AnimatedOpacityModifier class

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.

{@tool snippet}

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'),
        ),
      ],
    );
  }
}

{@end-tool}

See also:

• AnimatedCrossFade, for fading between two children.
• AnimatedSwitcher, for fading between many children in sequence.
• FadeTransition, an explicitly animated version of this widget, where an Animation is provided by the caller instead of being built in.
• SliverAnimatedOpacity, for automatically transitioning a sliver's opacity over a given duration whenever the given opacity changes.

Inheritance

• Object
• DiagnosticableTree
• Widget
• StatelessWidget
• SingleChildStatelessModifier
• SingleChildImplicitlyAnimatedModifier
• AnimatedOpacityModifier

Available extensions

• ModifierTransformer

Constructors

AnimatedOpacityModifier({Key? key, Widget? child, Curve curve = Curves.linear, required Duration duration, VoidCallback? onEnd, Key? modifierKey, required double opacity, 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

curve → Curve

The curve to apply when animating the parameters of this container.

final, inherited

duration → Duration

The duration over which to animate the parameters of this container.

final, inherited

hashCode → int

The hash code for this object.

no setter, inherited

key → Key?

Controls how one widget replaces another widget in the tree.

final, inherited

modifierKey → Key?

The actual key of the widget, which Modifier wrapped

final, inherited

onEnd → VoidCallback?

Called every time an animation completes.

final, inherited

opacity → double

The target opacity.

final

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

Methods

build(BuildContext context) → Widget

Describes the part of the user interface represented by this widget.

inherited

buildWithChild(BuildContext context, Widget? child) → Widget

A build method that receives an extra child parameter.

override

createElement() → SingleChildStatelessElement

Create a SingleChildStatelessElement

inherited

debugDescribeChildren() → List<DiagnosticsNode>

Returns a list of DiagnosticsNode objects describing this node's children.

inherited

debugFillProperties(DiagnosticPropertiesBuilder properties) → void

Add additional properties associated with the node.

inherited

modified() → Modifier

Available on Widget, provided by the ModifierTransformer extension

Transform normal widget to Modifier

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent 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, int wrapWidth = 65}) → 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.

inherited