What I am Implying to do is that if there is a Column and two containers in it. I want another widget pinned to to the first container which overlaps parts of the 2nd container and move with the first column (if i apply some special scroll effects).
Here is dummy code.
Column(
children: <Widget>[
Container(
height: 300,
child: <Some child widget which is pinned to this box and overlaps the second box>
),
Container(
height: 300,
)
],
)
If I have understood your question properly one way is to use two stack's itself like as follows.
Stack(
children: <Widget>[
Container(
height: 300,
margin: EdgeInsets.all(300),
),
Stack(children: <Widget>[SizedBox(height: 300,),TheWidgetYouWantToOverlap()],)
],
)
Related
I am creating chat bubbles, I want the width to be defined by the message itself, but then I added a "header" (a Row) with the name of the sender and a decorative line (a Container).
I want this line to fill the available space but when I expand it it pushes the width of the bubble to its maximum regardles of the width of the message. In this sceenshots you can see that the recieved messages are too wide for its content.
This is a simplified version of the code, If I don't put the expanded the red Container is invisible (width 0), with the expanded takes the maximum space available but I want column to remain of the width that determines the message.
Thanks a lot.
return Container(
color: Colors.grey.shade200,
constraints:
BoxConstraints(maxWidth: (MediaQuery.of(context).size.width * 0.7)),
child: Column(
mainAxisSize: MainAxisSize.min,
children: [
Row(
mainAxisSize: MainAxisSize.min,
children: [
Text("Juan"),
Expanded(
child: Container(
color: Colors.red,
height: 3,
),
)
],
),
Text("Text of the message"),
],
));
pskink nailed it. His answer in the comment:
you need: child: IntrinsicWidth(child: Column(... –
pskink
Hopes this also helps somebody else.
What is the best way to build a "nested bottom sheet" which behaves like this:
https://dribbble.com/shots/14139422-Mobile-banking-app-interactions?
Do I have to use NestedScrollView or CustomScrollView, or a completely different approach?
Update :
This is my result using SlidingUpPanel, but I still have two problems:
When sliding up the panel, the green and red containers stay behind the panel and do not scroll out of view at the top.
In landscape mode the containers are higher than the device, so this approach does not work. I need the panel to be attached to the bottom of the containers, so it is only visible when scrolling down.
Code:
SafeArea(
child: Scaffold(
body: SlidingUpPanel(
minHeight: MediaQuery.of(context).size.height - 479,
maxHeight: MediaQuery.of(context).size.height - 79,
panel: SingleChildScrollView(
child: Column(
children: [Text('Sliding Panel')],
),
),
body: SingleChildScrollView(
child: Column(
mainAxisAlignment: MainAxisAlignment.start,
children: [
Container(
height: 100,
color: Colors.green,
),
Container(
height: 300,
color: Colors.red,
)
],
),
),
),
),
);
Result:
I believe there is a Widget for what you want to do, since there is a widget for everything in Flutter. here is the link of the package
NOTE : you can also set minimum height of the widget when collapsed in order to control how much of the widget you can show when it is collapsed.
And here is the demo :
I would like to align a container at the bottom of the widget (given there is containers already at the top and some column in the middle)
So far I can align in at the top followed by some containers using Alignment.topCenter and column.
body: Align(
alignment: Alignment.topCenter,
child: Column(
mainAxisSize: MainAxisSize.min,
children: [
How can I then put one more container that is right at the bottom of the widget.
reason for this is I want the ad banner to appear at the top and at the bottom. the middle is the real content.
Add Column on top on Align Widget, & add at the bottom of its container with Expanded
Expanded(
child: Align(
alignment: Alignment.bottomCenter,
child: Container(
height: 100, // Give height of banner
color: Colors.green,
),
),
),
I'm creating a new widget that displays some bubbles, that should be connected by lines.
