Added CupertinoButton alignment property

[HansMuller]

Added an AlignmentGeometry valued alignment property to CupertinoButton which defines how the button's child is aligned within the available space. This generally only applies with the button size is constrained to have a different size than it would have by default.

The following example constrains the width of 3 buttons to be 300. Their alignment parameter is center (same as the default), centerRight, and centerLeft.

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';

class Home extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return CupertinoPageScaffold(
      child: Center(
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: <Widget>[
            SizedBox(
              width: 300,
              child: CupertinoButton.filled(
                alignment: Alignment.center,
                padding: EdgeInsets.all(16),
                onPressed: () { },
                child: Text('center'),
              ),
            ),
            SizedBox(height: 16),
            SizedBox(
              width: 300,
              child: CupertinoButton.filled(
                alignment: Alignment.centerRight,
                padding: EdgeInsets.all(16),
                onPressed: () { },
                child: Text('centerRight'),
              ),
            ),
            SizedBox(height: 16),
            SizedBox(
              width: 300,
              child: CupertinoButton.filled(
                alignment: Alignment.centerLeft,
                padding: EdgeInsets.all(16),
                onPressed: () { },
                child: Text('centerLeft'),
              ),
            ),
          ],
        ),
      ),
    );
  }
}

void main() {
  runApp(CupertinoApp(home: Home()));
}

[justinmc]

LGTM 👍

[justinmc]

Is this indentation correct?

[HansMuller]

Good point, fixed that.