FollowerLayer class
A composited layer that applies a transformation matrix to its children such that they are positioned to match a LeaderLayer.
If any of the ancestors of this layer have a degenerate matrix (e.g. scaling by zero), then the FollowerLayer will not be able to transform its child to the coordinate space of the LeaderLayer.
A linkedOffset property can be provided to further offset the child layer from the leader layer, for example if the child is to follow the linked layer at a distance rather than directly overlapping it.
- Inheritance
-
- Object
- Layer
- ContainerLayer
- FollowerLayer
Constructors
- FollowerLayer({required LayerLink link, bool? showWhenUnlinked = true, Offset? unlinkedOffset = Offset.zero, Offset? linkedOffset = Offset.zero})
- Creates a follower layer.
Properties
- alwaysNeedsAddToScene → bool
-
This disables retained rendering.
no setteroverride
- attached → bool
-
Whether the layer tree containing this layer is attached to an owner.
no setterinherited
- debugCreator ↔ Object?
-
The object responsible for creating this layer.
getter/setter pairinherited
- debugDisposed → bool
-
If asserts are enabled, returns whether dispose has
been called since the last time any retained resources were created.
no setterinherited
- debugHandleCount → int
-
Returns the number of objects holding a LayerHandle to this layer.
no setterinherited
- debugSubtreeNeedsAddToScene → bool?
-
Whether this or any descendant layer in the subtree needs addToScene.
no setterinherited
- depth → int
-
The depth of this layer in the layer tree.
no setterinherited
- engineLayer ↔ EngineLayer?
-
Stores the engine layer created for this layer in order to reuse engine
resources across frames for better app performance.
getter/setter pairinherited
- firstChild → Layer?
-
The first composited layer in this layer's child list.
no setterinherited
- hasChildren → bool
-
Returns whether this layer has at least one child layer.
no setterinherited
- hashCode → int
-
The hash code for this object.
no setterinherited
- lastChild → Layer?
-
The last composited layer in this layer's child list.
no setterinherited
- link ↔ LayerLink
-
The link to the LeaderLayer.
getter/setter pair
- linkedOffset ↔ Offset?
-
Offset from the origin of the leader layer to the origin of the child
layers, used when the layer is linked to a LeaderLayer.
getter/setter pair
- nextSibling → Layer?
-
This layer's next sibling in the parent layer's child list.
no setterinherited
- owner → Object?
-
The owner for this layer (null if unattached).
no setterinherited
- parent → ContainerLayer?
-
This layer's parent in the layer tree.
no setterinherited
- previousSibling → Layer?
-
This layer's previous sibling in the parent layer's child list.
no setterinherited
- runtimeType → Type
-
A representation of the runtime type of the object.
no setterinherited
- showWhenUnlinked ↔ bool?
-
Whether to show the layer's contents when the link does not point to a
LeaderLayer.
getter/setter pair
- subtreeHasCompositionCallbacks → bool
-
Whether the subtree rooted at this layer has any composition callback
observers.
no setterinherited
- unlinkedOffset ↔ Offset?
-
Offset from parent in the parent's coordinate system, used when the layer
is not linked to a LeaderLayer.
getter/setter pair
Methods
-
addChildrenToScene(
SceneBuilder builder) → void -
Uploads all of this layer's children to the engine.
inherited
-
addCompositionCallback(
CompositionCallback callback) → VoidCallback -
Adds a callback for when the layer tree that this layer is part of gets
composited, or when it is detached and will not be rendered again.
inherited
-
addToScene(
SceneBuilder builder) → void -
Override this method to upload this layer to the engine.
override
-
append(
Layer child) → void -
Adds the given layer to the end of this layer's child list.
inherited
-
applyTransform(
Layer? child, Matrix4 transform) → void -
Applies the transform that would be applied when compositing the given
child to the given matrix.
override
-
attach(
covariant Object owner) → void -
Mark this layer as attached to the given owner.
inherited
-
buildScene(
SceneBuilder builder) → Scene -
Consider this layer as the root and build a scene (a tree of layers)
in the engine.
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.
override
-
debugMarkClean(
) → void -
Mark that this layer is in sync with engine.
inherited
-
depthFirstIterateChildren(
) → List< Layer> -
Returns the descendants of this layer in depth first order.
inherited
-
describeClipBounds(
) → Rect? -
Describes the clip that would be applied to contents of this layer,
if any.
inherited
-
detach(
) → void -
Mark this layer as detached from its owner.
inherited
-
dispose(
) → void -
Clears any retained resources that this layer holds.
inherited
-
find<
S extends Object> (Offset localPosition) → S? -
Search this layer and its subtree for the first annotation of type
Sunder the point described bylocalPosition.inherited -
findAllAnnotations<
S extends Object> (Offset localPosition) → AnnotationResult< S> -
Search this layer and its subtree for all annotations of type
Sunder the point described bylocalPosition.inherited -
findAnnotations<
S extends Object> (AnnotationResult< S> result, Offset localPosition, {required bool onlyFirst}) → bool -
Search this layer and its subtree for annotations of type
Sat the location described bylocalPosition.override -
getLastTransform(
) → Matrix4? - The transform that was used during the last composition phase.
-
markNeedsAddToScene(
) → void -
Mark that this layer has changed and addToScene needs to be called.
inherited
-
noSuchMethod(
Invocation invocation) → dynamic -
Invoked when a nonexistent method or property is accessed.
inherited
-
redepthChild(
Layer child) → void -
Adjust the depth of the given
childto be greater than this node's own depth.inherited -
redepthChildren(
) → void -
Adjust the depth of this node's children, if any.
inherited
-
remove(
) → void -
Removes this layer from its parent layer's child list.
inherited
-
removeAllChildren(
) → void -
Removes all of this layer's children from its child list.
inherited
-
supportsRasterization(
) → bool -
Whether or not this layer, or any child layers, can be rasterized with
ui.Scene.toImage or ui.Scene.toImageSync.
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 brief description of this object, usually just the runtimeType and the
hashCode.
inherited
-
updateSubtreeNeedsAddToScene(
) → void -
Traverses the layer subtree starting from this layer and determines whether it needs addToScene.
inherited
Operators
-
operator ==(
Object other) → bool -
The equality operator.
inherited