CompositedTransformFollowerModifier class

A widget that follows a CompositedTransformTarget.

When this widget is composited during the compositing phase (which comes after the paint phase, as described in WidgetsBinding.drawFrame), it applies a transformation that brings targetAnchor of the linked CompositedTransformTarget and followerAnchor of this widget together. The two anchor points will have the same global coordinates, unless offset is not Offset.zero, in which case followerAnchor will be offset by offset in the linked CompositedTransformTarget's coordinate space.

The LayerLink object used as the link must be the same object as that provided to the matching CompositedTransformTarget.

The CompositedTransformTarget must come earlier in the paint order than this CompositedTransformFollower.

Hit testing on descendants of this widget will only work if the target position is within the box that this widget's parent considers to be hittable. If the parent covers the screen, this is trivially achievable, so this widget is usually used as the root of an OverlayEntry in an app-wide Overlay (e.g. as created by the MaterialApp widget's Navigator).

See also:

• CompositedTransformTarget, the widget that this widget can target.
• FollowerLayer, the layer that implements this widget's logic.
• Transform, which applies an arbitrary transform to a child.

Inheritance

• Object
• DiagnosticableTree
• Widget
• StatelessWidget
• SingleChildStatelessModifier
• CompositedTransformFollowerModifier

Available extensions

• ModifierTransformer

Constructors

CompositedTransformFollowerModifier({Key? key, Widget? child, Key? modifierKey, required LayerLink link, bool showWhenUnlinked = true, Offset offset = Offset.zero, Alignment targetAnchor = Alignment.topLeft, Alignment followerAnchor = Alignment.topLeft})

Creates a composited transform target widget.

const

Properties

followerAnchor → Alignment

The anchor point on this widget that will line up with followerAnchor on the linked CompositedTransformTarget.

final

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

link → LayerLink

The link object that connects this CompositedTransformFollower with a CompositedTransformTarget.

final

modifierKey → Key?

The actual key of the widget, which Modifier wrapped

final, inherited

offset → Offset

The additional offset to apply to the targetAnchor of the linked CompositedTransformTarget to obtain this widget's followerAnchor position.

final

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

showWhenUnlinked → bool

Whether to show the widget's contents when there is no corresponding CompositedTransformTarget with the same link.

final

targetAnchor → Alignment

The anchor point on the linked CompositedTransformTarget that followerAnchor will line up with.

final

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

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