Flutter: How to make a button expand to the size of its parent?

Question

I am trying to create square buttons, but Expanded doesn't seem to work the same as it does with containers. Take the following code for example

new Expanded(
 flex: 2,
   child: new Column(
     children: <Widget>[
       new Expanded(
         child:new Row(
           children: <Widget>[
             new Expanded(child: new MaterialButton(...)),
             new Expanded(child: new MaterialButton(....)),

             new Expanded(child: new Container(color: Colors.red)),
             new Expanded(child: new Container(color: Colors.green)),
           ]
         )
       )
     ],
   )
 )

 ....

It displays two buttons that are expanded horizontally, but not vertically. At the same time the containers will expand both horizontally and vertically. The same effect occurs if I do the following:

new Expanded(
 flex: 2,
   child: new Column(
     children: <Widget>[
       new Expanded(
         child:new Column(
           children: <Widget>[
             new Expanded(child: new MaterialButton(...)),
             new Expanded(child: new MaterialButton(....)),

             new Expanded(child: new Container(color: Colors.red)),
             new Expanded(child: new Container(color: Colors.green)),
           ]
         )
       )
     ],
   )
 )

 ....

Where I've changed the Row to Column. The buttons will expand vertically, but not horizontally, while the containers will do both.

Is there a way have my buttons expand to fit their parent both vertically and horizontally?

Answer 1

将crossAxisAlignment属性添加到您的Row ；

crossAxisAlignment: CrossAxisAlignment.stretch

Answer 2

Wrapping with a ButtonTheme with minWidth: double.infinity allows to provide constraints

ButtonTheme(
  minWidth: double.infinity,
  child: MaterialButton(
    onPressed: () {},
    child: Text('Raised Button'),
  ),
),

or after https://github.com/flutter/flutter/pull/19416 landed

  MaterialButton(
    onPressed: () {},
    child: SizedBox.expand(
      width: double.infinity, 
      child: Text('Raised Button'),
    ),
  ),

Answer 3

We can add Button insider Container.

Solution:

Container(
            width: double.infinity,
            child: RaisedButton(
              onPressed: null,
              child: Text('NEXT'),
            ),
          )

Answer 4

You can also try it

1. Using SizedBox

    SizedBox( width: double.maxFinite, // set width to maxFinite child: RaisedButton(...), )

2. Use MaterialButton 's minWidth property.

    MaterialButton( minWidth: double.maxFinite, // set minWidth to maxFinite color: Colors.blue, onPressed: () {}, child: Text("Button"), )

Answer 5

you can insert under child:column

crossAxisAlignment: CrossAxisAlignment.stretch

My code

My result

Answer 6

In Flutter 2.+ consider this solution:

ElevatedButton(
  style: ElevatedButton.styleFrom(
    minimumSize: const Size(double.infinity, double.infinity), // <--- this line helped me
  ),
  onPressed: () {},
  child: Icon(
    Icons.keyboard_return
  ),
)

Answer 7

MaterialButton(
          minWidth: MediaQuery.of(context).size.width, // set minWidth to width of the device screen
          onPressed: () {},
          child: Text("Button"),
        )

for reference https://api.flutter.dev/flutter/widgets/MediaQuery-class.html

Answer 8

VisualDensity is the thing you are looking for. Add it to the ButtonStyle object.

ElevatedButton(
  style: const ButtonStyle(
    visualDensity: VisualDensity(
      horizontal: VisualDensity.maximumDensity,
      vertical: VisualDensity.maximumDensity,
    ),
  ),
  ...
),