/// <summary>
/// Checks if this ring encloses a specific position.
/// </summary>
/// <param name="p">The position to check</param>
/// <returns>True is this ring encloses the position. False if the position
/// is outside, or ON the edge.</returns>
/// <remarks>Do not override. Any island polygons are intentionally ignored.</remarks>
internal bool IsRingEnclosing(IPosition p)
{
// Return if the position doesn't fall within the window of this polygon
if (!this.Extent.IsOverlap(p))
{
return(false);
}
// Set up a search line from the test position to the edge of this
// polygon's window.
IPosition east = new Position(this.Extent.Max.X, p.Y);
// Round off to the nearest micron on the ground
PointGeometry vs = new PointGeometry(p);
PointGeometry ve = new PointGeometry(east);
IDivider closest = null;
// For each divider we have in the list, locate the closest
// point of intersection with the search line.
foreach (IDivider d in m_Edge)
{
uint error;
if (d.LineGeometry.GetCloser(vs, ref ve, out error))
{
closest = d;
}
// Return if the vertex coincides with the closest point
// on the divider (point exactly on the edge of this polygon).
if (error != 0 || vs.IsCoincident(ve))
{
return(false);
}
}
// We SHOULD have got something.
if (closest == null)
{
return(false);
}
// The point can't be inside if we're dealing with an island, and the
// divider we've found is either a bridge, or a dangle that radiates outwards
// from the island (this assumes that points exactly coincident with the edge
// can be treated as "outside").
if (this is Island && closest.Left == closest.Right)
{
return(false);
}
// Which side of the divider does the directed line hit?
IDivider sideDivider;
Side side = Topology.GetSide(closest, vs, ve, out sideDivider);
// Check if we're hitting the divider from the inside. If this
// ring is an island, things are backwards.
if (this is Island)
{
if (side == Side.Right && sideDivider.Left == this)
{
return(true);
}
if (side == Side.Left && sideDivider.Right == this)
{
return(true);
}
}
else
{
if (side == Side.Left && sideDivider.Left == this)
{
return(true);
}
if (side == Side.Right && sideDivider.Right == this)
{
return(true);
}
}
return(false);
}