/// <summary>
/// Tries to merge ways to closed polygons. The ordering of waynodes is preserved during the merge process.
/// </summary>
/// <param name="ways">
/// An array of ways that should be merged. Ways may be given in any order and may already be closed. </param>
internal virtual void mergePolygons(TDWay[] ways)
{
this.polygons = new List <>();
this.dangling = new List <>();
this.illegal = new List <>();
Deque <TDWay> ungroupedWays = new ArrayDeque <TDWay>();
// initially all ways are ungrouped
foreach (TDWay tdWay in ways)
{
// reset reversed flag, may already be set when way is part of another relation
tdWay.ReversedInRelation = false;
// first extract all way that are closed polygons in their own right
if (isClosedPolygon(tdWay))
{
if (tdWay.WayNodes.length < MIN_NODES_POLYGON)
{
this.illegal.Add(tdWay);
}
else
{
Deque <TDWay> cluster = new ArrayDeque <TDWay>();
cluster.add(tdWay);
this.polygons.Add(cluster);
}
}
else
{
ungroupedWays.add(tdWay);
}
}
// all ways have been polygons, nice!
if (ungroupedWays.Empty)
{
return;
}
if (ungroupedWays.size() == 1)
{
this.dangling.Add(ungroupedWays.First);
return;
}
bool startNewPolygon = true;
while (true)
{
bool merge = false;
if (startNewPolygon)
{
// we start a new polygon either during first iteration or when
// the previous iterations merged ways to a closed polygon and there
// are still ungrouped ways left
Deque <TDWay> cluster = new ArrayDeque <TDWay>();
// get the first way of the yet ungrouped ways and form a new group
cluster.add(ungroupedWays.removeFirst());
this.polygons.Add(cluster);
startNewPolygon = false;
}
// test if we can merge the current polygon with an ungrouped way
IEnumerator <TDWay> it = ungroupedWays.GetEnumerator();
while (it.MoveNext())
{
TDWay current = it.Current;
Deque <TDWay> currentPolygonSegments = this.polygons[this.polygons.Count - 1];
// first way in current polygon
TDWay c1Start = currentPolygonSegments.First;
// last way in current polygon
TDWay c1End = currentPolygonSegments.Last;
long startFirst = c1Start.ReversedInRelation ? c1Start.WayNodes[c1Start.WayNodes.length - 1].Id : c1Start.WayNodes[0].Id;
long endLast = c1End.ReversedInRelation ? c1End.WayNodes[0].Id : c1End.WayNodes[c1End.WayNodes.length - 1].Id;
long currentFirst = current.WayNodes[0].Id;
long currentLast = current.WayNodes[current.WayNodes.length - 1].Id;
// current way end connects to the start of the current polygon (correct direction)
if (startFirst == currentLast)
{
merge = true;
//JAVA TO C# CONVERTER TODO TASK: .NET enumerators are read-only:
it.remove();
// add way to start of current polygon
currentPolygonSegments.offerFirst(current);
}
// // current way start connects to the start of the current polygon (reversed
// direction)
else if (startFirst == currentFirst)
{
current.ReversedInRelation = true;
merge = true;
//JAVA TO C# CONVERTER TODO TASK: .NET enumerators are read-only:
it.remove();
currentPolygonSegments.offerFirst(current);
}
// current way start connects to the end of the current polygon (correct direction)
else if (endLast == currentFirst)
{
merge = true;
//JAVA TO C# CONVERTER TODO TASK: .NET enumerators are read-only:
it.remove();
// add way to end of current polygon
currentPolygonSegments.offerLast(current);
}
// // current way end connects to the end of the current polygon (reversed direction)
else if (endLast == currentLast)
{
current.ReversedInRelation = true;
merge = true;
//JAVA TO C# CONVERTER TODO TASK: .NET enumerators are read-only:
it.remove();
// add way to end of current polygon
currentPolygonSegments.offerLast(current);
}
}
Deque <TDWay> currentCluster = this.polygons[this.polygons.Count - 1];
bool closed = isClosedPolygon(currentCluster);
// not a closed polygon and no more ways to merge
if (!closed)
{
if (ungroupedWays.Empty || !merge)
{
((List <TDWay>) this.dangling).AddRange(this.polygons[this.polygons.Count - 1]);
// may be a non operation when ungrouped is empty
((List <TDWay>) this.dangling).AddRange(ungroupedWays);
this.polygons.Remove(this.polygons.Count - 1);
return;
}
}
else
{
// built a closed polygon and no more ways left --> we are finished
if (ungroupedWays.Empty)
{
return;
}
startNewPolygon = true;
}
// if we are here, the polygon is not yet closed, but there are also some ungrouped ways
// which may be merge-able in the next iteration
}
}