/// <summary>
/// Constructor.
/// </summary>
/// <param name="x1">x-coordinate for line start point</param>
/// <param name="y1">y-coordinate for line start point</param>
/// <param name="x2">x-coordinate for line end point</param>
/// <param name="y2">y-coordinate for line end point</param>
/// <returns>None</returns>
public XYLine(double x1, double y1, double x2, double y2)
{
_p1 = new XYPoint();
_p2 = new XYPoint();
_p1.X = x1;
_p1.Y = y1;
_p2.X = x2;
_p2.Y = y2;
}
/// <summary>
/// Constructor.
/// </summary>
/// <param name="point1">Line start point</param>
/// <param name="point2">Line end point</param>
/// <returns>None</returns>
public XYLine(XYPoint point1, XYPoint point2)
{
_p1 = new XYPoint();
_p2 = new XYPoint();
_p1.X = point1.X;
_p1.Y = point1.Y;;
_p2.X = point2.X;
_p2.Y = point2.Y;
}
public void Equals()
{
XYPoint p1 = new XYPoint(2,3);
XYPoint p2 = new XYPoint(2,3);
XYPoint p3 = new XYPoint(2,-3);
XYLine l1 = new XYLine(2,3,3,4);
Assert.AreEqual(true, p1.Equals(p1),"Test1");
Assert.AreEqual(true, p1.Equals(p2),"Test2");
Assert.AreEqual(false, p1.Equals(p3),"Test3");
Assert.AreEqual(false, p1.Equals(l1),"Test4");
}
public void PropertyTest()
{
XYPoint xypoint = new XYPoint(2,3);
Assert.AreEqual((double) 2, xypoint.X);
Assert.AreEqual((double) 3, xypoint.Y);
xypoint.X = 6;
xypoint.Y = 7;
Assert.AreEqual((double) 6, xypoint.X);
Assert.AreEqual((double) 7, xypoint.Y);
}
/// <summary>
/// The method decides if the triangle formed by P(i-1), P(i) and
/// P(i+1) from Polygon are intersected by any of the other points
/// of the polygon.
/// </summary>
/// <param name="i">Middle index for the three points that forms the triangle</param>
/// <returns>
/// <p>true: If the triangle P(i-1), P(i), P(i+1) is intersected by other parts of Polygon</p>
/// <p>false: otherwise</p>
/// </returns>
protected bool IsIntersected(int i)
{
double x = 0;
double y = 0;
int n = Points.Count;
int im1 = i - 1;
int ip1 = i + 1;
if (i == 0)
{
im1 = n - 1;
}
else if (i == n - 1)
{
ip1 = 0;
}
XYPoint nodeim1 = new XYPoint((XYPoint)Points[im1]);
XYPoint nodei = new XYPoint((XYPoint)Points[i]);
XYPoint nodeip1 = new XYPoint((XYPoint)Points[ip1]);
XYPolygon localPolygon = new XYPolygon();
localPolygon.Points.Add(nodeim1);
localPolygon.Points.Add(nodei);
localPolygon.Points.Add(nodeip1);
int j = 0;
bool intersected = false;
while (((j < n - 1) && (!intersected)))
{
x = ((XYPoint)Points[j]).X;
y = ((XYPoint)Points[j]).Y;
if (((((j != im1) && (j != i)) && (j != ip1)) && XYGeometryTools.IsPointInPolygon(x, y, localPolygon)))
{
return(true);
}
else
{
j++;
}
}
return(false);
}
/// <summary>
/// Calculate intersection point between two line segments.
/// </summary>
/// <param name="p1">First point in first line</param>
/// <param name="p2">Second point in first line</param>
/// <param name="p3">First point in second line</param>
/// <param name="p4">Second point in second line</param>
/// <returns>Intersection point</returns>
public static XYPoint CalculateIntersectionPoint(XYPoint p1, XYPoint p2, XYPoint p3, XYPoint p4)
{
if (!DoLineSegmentsIntersect(p1, p2, p3, p4))
{
throw new System.Exception("Attempt to calculate intersection point between non intersecting lines. CalculateIntersectionPoint failed.");
}
XYPoint interSectionPoint = new XYPoint();
double a = p1.X * p2.Y - p2.X * p1.Y;
double b = p3.X * p4.Y - p4.X * p3.Y;
double c = (p1.X - p2.X) * (p3.Y - p4.Y) - (p3.X - p4.X) * (p1.Y - p2.Y);
interSectionPoint.X = (a * (p3.X - p4.X) - (b * (p1.X - p2.X))) / c;
interSectionPoint.Y = (a * (p3.Y - p4.Y) - (b * (p1.Y - p2.Y))) / c;
return(interSectionPoint);
}
/// <summary>
/// Finds the shortest distance between any line segment of the polyline
/// and the point.
/// </summary>
/// <param name="polyLine">PolyLine.</param>
/// <param name="point">Point</param>
/// <returns>
/// <p>Length of the shortest path between the polyline and the point.</p>
/// </returns>
public static double CalculatePolylineToPointDistance(XYPolyline polyLine, XYPoint point)
{
double dist = 0;
int i = 0;
while (i < polyLine.Points.Count - 1)
{
if (i == 0)
{
dist = CalculateLineToPointDistance(polyLine.GetLine(0), point);
}
else
{
dist = Math.Min(dist, CalculateLineToPointDistance(polyLine.GetLine(i), point));
}
i++;
}
return(dist);
}
/// <summary>
/// Returns an ArrayList of triangles of type XYPolygon describing the
/// triangalation of the polygon.
/// </summary>
/// <param></param>
/// <returns>
/// A triangulation of the polygon.
/// </returns>
public ArrayList GetTriangulation()
{
int i = 0;
int im1 = 0;
int ip1 = 0;
int n = 0;
XYPolygon LocalPolygon = new XYPolygon(this);
ArrayList TriangleList = new ArrayList();
while (LocalPolygon.Points.Count > 3)
{
i = LocalPolygon.FindEar();
n = LocalPolygon.Points.Count;
im1 = i - 1;
ip1 = i + 1;
if (i == 0)
{
im1 = n - 1;
}
else if (i == n - 1)
{
ip1 = 0;
}
XYPoint Nodeim1 = new XYPoint((XYPoint)LocalPolygon.Points[im1]);
XYPoint Nodei = new XYPoint((XYPoint)LocalPolygon.Points[i]);
XYPoint Nodeip1 = new XYPoint((XYPoint)LocalPolygon.Points[ip1]);
XYPolygon Triangle = new XYPolygon();
Triangle.Points.Add(Nodeim1);
Triangle.Points.Add(Nodei);
Triangle.Points.Add(Nodeip1);
TriangleList.Add(Triangle);
LocalPolygon.Points.RemoveAt(i);
}
TriangleList.Add(LocalPolygon);
return(TriangleList);
}
/// <summary>
/// Constructor.
