Annotation class abstract

Base annotation class that can be placed in the node flow

Creating Custom Annotations

To create a custom annotation, simply extend this class and implement:

  1. Size get size - Return the dimensions for automatic hit testing
  2. Widget buildWidget(BuildContext context) - Return your custom widget

Example:

class CustomAnnotation extends Annotation {
  final String title;
  final double width;
  final double height;

  CustomAnnotation({
    required super.id,
    required Offset position,
    required this.title,
    this.width = 150.0,
    this.height = 80.0,
  }) : super(
    type: 'custom',
    initialPosition: position,
  );

  @override
  Size get size => Size(width, height);

  @override
  Widget buildWidget(BuildContext context) {
    return Container(
      width: width,
      height: height,
      decoration: BoxDecoration(
        color: Colors.purple,
        borderRadius: BorderRadius.circular(12),
      ),
      child: Center(child: Text(title)),
    );
  }

  @override
  Map<String, dynamic> toJson() => {'title': title, 'width': width, 'height': height};

  @override
  void fromJson(Map<String, dynamic> json) {
    // Update properties from json if needed
  }
}

The framework automatically handles:

  • Hit testing via containsPoint() using your size
  • Positioning and coordinate transforms
  • Selection visual feedback
  • Drag and drop interactions (if isInteractive = true)
  • Z-index layering and rendering order
  • MobX reactivity for position and visibility changes
Implementers

Constructors

Annotation({required String id, required String type, required Offset initialPosition, int initialZIndex = 0, bool initialIsVisible = true, bool selected = false, bool isInteractive = true, Map<String, dynamic> metadata = const {}})

Properties

bounds → Rect
Automatically calculated bounding rectangle for hit testing.
no setter
hashCode → int
The hash code for this object.
no setterinherited
id → String
Unique identifier for this annotation.
final
isEmpty → bool
Whether this annotation is considered "empty" and has no content.
no setter
isInteractive → bool
Whether this annotation responds to user interactions.
final
isVisible ↔ bool
Whether the annotation is visible.
getter/setter pair
layer → AnnotationRenderLayer
The rendering layer for this annotation.
no setter
metadata → Map<String, dynamic>
Additional metadata for custom data storage.
final
monitoredNodeIds → Set<String>
The set of node IDs that this annotation monitors for position/size changes.
no setter
monitorNodes → bool
Whether this annotation should receive automatic node lifecycle callbacks.
no setter
position ↔ Offset
The annotation's logical position (before grid snapping).
getter/setter pair
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited
selected ↔ bool
Whether the annotation is currently selected.
getter/setter pair
shouldRemoveWhenEmpty → bool
Whether this annotation should be automatically removed when empty.
no setter
size → Size
The dimensions of the annotation for automatic hit testing.
no setter
type → String
The type of annotation (e.g., 'sticky', 'group', 'marker').
final
visualPosition ↔ Offset
The annotation's visual position (after grid snapping).
getter/setter pair
zIndex ↔ int
The annotation's z-index (rendering order within its layer).
getter/setter pair

Methods

buildWidget(BuildContext context) → Widget
Builds the visual representation of the annotation.
containsPoint(Offset point) → bool
Automatic hit testing based on position and size.
fromJson(Map<String, dynamic> json) → void
Deserializes JSON data into this annotation.
noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
inherited
onDragEnd() → void
Called when a drag operation ends on this annotation.
onDragMove(Offset delta, AnnotationDragContext context) → void
Called during drag with the movement delta.
onDragStart(AnnotationDragContext context) → void
Called when a drag operation starts on this annotation.
onNodeAdded(String nodeId, Rect nodeBounds, AnnotationDragContext context) → bool
Called when a new node is added to the graph.
onNodeMoved(String nodeId, Offset newPosition, AnnotationDragContext context) → void
Called when a node's position changes.
onNodeResized(String nodeId, Size newSize, AnnotationDragContext context) → void
Called when a node's size changes.
onNodesDeleted(Set<String> nodeIds, AnnotationDragContext context) → void
Called when nodes are deleted from the graph.
onNodeVisibilityChanged(String nodeId, bool isVisible) → void
Called when a node's visibility changes.
onSelectionChanged(Set<String> selectedNodeIds) → void
Called when the node selection changes.
toJson() → Map<String, dynamic>
Serializes this annotation to JSON.
toString() → String
A string representation of this object.
inherited

Operators

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