Improved gradient-movement

RGB.NET.Brushes/Gradients/AbstractGradient.cs

@@ -82,6 +82,22 @@ namespace RGB.NET.Brushes.Gradients
         /// <inheritdoc />
         public abstract Color GetColor(double offset);
 
+        /// <inheritdoc />
+        public virtual void Move(double offset)
+        {
+            offset /= 360.0;
+
+            foreach (GradientStop gradientStop in GradientStops)
+            {
+                gradientStop.Offset = gradientStop.Offset + offset;
+
+                if (gradientStop.Offset > 1)
+                    gradientStop.Offset -= 1;
+                else if (gradientStop.Offset < 0)
+                    gradientStop.Offset += 1;
+            }
+        }
+
         #endregion
     }
 }

RGB.NET.Brushes/Gradients/IGradient.cs

@@ -13,5 +13,11 @@ namespace RGB.NET.Brushes.Gradients
         /// <param name="offset">The percentage offset to take the <see cref="Color"/> from.</param>
         /// <returns>The <see cref="Color"/> at the specific offset.</returns>
         Color GetColor(double offset);
+
+        /// <summary>
+        /// Moves the <see cref="IGradient"/> by the provided offset.
+        /// </summary>
+        /// <param name="offset">The offset the <see cref="IGradient"/> should be moved.</param>
+        void Move(double offset);
     }
 }

RGB.NET.Brushes/Gradients/RainbowGradient.cs

@@ -56,6 +56,27 @@ namespace RGB.NET.Brushes.Gradients
             return new Color(hue, 1f, 1f);
         }
 
+        /// <inheritdoc />
+        public void Move(double offset)
+        {
+            // RainbowGradient is calculated inverse
+            offset *= -1;
+
+            StartHue += offset;
+            EndHue += offset;
+
+            if ((StartHue > 360) && (EndHue > 360))
+            {
+                StartHue -= 360;
+                EndHue -= 360;
+            }
+            else if ((StartHue < -360) && (EndHue < -360))
+            {
+                StartHue += 360;
+                EndHue += 360;
+            }
+        }
+
         #endregion
     }
 }