CompositedTransformFollower 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 causes it to provide its child with a coordinate space that matches that of the linked CompositedTransformTarget widget, offset by offset.

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:



CompositedTransformFollower({Key key, @required LayerLink link, bool showWhenUnlinked: true, Offset offset:, Widget child })
Creates a composited transform target widget. [...]


The link object that connects this CompositedTransformFollower with a CompositedTransformTarget. [...]
offset Offset
The offset to apply to the origin of the linked CompositedTransformTarget to obtain this widget's origin.
showWhenUnlinked bool
Whether to show the widget's contents when there is no corresponding CompositedTransformTarget with the same link. [...]
child Widget
The widget below this widget in the tree. [...]
final, inherited
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


createRenderObject(BuildContext context) RenderFollowerLayer
Creates an instance of the RenderObject class that this RenderObjectWidget represents, using the configuration described by this RenderObjectWidget. [...]
updateRenderObject(BuildContext context, covariant RenderFollowerLayer 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. [...]
createElement() SingleChildRenderObjectElement
RenderObjectWidgets always inflate to a RenderObjectElement subclass.
debugDescribeChildren() List<DiagnosticsNode>
Returns a list of DiagnosticsNode objects describing this node's children. [...]
@protected, inherited
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.
@protected, inherited
noSuchMethod(Invocation invocation) → dynamic
Invoked when a non-existent 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.debug }) String
Returns 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.


operator ==(dynamic other) bool
The equality operator. [...]