/// </summary>
/// <returns>None</returns>
public XYLine()
{
_p1 = new XYPoint();
_p2 = new XYPoint();
}
/// <summary>
/// The method calculates the intersection area of triangle a and b both
/// of type XYPolygon.
/// </summary>
/// <param name="triangleA">Triangle of type XYPolygon</param>
/// <param name="triangleB">Triangle of type XYPolygon</param>
/// <returns>
/// Intersection area between the triangles triangleA and triAngleB.
/// </returns>
protected static double TriangleIntersectionArea(XYPolygon triangleA, XYPolygon triangleB)
{
try
{
if (triangleA.Points.Count != 3 || triangleB.Points.Count != 3)
{
throw new System.Exception("Argument must be a polygon with 3 points");
}
int i = 1; // Index for "next" node in polygon a.
int j = -1; // Index for "next" node in polygon b.
// -1 indicates that the first has not yet been found.
double area = 0; // Intersection area. Returned.
XYPolygon intersectionPolygon = new XYPolygon(); // Intersection polygon.
XYPoint pFirst = new XYPoint(); // First intersection point between triangles
XYPoint p = new XYPoint(); // Latest intersection node found
p.X = ((XYPoint)triangleA.Points[0]).X;
p.Y = ((XYPoint)triangleA.Points[0]).Y;
Intersect(triangleA, triangleB, ref p, ref i, ref j, ref intersectionPolygon);
pFirst = p;
if (j != -1)
{
int jStop = Increase(j, 2);
bool complete = false;
int count = 0;
while (!complete)
{
// coordinates for vectors pointing to next triangleA and triangleB point respectively
double vax = ((XYPoint)triangleA.Points[i]).X - p.X;
double vay = ((XYPoint)triangleA.Points[i]).Y - p.Y;
double vbx = ((XYPoint)triangleB.Points[j]).X - p.X;
double vby = ((XYPoint)triangleB.Points[j]).Y - p.Y;
if (IsPointInPolygonOrOnEdge(p.X + EPSILON * vax, p.Y + EPSILON * vay, triangleB))
{
Intersect(triangleA, triangleB, ref p, ref i, ref j, ref intersectionPolygon);
}
else if (IsPointInPolygonOrOnEdge(p.X + EPSILON * vbx, p.Y + EPSILON * vby, triangleA))
{
Intersect(triangleB, triangleA, ref p, ref j, ref i, ref intersectionPolygon);
}
else // triangleA and triangleB only touches one another but do not intersect
{
area = 0;
return(area);
}
if (intersectionPolygon.Points.Count > 1)
{
complete = (CalculatePointToPointDistance(p, pFirst) < EPSILON);
}
count++;
if (count > 20)
{
throw new System.Exception("Failed to find intersection polygon");
}
}
area = intersectionPolygon.GetArea();
}
else
{
XYPoint pa = new XYPoint(); // internal point in triangle a
XYPoint pb = new XYPoint(); // internal point in triangle b
pa.X = (triangleA.GetX(0) + triangleA.GetX(1) + triangleA.GetX(2)) / 3;
pa.Y = (triangleA.GetY(0) + triangleA.GetY(1) + triangleA.GetY(2)) / 3;
pb.X = (triangleB.GetX(0) + triangleB.GetX(1) + triangleB.GetX(2)) / 3;
pb.Y = (triangleB.GetY(0) + triangleB.GetY(1) + triangleB.GetY(2)) / 3;
if (IsPointInPolygon(pa, triangleB) || IsPointInPolygon(pb, triangleA)) // triangleA is completely inside triangleB
{
area = Math.Min(triangleA.GetArea(), triangleB.GetArea());
}
else // triangleA and triangleB do dot intersect
{
area = 0;
}
}
return(area);
}
catch (System.Exception e)
{
throw new System.Exception("TriangleIntersectionArea failed", e);
}
}
/// <summary>
/// OverLoad of DoLineSegmentsIntersect(x1, y1, x2, y2, x3, y3, x4, y4)
/// </summary>
/// <param name="p1">First point in first line</param>
/// <param name="p2">Second point in first line</param>
/// <param name="p3">First point in second line</param>
/// <param name="p4">Second point in second line</param>
/// <returns>true if the line segmenst intersects otherwise false</returns>
public static bool DoLineSegmentsIntersect(XYPoint p1, XYPoint p2, XYPoint p3, XYPoint p4)
{
return DoLineSegmentsIntersect(p1.X, p1.Y, p2.X, p2.Y, p3.X, p3.Y, p4.X, p4.Y);
}
public static bool AIsPointInLineInterior(XYPoint point, XYLine line)
{
return IsPointInLineInterior(point, line);
}
/// <summary>
/// Determines if a point in inside or outside a polygon.
/// Works for both convex and concave polygons (Winding number test)
/// </summary>
/// <param name="point">Point</param>
/// <param name="polygon">Polygon</param>
/// <returns>
/// <p>true: If the point is inside the polygon</p>
/// <p>false: Otherwise.</p>
/// </returns>
public static bool IsPointInPolygon(XYPoint point, XYPolygon polygon)
{
return(IsPointInPolygon(point.X, point.Y, polygon));
}
/// <summary>
/// Constructor. Copies input line.
/// </summary>
/// <param name="line">Line to copy</param>
public XYLine(XYLine line)
{
_p1 = new XYPoint();
_p2 = new XYPoint();
_p1.X = line.P1.X;
_p1.Y = line.P1.Y;
_p2.X = line.P2.X;
_p2.Y = line.P2.Y;
}
public static double ACalculateLineToPointDistance(XYLine line, XYPoint point)
{
return CalculateLineToPointDistance(line, point);
}
/// <summary>
/// The method calculates the intersection points of triangle a and b both
/// of type XYPolygon.
/// </summary>
/// <param name="triangleA">triangle. The search is started along triangleA.</param>
/// <param name="triangleB">triangle. Intersection with this triangle are sought.</param>
/// <param name="p">Starting point for the search. p must be part of triangleA.</param>
/// <param name="i">on input: End index for the first line segment of triangleA in the search.
