NodeView<T0>

Description

Derive from this class to add custom UI to the view generated for a specific NodeView<T0>.Node type.

A VisualElement is built for every NodeView<T0>.Node that appears in a graph. A NodeView<T0> lets you inject custom UI into that generated element. Subclasses are discovered by their type parameter: for a NodeView<T0>.Node of type T, the concrete NodeView<T0> whose type argument matches is used, walking up the NodeView<T0>.Node inheritance chain if there is no exact match.

The NodeView<T0>.Node instance is available through NodeView<T0>.Node once the view is constructed. Access the generated visual element through NodeView<T0>.View and add custom UI to INodeView.Root.

Important: allocate custom UI in NodeView<T0>.OnViewBuilt and re-add it in NodeView<T0>.OnCullingChanged (when cullingEnabled is false). Do not allocate UI in NodeView<T0>.OnViewAttached: that callback can fire multiple times during a node's lifetime — for example when the user tabs away from and back to the graph view, or when a block node is dragged and re-parented — and any UI you allocate there accumulates as duplicates. When a node returns from being culled, the contents of INodeView.Root are cleared, so a cached reference is no longer parented; re-add it from NodeView<T0>.OnCullingChanged to avoid allocating a new element.

 // The Node type that this view customizes.
 class MyNode : Node
 {
     protected override void OnDefinePorts(IPortDefinitionContext context)
     {
         context.AddInputPort<float>("input");
     }
 }

 // This view is constructed for every MyNode instance in a graph.
 class MyNodeView : NodeView<MyNode>
 {
     Label m_Label;

     public override void OnViewBuilt()
     {
         // Allocate custom UI once, after the built-in UI is ready and before the node attaches to a
         // panel. Cache the reference so OnCullingChanged can re-add it without allocating again.
         m_Label = new Label($"Node: {Node.Title}");
         View.Root.Add(m_Label);
     }

     public override void OnCullingChanged(bool cullingEnabled)
     {
         // When cullingEnabled is false, the node has just returned from being culled and Root has
         // been cleared. Re-add the cached element — no allocation needed.
         if (!cullingEnabled && m_Label != null)
             View.Root.Add(m_Label);
     }
 }

Properties

Public Methods