geos::precision::GeometryPrecisionReducer Class Reference

Reduces the precision of a geom::Geometry according to the supplied geom::PrecisionModel, ensuring that the result is valid (unless specified otherwise). More...

#include <GeometryPrecisionReducer.h>

Public Member Functions
	GeometryPrecisionReducer (const geom::PrecisionModel &pm)
	GeometryPrecisionReducer (const geom::GeometryFactory &changeFactory)
	Create a reducer that will change the precision model of the new reduced Geometry.
void	setRemoveCollapsedComponents (bool remove)
void	setChangePrecisionModel (bool change)
	Sets whether the geom::PrecisionModel of the new reduced Geometry will be changed to be the geom::PrecisionModel supplied to specify the precision reduction. The default is to not change the precision model.
void	setUseAreaReducer (bool useAR)
void	setPointwise (bool pointwise)
	Sets whether the precision reduction will be done in pointwise fashion only.
std::unique_ptr< geom::Geometry >	reduce (const geom::Geometry &geom)

Static Public Member Functions
static std::unique_ptr< geom::Geometry >	reduce (const geom::Geometry &g, const geom::PrecisionModel &precModel)
static std::unique_ptr< geom::Geometry >	reducePointwise (const geom::Geometry &g, const geom::PrecisionModel &precModel)
static std::unique_ptr< geom::Geometry >	reduceKeepCollapsed (const geom::Geometry &g, const geom::PrecisionModel &precModel)

Detailed Description

Reduces the precision of a geom::Geometry according to the supplied geom::PrecisionModel, ensuring that the result is valid (unless specified otherwise).

By default the reduced result is topologically valid To ensure this a polygonal geometry is reduced in a topologically valid fashion (technically, by using snap-rounding). It can be forced to be reduced pointwise by using setPointwise(boolean). Note that in this case the result geometry may be invalid. Linear and point geometry is always reduced pointwise (i.e. without further change to its topology or structure), since this does not change validity.

By default the geometry precision model is not changed. This can be overridden by usingsetChangePrecisionModel(boolean).

Normally collapsed components (e.g. lines collapsing to a point) are not included in the result. This behavior can be changed by using setRemoveCollapsedComponents(boolean).

Constructor & Destructor Documentation

GeometryPrecisionReducer()

geos::precision::GeometryPrecisionReducer::GeometryPrecisionReducer ( const geom::GeometryFactory &  changeFactory )

inline

Create a reducer that will change the precision model of the new reduced Geometry.

Parameters

changeFactory

the factory for the created Geometry. Its PrecisionModel will be used for the reduction. NOTE: ownership left to caller must be kept alive for the whole lifetime of the returned Geometry.

Member Function Documentation

reduce()

static std::unique_ptr< geom::Geometry > geos::precision::GeometryPrecisionReducer::reduce ( const geom::Geometry &  g, const geom::PrecisionModel &  precModel  )

static

Convenience method for doing precision reduction on a single geometry, with collapses removed and keeping the geometry precision model the same, and preserving polygonal topology.

Parameters

g	the geometry to reduce
precModel	the precision model to use

Returns

the reduced geometry

setChangePrecisionModel()

void geos::precision::GeometryPrecisionReducer::setChangePrecisionModel ( bool  change )

inline

Sets whether the geom::PrecisionModel of the new reduced Geometry will be changed to be the geom::PrecisionModel supplied to specify the precision reduction. The default is to not change the precision model.

Parameters

change

if true the precision model of the created Geometry will be the the precisionModel supplied in the constructor.

setPointwise()

void geos::precision::GeometryPrecisionReducer::setPointwise ( bool  pointwise )

inline

Sets whether the precision reduction will be done in pointwise fashion only.

Pointwise precision reduction reduces the precision of the individual coordinates only, but does not attempt to recreate valid topology. This is only relevant for geometries containing polygonal components.

Parameters

pointwise

if reduction should be done pointwise only

setRemoveCollapsedComponents()

void geos::precision::GeometryPrecisionReducer::setRemoveCollapsedComponents ( bool  remove )

inline

Sets whether the reduction will result in collapsed components being removed completely, or simply being collapsed to an (invalid) Geometry of the same type.

Parameters

remove

if true collapsed components will be removed

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

• GeometryPrecisionReducer.h