How to set width to Material widget on Flutter? - dart

Question

I've a Material widget to wrap a MaterialButton to make border radius, but I can't set the width attribute to it. I tried use a SizedBox but not works, the Material widget keep using all space of screen.
Code:
return new SizedBox(
width: 40,
child: Material(
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(22.0)),
elevation: 18.0,
color: Color(0xFF801E48),
clipBehavior: Clip.antiAlias,
child: MaterialButton(
materialTapTargetSize: MaterialTapTargetSize.shrinkWrap,
height: 30.0,
child: new Text('Sair',
style:
new TextStyle(fontSize: 16.0, color: Colors.white)),
),
),
);
Result:
Clearly it not have 40.0 of width size.

Answer 1

A better approach is using Container widget. When you need to change width, height or add padding/margin to any widget you should wrap the target widget into a container. The container widget is for this kind of job.
Container(
width: myWidthValue, // Container child widget will get this width value
height: myHeghtValue, // Container child widget will get this height value
padding: allowPaddingToo, // padding is allowed too
child: Material(
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(22.0)),
elevation: 18.0,
color: Color(0xFF801E48),
clipBehavior: Clip.antiAlias, // Add This
child: MaterialButton(
materialTapTargetSize: MaterialTapTargetSize.shrinkWrap,
height: 30.0,
child: new Text('Sair',
style:
new TextStyle(fontSize: 16.0, color: Colors.white)),
onPressed: () {
setState(() {
_isNeedHelp = false;
});
},
),
),
);

Answer 2

This is how you can set the size, padding, and margin of widgets in general. here is an example for Button:
Container(
margin: EdgeInsets.only(top: 10), // Top Margin
child:
ElevatedButton(
style: TextButton.styleFrom(
// Inside Padding
padding: EdgeInsets.symmetric(horizontal: 0, vertical: 20),
// Width,Height
minimumSize: Size(300, 30),
),
child: Text('Upload Data'),
onPressed: () {submitForm();},
),
),

Answer 3

Solved using Padding:
return Padding(
padding: EdgeInsets.fromLTRB(50, 0, 50, 0),
child: Material(
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(22.0)),
elevation: 18.0,
color: Color(0xFF801E48),
clipBehavior: Clip.antiAlias, // Add This
child: MaterialButton(
materialTapTargetSize: MaterialTapTargetSize.shrinkWrap,
height: 30.0,
child: new Text('Sair',
style:
new TextStyle(fontSize: 16.0, color: Colors.white)),
onPressed: () {
setState(() {
_isNeedHelp = false;
});
},
),
),
);
Result: