/// <summary>
/// Updates info on the longest horizontal span that crosses this polygon (used
/// by <see cref="GetLabelPosition"/>)
/// </summary>
/// <param name="y">The Y-value of the scan line.</param>
/// <param name="minx">The X-value for the western end of the scan line.</param>
/// <param name="maxx">The X-value for the eastern end of the scan line.</param>
/// <param name="weight">Weighting factor to use when comparing span lengths versus
/// the initial best length.</param>
/// <param name="beststart">The position of the start of the best span.</param>
/// <param name="bestend">The position of the end of the best span.</param>
/// <param name="bestlen">The weighted length of the best span. This is what defines
/// the meaning of "best".</param>
void GetLabelSpan(double y, double minx, double maxx, double weight,
ref IPosition beststart, ref IPosition bestend, ref double bestlen)
{
// Define scan line.
ITerminal sloc = new FloatingTerminal(minx, y);
ITerminal eloc = new FloatingTerminal(maxx, y);
SegmentGeometry seg = new SegmentGeometry(sloc, eloc);
// Intersect with the map
IntersectionFinder xseg = new IntersectionFinder(seg, true);
// Arrange intersections along the scan line.
IntersectionResult xres = new IntersectionResult(xseg);
xres.Sort(true);
// Define start of the first span
IPosition start = sloc;
IPosition end = null;
// Go through each successive intersection, to locate spans
// that run through the interior of the polygon.
foreach (IntersectionData d in xres.Intersections)
{
// If the intersection is a graze
if (d.IsGraze)
{
// Just define the end of the graze as the end point (there's
// no point in trying to locate a label along the graze).
end = d.P2;
}
else
{
// Simple intersection...
// Get the next intersection
end = d.P1;
// Get the midpoint of the span.
IPosition mid = Position.CreateMidpoint(start, end);
// If the midpoint really falls inside this polygon, see whether the span
// length is bigger than what we already have (if anything).
if (this.IsEnclosing(mid))
{
double len = (end.X - start.X) / weight;
if (len > bestlen)
{
bestlen = len;
beststart = start;
bestend = end;
}
}
}
start = end;
}
}
/// <summary>
/// Updates info on the longest horizontal span that crosses this polygon (used
/// by <see cref="GetLabelPosition"/>)
/// </summary>
/// <param name="y">The Y-value of the scan line.</param>
/// <param name="minx">The X-value for the western end of the scan line.</param>
/// <param name="maxx">The X-value for the eastern end of the scan line.</param>
/// <param name="weight">Weighting factor to use when comparing span lengths versus
/// the initial best length.</param>
/// <param name="beststart">The position of the start of the best span.</param>
/// <param name="bestend">The position of the end of the best span.</param>
/// <param name="bestlen">The weighted length of the best span. This is what defines
/// the meaning of "best".</param>
void GetLabelSpan(double y, double minx, double maxx, double weight,
ref IPosition beststart, ref IPosition bestend, ref double bestlen)
{
// Define scan line.
ITerminal sloc = new FloatingTerminal(minx, y);
ITerminal eloc = new FloatingTerminal(maxx, y);
SegmentGeometry seg = new SegmentGeometry(sloc, eloc);
// Intersect with the map
IntersectionFinder xseg = new IntersectionFinder(seg, true);
// Arrange intersections along the scan line.
IntersectionResult xres = new IntersectionResult(xseg);
xres.Sort(true);
// Define start of the first span
IPosition start = sloc;
IPosition end = null;
// Go through each successive intersection, to locate spans
// that run through the interior of the polygon.
foreach (IntersectionData d in xres.Intersections)
{
// If the intersection is a graze
if (d.IsGraze)
{
// Just define the end of the graze as the end point (there's
// no point in trying to locate a label along the graze).
end = d.P2;
}
else
{
// Simple intersection...
// Get the next intersection
end = d.P1;
// Get the midpoint of the span.
IPosition mid = Position.CreateMidpoint(start, end);
// If the midpoint really falls inside this polygon, see whether the span
// length is bigger than what we already have (if anything).
if (this.IsEnclosing(mid))
{
double len = (end.X - start.X)/weight;
if (len>bestlen)
{
bestlen = len;
beststart = start;
bestend = end;
}
}
}
start = end;
}
}
/// <summary>
/// Intersects this multi-segment with itself. Only SIMPLE intersections will be
/// found. There are no special checks for multi-segments that graze themselves.
