GUI桌面环境

Gui/UILib/Animations/Easing.cs

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+using System;
+
+namespace CMLeonOS.UILib.Animations
+{
+    /// <summary>
+    /// Easing utilities for animations.
+    /// </summary>
+    internal static class Easing
+    {
+        /// <summary>
+        /// Calculate the value of an easing function.
+        /// </summary>
+        /// <param name="t">The absolute progress of the animation, from 0 to 1.</param>
+        /// <param name="type">The type of the easing function.</param>
+        /// <param name="direction">The direction of the easing function.</param>
+        /// <returns>The value of the easing function at the given progress.</returns>
+        /// <exception cref="ArgumentOutOfRangeException">An exception is thrown if the progress is out of range.</exception>
+        /// <exception cref="ArgumentException">An exception is thrown if the type or direction is ininvalid.</exception>
+        internal static double Ease(double t, EasingType type, EasingDirection direction)
+        {
+            if (t < 0 || t > 1) throw new ArgumentOutOfRangeException();
+            switch (type)
+            {
+                case EasingType.Linear:
+                    return t;
+                case EasingType.Sine:
+                    switch (direction)
+                    {
+                        case EasingDirection.In:
+                            return 1 - Math.Cos(t * Math.PI / 2);
+                        case EasingDirection.Out:
+                            return Math.Sin(t * Math.PI / 2);
+                        case EasingDirection.InOut:
+                            return -0.5 * (Math.Cos(Math.PI * t) - 1);
+                        default:
+                            throw new ArgumentException("Unknown easing direction.");
+                    }
+                default:
+                    throw new ArgumentException("Unknown easing type.");
+            }
+        }
+
+        /// <summary>
+        /// Linearly interpolate between two values.
+        /// </summary>
+        /// <param name="x">The first value.</param>
+        /// <param name="y">The second value.</param>
+        /// <param name="z">The value of the interpolation.</param>
+        /// <returns>The interpolated value.</returns>
+        internal static double Lerp(double x, double y, double z)
+        {
+            return x * (1 - z) + y * z;
+        }
+    }
+}