Flutter - FloatingActionButton in the center

Question

Is it possible to make the FloatingActionButton in the centre instead of the right side?

import 'package:flutter/material.dart';
import 'number.dart';
import 'keyboard.dart';

class ContaPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) => new Scaffold(
    body: new Column(
      children: <Widget>[
        new Number(),
        new Keyboard(),
      ],
    ),
    floatingActionButton: new FloatingActionButton(
      elevation: 0.0,
      child: new Icon(Icons.check),
      backgroundColor: new Color(0xFFE57373),
      onPressed: (){}
    )
  );
}

Answer 1

Try wrapping it in a Center widget or use a crossAxisAlignment of CrossAxisAlignment.center on your Column.

You should pick one part of your Column to be wrapped in a Flexible that will collapse to avoid overflow, or replace some or all of it with a ListView so users can scroll to see the parts that are hidden.

Answer 2

I don't know if this was added since this question was first answered, but there's now floatingActionButtonLocation property on the Scaffold class.

It would work like this in your original question:

class ContaPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) => new Scaffold(
    // ...

    floatingActionButton: new FloatingActionButton(
      // ...FloatingActionButton properties...
    ),

    // Here's the new attribute:

    floatingActionButtonLocation: FloatingActionButtonLocation.centerFloat,
  );
}

Also see the documentation:

• Scaffold class (search floatingActionButtonLocation): https://docs.flutter.io/flutter/material/Scaffold-class.html
• ...and the FloatingActionButtonLocation class: https://docs.flutter.io/flutter/material/FloatingActionButtonLocation-class.html

Answer 3

With the new flutter API you do that very easily just change the floatingActionButtonLocation property in the Scaffold to

FloatingActionButtonLocation.centerFloat

Example :

return new Scaffold(
  floatingActionButton: new FloatingActionButton(
    child: const Icon(Icons.add),
  ),
  floatingActionButtonLocation:    
      FloatingActionButtonLocation.centerFloat,
  bottomNavigationBar: new BottomAppBar(
    color: Colors.white,
    child: new Row(...),
  ),
);

Answer 4

You can use Container and Align widgets as below:

@override
Widget build(BuildContext context) {
    return new Scaffold(
      body: Center(

      ),
      floatingActionButton: Container(
        padding: EdgeInsets.only(bottom: 100.0),
        child: Align(
          alignment: Alignment.bottomCenter,
          child: FloatingActionButton.extended(
            onPressed: _getPhoneAuthResult,
            icon: Icon(Icons.phone_android),
            label: Text("Authenticate using Phone"),
          ),
        ),
      ),
      floatingActionButtonLocation: FloatingActionButtonLocation.centerFloat,
    );
  }

Answer 5

By changing the logic to use crossAxisAlignment, the mainAxisAlignment and the Flexible the FloatingActionButton were centered at the bottom of the screen

import 'package:flutter/material.dart';
import 'number.dart';
import 'keyboard.dart';

class ContaPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) => new Scaffold(
    body: new Column(
      crossAxisAlignment: CrossAxisAlignment.center,
      mainAxisAlignment: MainAxisAlignment.spaceBetween,       
      children: <Widget>[
        new Number(),
        new Keyboard(),
        new Flexible(
          child: new Container(
            padding: new EdgeInsets.only(bottom: 16.0),
            child: new FloatingActionButton(
              elevation: 0.0,
              child: new Icon(Icons.check),
              backgroundColor: new Color(0xFFE57373),
              onPressed: (){}
            )
          )         
        )
      ],
    ), 
  );
}

Answer 6

I modified the code, now the button is in the bottom center but I do not know if it will always stay in the bottom, regardless of the size of the screen.

import 'package:flutter/material.dart';
import 'number.dart';
import 'keyboard.dart';

class ContaPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) => new Scaffold(
    body: new Column(
      children: <Widget>[
        new Number(),
        new Keyboard(),
        new Stack(
          alignment: new FractionalOffset(0.5, 1.0),
          children: <Widget>[
            new FloatingActionButton(
              elevation: 0.0,
              child: new Icon(Icons.check),
              backgroundColor: new Color(0xFFE57373),
              onPressed: (){}
            )
          ],
        )
      ],
    ), 
  );
}