/// </summary>
/// <param name="xsect">The intersection results.</param>
/// <returns>The number of self-intersections found.</returns>
uint SelfIntersect(IntersectionResult xsect)
{
uint nx = 0;
// Get an array of cumulative distances for each segment.
IPointGeometry[] data = this.Data;
double[] cumdist = GetCumDist(data);
// Note start of initial segment (treat as the end of some imaginary line prior to the start).
double xs;
double ys;
double xe = data[0].X;
double ye = data[0].Y;
// How many line segments have we got?
int nseg = data.Length - 1;
// Loop through each segment, intersecting it with all subsequent
// segments, except for the one that immediately follows.
for (int iseg = 1; iseg <= (nseg - 2); iseg++)
{
// The start of this segment is the end of the previous one.
xs = xe;
ys = ye;
// Get the position of the end of the test segment
xe = data[iseg].X;
ye = data[iseg].Y;
// Compare against subsequent segments (except the next one)
for (int jseg = iseg + 2; jseg <= nseg; jseg++)
{
IPointGeometry start = data[jseg - 1];
IPointGeometry end = data[jseg];
double xi, yi;
if (Geom.CalcIntersect(start.X, start.Y, end.X, end.Y, xs, ys, xe, ye, out xi, out yi, true) != 0)
{
// Define distance to the intersection on the i-segment
double dx = xi - xs;
double dy = yi - ys;
double ilen = cumdist[iseg - 1] + Math.Sqrt(dx * dx + dy * dy);
// Likewise for the j-segment
dx = xi - start.X;
dy = yi - start.Y;
double jlen = cumdist[jseg - 1] + Math.Sqrt(dx * dx + dy * dy);
// Append TWO intersections.
xsect.Append(xi, yi, ilen);
xsect.Append(xi, yi, jlen);
nx += 2;
}
}
}
// Sort the intersections (DON'T set new sort values).
xsect.Sort(false);
// Return the number of intersections
return(nx);
}
/// <summary>
/// Intersects this multi-segment with itself. Only SIMPLE intersections will be
/// found. There are no special checks for multi-segments that graze themselves.
/// </summary>
/// <param name="xsect">The intersection results.</param>
/// <returns>The number of self-intersections found.</returns>
uint SelfIntersect(IntersectionResult xsect)
{
uint nx = 0;
// Get an array of cumulative distances for each segment.
IPointGeometry[] data = this.Data;
double[] cumdist = GetCumDist(data);
// Note start of initial segment (treat as the end of some imaginary line prior to the start).
double xs;
double ys;
double xe = data[0].X;
double ye = data[0].Y;
// How many line segments have we got?
int nseg = data.Length-1;
// Loop through each segment, intersecting it with all subsequent
// segments, except for the one that immediately follows.
for (int iseg=1; iseg<=(nseg-2); iseg++)
{
// The start of this segment is the end of the previous one.
xs = xe;
ys = ye;
// Get the position of the end of the test segment
xe = data[iseg].X;
ye = data[iseg].Y;
// Compare against subsequent segments (except the next one)
for (int jseg=iseg+2; jseg<=nseg; jseg++)
{
IPointGeometry start = data[jseg-1];
IPointGeometry end = data[jseg];
double xi, yi;
if (Geom.CalcIntersect(start.X, start.Y, end.X, end.Y, xs, ys, xe, ye, out xi, out yi, true)!=0)
{
// Define distance to the intersection on the i-segment
double dx = xi-xs;
double dy = yi-ys;
double ilen = cumdist[iseg-1] + Math.Sqrt(dx*dx + dy*dy);
// Likewise for the j-segment
dx = xi - start.X;
dy = yi - start.Y;
double jlen = cumdist[jseg-1] + Math.Sqrt(dx*dx + dy*dy);
// Append TWO intersections.
xsect.Append(xi, yi, ilen);
xsect.Append(xi, yi, jlen);
nx += 2;
}
}
}
// Sort the intersections (DON'T set new sort values).
xsect.Sort(false);
// Return the number of intersections
return nx;
}
