OGR
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OGRLinearRing Class Reference

#include <ogr_geometry.h>

Inheritance diagram for OGRLinearRing:
OGRLineString OGRCurve OGRGeometry

Public Member Functions

virtual const char * getGeometryName () const
 Fetch WKT name for geometry type. More...
 
virtual OGRGeometryclone () const
 Make a copy of this object. More...
 
virtual int isClockwise () const
 Returns TRUE if the ring has clockwise winding (or less than 2 points) More...
 
virtual void closeRings ()
 Force rings to be closed. More...
 
virtual double get_Area () const
 Compute area of ring. More...
 
virtual int WkbSize () const
 Returns size of related binary representation. More...
 
virtual OGRErr importFromWkb (unsigned char *, int=-1)
 Assign geometry from well known binary data. More...
 
virtual OGRErr exportToWkb (OGRwkbByteOrder, unsigned char *, OGRwkbVariant=wkbVariantOgc) const
 Convert a geometry into well known binary format. More...
 
- Public Member Functions inherited from OGRLineString
 OGRLineString ()
 Create an empty line string.
 
virtual OGRErr importFromWkt (char **)
 Assign geometry from well known text data. More...
 
virtual OGRErr exportToWkt (char **ppszDstText) const
 Convert a geometry into well known text format. More...
 
virtual int getDimension () const
 Get the dimension of this object. More...
 
virtual void empty ()
 Clear geometry information. This restores the geometry to it's initial state after construction, and before assignment of actual geometry. More...
 
virtual void getEnvelope (OGREnvelope *psEnvelope) const
 Computes and returns the bounding envelope for this geometry in the passed psEnvelope structure. More...
 
virtual void getEnvelope (OGREnvelope3D *psEnvelope) const
 Computes and returns the bounding envelope (3D) for this geometry in the passed psEnvelope structure. More...
 
virtual OGRBoolean IsEmpty () const
 Returns TRUE (non-zero) if the object has no points. More...
 
virtual double get_Length () const
 Returns the length of the curve. More...
 
virtual void StartPoint (OGRPoint *) const
 Return the curve start point. More...
 
virtual void EndPoint (OGRPoint *) const
 Return the curve end point. More...
 
virtual void Value (double, OGRPoint *) const
 Fetch point at given distance along curve. More...
 
virtual double Project (const OGRPoint *) const
 Project point on linestring. More...
 
virtual OGRLineStringgetSubLine (double, double, int) const
 Get the portion of linestring. More...
 
int getNumPoints () const
 Fetch vertex count. More...
 
void getPoint (int, OGRPoint *) const
 Fetch a point in line string. More...
 
double getX (int i) const
 Get X at vertex. More...
 
double getY (int i) const
 Get Y at vertex. More...
 
double getZ (int i) const
 Get Z at vertex. More...
 
virtual OGRBoolean Equals (OGRGeometry *) const
 Returns TRUE if two geometries are equivalent. More...
 
virtual void setCoordinateDimension (int nDimension)
 Set the coordinate dimension. More...
 
void setNumPoints (int nNewPointCount, int bZeroizeNewContent=TRUE)
 Set number of points in geometry. More...
 
void setPoint (int, OGRPoint *)
 Set the location of a vertex in line string. More...
 
void setPoint (int, double, double, double)
 Set the location of a vertex in line string. More...
 
void setPoints (int, OGRRawPoint *, double *=NULL)
 Assign all points in a line string. More...
 
void setPoints (int, double *padfX, double *padfY, double *padfZ=NULL)
 Assign all points in a line string. More...
 
void addPoint (OGRPoint *)
 Add a point to a line string. More...
 
void addPoint (double, double, double)
 Add a point to a line string. More...
 
void getPoints (OGRRawPoint *, double *=NULL) const
 Returns all points of line string. More...
 
void getPoints (void *pabyX, int nXStride, void *pabyY, int nYStride, void *pabyZ=NULL, int nZStride=0) const
 Returns all points of line string. More...
 
void addSubLineString (const OGRLineString *, int nStartVertex=0, int nEndVertex=-1)
 Add a segment of another linestring to this one. More...
 
void reversePoints (void)
 Reverse point order. More...
 
virtual OGRwkbGeometryType getGeometryType () const
 Fetch geometry type. More...
 
virtual OGRErr transform (OGRCoordinateTransformation *poCT)
 Apply arbitrary coordinate transformation to geometry. More...
 
virtual void flattenTo2D ()
 Convert geometry to strictly 2D. In a sense this converts all Z coordinates to 0.0. More...
 
virtual void segmentize (double dfMaxLength)
 Modify the geometry such it has no segment longer then the given distance. More...
 
virtual void swapXY ()
 Swap x and y coordinates. More...
 
