AnimatedCrossFade class

A widget that cross-fades between two given children and animates itself between their sizes.

The animation is controlled through the crossFadeState parameter. firstCurve and secondCurve represent the opacity curves of the two children. The firstCurve is inverted, i.e. it fades out when providing a growing curve like Curves.linear. The sizeCurve is the curve used to animate between the size of the fading-out child and the size of the fading-in child.

This widget is intended to be used to fade a pair of widgets with the same width. In the case where the two children have different heights, the animation crops overflowing children during the animation by aligning their top edge, which means that the bottom will be clipped.

The animation is automatically triggered when an existing AnimatedCrossFade is rebuilt with a different value for the crossFadeState property.

This code fades between two representations of the Flutter logo. It depends on a boolean field _first; when _first is true, the first logo is shown, otherwise the second logo is shown. When the field changes state, the AnimatedCrossFade widget cross-fades between the two forms of the logo over three seconds.

AnimatedCrossFade(
  duration: const Duration(seconds: 3),
  firstChild: const FlutterLogo(style: FlutterLogoStyle.horizontal, size: 100.0),
  secondChild: const FlutterLogo(style: FlutterLogoStyle.stacked, size: 100.0),
  crossFadeState: _first ? CrossFadeState.showFirst : CrossFadeState.showSecond,
)

Constructors

AnimatedCrossFade({Key key, @required Widget firstChild, @required Widget secondChild, Curve firstCurve: Curves.linear, Curve secondCurve: Curves.linear, Curve sizeCurve: Curves.linear, AlignmentGeometry alignment: Alignment.topCenter, @required CrossFadeState crossFadeState, @required Duration duration, AnimatedCrossFadeBuilder layoutBuilder: defaultLayoutBuilder }): Creates a cross-fade animation widget. [...]
const

Properties

alignment → AlignmentGeometry: How the children should be aligned while the size is animating. [...]
final
crossFadeState → CrossFadeState: The child that will be shown when the animation has completed.
final
duration → Duration: The duration of the whole orchestrated animation.
final
firstChild → Widget: The child that is visible when crossFadeState is CrossFadeState.showFirst. It fades out when transitioning crossFadeState from CrossFadeState.showFirst to CrossFadeState.showSecond and vice versa.
final
firstCurve → Curve: The fade curve of the first child. [...]
final
layoutBuilder → AnimatedCrossFadeBuilder: A builder that positions the firstChild and secondChild widgets. [...]
final
secondChild → Widget: The child that is visible when crossFadeState is CrossFadeState.showSecond. It fades in when transitioning crossFadeState from CrossFadeState.showFirst to CrossFadeState.showSecond and vice versa.
final
secondCurve → Curve: The fade curve of the second child. [...]
final
sizeCurve → Curve: The curve of the animation between the two children's sizes. [...]
final
hashCode → int: The hash code for this object. [...]
read-only, inherited
key → Key: Controls how one widget replaces another widget in the tree. [...]
final, inherited
runtimeType → Type: A representation of the runtime type of the object.
read-only, inherited

Methods

createState() → _AnimatedCrossFadeState: Creates the mutable state for this widget at a given location in the tree. [...]
override
debugFillProperties(DiagnosticPropertiesBuilder properties) → void: Add additional properties associated with the node. [...]
override
createElement() → StatefulElement: Creates a StatefulElement to manage this widget's location in the tree. [...]
inherited
debugDescribeChildren() → List<DiagnosticsNode>: Returns a list of DiagnosticsNode objects describing this node's children. [...]
@protected, inherited
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 toStringDeep. [...]
inherited
toString({DiagnosticLevel minLevel: DiagnosticLevel.debug }) → String: Returns 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 ==(dynamic other) → bool: The equality operator. [...]
inherited

Static Methods

defaultLayoutBuilder(Widget topChild, Key topChildKey, Widget bottomChild, Key bottomChildKey) → Widget: The default layout algorithm used by AnimatedCrossFade. [...]