/// <summary>
/// Finds the nearest point to the requested location that is within the tolerance radius.
/// </summary>
/// <param name="ProjectedRadius">The tolerance radius in projected units used to search for the nearest point that can be snapped to.</param>
/// <param name="x">x coordinate in projected map units</param>
/// <param name="y">y coordinate in projected map units</param>
/// <param name="curShape">The shape that is currently being created. Points from this shape are also checked.</param>
/// <param name="BestPoint">A PointD class with the location of the nearest point to snap to if there is are any within the tolerance, null if no points are found.</param>
/// <returns>Returns true if there is a point to snap to.</returns>
public bool CanSnap(double ProjectedRadius, double x, double y, ShapeClass curShape, ref System.Collections.ArrayList BestPoints)
{
System.Collections.IDictionaryEnumerator ie = m_lists.GetEnumerator();
PointD myBest = null;
System.Collections.ArrayList myBestPoints = null;
while (ie.MoveNext())
{
int snaplayeridx = (int)ie.Key;
// find any points that are within the tolerance in curShape.
for (int i = 0; i < curShape.NumPoints; i++)
{
PointD pt = curShape[i];
double d = pt.Dist(x, y);
if (d < ProjectedRadius)
{
if (myBest != null)
{
if (d < myBest.Dist(x, y))
{
myBest = pt;
}
}
else
{
myBest = pt;
}
}
}
if (myBest != null)
{
SnapData d = new SnapData(-1, -1, myBest);
myBestPoints = new System.Collections.ArrayList();
myBestPoints.Add(d);
}
if (CanSnap(ProjectedRadius, x, y, ref BestPoints))
{ // work with that best point.
if (myBest != null)
{
PointD tPoint = ((SnapData)BestPoints[0]).point;
if (myBest.Dist(x, y) < tPoint.Dist(x, y))
{
if (BestPoints == null)
{
BestPoints = new System.Collections.ArrayList();
}
BestPoints.AddRange(myBestPoints);
}
}
}
else
{
if (myBestPoints != null)
{
if (BestPoints == null)
{
BestPoints = new System.Collections.ArrayList();
}
BestPoints.AddRange(myBestPoints);
}
}
}
if (BestPoints == null)
{
return(false);
}
else
{
return(true);
}
}
/********************************************************************/
// Test the point if it's within the line segements of the curShape
// returns the insertIndex if within tolerance else -1
/********************************************************************/
private bool WithinTolerance(double x, double y, int shpIndex, double tol, ref double storeX, ref double storeY, ref int insertIndex)
{
int numPoints = 0;
Point p1, p2;
double m1, m2;
double dist, shortestDist = 9999999999;
double b1, b2;
double newX, newY;
int index = -1;
try
{
//get the array of points for this shape
MapWinGIS.Shapefile sf = m_Globals.CurrentLayer;
System.Array points = sf.QuickPoints(shpIndex, ref numPoints);
//System.Collections.ArrayList points = (System.Collections.ArrayList)m_Points[shpIndex];
if (numPoints <= 1)
{
return(false);
}
for (int p = 0; p < numPoints * 2 - 2; p += 2)
{
p1 = new Point((double)points.GetValue(p), (double)points.GetValue(p + 1));
p2 = new Point((double)points.GetValue(p + 2), (double)points.GetValue(p + 3));
//p1 = (Point)points[i];
//p2 = (Point)points[i+1];
//find the slope make sure there is no divide by zero
if (p2.x == p1.x)
{
m1 = 0;
}
else
{
m1 = (p2.y - p1.y) / (p2.x - p1.x);
}
//find the y-intercept
b1 = p1.y - m1 * p1.x;
//find the slope of the perpendicular line relative to the given point
if (m1 == 0)
{
m2 = 0;
}
else
{
m2 = -1 / m1;
}
//find the y-intercept of the perpendicular line relative to the given point
b2 = y - m2 * x;
//find the intersection point between the two lines
if (m1 - m2 == 0) // Horizontal line
{
newX = p1.x;
if (p1.y == p2.y)
{
newY = m1 * newX + b1;
newX = x;
}
else
{
newY = m1 * newX + b2;
}
}
else
{
newX = (b2 - b1) / (m1 - m2);
newY = m1 * newX + b1;
}
//check to make sure the new point is within the line segment
if (PointWithinLineSegementBounds(p1, p2, new Point(newX, newY)))
{
//find the dist between the cursor point and the new point
dist = PointD.Dist(x, y, newX, newY);
//keep track of the shortest distance
if (dist <= shortestDist)
{
storeX = newX;
storeY = newY;
shortestDist = dist;
index = p / 2;
}
}
}
if (shortestDist <= tol)
{
insertIndex = index + 1;
return(true);
}
}
catch (System.Exception ex)
{
m_MapWin.ShowErrorDialog(ex);
}
//the point is not within the line segment tolerance
insertIndex = -1;
return(false);
}
