feat(Interface): add Easing, InOutCubic

Dalamud/Interface/Animation/Easing.cs

@@ -0,0 +1,103 @@
+using System;
+using System.Diagnostics;
+using System.Numerics;
+
+namespace Dalamud.Interface.Animation
+{
+    public abstract class Easing
+    {
+        private readonly Stopwatch animationTimer = new();
+
+        private double valueInternal;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="Easing"/> class with the specified duration.
+        /// </summary>
+        /// <param name="duration">The animation duration.</param>
+        protected Easing(TimeSpan duration)
+        {
+            this.Duration = duration;
+        }
+
+        /// <summary>
+        /// Gets or sets the origin point of the animation.
+        /// </summary>
+        public Vector2? Point1 { get; set; }
+
+        /// <summary>
+        /// Gets or sets the destination point of the animation.
+        /// </summary>
+        public Vector2? Point2 { get; set; }
+
+        /// <summary>
+        /// Gets the resulting point at the current timestep.
+        /// </summary>
+        public Vector2 EasedPoint { get; private set; }
+
+        /// <summary>
+        /// Gets the current value of the animation, from 0 to 1.
+        /// </summary>
+        public double Value
+        {
+            get => this.valueInternal;
+            set
+            {
+                this.valueInternal = Math.Min(value, 1);
+
+                if (Point1.HasValue && Point2.HasValue)
+                    EasedPoint = Lerp(Point1.Value, Point2.Value, (float)this.valueInternal);
+            }
+        }
+
+        /// <summary>
+        /// Gets or sets the duration of the animation.
+        /// </summary>
+        public TimeSpan Duration { get; set; }
+
+        /// <summary>
+        /// Gets the progress of the animation, from 0 to 1.
+        /// </summary>
+        protected double Progress => this.animationTimer.ElapsedMilliseconds / this.Duration.TotalMilliseconds;
+
+        /// <summary>
+        /// Starts the animation from where it was last stopped, or from the start if it was never started before.
+        /// </summary>
+        public void Start()
+        {
+            this.animationTimer.Start();
+        }
+
+        /// <summary>
+        /// Stops the animation at the current point.
+        /// </summary>
+        public void Stop()
+        {
+            this.animationTimer.Stop();
+        }
+
+        /// <summary>
+        /// Restarts the animation.
+        /// </summary>
+        public void Restart()
+        {
+            this.animationTimer.Restart();
+        }
+
+        /// <summary>
+        /// Updates the animation.
+        /// </summary>
+        public abstract void Update();
+
+        private static float Lerp(float firstFloat, float secondFloat, float by)
+        {
+            return (firstFloat * (1 - @by)) + (secondFloat * by);
+        }
+
+        private static Vector2 Lerp(Vector2 firstVector, Vector2 secondVector, float by)
+        {
+            var retX = Lerp(firstVector.X, secondVector.X, by);
+            var retY = Lerp(firstVector.Y, secondVector.Y, by);
+            return new Vector2(retX, retY);
+        }
+    }
+}

Dalamud/Interface/Animation/EasingFunctions/InOutCubic.cs

@@ -0,0 +1,28 @@
+using System;
+using Serilog;
+
+namespace Dalamud.Interface.Animation.EasingFunctions
+{
+    /// <summary>
+    /// Class providing an "InOutCubic" easing animation.
+    /// </summary>
+    public class InOutCubic : Easing
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="InOutCubic"/> class.
+        /// </summary>
+        /// <param name="duration">The duration of the animation.</param>
+        public InOutCubic(TimeSpan duration)
+            : base(duration)
+        {
+            // ignored
+        }
+
+        /// <inheritdoc/>
+        public override void Update()
+        {
+            var p = this.Progress;
+            this.Value = p < 0.5 ? 4 * p * p * p : 1 - (Math.Pow((-2 * p) + 2, 3) / 2);
+        }
+    }
+}