QgsGeometryAnalyzer Class Reference
[QGIS analysis library.]

The QGis class provides vector geometry analysis functions. More...

#include <qgsgeometryanalyzer.h>

List of all members.

Public Member Functions

bool simplify (QgsVectorLayer *layer, const QString &shapefileName, double tolerance, bool onlySelectedFeatures=false, QProgressDialog *p=0)

Simplify vector layer using (a modified) Douglas-Peucker algorithm and write it to a new shape file.

bool centroids (QgsVectorLayer *layer, const QString &shapefileName, bool onlySelectedFeatures=false, QProgressDialog *p=0)

Calculate the true centroids, or 'center of mass' for a vector layer and write it to a new shape file.

bool extent (QgsVectorLayer *layer, const QString &shapefileName, bool onlySelectedFeatures=false, QProgressDialog *p=0)

Create a polygon based on the extent of all (selected) features and write it to a new shape file.

bool buffer (QgsVectorLayer *layer, const QString &shapefileName, double bufferDistance, bool onlySelectedFeatures=false, bool dissolve=false, int bufferDistanceField=-1, QProgressDialog *p=0)

Create buffers for a vector layer and write it to a new shape file.

bool convexHull (QgsVectorLayer *layer, const QString &shapefileName, bool onlySelectedFeatures=false, int uniqueIdField=-1, QProgressDialog *p=0)

Create convex hull(s) of a vector layer and write it to a new shape file.

bool dissolve (QgsVectorLayer *layer, const QString &shapefileName, bool onlySelectedFeatures=false, int uniqueIdField=-1, QProgressDialog *p=0)

Dissolve a vector layer and write it to a new shape file.

Private Member Functions

QList< double > simpleMeasure (QgsGeometry *geometry)

double perimeterMeasure (QgsGeometry *geometry, QgsDistanceArea &measure)

void simplifyFeature (QgsFeature &f, QgsVectorFileWriter *vfw, double tolerance)

Helper function to simplify an individual feature.

void centroidFeature (QgsFeature &f, QgsVectorFileWriter *vfw)

Helper function to get the cetroid of an individual feature.

void bufferFeature (QgsFeature &f, int nProcessedFeatures, QgsVectorFileWriter *vfw, bool dissolve, QgsGeometry **dissolveGeometry, double bufferDistance, int bufferDistanceField)

Helper function to buffer an individual feature.

void convexFeature (QgsFeature &f, int nProcessedFeatures, QgsGeometry **dissolveGeometry)

Helper function to get the convex hull of feature(s).

void dissolveFeature (QgsFeature &f, int nProcessedFeatures, QgsGeometry **dissolveGeometry)

Helper function to dissolve feature(s).

Detailed Description

The QGis class provides vector geometry analysis functions.

Definition at line 37 of file qgsgeometryanalyzer.h.

Member Function Documentation

bool QgsGeometryAnalyzer::simplify	(	QgsVectorLayer *	layer,
		const QString &	shapefileName,
		double	tolerance,
		bool	onlySelectedFeatures = `false`,
		QProgressDialog *	p = `0`
	)

Simplify vector layer using (a modified) Douglas-Peucker algorithm and write it to a new shape file.

Parameters:

	layer	input vector layer
	shapefileName	path to the output shp
	tolerance	(level of simplification)
	onlySelectedFeatures	if true, only selected features are considered, else all the features
	p	progress dialog (or 0 if no progress dialog is to be shown)

Note:: : added in version 1.4

Definition at line 31 of file qgsgeometryanalyzer.cpp.

References QgsVectorLayer::dataProvider(), QgsVectorDataProvider::encoding(), QgsVectorLayer::featureAtId(), QgsVectorLayer::featureCount(), QgsVectorDataProvider::fields(), QgsVectorDataProvider::geometryType(), QgsVectorLayer::nextFeature(), QgsVectorLayer::pendingAllAttributesList(), QgsVectorLayer::select(), QgsVectorLayer::selectedFeaturesIds(), simplifyFeature(), and QgsMapLayer::srs().

bool QgsGeometryAnalyzer::centroids	(	QgsVectorLayer *	layer,
		const QString &	shapefileName,
		bool	onlySelectedFeatures = `false`,
		QProgressDialog *	p = `0`
	)

Calculate the true centroids, or 'center of mass' for a vector layer and write it to a new shape file.

Parameters:

	layer	input vector layer
	shapefileName	path to the output shp
	onlySelectedFeatures	if true, only selected features are considered, else all the features
	p	progress dialog (or 0 if no progress dialog is to be shown)

Note:: : added in version 1.4

Definition at line 145 of file qgsgeometryanalyzer.cpp.

