gis::Polygon Class Reference

A polygon consisting of an outer ring and zero or more interior rings defining holes in the polygon. More...

#include <geometries.h>

Inheritance diagram for gis::Polygon:

Public Member Functions
Geometry_type	type () const override
	Gets the geometry type of the object. More...
bool	accept (Geometry_visitor *v) override=0
	Applies a hierarchical visitor to this geometry. More...
bool	is_empty () const override
	Check if this is an empty geometry. More...
Polygon *	clone () const override=0
virtual void	push_back (const Linearring &lr)=0
	Adds a linear ring to the polygon. More...
virtual void	push_back (Linearring &&lr)=0
virtual bool	empty () const =0
	Checks if the polygon is empty. More...
virtual std::size_t	size () const =0
	Returns the size of the polygon. More...
virtual Linearring &	exterior_ring ()=0
	Returns the exterior ring of the polygon. More...
virtual Linearring &	interior_ring (std::size_t n)=0
	Returns an interior ring of the polygon. More...
Public Member Functions inherited from gis::Geometry
	Geometry ()=default
virtual	~Geometry ()=default
	Geometry (const Geometry &)=default
Geometry &	operator= (const Geometry &)=default
virtual Coordinate_system	coordinate_system () const =0
	Gets the coordinate system. More...

Static Public Member Functions
static Polygon *	create_polygon (Coordinate_system coordinate_system)
	Creates a subclass of Polygon from a Coordinate_system. More...

Detailed Description

A polygon consisting of an outer ring and zero or more interior rings defining holes in the polygon.

Polygon is an instantiable type in SQL.

The interior rings must be inside the exterior ring (not enforced by the implementation).

Member Function Documentation

accept()

bool gis::Polygon::accept ( Geometry_visitor *  v )

overridepure virtual

Applies a hierarchical visitor to this geometry.

See also

gis::Geometry_visitor

Parameters

v	A hierarchical visitor.

Return values

true	The execution was aborted by the visitor.
false	The execution completed.

Implements gis::Surface.

Implemented in gis::Cartesian_polygon, and gis::Geographic_polygon.

clone()

Polygon * gis::Polygon::clone ( ) const

overridepure virtual

Implements gis::Geometry.

Implemented in gis::Cartesian_polygon, and gis::Geographic_polygon.

create_polygon()

Polygon * gis::Polygon::create_polygon ( Coordinate_system  coordinate_system )

static

Creates a subclass of Polygon from a Coordinate_system.

Parameters

[in]

coordinate_system

Coordinate system to create a Polygon for.

Returns

A pointer to a Polygon that caller must free when it is done with it.

empty()

virtual bool gis::Polygon::empty ( ) const

pure virtual

Checks if the polygon is empty.

The polygon is considered empty if it has no rings.

Return values

true	The polygon is empty.
false	The polygon is not empty.

Implemented in gis::Cartesian_polygon, and gis::Geographic_polygon.

exterior_ring()

virtual Linearring & gis::Polygon::exterior_ring ( )

pure virtual

Returns the exterior ring of the polygon.

Note

If the polygon currently has no exterior ring, an empty one is added.

Returns

The exterior ring.

Implemented in gis::Cartesian_polygon, and gis::Geographic_polygon.

interior_ring()

virtual Linearring & gis::Polygon::interior_ring ( std::size_t  n )

pure virtual

Returns an interior ring of the polygon.

Parameters

n	Ring number, zero indexed.

Returns

The interior ring.

Implemented in gis::Cartesian_polygon, and gis::Geographic_polygon.

is_empty()

bool gis::Polygon::is_empty ( ) const

inlineoverridevirtual

Check if this is an empty geometry.

The definition of empty geometries is the one in SFA-CA (OGC 06-103r4, Sect. 6.1.2.2), i.e., an empty point set.

Note

This is different from the function "empty", which returns true if a geometry contains no subgeometries. E.g., a geometry collection may contain another geometry collection which is empty. In this case, the "empty" function would return false on the outermost geometry collection, while "is_empty" would return true.

Return values

true	The geometry represents the empty point set.
false	The geometry represent a non-empty point set.

Implements gis::Geometry.

push_back() [1/2]

virtual void gis::Polygon::push_back ( const Linearring &  lr )

pure virtual

Adds a linear ring to the polygon.

The first ring will become the exterior ring. All following rings will be interior rings (holes).

Parameters

lr	The linear ring to add.

Implemented in gis::Cartesian_polygon, and gis::Geographic_polygon.

push_back() [2/2]

virtual void gis::Polygon::push_back ( Linearring &&  lr )

pure virtual

Implemented in gis::Cartesian_polygon, and gis::Geographic_polygon.

size()

virtual std::size_t gis::Polygon::size ( ) const

pure virtual

Returns the size of the polygon.

Returns

Number of rings in the polygon (exterior + interior).

Implemented in gis::Cartesian_polygon, and gis::Geographic_polygon.

type()

Geometry_type gis::Polygon::type ( ) const

inlineoverridevirtual

Gets the geometry type of the object.

Returns

The type of this object

Implements gis::Surface.

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

• sql/gis/geometries.h
• sql/gis/geometries.cc