Flutter ButtonRow padding

Question

I am developing an app in Flutter with Dart and am generally finding layout quite straightforward. However, I am running into a problem which I think is related to default padding between widgets.

I have two flutter ButtonRows in a Column which render with a quite large gap between them which I would like to eliminate. I guess it is caused by padding and have tried various approaches with no success so far. An extract from the code is as follows:

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      ...
      body: new Column(
        ...
        children: <Widget>[
          ...
          new Container(
            margin: new EdgeInsets.all(0.0),
            child: new Padding(
              padding: new EdgeInsets.all(0.0),
              child: new ButtonBar(
                ...
                children: <Widget>[
                  new MaterialButton(
                    ...
                  ),
                  new MaterialButton(
                    ...
                  ),
                ),
              ),
            ),
          ),
          new Container(
            margin: new EdgeInsets.all(0.0),
            child: new Padding(
              padding: new EdgeInsets.all(0.0),
              child: new ButtonBar(
                ...
                children: <Widget>[
                  new MaterialButton(
                    ...
                  ),
                  new MaterialButton(
                    ...
                  ),
                ],
              ),
            ),
          ),
        ],
      ),
    );
  }

Answer 1

You have different ways to customize buttons:

• customize ButtonTheme for ButtonBar
• use Row instead of ButtonBar
• implement your own button via InkWell
• etc

What to use depends on your cases/requirements. Here quick example of different ways:

class ButtonRowWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(
        title: new Text("Buttons"),
      ),
      body: new Column(mainAxisSize: MainAxisSize.min, children: <Widget>[
        new Container(
          child: new Text("widget ButtonBar:"),
          margin: new EdgeInsets.fromLTRB(0.0, 10.0, 0.0, 10.0),
        ),
        new ButtonBar(children: <Widget>[
          new FlatButton(
            child: new Text("Button 1"),
            onPressed: () => debugPrint("Button 1"),
          ),
          new FlatButton(
            child: new Text("Button 2"),
            onPressed: () => debugPrint("Button 2"),
          )
        ]),
        new Container(
          child: new Text("widget ButtonBar with custom ButtomTheme:"),
          margin: new EdgeInsets.fromLTRB(0.0, 10.0, 0.0, 10.0),
        ),
        new ButtonTheme(
          minWidth: 44.0,
          padding: new EdgeInsets.all(0.0),
          child: new ButtonBar(children: <Widget>[
            new FlatButton(
              child: new Text("Button 1"),
              onPressed: () => debugPrint("Button 1"),
            ),
            new FlatButton(
              child: new Text("Button 2"),
              onPressed: () => debugPrint("Button 2"),
            ),
          ]),
        ),
        new Container(
          child: new Text("widget Row with FlatButton:"),
          margin: new EdgeInsets.fromLTRB(0.0, 10.0, 0.0, 10.0),
        ),
        new Row(
          children: <Widget>[
            new FlatButton(
              child: new Text("Button 1"),
              onPressed: () => debugPrint("Button 1"),
            ),
            new FlatButton(
              child: new Text("Button 2"),
              onPressed: () => debugPrint("Button 2"),
            ),
          ],
        ),
        new Container(
          child: new Text("widget Row with InkWell"),
          margin: new EdgeInsets.fromLTRB(0.0, 10.0, 0.0, 10.0),
        ),
        new Row(
          children: <Widget>[
            new InkWell(
              child: new Text("Button 1"),
              onTap: () => debugPrint("Button 1"),
            ),
            new InkWell(
              child: new Text("Button 2"),
              onTap: () => debugPrint("Button 2"),
            ),
          ],
        )
      ]),
    );
  }
}

Debug paint can be helpful in this case.

Answer 2

Also, the ButtonBar itself has a buttonPadding attribute that you can customize.

Overrides the surrounding ButtonThemeData.padding to define the padding for a button's child (typically the button's label).

If null then it will use the surrounding ButtonBarTheme.buttonPadding. If that is null, it will default to 8.0 logical pixels on the left and right.

---

ButtonBar(
  buttonPadding: EdgeInsets.all(0),
  children: <Widget>[
    FlatButton(
      child: Text('Hello'),
      onPressed: () => print(),
      materialTapTargetSize: MaterialTapTargetSize.shrinkWrap,
    ),
  ],
),