Rotate Hue

Color RotateHue(float hue)
{
    float f, q;
    int i;

    if (hue >= 360f || hue <= 0)
        hue = 0;

    hue /= 60f;
    i = (int) Math.Floor(hue);
    f = hue - (float) i;
    q = 1 - f;

    int r, g, b;

    switch (i)
    {
        case 0:
            r = 255; g = (int)(255*f)%256; b = 0;
            break;
        case 1:
            r = (int)(255*q)%256; g = 255; b = 0;
            break;
        case 2:
            r = 0; g = 255; b = (int)(255*f)%256;
            break;
        case 3:
            r = 0; g = (int)(255*q)%256; b = 255;
            break;
        case 4:
            r = (int)(255*f)%256; g = 0; b = 255;
            break;
        default:
            r = 255; g = 0; b = (int)(255*q)%256;
            break;
    }

    return Color.FromArgb(r, g, b);
}