///<summary>
/// Converts a linearring to be sure it is clockwise.
///</summary>
///<remarks>Normal form is a unique representation
/// for Geometry's. It can be used to test whether two Geometrys are equal in a way that is
/// independent of the ordering of the coordinates within them. Normal form equality is a stronger
/// condition than topological equality, but weaker than pointwise equality. The definitions for
/// normal form use the standard lexicographical ordering for coordinates. Sorted in order of
/// coordinates means the obvious extension of this ordering to sequences of coordinates.
///</remarks>
private void Normalize(LinearRing ring, bool clockwise)
{
if (ring.IsEmpty())
{
return;
}
Coordinates uniqueCoordinates = new Coordinates();
for (int i = 0; i < ring.GetNumPoints() - 1; i++)
{
uniqueCoordinates.Add(ring.GetCoordinateN(i)); // copy all but last one into uniquecoordinates
}
Coordinate minCoordinate = MinCoordinate(ring.GetCoordinates());
Scroll(uniqueCoordinates, minCoordinate);
Coordinates ringCoordinates = ring.GetCoordinates();
ringCoordinates.Clear();
ringCoordinates.AddRange(uniqueCoordinates);
ringCoordinates.Add(uniqueCoordinates[0].Clone()); // add back in the closing point.
if (_cgAlgorithms.IsCCW(ringCoordinates) == clockwise)
{
ReversePointOrder(ringCoordinates);
}
}
/// <summary>
/// Initializes a Polygon with the given exterior boundary. The shell and holes
/// must conform to the assertions specified in the OpenGIS Simple Features
/// Specification for SQL.
/// </summary>
/// <param name="shell">
/// The outer boundary of the new Polygon, or null or an empty LinearRing if the empty
/// geometry is to be created. Must be oriented clockwise.
/// </param>
/// <param name="holes">
/// The inner boundaries of the new Polygon, or null or empty LinearRings if the empty
/// geometry is to be created. Each must be oriented counterclockwise.
/// </param>
/// <param name="precisionModel">
/// The specification of the grid of allowable points for this Polygon.
/// </param>
/// <param name="SRID">
/// The ID of the Spatial Reference System used by this Polygon.
/// </param>
internal Polygon(LinearRing shell, LinearRing[] holes, PrecisionModel precisionModel, int SRID) : base(precisionModel, SRID)
{
if (shell == null)
{
shell = _geometryFactory.CreateLinearRing(null);
}
if (holes == null)
{
holes = new LinearRing[] {};
}
//OPTIMIZE: - if fully optimzed, don't bother doing this test.
if (HasNullElements(holes))
{
throw new ArgumentNullException("holes must not contain null elements");
}
if (shell.IsEmpty() && HasNonEmptyElements(holes))
{
throw new ArgumentException("shell is empty but holes are not");
}
_shell = shell;
_holes = holes;
}
/// <summary>
/// Initializes a Polygon with the given exterior boundary. The shell and holes
/// must conform to the assertions specified in the OpenGIS Simple Features
/// Specification for SQL.
/// </summary>
/// <param name="shell">
/// The outer boundary of the new Polygon, or null or an empty LinearRing if the empty
/// geometry is to be created. Must be oriented clockwise.
/// </param>
/// <param name="holes">
/// The inner boundaries of the new Polygon, or null or empty LinearRings if the empty
/// geometry is to be created. Each must be oriented counterclockwise.
/// </param>
/// <param name="precisionModel">
/// The specification of the grid of allowable points for this Polygon.
/// </param>
/// <param name="SRID">
/// The ID of the Spatial Reference System used by this Polygon.
/// </param>
internal Polygon(LinearRing shell, LinearRing[] holes, PrecisionModel precisionModel, int SRID) : base(precisionModel, SRID)
{
if (shell == null)
{
shell = _geometryFactory.CreateLinearRing(null);
}
if (holes == null)
{
holes = new LinearRing[]{};
}
//OPTIMIZE: - if fully optimzed, don't bother doing this test.
if (HasNullElements(holes))
{
throw new ArgumentNullException("holes must not contain null elements");
}
if (shell.IsEmpty() && HasNonEmptyElements(holes))
{
throw new ArgumentException("shell is empty but holes are not");
}
_shell = shell;
_holes = holes;
}
/// <summary>
/// Determines if this polygon is empty.
/// </summary>
/// <returns>True if the polygon is empty.</returns>
public override bool IsEmpty()
{
return(_shell.IsEmpty());
}
///<summary>
/// Converts a linearring to be sure it is clockwise.
///</summary>
///<remarks>Normal form is a unique representation
/// for Geometry's. It can be used to test whether two Geometrys are equal in a way that is
/// independent of the ordering of the coordinates within them. Normal form equality is a stronger
/// condition than topological equality, but weaker than pointwise equality. The definitions for
/// normal form use the standard lexicographical ordering for coordinates. Sorted in order of
/// coordinates means the obvious extension of this ordering to sequences of coordinates.
///</remarks>
private void Normalize( LinearRing ring, bool clockwise )
{
if ( ring.IsEmpty() )
{
return;
}
Coordinates uniqueCoordinates = new Coordinates();
for ( int i=0; i < ring.GetNumPoints()-1; i++ )
{
uniqueCoordinates.Add( ring.GetCoordinateN( i ) ); // copy all but last one into uniquecoordinates
}
Coordinate minCoordinate = MinCoordinate( ring.GetCoordinates() );
Scroll( uniqueCoordinates, minCoordinate );
Coordinates ringCoordinates = ring.GetCoordinates();
ringCoordinates.Clear();
ringCoordinates.AddRange( uniqueCoordinates );
ringCoordinates.Add( uniqueCoordinates[0].Clone() ); // add back in the closing point.
if ( _cgAlgorithms.IsCCW( ringCoordinates ) == clockwise )
{
ReversePointOrder( ringCoordinates );
}
}