5-------6
|
4-------3
|
1-------2
I chose a ListView as the outer widget, if I understood it correctly this should give me the scrollability:
return Expanded(
child: ListView(
children: _createLWItems(_createBubbles()),
),
);
Children is a List of my inner widget. Each widget is a row, so I can place two bubbles next to each other:
return Container(
child: Row(
children: <Widget>[
Container(
child: bubbleItem1,
alignment: Alignment.centerLeft,
),
Container(
child: bubbleItem2,
alignment: Alignment.centerRight,
)
],
),
decoration: BoxDecoration( //TODO remove after testing
shape: BoxShape.rectangle,
border: Border.all(color: Colors.blue),
),
);
BubbleItem is only a Container with a BoxDecoration wrapped with a GestureDetector.
What I wanted to achieve is, that the left bubble is aligned to the left, and the right to the right, but instead, both are placed next to each other to the left, although row takes the entire width of my screen, as you can see (blue border):
As I read here there is a MainAxisAlignment for the row-widget but this would just align all childs left, right, centered, etc., not what I have in mind.
How can I place those bubbles the way I intend to?
If they are placed correctly I want to connect them with lines. Is there a way to do this without calculation? My idea would be to insert another widget between the bubbles that takes a line, but I'd need to tell it somehow, that it should take the entire space between the bubbles of his row.
At the moment I'm a bit unsure if I should calculate anything because I read something about 'you cannot calculate before it is rendered', but on the other hand I'm missing some understanding how to do it in flutter without it.
Alignment does work for Row children, but not in the way that you are expecting. If for example you had a Row child with half the height of the Row, you could use Alignment to specify if you want that child at the top or the bottom of the Row - the default is centered.
By default, the children are positioned sequentially within a Row (horizontally) as well as within a Column (vertically), which is what you've got in the screenshot you attached. If you simply wanted to position the 2 circles at the left and right ends of the Row, you could use a MainAxisAlignment value of spaceBetween, which places the free space evenly between the children.
If you want to also draw a line between the circles however, then you will not have any space left to distribute within the Row, so the MainAxisAlignment will not help. What you want instead is an Expanded widget within the Row, between the circles. This will create a widget that takes up all the remaining space within the Row, which is where you want your line to be.
Row(
children: <Widget>[
Container(
child: bubbleItem1,
alignment: Alignment.centerLeft,
),
Expanded(
child: Divider(),
),
Container(
child: bubbleItem2,
alignment: Alignment.centerRight,
)
],
)
You are giving the Alignment to the container's item, not the container itself
Try giving the Alignment to the Row
Container getContainer(){
return Container(
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: <Widget>[
Container(
height: 50,
width: 50,
child: Center(child: Text("Left")),
),
Container(
height: 50,
width: 50,
child: Center(child: Text("Right")),
)
],
),
decoration: BoxDecoration( //TODO remove after testing
shape: BoxShape.rectangle,
border: Border.all(color: Colors.blue),
),
);
}
TL;DR Need the container to fill the vertical space so that it can act as a ontap listener. Have tried most solutions but nothing seems to work.
So what I am trying to do is to make my container fill up the vertical space while still having a fixed width. Two first is what I have and third is what I want. The idea is to have the container transparent with a gesture ontap listener. If anyone have a better idea as for a different solution, feel free to suggest.
Widget build(BuildContext context) {
return new GestureDetector(
onHorizontalDragUpdate: _move,
onHorizontalDragEnd: _handleDragEnd,
child: new Stack(
children: <Widget>[
new Positioned.fill(
child: new Row(
mainAxisAlignment: MainAxisAlignment.end,
children: <Widget>[
new Container(
child: new IconButton(
padding: new EdgeInsets.only(top: 16.0, bottom: 16.0, left: 24.0, right: 24.0),
icon: new Icon(Icons.warning),
color: Colors.black12,
onPressed: () {},
)
),
],
),
),
new SlideTransition(
position: new Tween<Offset>(
begin: Offset(0.0, 0.0),
end: const Offset(-0.6, 0.0),
).animate(_animation),
child: new Card(
child: new Row(
children: <Widget>[
new Container(
width: 20.0,
height: 20.0,
color: Colors.amber,
),
new Expanded(
child: new Column(
mainAxisSize: MainAxisSize.min,
children: <Widget>[
_getListTile(),
_ifStoplineIsToBeShown()
],
),
)
],
)
),
),
],
)
);
}
I am quite sure that i have been missing something considering the fact that I have tried a lot of different things and nothing seems to work.