References centroidFeature(), QgsVectorLayer::dataProvider(), QgsVectorDataProvider::encoding(), QgsVectorLayer::featureAtId(), QgsVectorLayer::featureCount(), QgsVectorDataProvider::fields(), QgsVectorLayer::nextFeature(), QgsVectorLayer::pendingAllAttributesList(), QgsVectorLayer::select(), QgsVectorLayer::selectedFeaturesIds(), QgsMapLayer::srs(), and QGis::WKBPoint.

bool QgsGeometryAnalyzer::extent	(	QgsVectorLayer *	layer,
		const QString &	shapefileName,
		bool	onlySelectedFeatures = `false`,
		QProgressDialog *	p = `0`
	)

Create a polygon based on the extent of all (selected) features and write it to a new shape file.

Parameters:

	layer	input vector layer
	shapefileName	path to the output shp
	onlySelectedFeatures	if true, only selected features are considered, else all the features
	p	progress dialog (or 0 if no progress dialog is to be shown)

Note:: : added in version 1.4

Definition at line 259 of file qgsgeometryanalyzer.cpp.

References QgsVectorLayer::boundingBoxOfSelected(), QgsVectorLayer::dataProvider(), QgsVectorDataProvider::encoding(), QgsMapLayer::extent(), QgsGeometry::fromRect(), QgsFeature::setAttributeMap(), QgsFeature::setGeometry(), QgsMapLayer::srs(), QGis::WKBPolygon, and QgsRectangle::xMinimum().

bool QgsGeometryAnalyzer::buffer	(	QgsVectorLayer *	layer,
		const QString &	shapefileName,
		double	bufferDistance,
		bool	onlySelectedFeatures = `false`,
		bool	dissolve = `false`,
		int	bufferDistanceField = `-1`,
		QProgressDialog *	p = `0`
	)

Create buffers for a vector layer and write it to a new shape file.

Parameters:

	layer	input vector layer
	shapefileName	path to the output shp
	bufferDistance	distance for buffering (if no buffer field is specified)
	onlySelectedFeatures	if true, only selected features are considered, else all the features
	dissolve	if true, merge all the buffers to a big multipolygon
	bufferDistanceField	index of the attribute field that contains the buffer distance (or -1 if all features have the same buffer distance)
	p	progress dialog (or 0 if no progress dialog is to be shown)

Note:: : added in version 1.3

Definition at line 747 of file qgsgeometryanalyzer.cpp.

References bufferFeature(), QgsVectorLayer::dataProvider(), dissolveFeature(), QgsVectorDataProvider::encoding(), QgsVectorLayer::featureAtId(), QgsVectorLayer::featureCount(), QgsVectorDataProvider::fields(), QgsVectorLayer::nextFeature(), QgsVectorLayer::pendingAllAttributesList(), QgsDebugMsg, QgsVectorLayer::select(), QgsVectorLayer::selectedFeaturesIds(), QgsFeature::setGeometry(), QgsMapLayer::srs(), QGis::WKBMultiPolygon, and QGis::WKBPolygon.

bool QgsGeometryAnalyzer::convexHull	(	QgsVectorLayer *	layer,
		const QString &	shapefileName,
		bool	onlySelectedFeatures = `false`,
		int	uniqueIdField = `-1`,
		QProgressDialog *	p = `0`
	)

Create convex hull(s) of a vector layer and write it to a new shape file.

Parameters:

	layer	input vector layer
	shapefileName	path to the output shp
	onlySelectedFeatures	if true, only selected features are considered, else all the features
	uniqueIdField	index of the attribute field that contains the unique convex hull id (or -1 if all features have the same buffer distance)
	p	progress dialog (or 0 if no progress dialog is to be shown)

Note:: : added in version 1.4

Definition at line 380 of file qgsgeometryanalyzer.cpp.

References convexFeature(), QgsGeometry::convexHull(), QgsVectorLayer::dataProvider(), dissolveFeature(), QgsVectorDataProvider::encoding(), QgsVectorLayer::featureAtId(), QgsVectorLayer::featureCount(), QgsVectorLayer::nextFeature(), QgsVectorLayer::pendingAllAttributesList(), QgsDebugMsg, QgsVectorLayer::select(), QgsVectorLayer::selectedFeaturesIds(), QgsFeature::setAttributeMap(), QgsFeature::setGeometry(), simpleMeasure(), QgsMapLayer::srs(), and QGis::WKBPolygon.

bool QgsGeometryAnalyzer::dissolve	(	QgsVectorLayer *	layer,
		const QString &	shapefileName,
		bool	onlySelectedFeatures = `false`,
		int	uniqueIdField = `-1`,
		QProgressDialog *	p = `0`
	)

Dissolve a vector layer and write it to a new shape file.

