AnimatedOpacity class Null safety

Animated version of Opacity which automatically transitions the child's opacity over a given duration whenever the given opacity changes.

Animating an opacity is relatively expensive because it requires painting the child into an intermediate buffer.

Here's an illustration of what using this widget looks like, using a curve of Curves.fastOutSlowIn.

link 
class LogoFade extends StatefulWidget {
  const LogoFade({super.key});

  @override
  State<LogoFade> createState() => LogoFadeState();
}

class LogoFadeState extends State<LogoFade> {
  double opacityLevel = 1.0;

  void _changeOpacity() {
    setState(() => opacityLevel = opacityLevel == 0 ? 1.0 : 0.0);
  }

  @override
  Widget build(BuildContext context) {
    return Column(
      mainAxisAlignment: MainAxisAlignment.center,
      children: <Widget>[
        AnimatedOpacity(
          opacity: opacityLevel,
          duration: const Duration(seconds: 3),
          child: const FlutterLogo(),
        ),
        ElevatedButton(
          onPressed: _changeOpacity,
          child: const Text('Fade Logo'),
        ),
      ],
    );
  }
}

See also:

Inheritance

Constructors

AnimatedOpacity({Key? key, Widget? child, required double opacity, Curve curve = Curves.linear, required Duration duration, VoidCallback? onEnd, bool alwaysIncludeSemantics = false})
Creates a widget that animates its opacity implicitly.
const

Properties

alwaysIncludeSemantics → bool
Whether the semantic information of the children is always included.
final
child → Widget?
The widget below this widget in the tree.
final
curve → Curve
The curve to apply when animating the parameters of this container.
finalinherited
duration → Duration
The duration over which to animate the parameters of this container.
finalinherited
hashCode → int
The hash code for this object.
nonVirtual">@nonVirtualread-onlyinherited
key → Key?
Controls how one widget replaces another widget in the tree.
finalinherited
onEnd → VoidCallback?
Called every time an animation completes.
finalinherited
opacity → double
The target opacity.
final
runtimeType → Type
A representation of the runtime type of the object.
read-onlyinherited

Methods

createElement() → StatefulElement
Creates a StatefulElement to manage this widget's location in the tree.
inherited
createState() → ImplicitlyAnimatedWidgetState<AnimatedOpacity>
Creates the mutable state for this widget at a given location in the tree.
override
debugDescribeChildren() → List<DiagnosticsNode>
Returns a list of DiagnosticsNode objects describing this node's children.
protected">@protectedinherited
debugFillProperties(DiagnosticPropertiesBuilder properties) → void
Add additional properties associated with the node.
override
noSuchMethod(Invocation invocation) → dynamic
Invoked when a non-existent method or property is accessed.
inherited
toDiagnosticsNode({String? name, DiagnosticsTreeStyle? style}) → DiagnosticsNode
Returns a debug representation of the object that is used by debugging tools and by DiagnosticsNode.toStringDeep.
inherited
toString({DiagnosticLevel minLevel = DiagnosticLevel.info}) → String
A string representation of this object.
inherited
toStringDeep({String prefixLineOne = '', String? prefixOtherLines, DiagnosticLevel minLevel = DiagnosticLevel.debug}) → String
Returns a string representation of this node and its descendants.
inherited
toStringShallow({String joiner = ', ', DiagnosticLevel minLevel = DiagnosticLevel.debug}) → String
Returns a one-line detailed description of the object.
inherited
toStringShort() → String
A short, textual description of this widget.
inherited

Operators

operator ==(Object other) → bool
The equality operator.
nonVirtual">@nonVirtualinherited