/// <summary>
/// Since polygons from countries and provinces are not perfectly aligned in all cases, this method will take the largest contour and assume this is the resulting polygon
/// (even if it's not closed...)
/// </summary>
public Polygon ToPolygonFromLargestLineStrip()
{
// Check for empty result
if ((closedPolygons.Count == 0 ||
(closedPolygons.Count == 1 && closedPolygons[0].pointList.Count == 0)) &&
(openPolygons.Count == 0 ||
(openPolygons.Count == 1 && openPolygons[0].pointList.Count == 0)))
{
return(null);
}
// Get the largest contour (open or closed)
int maxPoints = -1;
PointChain largestPointChain = null;
foreach (PointChain pointChain in closedPolygons)
{
if (pointChain.pointList.Count > maxPoints)
{
maxPoints = pointChain.pointList.Count;
largestPointChain = pointChain;
}
}
foreach (PointChain pointChain in openPolygons)
{
if (pointChain.pointList.Count > maxPoints)
{
maxPoints = pointChain.pointList.Count;
largestPointChain = pointChain;
}
}
// ... and create a new polygon from that
if (maxPoints < 0)
{
return(null);
}
Polygon polygon = new Polygon();
Contour contour = new Contour();
contour.AddRange(largestPointChain.pointList);
polygon.AddContour(contour);
// add other closed polygons
foreach (PointChain pointChain in closedPolygons)
{
if (largestPointChain != pointChain)
{
Contour otherContour = new Contour();
otherContour.AddRange(pointChain.pointList);
if (!contour.Contains(otherContour))
{
polygon.AddContour(otherContour);
}
}
}
FixOrientation(polygon);
return(polygon);
}
// Links another pointChain onto this point chain.
public bool LinkPointChain(PointChain chain)
{
Vector2 firstPoint = pointList[0];
Vector2 lastPoint = pointList[pointList.Count - 1];
Vector2 chainFront = chain.pointList[0];
Vector2 chainBack = chain.pointList[chain.pointList.Count - 1];
if (Point.PointEquals(chainFront, lastPoint))
{
List <Vector2> temp = new List <Vector2>(chain.pointList);
temp.RemoveAt(0);
pointList.AddRange(temp);
chain.pointList.Clear();
return(true);
}
if (Point.PointEquals(chainBack, firstPoint))
{
pointList.RemoveAt(0); // Remove the first element, and join this list to chain.pointList.
List <Vector2> temp = new List <Vector2>(chain.pointList);
temp.AddRange(pointList);
pointList = temp;
chain.pointList.Clear();
return(true);
}
if (Point.PointEquals(chainFront, firstPoint))
{
pointList.RemoveAt(0); // Remove the first element, and join to reversed chain.pointList
List <Vector2> temp = new List <Vector2>(chain.pointList);
temp.Reverse();
temp.AddRange(pointList);
pointList = temp;
chain.pointList.Clear();
return(true);
}
if (Point.PointEquals(chainBack, lastPoint))
{
pointList.RemoveAt(pointList.Count - 1);
List <Vector2> temp = new List <Vector2>(chain.pointList);
temp.Reverse();
pointList.AddRange(temp);
chain.pointList.Clear();
return(true);
}
return(false);
}
public void Add(Segment s)
{
// j iterates through the openPolygon chains.
for (int j = 0; j < openPolygons.Count; j++)
{
PointChain chain = openPolygons [j];
if (!chain.LinkSegment(s))
{
continue;
}
if (chain.closed)
{
if (chain.pointList.Count == 2)
{
// We tried linking the same segment (but flipped end and start) to
// a chain. (i.e. chain was <p0, p1>, we tried linking Segment(p1, p0)
// so the chain was closed illegally.
chain.closed = false;
return;
}
closedPolygons.Add(chain);
openPolygons.RemoveAt(j);
return;
}
int k = openPolygons.Count;
for (int i = j + 1; i < k; i++)
{
// Try to connect this open link to the rest of the chains.
// We won't be able to connect this to any of the chains preceding this one
// because we know that linkSegment failed on those.
if (chain.LinkPointChain(openPolygons [i]))
{
openPolygons.RemoveAt(i);
return;
}
}
return;
}
PointChain newChain = new PointChain(s);
openPolygons.Add(newChain);
}