AnimatedPositioned class

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

Only works if it's the child of a Stack.

This widget is a good choice if the size of the child would end up changing as a result of this animation. If the size is intended to remain the same, with only the position changing over time, then consider SlideTransition instead. SlideTransition only triggers a repaint each frame of the animation, whereas AnimatedPositioned will trigger a relayout as well.

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

For the animation, you can choose a curve as well as a duration and the widget will automatically animate to the new target position. If you require more control over the animation (e.g. if you want to stop it mid-animation), consider using a PositionedTransition instead, which takes a provided Animation as an argument. While that allows you to fine-tune the animation, it also requires more development overhead as you have to manually manage the lifecycle of the underlying AnimationController.

The following example transitions an AnimatedPositioned between two states. It adjusts the height, width, and Positioned properties when tapped.
link

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

See also:

Inheritance

Constructors

AnimatedPositioned({Key? key, required Widget child, double? left, double? top, double? right, double? bottom, double? width, double? height, Curve curve = Curves.linear, required Duration duration, VoidCallback? onEnd})
Creates a widget that animates its position implicitly.
const
AnimatedPositioned.fromRect({Key? key, required Widget child, required Rect rect, Curve curve = Curves.linear, required Duration duration, VoidCallback? onEnd})
Creates a widget that animates the rectangle it occupies implicitly.

Properties

bottom → double?
The offset of the child's bottom edge from the bottom of the stack.
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.
no setterinherited
height → double?
The child's height.
final
key → Key?
Controls how one widget replaces another widget in the tree.
finalinherited
left → double?
The offset of the child's left edge from the left of the stack.
final
onEnd → VoidCallback?
Called every time an animation completes.
finalinherited
The offset of the child's right edge from the right of the stack.
final
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited
top → double?
The offset of the child's top edge from the top of the stack.
final
width → double?
The child's width.
final

Methods

createElement() → StatefulElement
Creates a StatefulElement to manage this widget's location in the tree.
inherited
createState() → AnimatedWidgetBaseState<AnimatedPositioned>
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.
inherited
debugFillProperties(DiagnosticPropertiesBuilder properties) → void
Add additional properties associated with the node.
override
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}) → 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