/// <summary>
/// Method to see if the given XY value is within the reach of the lamps.
/// </summary>
/// <param name="p">p the point containing the X,Y value</param>
/// <returns>true if within reach, false otherwise.</returns>
private static bool CheckPointInLampsReach(CGPoint p)
{
CGPoint v1 = new CGPoint(Lime.x - Red.x, Lime.y - Red.y);
CGPoint v2 = new CGPoint(Blue.x - Red.x, Blue.y - Red.y);
CGPoint q = new CGPoint(p.x - Red.x, p.y - Red.y);
double s = HueColorConverter.CrossProduct(q, v2) / HueColorConverter.CrossProduct(v1, v2);
double t = HueColorConverter.CrossProduct(v1, q) / HueColorConverter.CrossProduct(v1, v2);
if ((s >= 0.0f) && (t >= 0.0f) && (s + t <= 1.0f))
{
return(true);
}
else
{
return(false);
}
}
/// <summary>
/// Get XY from red,green,blue ints
/// </summary>
/// <param name="red"></param>
/// <param name="green"></param>
/// <param name="blue"></param>
/// <returns></returns>
public static CGPoint XyFromColor(int red, int green, int blue)
{
double r = (red > 0.04045f) ? Math.Pow((red + 0.055f) / (1.0f + 0.055f), 2.4f) : (red / 12.92f);
double g = (green > 0.04045f) ? Math.Pow((green + 0.055f) / (1.0f + 0.055f), 2.4f) : (green / 12.92f);
double b = (blue > 0.04045f) ? Math.Pow((blue + 0.055f) / (1.0f + 0.055f), 2.4f) : (blue / 12.92f);
double X = r * 0.4360747f + g * 0.3850649f + b * 0.0930804f;
double Y = r * 0.2225045f + g * 0.7168786f + b * 0.0406169f;
double Z = r * 0.0139322f + g * 0.0971045f + b * 0.7141733f;
double cx = X / (X + Y + Z);
double cy = Y / (X + Y + Z);
if (Double.IsNaN(cx))
{
cx = 0.0f;
}
if (Double.IsNaN(cy))
{
cy = 0.0f;
}
//Check if the given XY value is within the colourreach of our lamps.
CGPoint xyPoint = new CGPoint(cx, cy);
bool inReachOfLamps = HueColorConverter.CheckPointInLampsReach(xyPoint);
if (!inReachOfLamps)
{
//It seems the colour is out of reach
//let's find the closes colour we can produce with our lamp and send this XY value out.
//Find the closest point on each line in the triangle.
CGPoint pAB = HueColorConverter.GetClosestPointToPoint(Red, Lime, xyPoint);
CGPoint pAC = HueColorConverter.GetClosestPointToPoint(Blue, Red, xyPoint);
CGPoint pBC = HueColorConverter.GetClosestPointToPoint(Lime, Blue, xyPoint);
//Get the distances per point and see which point is closer to our Point.
double dAB = HueColorConverter.GetDistanceBetweenTwoPoints(xyPoint, pAB);
double dAC = HueColorConverter.GetDistanceBetweenTwoPoints(xyPoint, pAC);
double dBC = HueColorConverter.GetDistanceBetweenTwoPoints(xyPoint, pBC);
double lowest = dAB;
CGPoint closestPoint = pAB;
if (dAC < lowest)
{
lowest = dAC;
closestPoint = pAC;
}
if (dBC < lowest)
{
lowest = dBC;
closestPoint = pBC;
}
//Change the xy value to a value which is within the reach of the lamp.
cx = closestPoint.x;
cy = closestPoint.y;
}
return(new CGPoint(cx, cy));
}