constraints property

BoxConstraints constraints

Optional size constraints for the button.

When unspecified, defaults to:

const BoxConstraints(
  minWidth: kMinInteractiveDimension,
  minHeight: kMinInteractiveDimension,

where kMinInteractiveDimension is 48.0, and then with visual density applied.

The default constraints ensure that the button is accessible. Specifying this parameter enables creation of buttons smaller than the minimum size, but it is not recommended.

The visual density uses the visualDensity parameter if specified, and Theme.of(context).visualDensity otherwise.


final BoxConstraints constraints