I have also uploaded an image with the debug painting here.
PS. I know I have set the height to a fixed value, but this is the only way to show the container.
The trick is to combine an IntrinsicHeight widget and a Row with crossAxisAlignment: CrossAxisAlignment.stretch
This force the children of Row to expand vertically, but Row will take the least amount of vertical space possible.
Card(
child: IntrinsicHeight(
child: Row(
crossAxisAlignment: CrossAxisAlignment.stretch,
children: <Widget>[
Container(
width: 20.0,
color: Colors.amber,
),
// Expanded(...)
],
),
)
)
To stretch the container to full height of the parent use property constraints:BoxConstraints.expand() in container widget. Container occupy the complete space independent of the of child widget
Container(
color: Colors.green,
child: Text("Flutter"),
constraints: BoxConstraints.expand(),
)
Please refer the link Container Cheat sheet for more about container
Simply pass in: double.infinity.
If you want a Container to fill all available space, you can just pass in:
width: double.infinity,
height: double.infinity
Explanation:
In Flutter, a child widget cannot exceed the "layout constraints" imposed by its parent widget. During the layout phase, Flutter engine uses a constraint solver to automatically correct "out-of-bound" values into what's allowed by its parent constraints.
For example, if you have a Container that's 50x50, and for its child, you pass in another Container that's 300x300, the inner container will be automatically corrected to "not exceed its parent", thus 50x50. Therefore, using sufficiently large values would always make sure you "fill parent".
In fact, even BoxConstraints.expand() exploits the same idea internally. If you open up the source code of expand(), you will see:
/// Creates box constraints that expand to fill another box constraints.
///
/// If width or height is given, the constraints will require exactly the
/// given value in the given dimension.
const BoxConstraints.expand({
double width,
double height,
}) : minWidth = width ?? double.infinity,
maxWidth = width ?? double.infinity,
minHeight = height ?? double.infinity,
maxHeight = height ?? double.infinity;
So if you are absolutely certain you want to fill all spaces, you can intuitively pass in a number bigger than the parent (or larger than the whole screen), like double.infinity.
As of Jan 2020 the simplest is to use an Expanded Widget
Expanded(flex: 1,
child: Container(..),
),
https://api.flutter.dev/flutter/widgets/Expanded-class.html
There are many answers which suggest using two things
constraints: BoxConstraints.expand(),
height: double.infinity,
But both these answer will give you an error like
BoxConstraints forces an infinite height.
We can avoid these by calculating the height of the screen like
App Bar
Top Bar Space(Exist on the above App Bar)
Remaining screen
1. Get the MediaQuery
final mediaQuery = MediaQuery.of(context);
2. Declare the AppBar Widget and same App Bar instance should be used in Scaffold App Bar
final PreferredSizeWidget appBar = AppBar(
title: Text('Home'),
);
3. Use calculated height
Container(
width: mediaQuery.size.width,
height: (mediaQuery.size.height -
appBar.preferredSize.height -
mediaQuery.padding.top),
color: Colors.red,
),
Output:
Set the height or width of a container to double.maxFinite
Container(
height: double.maxFinite,
width: 100,)
You can make your widget take the full size of a Container widget, and then set the container's height and/or width to double.maxFinite. This will make the Container take the height and/or width or its parent widget
I propose using Expanded widget (which allows us to avoid IntrinsicHeight widget), combine it with the Container's alignment property and therefore make it work properly even if the Container is not the only one at the screen.
Expanded(
child: Container(
alignment: Alignment.center,
child: Text('Your text', textAlign: TextAlign.center))),
That way one also avoids potential app's crash which occurs often when you accidentally expand to infinity some parts of the widget tree both horizontally and vertically (that is why you are not able to use BoxConstraints widget in many cases).
One can read more about the problems of passing constraints in Flutter here - a must read: https://medium.com/flutter-community/flutter-the-advanced-layout-rule-even-beginners-must-know-edc9516d1a2
This work works for me
height: MediaQuery.of(context).size.height,