Started work on the keyframe engine to tie everything together!

src/Artemis.Core/Models/Profile/KeyframeEngines/KeyframeEngine.cs

@@ -0,0 +1,65 @@
+using System;
+using System.Collections.Generic;
+using Artemis.Core.Exceptions;
+using Artemis.Core.Models.Profile.LayerProperties;
+
+namespace Artemis.Core.Models.Profile.KeyframeEngines
+{
+    public abstract class KeyframeEngine
+    {
+        /// <summary>
+        ///     Indicates whether <see cref="Initialize" /> has been called.
+        /// </summary>
+        public bool Initialized { get; private set; }
+
+        /// <summary>
+        ///     The layer property this keyframe engine applies to.
+        /// </summary>
+        public BaseLayerProperty LayerProperty { get; set; }
+
+        /// <summary>
+        ///     The keyframe progress in milliseconds.
+        /// </summary>
+        public double Progress { get; set; }
+
+        /// <summary>
+        ///     The types this keyframe engine supports.
+        /// </summary>
+        public abstract List<Type> CompatibleTypes { get; }
+
+        /// <summary>
+        ///     Associates the keyframe engine with the provided layer property.
+        /// </summary>
+        /// <param name="layerProperty"></param>
+        public void Initialize(BaseLayerProperty layerProperty)
+        {
+            if (Initialized)
+                throw new ArtemisCoreException("Cannot initialize the same keyframe engine twice");
+            if (!CompatibleTypes.Contains(layerProperty.Type))
+                throw new ArtemisCoreException($"This property engine does not support the provided type {layerProperty.Type.Name}");
+
+            LayerProperty = layerProperty;
+            Initialized = true;
+        }
+
+        /// <summary>
+        ///     Updates the engine's progress
+        /// </summary>
+        /// <param name="deltaTime"></param>
+        public void Update(double deltaTime)
+        {
+            if (!Initialized)
+                return;
+
+            Progress += deltaTime;
+
+            // LayerProperty determines what's next: reset, stop, continue
+        }
+
+        /// <summary>
+        ///     Gets the current value, if the progress is in between two keyframes the value will be interpolated
+        /// </summary>
+        /// <returns></returns>
+        public abstract object GetCurrentValue();
+    }
+}