IconButton constructor Null safety

const IconButton(
  1. {Key? key,
  2. double iconSize,
  3. VisualDensity? visualDensity,
  4. EdgeInsetsGeometry padding,
  5. AlignmentGeometry alignment,
  6. double? splashRadius,
  7. Color? color,
  8. Color? focusColor,
  9. Color? hoverColor,
  10. Color? highlightColor,
  11. Color? splashColor,
  12. Color? disabledColor,
  13. required VoidCallback? onPressed,
  14. MouseCursor mouseCursor,
  15. FocusNode? focusNode,
  16. bool autofocus,
  17. String? tooltip,
  18. bool enableFeedback,
  19. BoxConstraints? constraints,
  20. required Widget icon}
)

Creates an icon button.

Icon buttons are commonly used in the AppBar.actions field, but they can be used in many other places as well.

Requires one of its ancestors to be a Material widget.

The iconSize, padding, autofocus, and alignment arguments must not be null (though they each have default values).

The icon argument must be specified, and is typically either an Icon or an ImageIcon.

Implementation

const IconButton({
  Key? key,
  this.iconSize = 24.0,
  this.visualDensity,
  this.padding = const EdgeInsets.all(8.0),
  this.alignment = Alignment.center,
  this.splashRadius,
  this.color,
  this.focusColor,
  this.hoverColor,
  this.highlightColor,
  this.splashColor,
  this.disabledColor,
  required this.onPressed,
  this.mouseCursor = SystemMouseCursors.click,
  this.focusNode,
  this.autofocus = false,
  this.tooltip,
  this.enableFeedback = true,
  this.constraints,
  required this.icon,
}) : assert(iconSize != null),
     assert(padding != null),
     assert(alignment != null),
     assert(splashRadius == null || splashRadius > 0),
     assert(autofocus != null),
     assert(icon != null),
     super(key: key);