/// on output: End index for the last intersected line segment in triangleA.</param>
/// <param name="j">on input: -1 if vertices before intersection is not to be added to list.
/// on output: End index for last intersected line segment of triangleB.</param>
/// <param name="intersectionPolygon">polygon eventuallu describing the
/// intersection area between triangleA and triangleB</param>
/// <returns>
/// The p, i, j and intersectionPolygon are called by reference and modified in the method.
/// </returns>
private static void Intersect (XYPolygon triangleA, XYPolygon triangleB,
ref XYPoint p, ref int i, ref int j,
ref XYPolygon intersectionPolygon)
{
XYLine lineA;
XYLine lineB;
int im1 = Decrease(i, 2); // "i-1"
int count1 = 0;
bool found = false;
while ((count1 < 3) && (!found))
{
lineA = triangleA.GetLine(im1);
if (count1 == 0)
{
lineA.P1.X = p.X;
lineA.P1.Y = p.Y;
}
double MinDist = -1; // Distance used when a line is crossed more than once
int jm1 = 0; // "j-1"
int jm1Store = -1;
while (jm1 < 3)
{
lineB = triangleB.GetLine(jm1);
found = IntersectionPoint(lineA, lineB, ref p);
double Dist = CalculatePointToPointDistance(lineA.P1,p);
if (Dist < EPSILON)
{
found = false;
}
if (found)
{
if ((MinDist < 0) || (Dist < MinDist))
{
MinDist = Dist;
jm1Store = jm1;
}
}
jm1++;
}
if ( jm1Store > -1 )
{
lineB = triangleB.GetLine(jm1Store);
found = IntersectionPoint(lineA, lineB, ref p);
XYPoint HelpCoordinate = new XYPoint(p.X, p.Y);
XYPoint HelpNode = new XYPoint(HelpCoordinate);
intersectionPolygon.Points.Add(HelpNode);
j = Increase(jm1Store,2);
}
if (!found)
{
count1++;
im1 = Increase(im1,2);
i = Increase(i,2);
if (j!=-1)
{
XYPoint HelpCoordinate = new XYPoint(lineA.P2.X, lineA.P2.Y);
XYPoint HelpNode = new XYPoint(HelpCoordinate);
intersectionPolygon.Points.Add(HelpNode);
}
}
}
lineA = triangleA.GetLine(Decrease(i, 2));
if ( CalculatePointToPointDistance(p, lineA.P2)<EPSILON )
{
i = Increase(i, 2);
}
lineB = triangleB.GetLine(Decrease(j, 2));
if ( CalculatePointToPointDistance(p, lineB.P2)<EPSILON )
{
j = Increase(j, 2);
}
}
/// <summary>
/// Returns the distance between the two points.
/// </summary>
/// <param name="p1">Point</param>
/// <param name="p2">Point</param>
/// <returns>Point to point distance</returns>
public static double CalculatePointToPointDistance(XYPoint p1, XYPoint p2)
{
return(Math.Sqrt((p1.X - p2.X) * (p1.X - p2.X) + (p1.Y - p2.Y) * (p1.Y - p2.Y)));
}
/// <summary>
/// Calculates length of line inside polygon. Parts of the line that is on the edge of
/// the polygon only counts with half their length.
/// </summary>
/// <param name="line">Line</param>
/// <param name="polygon">Polygon</param>
/// <returns>
/// Length of line inside polygon.
/// </returns>
protected static double CalculateLengthOfLineInsidePolygon(XYLine line, XYPolygon polygon)
{
ArrayList lineList = new ArrayList();
lineList.Add(new XYLine(line));
for (int i = 0; i < polygon.Points.Count; i++) // For all lines in the polygon
{
for (int n = 0; n < lineList.Count; n++)
{
if (lineList.Count > 1000)
{
throw new Exception("Problems in ElementMapper, line has been cut in more than 1000 pieces !!!");
}
if (DoLineSegmentsIntersect((XYLine)lineList[n], polygon.GetLine(i)))
{
// Split the intersecting line into two lines
XYPoint IntersectionPoint = new XYPoint(CalculateIntersectionPoint((XYLine)lineList[n], polygon.GetLine(i)));
lineList.Add(new XYLine(IntersectionPoint, ((XYLine) lineList[n]).P2));
((XYLine) lineList[n]).P2.X = IntersectionPoint.X;
((XYLine) lineList[n]).P2.Y = IntersectionPoint.Y;
break;
}
}
}
for (int i = 0; i < lineList.Count; i++)
{
if (lineList.Count > 1000)
{
throw new Exception("Problems in ElementMapper, line has been cuttes in more than 100 pieces !!!");
}
for (int j = 0; j < polygon.Points.Count; j++)
{
if (IsPointInLineInterior( polygon.GetLine(j).P1, ((XYLine) lineList[i])))
{
lineList.Add(new XYLine(polygon.GetLine(j).P1, ((XYLine) lineList[i]).P2));
((XYLine) lineList[i]).P2.X = polygon.GetLine(j).P1.X;
((XYLine) lineList[i]).P2.Y = polygon.GetLine(j).P1.Y;
}
}
}
double lengthInside = 0;
for (int i = 0; i < lineList.Count; i++)
{
double sharedLength = 0;
for (int j = 0; j < polygon.Points.Count; j++)
{
sharedLength += CalculateSharedLength(((XYLine) lineList[i]), polygon.GetLine(j));
}
if (sharedLength > EPSILON)
{
lengthInside += sharedLength/2;
}
else if (IsPointInPolygon(((XYLine) lineList[i]).GetMidpoint(), polygon))
{
lengthInside += ((XYLine) lineList[i]).GetLength();
}
}
return lengthInside;
}
/// <summary>
/// The method calculates the intersection area of triangle a and b both
/// of type XYPolygon.
/// </summary>
/// <param name="triangleA">Triangle of type XYPolygon</param>
/// <param name="triangleB">Triangle of type XYPolygon</param>
/// <returns>
/// Intersection area between the triangles triangleA and triAngleB.
/// </returns>
protected static double TriangleIntersectionArea(XYPolygon triangleA, XYPolygon triangleB)
{
try
{
if (triangleA.Points.Count != 3 || triangleB.Points.Count != 3)
{
throw new System.Exception("Argument must be a polygon with 3 points");
}
int i = 1; // Index for "next" node in polygon a.
int j = -1; // Index for "next" node in polygon b.
