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OGRGeometry Class Reference

#include <ogr_geometry.h>

Inheritance diagram for OGRGeometry:

OGRCurve OGRGeometryCollection OGRPoint OGRSurface OGRLineString OGRMultiLineString OGRMultiPoint OGRMultiPolygon OGRPolygon OGRLinearRing List of all members.

Public Member Functions

virtual int getDimension ()=0
virtual int getCoordinateDimension ()=0
virtual OGRBoolean IsEmpty ()
virtual OGRBoolean IsSimple ()
virtual void empty ()=0
virtual OGRGeometryclone ()=0
virtual void getEnvelope (OGREnvelope *psEnvelope)=0
virtual int WkbSize ()=0
virtual OGRErr importFromWkb (unsigned char *, int=-1)=0
virtual OGRErr exportToWkb (OGRwkbByteOrder, unsigned char *)=0
virtual OGRErr importFromWkt (char **ppszInput)=0
virtual OGRErr exportToWkt (char **ppszDstText)=0
virtual OGRwkbGeometryType getGeometryType ()=0
virtual const char * getGeometryName ()=0
virtual void dumpReadable (FILE *, const char *=NULL)
virtual void flattenTo2D ()=0
virtual char * exportToGML () const
void assignSpatialReference (OGRSpatialReference *poSR)
OGRSpatialReferencegetSpatialReference (void)
virtual OGRErr transform (OGRCoordinateTransformation *poCT)=0
OGRErr transformTo (OGRSpatialReference *poSR)
virtual OGRBoolean Intersect (OGRGeometry *)
virtual OGRBoolean Equal (OGRGeometry *)=0

Detailed Description

Abstract base class for all geometry classes.

Note that the family of spatial analysis methods (Equal(), Disjoint(), ..., ConvexHull(), Buffer(), ...) are not implemented at ths time. Some other required and optional geometry methods have also been omitted at this time.


Member Function Documentation

void OGRGeometry::assignSpatialReference OGRSpatialReference poSR  ) 
 

Assign spatial reference to this object. Any existing spatial reference is replaced, but under no circumstances does this result in the object being reprojected. It is just changing the interpretation of the existing geometry. Note that assigning a spatial reference increments the reference count on the OGRSpatialReference, but does not copy it.

This is similar to the SFCOM IGeometry::put_SpatialReference() method.

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

Parameters:
poSR new spatial reference system to apply.

OGRGeometry * OGRGeometry::clone  )  [pure 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.

Implemented in OGRPoint, OGRLineString, OGRLinearRing, OGRPolygon, OGRGeometryCollection, OGRMultiPolygon, OGRMultiPoint, and OGRMultiLineString.

void OGRGeometry::dumpReadable FILE *  fp,
const char *  pszPrefix = NULL
[virtual]
 

Dump geometry in well known text format to indicated output file.

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

Parameters:
fp the text file to write the geometry to.
pszPrefix the prefix to put on each line of output.

void OGRGeometry::empty  )  [pure virtual]
 

Clear geometry information. This restores the geometry to it's initial state after construction, and before assignment of actual geometry.

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

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

Implemented in OGRPoint, OGRLineString, OGRPolygon, and OGRGeometryCollection.

int OGRGeometry::Equal OGRGeometry poOtherGeom  )  [pure virtual]
 

Returns two if two geometries are equivalent.

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

Returns:
TRUE if equivalent or FALSE otherwise.

Implemented in OGRPoint, OGRLineString, OGRPolygon, and OGRGeometryCollection.

char * OGRGeometry::exportToGML  )  const [virtual]
 

Convert a geometry into GML format.

The GML geometry is expressed directly in terms of GML basic data types assuming the this is available in the gml namespace. The returned string should be freed with CPLFree() when no longer required.

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

Returns:
A GML fragment or NULL in case of error.

OGRErr OGRGeometry::exportToWkb OGRwkbByteOrder  eByteOrder,
unsigned char *  pabyData
[pure 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:
eByteOrder One of wkbXDR or wkbNDR indicating MSB or LSB byte order respectively.
pabyData a buffer into which the binary representation is written. This buffer must be at least OGRGeometry::WkbSize() byte in size.
Returns:
Currently OGRERR_NONE is always returned.

Implemented in OGRPoint, OGRLineString, OGRLinearRing, OGRPolygon, and OGRGeometryCollection.

OGRErr OGRGeometry::exportToWkt char **  ppszDstText  )  [pure virtual]
 

Convert a geometry into well known text format.

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

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

Parameters:
ppszDstText a text buffer is allocated by the program, and assigned to the passed pointer.
Returns:
Currently OGRERR_NONE is always returned.

Implemented in OGRPoint, OGRLineString, OGRPolygon, OGRGeometryCollection, OGRMultiPolygon, OGRMultiPoint, and OGRMultiLineString.

void OGRGeometry::flattenTo2D  )  [pure virtual]
 

Convert geometry to strictly 2D. In a sense this converts all Z coordinates to 0.0.

This method is the same as the C function OGR_G_FlattenTo2D().

Implemented in OGRPoint, OGRLineString, OGRPolygon, and OGRGeometryCollection.

int OGRGeometry::getCoordinateDimension  )  [pure virtual]
 

Get the dimension of the coordinates in this object.

This method corresponds to the SFCOM IGeometry::GetDimension() method.

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

Returns:
in practice this always returns 2 indicating that coordinates are specified within a two dimensional space.

Implemented in OGRPoint, OGRLineString, OGRPolygon, and OGRGeometryCollection.

int OGRGeometry::getDimension  )  [pure virtual]
 

Get the dimension of this object.

