AnimatedWidget class abstract

A widget that rebuilds when the given Listenable changes value.

AnimatedWidget is most commonly used with Animation objects, which are Listenable, but it can be used with any Listenable, including ChangeNotifier and ValueNotifier.

AnimatedWidget is most useful for widgets that are otherwise stateless. To use AnimatedWidget, subclass it and implement the build function.

For more complex case involving additional state, consider using AnimatedBuilder or ListenableBuilder.

Relationship to ImplicitlyAnimatedWidgets

AnimatedWidgets (and their subclasses) take an explicit Listenable as argument, which is usually an Animation derived from an AnimationController. In most cases, the lifecycle of that AnimationController has to be managed manually by the developer. In contrast to that, ImplicitlyAnimatedWidgets (and their subclasses) automatically manage their own internal AnimationController making those classes easier to use as no external Animation has to be provided by the developer. If you only need to set a target value for the animation and configure its duration/curve, consider using (a subclass of) ImplicitlyAnimatedWidgets instead of (a subclass of) this class.

Common animated widgets

A number of animated widgets ship with the framework. They are usually named FooTransition, where Foo is the name of the non-animated version of that widget. The subclasses of this class should not be confused with subclasses of ImplicitlyAnimatedWidget (see above), which are usually named AnimatedFoo. Commonly used animated widgets include:

• ListenableBuilder, which uses a builder pattern that is useful for complex Listenable use cases.
• AnimatedBuilder, which uses a builder pattern that is useful for complex Animation use cases.
• AlignTransition, which is an animated version of Align.
• DecoratedBoxTransition, which is an animated version of DecoratedBox.
• DefaultTextStyleTransition, which is an animated version of DefaultTextStyle.
• PositionedTransition, which is an animated version of Positioned.
• RelativePositionedTransition, which is an animated version of Positioned.
• RotationTransition, which animates the rotation of a widget.
• ScaleTransition, which animates the scale of a widget.
• SizeTransition, which animates its own size.
• SlideTransition, which animates the position of a widget relative to its normal position.
• FadeTransition, which is an animated version of Opacity.
• AnimatedModalBarrier, which is an animated version of ModalBarrier.