AnnotationLayer<T> class

A rendering layer for annotations in the node flow editor.

This widget serves as a rendering layer that displays annotations on the canvas. It automatically:

  • Observes annotation changes via MobX for reactive updates
  • Sorts annotations by z-index for proper layering
  • Applies filtering to show specific annotation types
  • Handles selection and highlight visual feedback
  • Wires gesture callbacks to individual AnnotationWidget instances
  • Uses RepaintBoundary for optimized rendering

Layer Architecture

The node flow editor typically uses two annotation layers:

  1. Background layer: Renders GroupAnnotations behind nodes
  2. Foreground layer: Renders sticky notes and markers above connections

Example Usage

// Background layer for groups
AnnotationLayer<MyNodeData>.background(controller)

// Foreground layer for stickies and markers
AnnotationLayer<MyNodeData>.foreground(controller)

// Custom filtered layer
AnnotationLayer<MyNodeData>(
  controller: controller,
  filter: (annotation) => annotation is StickyAnnotation,
)

See also:

Inheritance
Available extensions

Constructors

AnnotationLayer({Key? key, required NodeFlowController<T> controller, bool filter(Annotation)?, void onAnnotationTap(Annotation annotation)?, void onAnnotationDoubleTap(Annotation annotation)?, void onAnnotationContextMenu(Annotation annotation, Offset globalPosition)?, void onAnnotationMouseEnter(Annotation annotation)?, void onAnnotationMouseLeave(Annotation annotation)?})
Creates an annotation layer.
const

Properties

controller → NodeFlowController<T>
The node flow controller managing the annotations.
final
filter → bool Function(Annotation)?
Optional filter to determine which annotations to render.
final
hashCode → int
The hash code for this object.
no setterinherited
key → Key?
Controls how one widget replaces another widget in the tree.
finalinherited
onAnnotationContextMenu → void Function(Annotation annotation, Offset globalPosition)?
Callback invoked when an annotation is right-clicked (context menu).
final
onAnnotationDoubleTap → void Function(Annotation annotation)?
Callback invoked when an annotation is double-tapped.
final
onAnnotationMouseEnter → void Function(Annotation annotation)?
Callback invoked when mouse enters an annotation.
final
onAnnotationMouseLeave → void Function(Annotation annotation)?
Callback invoked when mouse leaves an annotation.
final
onAnnotationTap → void Function(Annotation annotation)?
Callback invoked when an annotation is tapped.
final
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited

Methods

build(BuildContext context) → Widget
Describes the part of the user interface represented by this widget.
override
createElement() → StatelessElement
Creates a StatelessElement to manage this widget's location in the tree.
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, 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
withAnnotationLayer(NodeFlowController<T> controller) → Widget

Available on Widget, provided by the AnnotationLayerSupport extension

Wraps this widget with an annotation layer.

Operators

operator ==(Object other) → bool
The equality operator.
inherited

Static Methods

background<T>(NodeFlowController<T> controller, {void onAnnotationTap(Annotation annotation)?, void onAnnotationDoubleTap(Annotation annotation)?, void onAnnotationContextMenu(Annotation annotation, Offset globalPosition)?, void onAnnotationMouseEnter(Annotation annotation)?, void onAnnotationMouseLeave(Annotation annotation)?}) → AnnotationLayer<T>
Creates a background annotation layer that renders only groups.
foreground<T>(NodeFlowController<T> controller, {void onAnnotationTap(Annotation annotation)?, void onAnnotationDoubleTap(Annotation annotation)?, void onAnnotationContextMenu(Annotation annotation, Offset globalPosition)?, void onAnnotationMouseEnter(Annotation annotation)?, void onAnnotationMouseLeave(Annotation annotation)?}) → AnnotationLayer<T>
Creates a foreground annotation layer that renders everything except groups.