// -1 indicates that the first has not yet been found.
double area = 0; // Intersection area. Returned.
XYPolygon intersectionPolygon = new XYPolygon(); // Intersection polygon.
XYPoint pFirst = new XYPoint(); // First intersection point between triangles
XYPoint p = new XYPoint(); // Latest intersection node found
p.X = ((XYPoint) triangleA.Points[0]).X;
p.Y = ((XYPoint) triangleA.Points[0]).Y;
Intersect(triangleA, triangleB, ref p, ref i, ref j, ref intersectionPolygon);
pFirst = p;
if (j != -1)
{
int jStop = Increase(j, 2);
bool complete = false;
int count = 0;
while (!complete)
{
// coordinates for vectors pointing to next triangleA and triangleB point respectively
double vax= ((XYPoint) triangleA.Points[i]).X - p.X;
double vay= ((XYPoint) triangleA.Points[i]).Y - p.Y;
double vbx= ((XYPoint) triangleB.Points[j]).X - p.X;
double vby= ((XYPoint) triangleB.Points[j]).Y - p.Y;
if(IsPointInPolygonOrOnEdge(p.X + EPSILON*vax, p.Y + EPSILON*vay, triangleB))
{
Intersect(triangleA, triangleB, ref p, ref i, ref j, ref intersectionPolygon);
}
else if(IsPointInPolygonOrOnEdge(p.X + EPSILON*vbx, p.Y + EPSILON*vby, triangleA))
{
Intersect(triangleB, triangleA, ref p, ref j, ref i, ref intersectionPolygon);
}
else // triangleA and triangleB only touches one another but do not intersect
{
area = 0;
return area;
}
if (intersectionPolygon.Points.Count > 1)
{
complete = (CalculatePointToPointDistance(p, pFirst) < EPSILON);
}
count++;
if ( count > 20 )
{
throw new System.Exception("Failed to find intersection polygon");
}
}
area = intersectionPolygon.GetArea();
}
else
{
XYPoint pa = new XYPoint(); // internal point in triangle a
XYPoint pb = new XYPoint(); // internal point in triangle b
pa.X = (triangleA.GetX(0)+triangleA.GetX(1)+triangleA.GetX(2))/3;
pa.Y = (triangleA.GetY(0)+triangleA.GetY(1)+triangleA.GetY(2))/3;
pb.X = (triangleB.GetX(0)+triangleB.GetX(1)+triangleB.GetX(2))/3;
pb.Y = (triangleB.GetY(0)+triangleB.GetY(1)+triangleB.GetY(2))/3;
if (IsPointInPolygon(pa,triangleB) || IsPointInPolygon(pb,triangleA)) // triangleA is completely inside triangleB
{
area = Math.Min(triangleA.GetArea(),triangleB.GetArea());
}
else // triangleA and triangleB do dot intersect
{
area = 0;
}
}
return area;
}
catch (System.Exception e)
{
throw new System.Exception("TriangleIntersectionArea failed",e);
}
}
/// <summary>
/// Calculates the length that two lines overlap.
/// </summary>
/// <param name="lineA">Line</param>
/// <param name="lineB">Line</param>
/// <returns>
/// Length of shared line segment.
/// </returns>
protected static double CalculateSharedLength(XYLine lineA, XYLine lineB)
{
if ( Math.Abs(lineA.P2.X-lineA.P1.X)<EPSILON && Math.Abs(lineB.P2.X-lineB.P1.X)<EPSILON &&Math.Abs(lineA.P1.X-lineB.P1.X)<EPSILON)
{
double YP1A = Math.Min(lineA.P1.Y, lineA.P2.Y);
double YP2A = Math.Max(lineA.P1.Y, lineA.P2.Y);
double YP1B = Math.Min(lineB.P1.Y, lineB.P2.Y);
double YP2B = Math.Max(lineB.P1.Y, lineB.P2.Y);
double YP1 = Math.Max(YP1A, YP1B);
double YP2 = Math.Min(YP2A, YP2B);
if (YP1 < YP2)
{
return YP2-YP1;
}
else
{
return 0;
}
}
else if(Math.Abs(lineA.P2.X-lineA.P1.X)<EPSILON || Math.Abs(lineB.P2.X-lineB.P1.X)<EPSILON)
{
return 0;
}
else
{
XYPoint P1A = new XYPoint();
XYPoint P2A = new XYPoint();
if (lineA.P1.X < lineA.P2.X)
{
P1A = lineA.P1;
P2A = lineA.P2;
}
else
{
P1A = lineA.P2;
P2A = lineA.P1;
}
XYPoint P1B = new XYPoint();
XYPoint P2B = new XYPoint();
if (lineB.P1.X < lineB.P2.X)
{
P1B = lineB.P1;
P2B = lineB.P2;
}
else
{
P1B = lineB.P2;
P2B = lineB.P1;
}
double alphaA = (P2A.Y - P1A.Y)/(P2A.X - P1A.X);
double betaA = -alphaA*P2A.X + P2A.Y;
double alphaB = (P2B.Y - P1B.Y)/(P2B.X - P1B.X);
double betaB = -alphaA*P2B.X + P2B.Y;
if (Math.Abs(alphaA-alphaB)<EPSILON && Math.Abs(betaA-betaB)<EPSILON)
{
double x1 = Math.Max(P1A.X, P1B.X);
double x2 = Math.Min(P2A.X, P2B.X);
if (x1 < x2)
{
XYLine line = new XYLine(x1, alphaA*x1+betaA, x2, alphaA*x2+betaA);
return line.GetLength();
}
else
{
return 0;
}
}
else
{
return 0;
}
}
}
/// <summary>
/// Calculate intersection point between two line segments.