- Public Member Functions inherited from OGRCurve
virtual int get_IsClosed () const
 Return TRUE if curve is closed. More...
 
- Public Member Functions inherited from OGRGeometry
virtual int getCoordinateDimension () const
 Get the dimension of the coordinates in this object. More...
 
virtual OGRBoolean IsValid () const
 Test if the geometry is valid. More...
 
virtual OGRBoolean IsSimple () const
 Test if the geometry is simple. More...
 
virtual OGRBoolean IsRing () const
 Test if the geometry is a ring. More...
 
virtual void dumpReadable (FILE *, const char *=NULL, char **papszOptions=NULL) const
 Dump geometry in well known text format to indicated output file. More...
 
virtual char * exportToGML (const char *const *papszOptions=NULL) const
 Convert a geometry into GML format. More...
 
virtual char * exportToKML () const
 Convert a geometry into KML format. More...
 
virtual char * exportToJson () const
 Convert a geometry into GeoJSON format. More...
 
void assignSpatialReference (OGRSpatialReference *poSR)
 Assign spatial reference to this object. More...
 
OGRSpatialReferencegetSpatialReference (void) const
 Returns spatial reference system for object. More...
 
OGRErr transformTo (OGRSpatialReference *poSR)
 Transform geometry to new spatial reference system. More...
 
virtual OGRBoolean Intersects (OGRGeometry *) const
 Do these features intersect? More...
 
virtual OGRBoolean Disjoint (const OGRGeometry *) const
 Test for disjointness. More...
 
virtual OGRBoolean Touches (const OGRGeometry *) const
 Test for touching. More...
 
virtual OGRBoolean Crosses (const OGRGeometry *) const
 Test for crossing. More...
 
virtual OGRBoolean Within (const OGRGeometry *) const
 Test for containment. More...
 
virtual OGRBoolean Contains (const OGRGeometry *) const
 Test for containment. More...
 
virtual OGRBoolean Overlaps (const OGRGeometry *) const
 Test for overlap. More...
 
virtual OGRGeometryBoundary () const
 Compute boundary. More...
 
virtual double Distance (const OGRGeometry *) const
 Compute distance between two geometries. More...
 
virtual OGRGeometryConvexHull () const
 Compute convex hull. More...
 
virtual OGRGeometryBuffer (double dfDist, int nQuadSegs=30) const
 Compute buffer of geometry. More...
 
virtual OGRGeometryIntersection (const OGRGeometry *) const
 Compute intersection. More...
 
virtual OGRGeometryUnion (const OGRGeometry *) const
 Compute union. More...
 
virtual OGRGeometryUnionCascaded () const
 Compute union using cascading. More...
 
virtual OGRGeometryDifference (const OGRGeometry *) const
 Compute difference. More...
 
virtual OGRGeometrySymDifference (const OGRGeometry *) const
 Compute symmetric difference. More...
 
virtual OGRErr Centroid (OGRPoint *poPoint) const
 Compute the geometry centroid. More...
 
virtual OGRGeometrySimplify (double dTolerance) const
 Simplify the geometry. More...
 
OGRGeometrySimplifyPreserveTopology (double dTolerance) const
 Simplify the geometry while preserving topology. More...
 
virtual OGRGeometryPolygonize () const
 Polygonizes a set of sparse edges. More...
 
virtual OGRGeometrySymmetricDifference (const OGRGeometry *) const CPL_WARN_DEPRECATED("Non standard method. Use SymDifference() instead")
 Compute symmetric difference (deprecated) More...
 
virtual OGRGeometrygetBoundary () const CPL_WARN_DEPRECATED("Non standard method. Use Boundary() instead")
 Compute boundary (deprecated) More...
 

Friends

class OGRPolygon
 

Detailed Description

Concrete representation of a closed ring.

This class is functionally equivelent to an OGRLineString, but has a separate identity to maintain alignment with the OpenGIS simple feature data model. It exists to serve as a component of an OGRPolygon.

The OGRLinearRing has no corresponding free standing well known binary representation, so importFromWkb() and exportToWkb() will not actually work. There is a non-standard GDAL WKT representation though.

Because OGRLinearRing is not a "proper" free standing simple features object, it cannot be directly used on a feature via SetGeometry(), and cannot genearally be used with GEOS for operations like Intersects(). Instead the polygon should be used, or the OGRLinearRing should be converted to an OGRLineString for such operations.

