StateView<T0>

Description

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

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

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

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

 // The State type that this view customizes.
 class MyState : State
 {
 }

 // This view is constructed for every MyState instance in a state machine.
 class MyStateView : StateView<MyState>
 {
     Label m_Label;

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

     public override void OnCullingChanged(bool cullingEnabled)
     {
         // When cullingEnabled is false, the state 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