port from perforce

intromat/NodeNetworkToolkit/ValueNode/ValueNodeOutputViewModel.cs

@@ -0,0 +1,45 @@
+using System;
+using System.Reactive.Concurrency;
+using NodeNetwork.ViewModels;
+using NodeNetwork.Views;
+using ReactiveUI;
+
+namespace NodeNetwork.Toolkit.ValueNode
+{
+    /// <summary>
+    /// A viewmodel for a node output that produces a value based on the inputs.
+    /// </summary>
+    /// <typeparam name="T">The type of object produced by this output.</typeparam>
+    public class ValueNodeOutputViewModel<T> : NodeOutputViewModel
+    {
+        static ValueNodeOutputViewModel()
+        {
+            NNViewRegistrar.AddRegistration(() => new NodeOutputView(), typeof(IViewFor<ValueNodeOutputViewModel<T>>));
+        }
+        
+        #region Value
+        /// <summary>
+        /// Observable that produces the value every time it changes.
+        /// </summary>
+        public IObservable<T> Value
+        {
+            get => _value;
+            set => this.RaiseAndSetIfChanged(ref _value, value);
+        }
+        private IObservable<T> _value;
+        #endregion
+
+        #region CurrentValue
+        /// <summary>
+        /// The latest value produced by this output.
+        /// </summary>
+        public T CurrentValue => _currentValue.Value;
+        private readonly ObservableAsPropertyHelper<T> _currentValue;
+        #endregion
+
+        public ValueNodeOutputViewModel()
+        {
+            this.WhenAnyObservable(vm => vm.Value).ToProperty(this, vm => vm.CurrentValue, out _currentValue, false, Scheduler.Immediate);
+        }
+    }
+}