This method corresponds to the SFCOM IGeometry::GetDimension() method. It indicates the dimension of the object, but does not indicate the dimension of the underlying space (as indicated by OGRGeometry::getCoordinateDimension()).

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

Returns:
0 for points, 1 for lines and 2 for surfaces.

Implemented in OGRPoint, OGRLineString, OGRPolygon, and OGRGeometryCollection.

void OGRGeometry::getEnvelope OGREnvelope psEnvelope  )  [pure virtual]
 

Computes and returns the bounding envelope for this geometry in the passed psEnvelope structure.

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

Parameters:
psEnvelope the structure in which to place the results.

Implemented in OGRPoint, OGRLineString, OGRPolygon, and OGRGeometryCollection.

const char * OGRGeometry::getGeometryName  )  [pure 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.

Implemented in OGRPoint, OGRLineString, OGRLinearRing, OGRPolygon, OGRGeometryCollection, OGRMultiPolygon, OGRMultiPoint, and OGRMultiLineString.

OGRwkbGeometryType OGRGeometry::getGeometryType  )  [pure virtual]
 

Fetch geometry type.

Note that the geometry type may include the 2.5D flag. To get a 2D flattened version of the geometry type apply the wkbFlatten() macro to the return result.

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

Returns:
the geometry type code.

Implemented in OGRPoint, OGRLineString, OGRPolygon, OGRGeometryCollection, OGRMultiPolygon, OGRMultiPoint, and OGRMultiLineString.

OGRSpatialReference * OGRGeometry::getSpatialReference void   )  [inline]
 

Returns spatial reference system for object.

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

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

Returns:
a reference to the spatial reference object. The object may be shared with many geometry objects, and should not be modified.

OGRErr OGRGeometry::importFromWkb unsigned char *  pabyData,
int  nSize = -1
[pure 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:
pabyData the binary input data.
nSize the 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.

Implemented in OGRPoint, OGRLineString, OGRLinearRing, OGRPolygon, and OGRGeometryCollection.

OGRErr OGRGeometry::importFromWkt char **  ppszInput  )  [pure virtual]
 

Assign geometry from well known text data.

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

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

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

Parameters:
ppszInput pointer to a pointer to the source text. The pointer is updated to pointer after the consumed text.
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.

Implemented in OGRPoint, OGRLineString, OGRPolygon, OGRGeometryCollection, OGRMultiPolygon, OGRMultiPoint, and OGRMultiLineString.

OGRBoolean OGRGeometry::Intersect OGRGeometry poOtherGeom  )  [virtual]
 

Do these features intersect?

Currently this is not implemented in a rigerous fashion, and generally just tests whether the envelopes of the two features intersect. Eventually this will be made rigerous.

The poOtherGeom argument may be safely NULL, but in this case the method will always return FALSE.

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

Parameters:
poOtherGeom the other geometry to test against.
Returns:
TRUE if the geometries intersect, otherwise FALSE.

OGRBoolean OGRGeometry::IsEmpty  )  [inline, virtual]
 

Returns TRUE (non-zero) if the object has no points. Normally this returns FALSE except between when an object is instantiated and points have been assigned.

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

NOTE: This method is hardcoded to return FALSE at this time.

Returns:
TRUE if object is empty, otherwise FALSE.

OGRBoolean OGRGeometry::IsSimple  )  [inline, virtual]
 

Returns TRUE if the geometry is simple.

Returns TRUE if the geometry has no anomalous geometric points, such as self intersection or self tangency. The description of each instantiable geometric class will include the specific conditions that cause an instance of that class to be classified as not simple.

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

NOTE: This method is hardcoded to return TRUE at this time.

Returns:
TRUE if object is simple, otherwise FALSE.

OGRErr OGRGeometry::transform OGRCoordinateTransformation poCT  )  [pure virtual]
 

Apply arbitrary coordinate transformation to geometry.

This method will transform the coordinates of a geometry from their current spatial reference system to a new target spatial reference system. Normally this means reprojecting the vectors, but it could include datum shifts, and changes of units.

Note that this method does not require that the geometry already have a spatial reference system. It will be assumed that they can be treated as having the source spatial reference system of the OGRCoordinateTransformation object, and the actual SRS of the geometry will be ignored. On successful completion the output OGRSpatialReference of the OGRCoordinateTransformation will be assigned to the geometry.

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

Parameters:
poCT the transformation to apply.
Returns:
OGRERR_NONE on success or an error code.

Implemented in OGRPoint, OGRLineString, OGRPolygon, and OGRGeometryCollection.

OGRErr OGRGeometry::transformTo OGRSpatialReference poSR  ) 
 

Transform geometry to new spatial reference system.

This method will transform the coordinates of a geometry from their current spatial reference system to a new target spatial reference system. Normally this means reprojecting the vectors, but it could include datum shifts, and changes of units.

This method will only work if the geometry already has an assigned spatial reference system, and if it is transformable to the target coordinate system.

Because this method requires internal creation and initialization of an OGRCoordinateTransformation object it is significantly more expensive to use this method to transform many geometries than it is to create the OGRCoordinateTransformation in advance, and call transform() with that transformation. This method exists primarily for convenience when only transforming a single geometry.

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

Parameters:
poSR spatial reference system to transform to.
Returns:
OGRERR_NONE on success, or an error code.

int OGRGeometry::WkbSize  )  [pure 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.

Implemented in OGRPoint, OGRLineString, OGRLinearRing, OGRPolygon, and OGRGeometryCollection.


The documentation for this class was generated from the following files:
Generated on Thu Nov 13 00:06:50 2003 for OGR by doxygen 1.3.4