FadeTransition class

Animates the opacity of a widget.

For a widget that automatically animates between the sizes of two children, fading between them, see AnimatedCrossFade.

Here's an illustration of the FadeTransition widget, with it's opacity animated by a CurvedAnimation set to Curves.fastOutSlowIn:

The following code implements the FadeTransition using the Flutter logo:

To create a local project with this code sample, run:
flutter create --sample=widgets.FadeTransition.1 mysample

Hit testing

Setting the opacity to zero does not prevent hit testing from being applied to the descendants of the FadeTransition widget. This can be confusing for the user, who may not see anything, and may believe the area of the interface where the FadeTransition is hiding a widget to be non-interactive.

With certain widgets, such as Flow, that compute their positions only when they are painted, this can actually lead to bugs (from unexpected geometry to exceptions), because those widgets are not painted by the FadeTransition widget at all when the opacity animation reaches zero.

To avoid such problems, it is generally a good idea to combine this widget with an IgnorePointer that one enables when the opacity animation reaches zero. This prevents interactions with any children in the subtree when the child is not visible. For performance reasons, when implementing this, care should be taken not to rebuild the relevant widget (e.g. by calling State.setState) except at the transition point.

See also:



FadeTransition({Key? key, required Animation<double> opacity, bool alwaysIncludeSemantics = false, Widget? child})
Creates an opacity transition.


alwaysIncludeSemantics bool
Whether the semantic information of the children is always included.
child Widget?
The widget below this widget in the tree.
hashCode int
The hash code for this object.
no setterinherited
key Key?
Controls how one widget replaces another widget in the tree.
opacity Animation<double>
The animation that controls the opacity of the child.
runtimeType Type
A representation of the runtime type of the object.
no setterinherited


createElement() SingleChildRenderObjectElement
RenderObjectWidgets always inflate to a RenderObjectElement subclass.
createRenderObject(BuildContext context) RenderAnimatedOpacity
Creates an instance of the RenderObject class that this RenderObjectWidget represents, using the configuration described by this RenderObjectWidget.
debugDescribeChildren() List<DiagnosticsNode>
Returns a list of DiagnosticsNode objects describing this node's children.
debugFillProperties(DiagnosticPropertiesBuilder properties) → void
Add additional properties associated with the node.
didUnmountRenderObject(covariant RenderObject renderObject) → void
A render object previously associated with this widget has been removed from the tree. The given RenderObject will be of the same type as returned by this object's createRenderObject.
noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
toDiagnosticsNode({String? name, DiagnosticsTreeStyle? style}) DiagnosticsNode
Returns a debug representation of the object that is used by debugging tools and by DiagnosticsNode.toStringDeep.
toString({DiagnosticLevel minLevel = DiagnosticLevel.info}) String
A string representation of this object.
toStringDeep({String prefixLineOne = '', String? prefixOtherLines, DiagnosticLevel minLevel = DiagnosticLevel.debug}) String
Returns a string representation of this node and its descendants.
toStringShallow({String joiner = ', ', DiagnosticLevel minLevel = DiagnosticLevel.debug}) String
Returns a one-line detailed description of the object.
toStringShort() String
A short, textual description of this widget.
updateRenderObject(BuildContext context, covariant RenderAnimatedOpacity renderObject) → void
Copies the configuration described by this RenderObjectWidget to the given RenderObject, which will be of the same type as returned by this object's createRenderObject.


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