AnimatedSwitcher class
A widget that by default does a cross-fade between a new widget and the widget previously set on the AnimatedSwitcher as a child.
If they are swapped fast enough (i.e. before duration elapses), more than one previous child can exist and be transitioning out while the newest one is transitioning in.
If the "new" child is the same widget type and key as the "old" child, but with different parameters, then AnimatedSwitcher will not do a transition between them, since as far as the framework is concerned, they are the same widget and the existing widget can be updated with the new parameters. To force the transition to occur, set a Key on each child widget that you wish to be considered unique (typically a ValueKey on the widget data that distinguishes this child from the others).
The same key can be used for a new child as was used for an already-outgoing child; the two will not be considered related. (For example, if a progress indicator with key A is first shown, then an image with key B, then another progress indicator with key A again, all in rapid succession, then the old progress indicator and the image will be fading out while a new progress indicator is fading in.)
The type of transition can be changed from a cross-fade to a custom transition by setting the transitionBuilder.
To create a local project with this code sample, run:
flutter create --sample=widgets.AnimatedSwitcher.1 mysample
See also:
- AnimatedCrossFade, which only fades between two children, but also interpolates their sizes, and is reversible.
- AnimatedOpacity, which can be used to switch between nothingness and a given child by fading the child in and out.
- FadeTransition, which AnimatedSwitcher uses to perform the transition.
- Inheritance
-
- Object
- DiagnosticableTree
- Widget
- StatefulWidget
- AnimatedSwitcher
Constructors
- AnimatedSwitcher({Key? key, Widget? child, required Duration duration, Duration? reverseDuration, Curve switchInCurve = Curves.linear, Curve switchOutCurve = Curves.linear, AnimatedSwitcherTransitionBuilder transitionBuilder = AnimatedSwitcher.defaultTransitionBuilder, AnimatedSwitcherLayoutBuilder layoutBuilder = AnimatedSwitcher.defaultLayoutBuilder})
-
Creates an AnimatedSwitcher.
const
Properties
- child → Widget?
-
The current child widget to display. If there was a previous child, then
that child will be faded out using the switchOutCurve, while the new
child is faded in with the switchInCurve, over the duration.
final
- duration → Duration
-
The duration of the transition from the old child value to the new one.
final
- hashCode → int
-
The hash code for this object.
no setterinherited
- key → Key?
-
Controls how one widget replaces another widget in the tree.
finalinherited
- layoutBuilder → AnimatedSwitcherLayoutBuilder
-
A function that wraps all of the children that are transitioning out, and
the child that's transitioning in, with a widget that lays all of them
out. This is called every time this widget is built. The function must not
return null.
final
- reverseDuration → Duration?
-
The duration of the transition from the new child value to the old one.
final
- runtimeType → Type
-
A representation of the runtime type of the object.
no setterinherited
- switchInCurve → Curve
-
The animation curve to use when transitioning in a new child.
final
- switchOutCurve → Curve
-
The animation curve to use when transitioning a previous child out.
final
- transitionBuilder → AnimatedSwitcherTransitionBuilder
-
A function that wraps a new child with an animation that transitions
the child in when the animation runs in the forward direction and out
when the animation runs in the reverse direction. This is only called
when a new child is set (not for each build), or when a new
transitionBuilder is set. If a new transitionBuilder is set, then
the transition is rebuilt for the current child and all previous children
using the new transitionBuilder. The function must not return null.
final
Methods
-
createElement(
) → StatefulElement -
Creates a StatefulElement to manage this widget's location in the tree.
inherited
-
createState(
) → State< AnimatedSwitcher> -
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, 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
Static Methods
-
defaultLayoutBuilder(
Widget? currentChild, List< Widget> previousChildren) → Widget - The layout builder used as the default value of layoutBuilder.
-
defaultTransitionBuilder(
Widget child, Animation< double> animation) → Widget - The transition builder used as the default value of transitionBuilder.