/// <summary>
/// Simplification by using Douglas-Peucker variant algorithm
/// </summary>
/// <param name="points">input points</param>
/// <param name="maxPoints">the maximum number of points of the simplified polyline</param>
/// <returns>simplified polyline</returns>
private static bool[] SimplifyByDouglasPeuckerNHelp(GPoint[] points, int maxPoints)
{
int pointCount = points.Length;
bool[] keys = new bool[pointCount];
keys[0] = true; // the first point is always a key
keys[pointCount - 1] = true; // the last point is always a key
int keyCount = 2;
PriorityQueue <SubPolyAlt> queue = new PriorityQueue <SubPolyAlt>();
SubPolyAlt subPoly = new SubPolyAlt(0, pointCount - 1);
subPoly.KeyInfo = FindKey(points, subPoly.First, subPoly.Last);
queue.Push(subPoly); // add complete poly
while (!queue.IsEmpty())
{
subPoly = queue.Top(); // take a sub poly
queue.Pop();
// store the key
keys[subPoly.KeyInfo.Index] = true;
// check point count tolerance
keyCount++;
if (keyCount == maxPoints)
{
break;
}
// split the polyline at the key and recurse
SubPolyAlt left = new SubPolyAlt(subPoly.First, subPoly.KeyInfo.Index);
left.KeyInfo = FindKey(points, left.First, left.Last);
if (left.KeyInfo.Index > 0)
{
queue.Push(left);
}
SubPolyAlt right = new SubPolyAlt(subPoly.KeyInfo.Index, subPoly.Last);
right.KeyInfo = FindKey(points, right.First, right.Last);
if (right.KeyInfo.Index > 0)
{
queue.Push(right);
}
}
return(keys);
}
public int CompareTo(object obj)
{
SubPolyAlt other = obj as SubPolyAlt;
if (other == null)
{
return(-1);
}
if (KeyInfo.Dist2 < other.KeyInfo.Dist2)
{
return(-1);
}
else if (KeyInfo.Dist2 < other.KeyInfo.Dist2)
{
return(1);
}
else
{
return(0);
}
}