/// </summary>
/// <param name="p1">First point in first line</param>
/// <param name="p2">Second point in first line</param>
/// <param name="p3">First point in second line</param>
/// <param name="p4">Second point in second line</param>
/// <returns>Intersection point</returns>
public static XYPoint CalculateIntersectionPoint(XYPoint p1, XYPoint p2, XYPoint p3, XYPoint p4)
{
if (!DoLineSegmentsIntersect(p1,p2,p3,p4))
{
throw new System.Exception("Attempt to calculate intersection point between non intersecting lines. CalculateIntersectionPoint failed.");
}
XYPoint interSectionPoint = new XYPoint();
double a = p1.X * p2.Y - p2.X * p1.Y;
double b = p3.X * p4.Y - p4.X * p3.Y;
double c = (p1.X - p2.X) * (p3.Y - p4.Y) - (p3.X - p4.X) * (p1.Y - p2.Y);
interSectionPoint.X = (a * (p3.X - p4.X) - (b * (p1.X - p2.X))) / c;
interSectionPoint.Y = (a * (p3.Y - p4.Y) - (b * (p1.Y - p2.Y))) / c;
return interSectionPoint;
}
/// <summary>
/// OverLoad of DoLineSegmentsIntersect(x1, y1, x2, y2, x3, y3, x4, y4)
/// </summary>
/// <param name="p1">First point in first line</param>
/// <param name="p2">Second point in first line</param>
/// <param name="p3">First point in second line</param>
/// <param name="p4">Second point in second line</param>
/// <returns>true if the line segmenst intersects otherwise false</returns>
public static bool DoLineSegmentsIntersect(XYPoint p1, XYPoint p2, XYPoint p3, XYPoint p4)
{
return(DoLineSegmentsIntersect(p1.X, p1.Y, p2.X, p2.Y, p3.X, p3.Y, p4.X, p4.Y));
}
/// <summary>
/// Calculates length of line inside polygon. Parts of the line that is on the edge of
/// the polygon only counts with half their length.
/// </summary>
/// <param name="line">Line</param>
/// <param name="polygon">Polygon</param>
/// <returns>
/// Length of line inside polygon.
/// </returns>
protected static double CalculateLengthOfLineInsidePolygon(XYLine line, XYPolygon polygon)
{
ArrayList lineList = new ArrayList();
lineList.Add(new XYLine(line));
for (int i = 0; i < polygon.Points.Count; i++) // For all lines in the polygon
{
for (int n = 0; n < lineList.Count; n++)
{
if (lineList.Count > 1000)
{
throw new Exception("Problems in ElementMapper, line has been cut in more than 1000 pieces !!!");
}
if (DoLineSegmentsIntersect((XYLine)lineList[n], polygon.GetLine(i)))
{
// Split the intersecting line into two lines
XYPoint IntersectionPoint = new XYPoint(CalculateIntersectionPoint((XYLine)lineList[n], polygon.GetLine(i)));
lineList.Add(new XYLine(IntersectionPoint, ((XYLine)lineList[n]).P2));
((XYLine)lineList[n]).P2.X = IntersectionPoint.X;
((XYLine)lineList[n]).P2.Y = IntersectionPoint.Y;
break;
}
}
}
for (int i = 0; i < lineList.Count; i++)
{
if (lineList.Count > 1000)
{
throw new Exception("Problems in ElementMapper, line has been cuttes in more than 100 pieces !!!");
}
for (int j = 0; j < polygon.Points.Count; j++)
{
if (IsPointInLineInterior(polygon.GetLine(j).P1, ((XYLine)lineList[i])))
{
lineList.Add(new XYLine(polygon.GetLine(j).P1, ((XYLine)lineList[i]).P2));
((XYLine)lineList[i]).P2.X = polygon.GetLine(j).P1.X;
((XYLine)lineList[i]).P2.Y = polygon.GetLine(j).P1.Y;
}
}
}
double lengthInside = 0;
for (int i = 0; i < lineList.Count; i++)
{
double sharedLength = 0;
for (int j = 0; j < polygon.Points.Count; j++)
{
sharedLength += CalculateSharedLength(((XYLine)lineList[i]), polygon.GetLine(j));
}
if (sharedLength > EPSILON)
{
lengthInside += sharedLength / 2;
}
else if (IsPointInPolygon(((XYLine)lineList[i]).GetMidpoint(), polygon))
{
lengthInside += ((XYLine)lineList[i]).GetLength();
}
}
return(lengthInside);
}
/// <summary>
/// Returns an ArrayList of triangles of type XYPolygon describing the
/// triangalation of the polygon.
/// </summary>
/// <param></param>
/// <returns>
/// A triangulation of the polygon.
/// </returns>
public ArrayList GetTriangulation()
{
int i = 0;
int im1 = 0;
int ip1 = 0;
int n = 0;
XYPolygon LocalPolygon = new XYPolygon(this);
ArrayList TriangleList = new ArrayList();
while (LocalPolygon.Points.Count > 3)
{
i = LocalPolygon.FindEar();
n = LocalPolygon.Points.Count;
im1 = i-1;
ip1 = i+1;
if (i == 0)
{
im1 = n-1;
}
else if (i == n-1)
{
ip1 = 0;
}
XYPoint Nodeim1 = new XYPoint((XYPoint)LocalPolygon.Points[im1]);
XYPoint Nodei = new XYPoint((XYPoint)LocalPolygon.Points[i]);
XYPoint Nodeip1 = new XYPoint((XYPoint)LocalPolygon.Points[ip1]);
XYPolygon Triangle = new XYPolygon();
Triangle.Points.Add(Nodeim1);
Triangle.Points.Add(Nodei);
Triangle.Points.Add(Nodeip1);
TriangleList.Add(Triangle);
LocalPolygon.Points.RemoveAt(i);
}
TriangleList.Add(LocalPolygon);
return TriangleList;
}
/// <summary>
/// Calculates the length that two lines overlap.
/// </summary>
/// <param name="lineA">Line</param>
/// <param name="lineB">Line</param>
/// <returns>
/// Length of shared line segment.
