like this and setting shrinkWrap to true:
...
GridView.count(
primary: false,
padding: /* You can add padding: */ You can add padding const EdgeInsets.all(20),
crossAxisCount: /* This makes it 2x2: */ 2,
shrinkWrap: true,
children: generateProximityEventCards(snapshot.data),
...
Is this what you exactly want?
do let me know so that I can update the code for you
import 'package:flutter/material.dart';
class List extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
backgroundColor: Colors.white,
title: Text('Inicio', style: TextStyle(color: Colors.black, fontSize: 18.0),),
),
body: GridView.count(
shrinkWrap: true,
crossAxisCount: 2,
children: List.generate(
50,//this is the total number of cards
(index){
return Container(
child: Card(
color: Colors.blue,
),
);
}
),
),
);
}
}
I display a custom-made bottom app bar in a Stack because of keyboard padding reasons. The custom widget is fully opaque as it should be until it's a child of a Stack in which case, the content behind it starts to be visible since the color's opacity somehow changes.
As you can see, it's only the "main" color that's transparent. Icons remain opaque.
This is the build method of my custom BottomBar widget which is then just regularly put into a Stack. I have tried using a Material and even a simple Container in place of the BottomAppBar widget but the results are the same.
#override
Widget build(BuildContext context) {
return BottomAppBar(
color: Colors.blue.withOpacity(1),
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: <Widget>[
IconButton(
icon: Icon(MdiIcons.plusBoxOutline),
onPressed: () {},
),
Text('Edited 11:57'),
IconButton(
icon: Icon(MdiIcons.dotsVertical),
onPressed: () {},
),
],
),
);
}
Can you interact with the BottomAppBar ? It looks like an order problem. Try to put the BottomAppBar as last in the Stack children.
Note that BottomAppBar doesn't have a constant size, if you did not add it to Scaffold bottomNavigationBar named parameter has a size if this is not null. Below is peace of code in Scaffold dart file:
double bottomNavigationBarTop;
if (hasChild(_ScaffoldSlot.bottomNavigationBar)) {
final double bottomNavigationBarHeight = layoutChild(_ScaffoldSlot.bottomNavigationBar, fullWidthConstraints).height;
bottomWidgetsHeight += bottomNavigationBarHeight;
bottomNavigationBarTop = math.max(0.0, bottom - bottomWidgetsHeight);
positionChild(_ScaffoldSlot.bottomNavigationBar, Offset(0.0, bottomNavigationBarTop));
}
You can even develop your own Widget without BottomAppBar but if you want things like centerDocked and things like circular notched, you will have to do more stuff (anyway you have flexibility to custom design the way you want).
Here is a simple example to do that(one way to do that):
import 'package:flutter/material.dart';
class CustomBottomBar extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Scaffold(
body: Stack(
children: <Widget>[
Container(
margin: EdgeInsets.only(bottom: 50),
color: Colors.greenAccent, // if you want this color under bottom bar add the margin to list view
child: ListView.builder(
itemCount: 100,
itemBuilder: (_, int index) => Text("Text $index"),
),
),
Positioned(
bottom: 0,
child: Container(
color: Colors.amber.withOpacity(.5),
width: MediaQuery.of(context).size.width,
height: 50,
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
children: List.generate(4, (int index) => Text("Text $index")), // you can make these clickable by wrapping with InkWell or any gesture widget
),
),
),
],
),
);
}
}
I am use Flutter for web for make website. I want make webpage scroll when user scroll down like normal website.
I am try use Stack so I can place custom background behind widgets. This background must scroll when user scroll (must stick to widgets in front so background change).
(I cannot set background color using Scaffold because my background is use CustomPainter)
But I want center the widgets on webpage, so I wrap SingleChildScrollView in Center widget. But now on large horizontal screen the CustomPaintWidget() is not fill screen (there is blank space). I have try replace my CustomPaintWidget() with Container to test, but same issue.
Here my code:
Center(
child: SingleChildScrollView(
child:Stack(children: <Widget>[
CustomPaintWidget(),
Widgets(),
],),
Anyone know solution?
How to center widgets but also make background stretch?
Thanks!
SingleChildScrollView by definition shriknwraps it's child.
What you should try is
return SingleChildScrollView(
scrollDirection: Axis.horizontal,
child: ConstrainedBox(
//Use MediaQuery.of(context).size.height for max Height
constraints: BoxConstraints(minHeight: MediaQuery.of(context).size.height),
child: Center(
child: //Widget,
),
),
);
I think you can try something like:
#override
Widget build(BuildContext context) {
return Scaffold(
body: Stack(
children: <Widget>[
CustomPaintWidget(),
Center(
child: SingleChildScrollView(
child: Widgets(),
),
)
],
));
}
read that post, I think is all you need https://medium.com/#swav.kulinski/spike-parallax-in-flutter-seven-lines-of-code-16a1890d8d32
I know it is too late to answer but s.o may need it in future
You have to use Stack
for instance:
your MainClass:
class _BodyState extends State<Body> {
#override
Widget build(BuildContext context) {
return Scaffold(
body: Stack(
children: [
ScrollViewClass(),
Column(
children: [
//YOUR ITEMS
]),
);
ScrollviewClass:
class ScrollViewClass extends StatefulWidget {
#override
_ScrollViewClassState createState() => _ScrollViewClassState();
}
class _ScrollViewClassState extends State<ScrollViewClass> {
#override
Widget build(BuildContext context) {
return Scaffold(
body: Container(
margin: EdgeInsets.only(top: 260, bottom: 100),
child: ListView(
children: [
Container(
child: SingleChildScrollView(
scrollDirection: Axis.vertical,
child: ConstrainedBox(
//Use MediaQuery.of(context).size.height for max Height
constraints: BoxConstraints(
minHeight: MediaQuery.of(context).size.height),
child: Column(
children: [
//ADD YOUR ITEMS LIKE IMAGE, TEXT, CARD ETC...
Center(child: Image.asset('assets/app_name.png')),
Center(child: Image.asset('assets/app_name.png')),
Center(child: Image.asset('assets/app_name.png')),
Center(child: Image.asset('assets/app_name.png')),
Center(child: Text('fdgdfg')),
Center(child: Text('fdgdfg')),
],
)),
),
)
],
),
));
}
}
I know this is not the OP's scenario, but for others - If there is something above your scroll view, using the full height of the page will cause the scrollview to scroll prematurely, because the combined height of the widgets is now greater than the page height. Use LayoutBuilder instead of MediaQuery.of(context).size.height.
LayoutBuilder(builder: ((context, constraints) {
return SingleChildScrollView(
child: ConstrainedBox(
constraints: BoxConstraints(
minHeight: constraints.maxHeight),
child: Center(child: child)),
);
})