Added RainbowBrush

Devices/Keyboard/Brushes/LinearGradientBrush.cs

@@ -6,6 +6,7 @@ using System;
 using System.Collections.Generic;
 using System.Drawing;
 using System.Linq;
+using CUE.NET.Helper;
 
 namespace CUE.NET.Devices.Keyboard.Brushes
 {
@@ -48,36 +49,10 @@ namespace CUE.NET.Devices.Keyboard.Brushes
             if (!GradientStops.Any()) return Color.Transparent;
             if (GradientStops.Count == 1) return GradientStops.First().Color;
 
-            // Based on https://dotupdate.wordpress.com/2008/01/28/find-the-color-of-a-point-in-a-lineargradientbrush/
-
             PointF startPoint = new PointF(StartPoint.X * rectangle.Width, StartPoint.Y * rectangle.Height);
             PointF endPoint = new PointF(EndPoint.X * rectangle.Width, EndPoint.Y * rectangle.Height);
 
-            PointF intersectingPoint;
-            if (startPoint.Y.Equals(endPoint.Y)) // Horizontal case
-                intersectingPoint = new PointF(point.X, startPoint.Y);
-
-            else if (startPoint.X.Equals(endPoint.X)) // Vertical case
-                intersectingPoint = new PointF(startPoint.X, point.Y);
-
-            else // Diagnonal case
-            {
-                float slope = (endPoint.Y - startPoint.Y) / (endPoint.X - startPoint.X);
-                float orthogonalSlope = -1 / slope;
-                
-                float startYIntercept = startPoint.Y - slope * startPoint.X;
-                float pointYIntercept = point.Y - orthogonalSlope * point.X;
-
-                float intersectingPointX = (pointYIntercept - startYIntercept) / (slope - orthogonalSlope);
-                float intersectingPointY = slope * intersectingPointX + startYIntercept;
-                intersectingPoint = new PointF(intersectingPointX, intersectingPointY);
-            }
-
-            // Calculate distances relative to the vector start
-            float intersectDistance = CalculateDistance(intersectingPoint, startPoint, endPoint);
-            float gradientLength = CalculateDistance(endPoint, startPoint, endPoint);
-
-            float offset = intersectDistance / gradientLength;
+            float offset = GradientHelper.CalculateGradientOffset(startPoint, endPoint, point);
 
             // Clip the input if before or after the max/min offset values
             float max = GradientStops.Max(n => n.Offset);
@@ -103,21 +78,6 @@ namespace CUE.NET.Devices.Keyboard.Brushes
             return Color.FromArgb(colA, colR, colG, colB);
         }
 
-        // Based on https://dotupdate.wordpress.com/2008/01/28/find-the-color-of-a-point-in-a-lineargradientbrush/
-        /// <summary>
-        /// Returns the signed magnitude of a point on a vector
-        /// </summary>
-        private float CalculateDistance(PointF point, PointF origin, PointF direction)
-        {
-            float distance = (float)Math.Sqrt((point.Y - origin.Y) * (point.Y - origin.Y) + (point.X - origin.X) * (point.X - origin.X));
-
-            return (((point.Y < origin.Y) && (direction.Y > origin.Y)) ||
-                ((point.Y > origin.Y) && (direction.Y < origin.Y)) ||
-                ((point.Y.Equals(origin.Y)) && (point.X < origin.X) && (direction.X > origin.X)) ||
-                ((point.Y.Equals(origin.Y)) && (point.X > origin.X) && (direction.X < origin.X)))
-                ? -distance : distance;
-        }
-
         #endregion
     }
 }

Devices/Keyboard/Brushes/RainbowBrush.cs

@@ -0,0 +1,71 @@
+using System;
+using System.Drawing;
+using CUE.NET.Helper;
+
+namespace CUE.NET.Devices.Keyboard.Brushes
+{
+    public class RainbowBrush : IBrush
+    {
+        #region Properties & Fields
+
+        public PointF StartPoint { get; set; } = new PointF(0f, 0.5f);
+        public PointF EndPoint { get; set; } = new PointF(1f, 0.5f);
+        public float StartHue { get; set; }
+        public float EndHue { get; set; }
+
+        #endregion
+
+        #region Constructors
+
+        public RainbowBrush(float startHue = 0f, float endHue = 360f)
+        {
+            this.StartHue = startHue;
+            this.EndHue = endHue;
+        }
+
+        public RainbowBrush(PointF startPoint, PointF endPoint, float startHue = 0f, float endHue = 360f)
+        {
+            this.StartPoint = startPoint;
+            this.EndPoint = endPoint;
+            this.StartHue = startHue;
+            this.EndHue = endHue;
+        }
+
+        #endregion
+
+        #region Methods
+
+        public Color GetColorAtPoint(RectangleF rectangle, PointF point)
+        {
+            PointF startPoint = new PointF(StartPoint.X * rectangle.Width, StartPoint.Y * rectangle.Height);
+            PointF endPoint = new PointF(EndPoint.X * rectangle.Width, EndPoint.Y * rectangle.Height);
+
+            float offset = GradientHelper.CalculateGradientOffset(startPoint, endPoint, point);
+            float range = EndHue - StartHue;
+            float progress = (StartHue + (range * offset)) / 360f;
+
+            float div = (Math.Abs(progress % 1) * 6);
+            int value = (int)((div % 1) * 255);
+
+            switch ((int)div)
+            {
+                case 0:
+                    return Color.FromArgb(255, 255, value, 0);
+                case 1:
+                    return Color.FromArgb(255, 255 - value, 255, 0);
+                case 2:
+                    return Color.FromArgb(255, 0, 255, value);
+                case 3:
+                    return Color.FromArgb(255, 0, 255 - value, 255);
+                case 4:
+                    return Color.FromArgb(255, value, 0, 255);
+                case 5:
+                    return Color.FromArgb(255, 255, 0, 255 - value);
+                default:
+                    return Color.Transparent;
+            }
+        }
+
+        #endregion
+    }
+}