Member Function Documentation

OGRGeometry * OGRLinearRing::clone ( ) const
virtual

Make a copy of this object.

This method relates to the SFCOM IGeometry::clone() method.

This method is the same as the C function OGR_G_Clone().

Returns
a new object instance with the same geometry, and spatial reference system as the original.

Reimplemented from OGRLineString.

References OGRGeometry::assignSpatialReference(), OGRGeometry::getSpatialReference(), and OGRLineString::setPoints().

void OGRLinearRing::closeRings ( )
virtual

Force rings to be closed.

If this geometry, or any contained geometries has polygon rings that are not closed, they will be closed by adding the starting point at the end.

Reimplemented from OGRGeometry.

References OGRLineString::addPoint(), OGRLineString::getPoint(), OGRLineString::getX(), OGRLineString::getY(), and OGRLineString::getZ().

OGRErr OGRLinearRing::exportToWkb ( OGRwkbByteOrder  eByteOrder,
unsigned char *  pabyData,
OGRwkbVariant  eWkbVariant = wkbVariantOgc 
) const
virtual

Convert a geometry into well known binary format.

This method relates to the SFCOM IWks::ExportToWKB() method.

This method is the same as the C function OGR_G_ExportToWkb().

Parameters
eByteOrderOne of wkbXDR or wkbNDR indicating MSB or LSB byte order respectively.
pabyDataa buffer into which the binary representation is written. This buffer must be at least OGRGeometry::WkbSize() byte in size.
eWkbVariantWhat standard to use when exporting geometries with three dimensions (or more). The default wkbVariantOgc is the historical OGR variant. wkbVariantIso is the variant defined in ISO SQL/MM and adopted by OGC for SFSQL 1.2.
Returns
Currently OGRERR_NONE is always returned.

Reimplemented from OGRLineString.

References CPLError(), and OGRLineString::setNumPoints().

double OGRLinearRing::get_Area ( ) const
virtual

Compute area of ring.

The area is computed according to Green's Theorem:

Area is "Sum(x(i)*(y(i+1) - y(i-1)))/2" for i = 0 to pointCount-1, assuming the last point is a duplicate of the first.

Returns
computed area.

References CPLDebug(), OGRLineString::getEnvelope(), OGRLineString::getNumPoints(), OGRPoint::getX(), OGRLineString::getX(), OGRPoint::getY(), and OGRLineString::getY().

Referenced by OGRPolygon::get_Area().

const char * OGRLinearRing::getGeometryName ( ) const
virtual

Fetch WKT name for geometry type.

There is no SFCOM analog to this method.

This method is the same as the C function OGR_G_GetGeometryName().

Returns
name used for this geometry type in well known text format. The returned pointer is to a static internal string and should not be modified or freed.

Reimplemented from OGRLineString.

OGRErr OGRLinearRing::importFromWkb ( unsigned char *  pabyData,
int  nSize = -1 
)
virtual

Assign geometry from well known binary data.

The object must have already been instantiated as the correct derived type of geometry object to match the binaries type. This method is used by the OGRGeometryFactory class, but not normally called by application code.

This method relates to the SFCOM IWks::ImportFromWKB() method.

This method is the same as the C function OGR_G_ImportFromWkb().

Parameters
pabyDatathe binary input data.
nSizethe size of pabyData in bytes, or zero if not known.
Returns
OGRERR_NONE if all goes well, otherwise any of OGRERR_NOT_ENOUGH_DATA, OGRERR_UNSUPPORTED_GEOMETRY_TYPE, or OGRERR_CORRUPT_DATA may be returned.

Reimplemented from OGRLineString.

int OGRLinearRing::isClockwise ( ) const
virtual

Returns TRUE if the ring has clockwise winding (or less than 2 points)

Returns
TRUE if clockwise otherwise FALSE.

References OGRLineString::getPoint(), and OGRLineString::setPoint().

Referenced by OGRGeometryFactory::organizePolygons().

int OGRLinearRing::WkbSize ( ) const
virtual

Returns size of related binary representation.

This method returns the exact number of bytes required to hold the well known binary representation of this geometry object. Its computation may be slightly expensive for complex geometries.

This method relates to the SFCOM IWks::WkbSize() method.

This method is the same as the C function OGR_G_WkbSize().

Returns
size of binary representation in bytes.

Reimplemented from OGRLineString.


The documentation for this class was generated from the following files:

Generated for GDAL by doxygen 1.8.11.