Positioned is a widget that comes built-in with flutter SDK. Postioned does exactly what it sounds like, which is it arbitrarily positioned widgets on top of each other. It is usually used to position child widgets in Stack widget or similar. It only works for Stateless and Stateful widgets.
To center align the text in a Text widget, provide textAlign property with value TextAlign. center .
To center a widget you can use MainAxisAlignment. center method. And in this way, you can center any widget.
You can use the Positioned.fill
with Align
inside a Stack
:
Stack(
children: <Widget>[
Positioned.fill(
child: Align(
alignment: Alignment.centerRight,
child: ....
),
),
],
),
You can simply use the alignment
option present in Stack
child: Stack(
alignment: Alignment.center
)
Remove everything, but this:
Align(
alignment: Alignment.bottomCenter,
child: new ButtonBar(
alignment: MainAxisAlignment.center,
children: <Widget>[
new OutlineButton(
onPressed: () {
Navigator.push(
context,
new MaterialPageRoute(
builder: (context) => new LoginPage()));
},
child: new Text(
"Login",
style: new TextStyle(color: Colors.white),
),
),
new RaisedButton(
color: Colors.white,
onPressed: () {
Navigator.push(
context,
new MaterialPageRoute(
builder: (context) =>
new RegistrationPage()));
},
child: new Text(
"Register",
style: new TextStyle(color: Colors.black),
),
)
],
),
)
In my theory, the additional Container
is destroying it. I would advise you to just surround this by adding Padding
:
Padding(
padding: EdgeInsets.only(bottom: 20.0),
child: Align...
),
This seems a lot more reasonable to me than the Positioned
and also I do not quite understand your Column
with a single child only.
For anyone who is reaching here and is not able to solve their issue, I used to make my widget horizontally center by setting both right and left to 0 like below:
Stack(
children: <Widget>[
Positioned(
top: 100,
left: 0,
right: 0,
child: Text("Search",
style: TextStyle(
color: Color(0xff757575),
fontWeight: FontWeight.w700,
fontFamily: "Roboto",
fontStyle: FontStyle.normal,
fontSize: 56.0,
),
textAlign: TextAlign.center,
),
),
]
)
A Stack
allows you to stack elements on top of each other, with the last element in the array taking the highest priority. You can use Align
, Positioned
, or Container
to position the children of a stack.
Align
Widgets are moved by setting the alignment with Alignment
, which has static properties like topCenter
, bottomRight, and so on. Or you can take full control and set Alignment(1.0, -1.0)
, which takes x,y values ranging from 1.0 to -1.0, with (0,0) being the center of the screen.
Stack(
children: [
Align(
alignment: Alignment.topCenter,
child: Container(
height: 80,
width: 80, color: Colors.blueAccent
),
),
Align(
alignment: Alignment.center,
child: Container(
height: 80,
width: 80, color: Colors.deepPurple
),
),
Container(
alignment: Alignment.bottomCenter,
// alignment: Alignment(1.0, -1.0),
child: Container(
height: 80,
width: 80, color: Colors.amber
),
)
]
)
Thanks to all of the above answers I'd like to share something that may come in handy in some certain cases. So lets see what happens when you use Positioned:( right: 0.0, left:0.0, bottom:0.0)
:
Padding(
padding: const EdgeInsets.all(4.0),
child: Stack(
children: <Widget>[
Positioned(
bottom: 0.0,
right: 0.0,
left: 0.0,
child: Padding(
padding: const EdgeInsets.symmetric(horizontal: 8.0),
child: Container(
color: Colors.blue,
child: Center(
child: Text('Hello',
style: TextStyle(color: Color(0xffF6C37F),
fontSize: 46, fontWeight: FontWeight.bold),),
)
),
)
),
],
),
),
This would be the output of the above code:
As you can see it would fill the whole width with the container even though you don't want it and you just want the container to wrap its children. so for this you can try trick below:
Padding(
padding: const EdgeInsets.all(4.0),
child: Stack(
children: <Widget>[
Positioned(
bottom: 0.0,
right: 0.0,
left: 0.0,
child: Row(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Container(),
Padding(
padding: const EdgeInsets.symmetric(horizontal: 8.0),
child: Container(
color: Colors.blue,
child: Text('Hello',
style: TextStyle(color: Color(0xffF6C37F),
fontSize: 46, fontWeight: FontWeight.bold),)
),
),
Container(),
],
)
),
],
),
),
The Problem is the Container that gets the smallest possible size.
Just give a width:
to the Container (in red) and you are done.
width: MediaQuery.of(context).size.width
new Positioned(
bottom: 0.0,
child: new Container(
width: MediaQuery.of(context).size.width,
color: Colors.red,
margin: const EdgeInsets.all(0.0),
child: new Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
new Align(
alignment: Alignment.bottomCenter,
child: new ButtonBar(
alignment: MainAxisAlignment.center,
children: <Widget>[
new OutlineButton(
onPressed: null,
child: new Text(
"Login",
style: new TextStyle(color: Colors.white),
),
),
new RaisedButton(
color: Colors.white,
onPressed: null,
child: new Text(
"Register",
style: new TextStyle(color: Colors.black),
),
)
],
),
)
],
),
),
),
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