/// </returns>
protected static double CalculateSharedLength(XYLine lineA, XYLine lineB)
{
if (Math.Abs(lineA.P2.X - lineA.P1.X) < EPSILON && Math.Abs(lineB.P2.X - lineB.P1.X) < EPSILON && Math.Abs(lineA.P1.X - lineB.P1.X) < EPSILON)
{
double YP1A = Math.Min(lineA.P1.Y, lineA.P2.Y);
double YP2A = Math.Max(lineA.P1.Y, lineA.P2.Y);
double YP1B = Math.Min(lineB.P1.Y, lineB.P2.Y);
double YP2B = Math.Max(lineB.P1.Y, lineB.P2.Y);
double YP1 = Math.Max(YP1A, YP1B);
double YP2 = Math.Min(YP2A, YP2B);
if (YP1 < YP2)
{
return(YP2 - YP1);
}
else
{
return(0);
}
}
else if (Math.Abs(lineA.P2.X - lineA.P1.X) < EPSILON || Math.Abs(lineB.P2.X - lineB.P1.X) < EPSILON)
{
return(0);
}
else
{
XYPoint P1A = new XYPoint();
XYPoint P2A = new XYPoint();
if (lineA.P1.X < lineA.P2.X)
{
P1A = lineA.P1;
P2A = lineA.P2;
}
else
{
P1A = lineA.P2;
P2A = lineA.P1;
}
XYPoint P1B = new XYPoint();
XYPoint P2B = new XYPoint();
if (lineB.P1.X < lineB.P2.X)
{
P1B = lineB.P1;
P2B = lineB.P2;
}
else
{
P1B = lineB.P2;
P2B = lineB.P1;
}
double alphaA = (P2A.Y - P1A.Y) / (P2A.X - P1A.X);
double betaA = -alphaA * P2A.X + P2A.Y;
double alphaB = (P2B.Y - P1B.Y) / (P2B.X - P1B.X);
double betaB = -alphaA * P2B.X + P2B.Y;
if (Math.Abs(alphaA - alphaB) < EPSILON && Math.Abs(betaA - betaB) < EPSILON)
{
double x1 = Math.Max(P1A.X, P1B.X);
double x2 = Math.Min(P2A.X, P2B.X);
if (x1 < x2)
{
XYLine line = new XYLine(x1, alphaA * x1 + betaA, x2, alphaA * x2 + betaA);
return(line.GetLength());
}
else
{
return(0);
}
}
else
{
return(0);
}
}
}
private XYPoint CreateXYPoint(IElementSet elementSet, int index)
{
if (elementSet.ElementType != ElementType.XYPoint)
{
throw new System.Exception("Cannot create XYPoint");
}
XYPoint xyPoint = new XYPoint();
xyPoint.X = elementSet.GetXCoordinate(index,0);
xyPoint.Y = elementSet.GetYCoordinate(index,0);
return xyPoint;
}
public void Protected_IsPointInLineInterior()
{
XYPoint point = new XYPoint();
Assert.AreEqual(false,AXYGeometryTools.AIsPointInLineInterior(new XYPoint(0,0), new XYLine(0, 0, 1, 1)),"Test1");
Assert.AreEqual(true,AXYGeometryTools.AIsPointInLineInterior(new XYPoint(0.5,0.5), new XYLine(0, 0, 1, 1)),"Test2");
Assert.AreEqual(false,AXYGeometryTools.AIsPointInLineInterior(new XYPoint(1,1), new XYLine(0, 0, 1, 1)),"Test3");
Assert.AreEqual(false,AXYGeometryTools.AIsPointInLineInterior(new XYPoint(0.5,0), new XYLine(0, 0, 1, 1)),"Test4");
Assert.AreEqual(false,AXYGeometryTools.AIsPointInLineInterior(new XYPoint(20,40), new XYLine(20, 40, 20, 0)),"Test5");
}
/// <summary>
/// Constructor.
/// </summary>
/// <returns>None</returns>
public XYPoint(XYPoint xypoint)
{
_x = xypoint.X;
_y = xypoint.Y;
}
public static bool AIntersectionPoint(XYLine lineA, XYLine lineB, ref XYPoint intersectionPoint)
{
return IntersectionPoint(lineA, lineB, ref intersectionPoint);
}
/// <summary>
/// The method calculates the intersection points of triangle a and b both
/// of type XYPolygon.
/// </summary>
/// <param name="triangleA">triangle. The search is started along triangleA.</param>
/// <param name="triangleB">triangle. Intersection with this triangle are sought.</param>
/// <param name="p">Starting point for the search. p must be part of triangleA.</param>
/// <param name="i">on input: End index for the first line segment of triangleA in the search.
/// on output: End index for the last intersected line segment in triangleA.</param>
/// <param name="j">on input: -1 if vertices before intersection is not to be added to list.
/// on output: End index for last intersected line segment of triangleB.</param>
/// <param name="intersectionPolygon">polygon eventuallu describing the
/// intersection area between triangleA and triangleB</param>
/// <returns>
/// The p, i, j and intersectionPolygon are called by reference and modified in the method.
/// </returns>
private static void Intersect(XYPolygon triangleA, XYPolygon triangleB,
ref XYPoint p, ref int i, ref int j,
ref XYPolygon intersectionPolygon)
{
XYLine lineA;
XYLine lineB;
int im1 = Decrease(i, 2); // "i-1"
int count1 = 0;
bool found = false;
while ((count1 < 3) && (!found))
{
lineA = triangleA.GetLine(im1);
if (count1 == 0)
{
lineA.P1.X = p.X;
lineA.P1.Y = p.Y;
}
double MinDist = -1; // Distance used when a line is crossed more than once
int jm1 = 0; // "j-1"
int jm1Store = -1;
while (jm1 < 3)
{
lineB = triangleB.GetLine(jm1);
found = IntersectionPoint(lineA, lineB, ref p);
double Dist = CalculatePointToPointDistance(lineA.P1, p);
if (Dist < EPSILON)
{
found = false;
}
if (found)
{
if ((MinDist < 0) || (Dist < MinDist))
{
MinDist = Dist;
jm1Store = jm1;
}
}
jm1++;
}
if (jm1Store > -1)
{
lineB = triangleB.GetLine(jm1Store);
found = IntersectionPoint(lineA, lineB, ref p);
XYPoint HelpCoordinate = new XYPoint(p.X, p.Y);
XYPoint HelpNode = new XYPoint(HelpCoordinate);
intersectionPolygon.Points.Add(HelpNode);
j = Increase(jm1Store, 2);
}
if (!found)
{
count1++;
im1 = Increase(im1, 2);
i = Increase(i, 2);
if (j != -1)
{
XYPoint HelpCoordinate = new XYPoint(lineA.P2.X, lineA.P2.Y);
XYPoint HelpNode = new XYPoint(HelpCoordinate);
intersectionPolygon.Points.Add(HelpNode);
}
}
}
lineA = triangleA.GetLine(Decrease(i, 2));
if (CalculatePointToPointDistance(p, lineA.P2) < EPSILON)
{
i = Increase(i, 2);
}
lineB = triangleB.GetLine(Decrease(j, 2));
if (CalculatePointToPointDistance(p, lineB.P2) < EPSILON)
{
j = Increase(j, 2);
}
}
/// <summary>
/// Returns the distance between the two points.
