/// <summary>
/// Calculates callout balloon vertexes suitable for curve drawing
/// </summary>
/// <param name="body">Balloon body coordinates</param>
/// <param name="target">A point of balloon leg attachment</param>
/// <param name="legSweep">Length of balloon leg attachment breach at balloon body edge, expressed in radians (arc length). A value such as PI/16 yields good results</param>
/// <returns>An array of vertex points</returns>
public static Point[] VectorizeBalloon(Rectangle body, Point target, double legSweep)
{
List <Point> result = new List <Point>();
Point center = new Point(body.Left + body.Width / 2, body.Top + body.Height / 2);
PolarPoint trg = new PolarPoint(center, target);
Point legStart = CartesianUtils.FindRayFromRectangleCenterSideIntersection(
body,
CartesianUtils.WrapAngle(trg.Theta, -legSweep / 2));
Point legEnd = CartesianUtils.FindRayFromRectangleCenterSideIntersection(
body,
CartesianUtils.WrapAngle(trg.Theta, +legSweep / 2));
result.Add(new Point(body.Left, body.Top));
result.Add(new Point(body.Right, body.Top));
result.Add(new Point(body.Right, body.Bottom));
result.Add(new Point(body.Left, body.Bottom));
result.Add(legStart);
result.Add(target);
result.Add(legEnd);
//reorder points by azimuth so the curve can close and look like a balloon
result.Sort((p1, p2) => {
PolarPoint pp1 = new PolarPoint(center, p1);
PolarPoint pp2 = new PolarPoint(center, p2);
if (pp1.Theta > pp2.Theta)
{
return(-1);
}
else
{
return(+1);
}
});
return(result.ToArray());
}
/// <summary>
/// Initializes polar coordinates from 2-d cartesian coordinates of 'x1, y1, x2, y2' format
/// </summary>
public PolarPoint(int x1, int y1, int x2, int y2)
{
this = CartesianUtils.VectorToPolarPoint(x1, y1, x2, y2);
}
/// <summary>
/// Initializes polar coordinates from 2-d cartesian coordinates
/// </summary>
public PolarPoint(Point center, Point point)
{
this = CartesianUtils.PointToPolarPoint(center, point);
}
