Added color-blending

Helper/ColorHelper.cs

@@ -0,0 +1,49 @@
+// ReSharper disable MemberCanBePrivate.Global
+
+using System.Drawing;
+
+namespace CUE.NET.Helper
+{
+    public static class ColorHelper
+    {
+        public static float GetFloatA(this Color color)
+        {
+            return color.A / 255f;
+        }
+
+        public static float GetFloatR(this Color color)
+        {
+            return color.R / 255f;
+        }
+
+        public static float GetFloatG(this Color color)
+        {
+            return color.G / 255f;
+        }
+
+        public static float GetFloatB(this Color color)
+        {
+            return color.B / 255f;
+        }
+
+        public static Color Blend(this Color bg, Color fg)
+        {
+            if (fg.A == 255)
+                return fg;
+
+            if (fg.A == 0)
+                return bg;
+
+            float resultA = (1 - (1 - fg.GetFloatA()) * (1 - bg.GetFloatA()));
+            float resultR = (fg.GetFloatR() * fg.GetFloatA() / resultA + bg.GetFloatR() * bg.GetFloatA() * (1 - fg.GetFloatA()) / resultA);
+            float resultG = (fg.GetFloatG() * fg.GetFloatA() / resultA + bg.GetFloatG() * bg.GetFloatA() * (1 - fg.GetFloatA()) / resultA);
+            float resultB = (fg.GetFloatB() * fg.GetFloatA() / resultA + bg.GetFloatB() * bg.GetFloatA() * (1 - fg.GetFloatA()) / resultA);
+            return CreateColorFromFloat(resultA, resultR, resultG, resultB);
+        }
+
+        public static Color CreateColorFromFloat(float a, float r, float g, float b)
+        {
+            return Color.FromArgb((int)(a * 255), (int)(r * 255), (int)(g * 255), (int)(b * 255));
+        }
+    }
+}