/// </summary>
/// <param name="p1">Point</param>
/// <param name="p2">Point</param>
/// <returns>Point to point distance</returns>
public static double CalculatePointToPointDistance(XYPoint p1, XYPoint p2)
{
return Math.Sqrt( (p1.X-p2.X)*(p1.X-p2.X)+(p1.Y -p2.Y )*(p1.Y -p2.Y ) );
}
/// <summary>
/// Determines if a point is included in a lines interior. I.e. included
/// in the line and not an endpoint.
/// <p>Overload to:IsPointInLineInterior(double x, double y, XYLine line)</p>
/// </summary>
/// <param name="point">Point.</param>
/// <param name="line">Line.</param>
/// <returns>
/// <p>Determines if a point is included in a line.</p>
/// </returns>
protected static bool IsPointInLineInterior(XYPoint point, XYLine line)
{
return(IsPointInLineInterior(point.X, point.Y, line));
}
/// <summary>
/// The method decides if the triangle formed by P(i-1), P(i) and
/// P(i+1) from Polygon are intersected by any of the other points
/// of the polygon.
/// </summary>
/// <param name="i">Middle index for the three points that forms the triangle</param>
/// <returns>
/// <p>true: If the triangle P(i-1), P(i), P(i+1) is intersected by other parts of Polygon</p>
/// <p>false: otherwise</p>
/// </returns>
protected bool IsIntersected(int i)
{
double x = 0;
double y = 0;
int n = Points.Count;
int im1 = i-1;
int ip1 = i+1;
if (i == 0)
{
im1 = n-1;
}
else if (i == n-1)
{
ip1 = 0;
}
XYPoint nodeim1 = new XYPoint((XYPoint) Points[im1]);
XYPoint nodei = new XYPoint((XYPoint) Points[i]);
XYPoint nodeip1 = new XYPoint((XYPoint) Points[ip1]);
XYPolygon localPolygon = new XYPolygon();
localPolygon.Points.Add(nodeim1);
localPolygon.Points.Add(nodei);
localPolygon.Points.Add(nodeip1);
int j = 0;
bool intersected = false;
while (((j < n-1) && (!intersected)))
{
x = ((XYPoint) Points[j]).X;
y = ((XYPoint) Points[j]).Y;
if (((((j!=im1) && (j!=i)) && (j!=ip1)) && XYGeometryTools.IsPointInPolygon(x,y,localPolygon)))
{
return true;
}
else
{
j++;
}
}
return false;
}
/// <summary>
/// Checks if the lines lineA and lineB shares a point either as a real
/// crossing point or as a shared end point or a end point of the one
/// line being in the other line.
/// </summary>
/// <param name="Linea">Line.</param>
/// <param name="Lineb">Line.</param>
/// <param name="intersectionPoint">Point.</param>
/// <returns>
/// <p>True if lineA and lineB has shared point. False otherwise</p>
/// <p>The shared point if any is returned in the intersectionPoint
/// parameter that is called by reference</p>
/// </returns>
protected static bool IntersectionPoint(XYLine Linea, XYLine Lineb, ref XYPoint intersectionPoint)
{
if( DoLineSegmentsIntersect(Linea, Lineb))
{
intersectionPoint = CalculateIntersectionPoint(Linea, Lineb);
return true;
}
if( IsPointInLine(Linea.P2, Lineb))
{
intersectionPoint = Linea.P2;
return true;
}
if( IsPointInLine(Lineb.P2, Linea))
{
intersectionPoint = Lineb.P2;
return true;
}
if( IsPointInLine(Lineb.P1, Linea))
{
intersectionPoint = Lineb.P1;
return true;
}
if( IsPointInLine(Linea.P1, Lineb))
{
intersectionPoint = Linea.P1;
return true;
}
return false;
}
/// <summary>
/// Static method that validates an object with an IElementSet interface. The method
/// raises an Exception in case IElementSet does not describe a valid ElementSet.
/// The checks made are:
/// <p>ElementType: Check</p>
/// <p>XYPoint: Only one vertex in each element.</p>
/// <p>XYPolyline: At least two vertices in each element.</p>
/// <p> All line segments in each element has length > 0</p>
/// <p>XYPolygon: At least three vertices in each element.</p>
/// <p> Area of each element is larger than 0</p>
/// <p> All line segments in each element has length > 0</p>
/// <p> No line segments within an element crosses.</p>
/// </summary>
///
/// <param name="elementSet">Object that implement the IElementSet interface</param>
///
/// <returns>
/// The method has no return value.
/// </returns>
public static void CheckElementSet(IElementSet elementSet)
{
try
{
if(elementSet.ElementType == ElementType.XYPoint)
{
for (int i = 0; i < elementSet.ElementCount; i++)
{
try
{
if(elementSet.GetVertexCount(i) != 1)
{
throw new System.Exception("Number of vertices in point element is different from 1.");
}
}
catch (System.Exception e)
{
throw new System.Exception("ElementID = "+elementSet.GetElementID(i),e);
}
}
}
else if(elementSet.ElementType == ElementType.XYPolyLine)
{
for (int i = 0; i < elementSet.ElementCount; i++)
{
try
{
XYPolyline xypolyline = new XYPolyline();
for (int j = 0; j < elementSet.GetVertexCount(i); j++)
{
XYPoint xypoint = new XYPoint(elementSet.GetXCoordinate(i,j),elementSet.GetYCoordinate(i,j));
xypolyline.Points.Add(xypoint);
}
xypolyline.Validate();
}
catch (System.Exception e)
{
throw new System.Exception("ElementID = "+elementSet.GetElementID(i),e);
}
}
}
else if(elementSet.ElementType == ElementType.XYPolygon)
{
for (int i = 0; i < elementSet.ElementCount; i++)
{
try
{
XYPolygon xypolygon = new XYPolygon();
for (int j = 0; j < elementSet.GetVertexCount(i); j++)
{
XYPoint xypoint = new XYPoint(elementSet.GetXCoordinate(i,j),elementSet.GetYCoordinate(i,j));
xypolygon.Points.Add(xypoint);
}
xypolygon.Validate();
}
catch (System.Exception e)
{
throw new System.Exception("ElementID = "+elementSet.GetElementID(i),e);
}
}
}
}
catch (System.Exception e)
{
throw new System.Exception("ElementSet with ID = "+elementSet.ID+" is invalid",e);
}
}
/// <summary>
/// Determines if a point is included in a lines interior. I.e. included
/// in the line and not an endpoint.
