/// <summary>
/// Inflates balloon body and target point
/// </summary>
public static void InflateBalloon(ref Rectangle body, ref Point target, int deltaBody, int deltaTarget)
{
Point center = new Point(body.Left + body.Width / 2, body.Top + body.Height / 2);
PolarPoint pp = new PolarPoint(center, target);
body.Inflate(deltaBody, deltaBody);
pp.R += deltaTarget;
target = pp.Point;
target.Offset(center.X, center.Y);
}
/// <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>
/// Returns a point of intersection between a ray cast from the center of a rectangle
/// under certain polar coordinate angle and a rectangle side
/// </summary>
public static Point FindRayFromRectangleCenterSideIntersection(Rectangle rect, double theta)
{
Point center = new Point(rect.Left + rect.Width / 2, rect.Top + rect.Height / 2);
double rayLength = rect.Width > rect.Height ? rect.Width : rect.Height; //make ray "infinite" in comparison to rect
if (rayLength < 100)
{
rayLength = 100; //safeguard
}
PolarPoint rayEnd = new PolarPoint(rayLength, theta); //create ray "end" point
double k = (rayEnd.Point.X != 0)? ((double)rayEnd.Point.Y) / ((double)rayEnd.Point.X) : 0; //get line incline aka. y = kx
int x, y;
List <Point> lst = new List <Point>();
//north
x = center.X + ((k != 0) ? (int)((rect.Top - center.Y) / k) : 0);
y = rect.Top;
if ((x >= rect.Left) &&
(x <= rect.Right))
{
lst.Add(new Point(x, y));
}
//south
x = center.X + ((k != 0) ? (int)((rect.Bottom - center.Y) / k) : 0);
y = rect.Bottom;
if ((x >= rect.Left) &&
(x <= rect.Right))
{
lst.Add(new Point(x, y));
}
//east
x = rect.Right;
y = center.Y + (int)(k * (rect.Right - center.X));
if ((y >= rect.Top) &&
(y <= rect.Bottom))
{
lst.Add(new Point(x, y));
}
//west
x = rect.Left;
y = center.Y + (int)(k * (rect.Left - center.X));
if ((y >= rect.Top) &&
(y <= rect.Bottom))
{
lst.Add(new Point(x, y));
}
Point minPoint = new Point(int.MaxValue, int.MaxValue);
int minDistance = int.MaxValue;
Point re = rayEnd.Point; //rayEnd is relative to absolute 0,0
re.Offset(center.X, center.Y); // need to make relative to rectangle center
foreach (Point p in lst) //find closest point
{
int dst = Distance(p, re);
if (dst < minDistance)
{
minPoint = p;
minDistance = dst;
}
}
return(minPoint);
}