Preview class base

Annotation used to mark functions that return a widget preview.

NOTE: this interface is not stable and will change.

Functions annotated with @Preview() must return a Widget or WidgetBuilder and be public. This annotation can only be applied to top-level functions, static methods defined within a class, and public Widget constructors and factories with no required arguments.
link 
@Preview(name: 'Top-level preview')
Widget preview() => const Text('Foo');

@Preview(name: 'Builder preview')
WidgetBuilder builderPreview() {
  return (BuildContext context) {
    return const Text('Builder');
  };
}

class MyWidget extends StatelessWidget {
  @Preview(name: 'Constructor preview')
  const MyWidget.preview({super.key});

  @Preview(name: 'Factory constructor preview')
  factory MyWidget.factoryPreview() => const MyWidget.preview();

  @Preview(name: 'Static preview')
  static Widget previewStatic() => const Text('Static');

  @override
  Widget build(BuildContext context) {
    return const Text('MyWidget');
  }
}

Important Note: all values provided to the @Preview() annotation must be constant, and callback parameters must also be static and non-private. These restrictions do not apply when creating instances of Preview at runtime, including within Preview.transform().

See also:

Constructors

Preview({String group = 'Default', String? name, Size? size, double? textScaleFactor, WidgetWrapper? wrapper, PreviewTheme? theme, Brightness? brightness, PreviewLocalizations? localizations})
Annotation used to mark functions that return widget previews.
const

Properties

brightness → Brightness?
Sets the initial theme brightness.
final
group → String
The group the preview belongs to.
final
hashCode → int
The hash code for this object.
no setterinherited
localizations → PreviewLocalizations?
A callback to return a localization configuration to be applied to the previewed Widget.
final
name → String?
A description to be displayed alongside the preview.
final
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited
size → Size?
Artificial constraints to be applied to the previewed widget.
final
textScaleFactor → double?
Applies font scaling to text within the previewed widget.
final
theme → PreviewTheme?
A callback to return Material and Cupertino theming data to be applied to the previewed Widget.
final
wrapper → WidgetWrapper?
Wraps the previewed Widget in a Widget tree.
final

Methods

noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
inherited
toBuilder() → PreviewBuilder
Creates a PreviewBuilder initialized with the values set in this preview.
toString() → String
A string representation of this object.
inherited
transform() → Preview
Applies a transformation to the current Preview.

Operators

operator ==(Object other) → bool
The equality operator.
inherited