/// <p>Overload to:IsPointInLineInterior(double x, double y, XYLine line)</p>
/// </summary>
/// <param name="point">Point.</param>
/// <param name="line">Line.</param>
/// <returns>
/// <p>Determines if a point is included in a line.</p>
/// </returns>
protected static bool IsPointInLineInterior(XYPoint point, XYLine line)
{
return IsPointInLineInterior( point.X, point.Y, line);
}
/// <summary>
/// Static method that validates an object with an IElementSet interface. The method
/// raises an Exception in case IElementSet does not describe a valid ElementSet.
/// The checks made are:
/// <p>ElementType: Check</p>
/// <p>XYPoint: Only one vertex in each element.</p>
/// <p>XYPolyline: At least two vertices in each element.</p>
/// <p> All line segments in each element has length > 0</p>
/// <p>XYPolygon: At least three vertices in each element.</p>
/// <p> Area of each element is larger than 0</p>
/// <p> All line segments in each element has length > 0</p>
/// <p> No line segments within an element crosses.</p>
/// </summary>
///
/// <param name="elementSet">Object that implement the IElementSet interface</param>
///
/// <returns>
/// The method has no return value.
/// </returns>
public static void CheckElementSet(IElementSet elementSet)
{
try
{
if (elementSet.ElementType == ElementType.XYPoint)
{
for (int i = 0; i < elementSet.ElementCount; i++)
{
try
{
if (elementSet.GetVertexCount(i) != 1)
{
throw new System.Exception("Number of vertices in point element is different from 1.");
}
}
catch (System.Exception e)
{
throw new System.Exception("ElementID = " + elementSet.GetElementID(i), e);
}
}
}
else if (elementSet.ElementType == ElementType.XYPolyLine)
{
for (int i = 0; i < elementSet.ElementCount; i++)
{
try
{
XYPolyline xypolyline = new XYPolyline();
for (int j = 0; j < elementSet.GetVertexCount(i); j++)
{
XYPoint xypoint = new XYPoint(elementSet.GetXCoordinate(i, j), elementSet.GetYCoordinate(i, j));
xypolyline.Points.Add(xypoint);
}
xypolyline.Validate();
}
catch (System.Exception e)
{
throw new System.Exception("ElementID = " + elementSet.GetElementID(i), e);
}
}
}
else if (elementSet.ElementType == ElementType.XYPolygon)
{
for (int i = 0; i < elementSet.ElementCount; i++)
{
try
{
XYPolygon xypolygon = new XYPolygon();
for (int j = 0; j < elementSet.GetVertexCount(i); j++)
{
XYPoint xypoint = new XYPoint(elementSet.GetXCoordinate(i, j), elementSet.GetYCoordinate(i, j));
xypolygon.Points.Add(xypoint);
}
xypolygon.Validate();
}
catch (System.Exception e)
{
throw new System.Exception("ElementID = " + elementSet.GetElementID(i), e);
}
}
}
}
catch (System.Exception e)
{
throw new System.Exception("ElementSet with ID = " + elementSet.ID + " is invalid", e);
}
}
/// <summary>
/// Calculates the distance from a polyline to a point in the plane.
/// The algorithm decides weather the point lies besides the line
/// segment in which case the distance is the length along a line
/// perpendicular to the line. Alternatively the distance is the
/// smallest of the distances to either endpoint.
/// </summary>
/// <param name="line">Line</param>
/// <param name="point">Point</param>
/// <returns>
/// <p>Length of the shortest path between the line and the point.</p>
/// </returns>
protected static double CalculateLineToPointDistance (XYLine line, XYPoint point)
{
double dist = 0;
double a = Math.Sqrt((line.P2.X-point.X)*(line.P2.X-point.X) + (line.P2.Y-point.Y)*(line.P2.Y-point.Y));
double b = Math.Sqrt((line.P2.X-line.P1.X)*(line.P2.X-line.P1.X)+(line.P2.Y-line.P1.Y)*(line.P2.Y-line.P1.Y));
double c = Math.Sqrt((line.P1.X-point.X)*(line.P1.X-point.X)+(line.P1.Y-point.Y)*(line.P1.Y-point.Y));
if ((a == 0) || (c == 0))
{
dist = 0;
}
else if (b == 0)
{
dist = a;
}
else
{
double alpha = Math.Acos((b*b+c*c-a*a)/(2*b*c));
double beta = Math.Acos((a*a+b*b-c*c)/(2*a*b));
if (Math.Max(alpha,beta)<Math.PI/2)
{
dist = Math.Abs((line.P2.X-line.P1.X)*(line.P1.Y-point.Y)-(line.P1.X-point.X)*(line.P2.Y-line.P1.Y))/b;
}
else
{
dist = Math.Min(a, c);
}
}
return dist;
}
/// <summary>
/// Constructor.
/// </summary>
/// <returns>None</returns>
public XYLine()
{
_p1 = new XYPoint();
_p2 = new XYPoint();
}
/// <summary>
/// Finds the shortest distance between any line segment of the polyline
/// and the point.
/// </summary>
/// <param name="polyLine">PolyLine.</param>
/// <param name="point">Point</param>
/// <returns>
/// <p>Length of the shortest path between the polyline and the point.</p>
/// </returns>
public static double CalculatePolylineToPointDistance (XYPolyline polyLine, XYPoint point)
{
double dist = 0;
int i = 0;
while (i < polyLine.Points.Count - 1)
{
if (i == 0)
{
dist = CalculateLineToPointDistance (polyLine.GetLine(0), point);
}
else
{
dist = Math.Min(dist, CalculateLineToPointDistance (polyLine.GetLine(i), point));
}
i++;
}
return dist;
}
/// <summary>
/// Determines if a point in inside or outside a polygon.
/// Works for both convex and concave polygons (Winding number test)
/// </summary>
/// <param name="point">Point</param>
/// <param name="polygon">Polygon</param>
/// <returns>
/// <p>true: If the point is inside the polygon</p>
/// <p>false: Otherwise.</p>
/// </returns>
public static bool IsPointInPolygon(XYPoint point, XYPolygon polygon)
{
return IsPointInPolygon(point.X, point.Y, polygon);
}
/// <summary>
/// Constructor.
/// </summary>
/// <returns>None</returns>
public XYPoint(XYPoint xypoint)
{
_x = xypoint.X;
_y = xypoint.Y;
}