Parameters:

	layer	input vector layer
	shapefileName	path to the output shp
	onlySelectedFeatures	if true, only selected features are considered, else all the features
	uniqueIdField	index of the attribute field that contains the unique id to dissolve on (or -1 if all features should be dissolved together)
	p	progress dialog (or 0 if no progress dialog is to be shown)

Note:: : added in version 1.4

Definition at line 590 of file qgsgeometryanalyzer.cpp.

References QgsVectorLayer::dataProvider(), dissolveFeature(), QgsVectorDataProvider::encoding(), QgsVectorLayer::featureAtId(), QgsVectorLayer::featureCount(), QgsVectorDataProvider::fields(), QgsVectorDataProvider::geometryType(), QgsVectorLayer::nextFeature(), QgsVectorLayer::pendingAllAttributesList(), QgsVectorLayer::select(), QgsVectorLayer::selectedFeaturesIds(), QgsFeature::setAttributeMap(), QgsFeature::setGeometry(), and QgsMapLayer::srs().

QList< double > QgsGeometryAnalyzer::simpleMeasure ( QgsGeometry * geometry ) [private]

Definition at line 329 of file qgsgeometryanalyzer.cpp.

References QgsGeometry::asPoint(), QgsDistanceArea::measure(), perimeterMeasure(), QGis::Polygon, QgsGeometry::type(), QGis::WKBPoint, QgsGeometry::wkbType(), QgsPoint::x(), and QgsPoint::y().

Referenced by convexHull().

double QgsGeometryAnalyzer::perimeterMeasure	(	QgsGeometry *	geometry,
		QgsDistanceArea &	measure
	)			`[private]`

Definition at line 352 of file qgsgeometryanalyzer.cpp.

References QgsGeometry::asMultiPolygon(), QgsGeometry::asPolygon(), QgsGeometry::fromPolyline(), QgsGeometry::isMultipart(), and QgsDistanceArea::measure().

Referenced by simpleMeasure().

void QgsGeometryAnalyzer::simplifyFeature	(	QgsFeature &	f,
		QgsVectorFileWriter *	vfw,
		double	tolerance
	)			`[private]`

Helper function to simplify an individual feature.

Definition at line 122 of file qgsgeometryanalyzer.cpp.

References QgsVectorFileWriter::addFeature(), QgsFeature::attributeMap(), QgsFeature::geometry(), QgsFeature::setAttributeMap(), QgsFeature::setGeometry(), and QgsGeometry::simplify().

Referenced by simplify().

void QgsGeometryAnalyzer::centroidFeature	(	QgsFeature &	f,
		QgsVectorFileWriter *	vfw
	)			`[private]`

Helper function to get the cetroid of an individual feature.

Definition at line 236 of file qgsgeometryanalyzer.cpp.

References QgsVectorFileWriter::addFeature(), QgsFeature::attributeMap(), QgsGeometry::centroid(), QgsFeature::geometry(), QgsFeature::setAttributeMap(), and QgsFeature::setGeometry().

Referenced by centroids().

void QgsGeometryAnalyzer::bufferFeature	(	QgsFeature &	f,
		int	nProcessedFeatures,
		QgsVectorFileWriter *	vfw,
		bool	dissolve,
		QgsGeometry **	dissolveGeometry,
		double	bufferDistance,
		int	bufferDistanceField
	)			`[private]`

Helper function to buffer an individual feature.

Definition at line 854 of file qgsgeometryanalyzer.cpp.

References QgsVectorFileWriter::addFeature(), QgsFeature::attributeMap(), QgsGeometry::buffer(), QgsGeometry::combine(), QgsFeature::geometry(), QgsFeature::setAttributeMap(), and QgsFeature::setGeometry().

Referenced by buffer().

void QgsGeometryAnalyzer::convexFeature	(	QgsFeature &	f,
		int	nProcessedFeatures,
		QgsGeometry **	dissolveGeometry
	)			`[private]`

Helper function to get the convex hull of feature(s).

Definition at line 564 of file qgsgeometryanalyzer.cpp.

References QgsGeometry::combine(), QgsGeometry::convexHull(), and QgsFeature::geometry().

Referenced by convexHull().

void QgsGeometryAnalyzer::dissolveFeature	(	QgsFeature &	f,
		int	nProcessedFeatures,
		QgsGeometry **	dissolveGeometry
	)			`[private]`

Helper function to dissolve feature(s).

Definition at line 724 of file qgsgeometryanalyzer.cpp.

References QgsGeometry::asWkb(), QgsGeometry::combine(), QgsFeature::geometry(), and QgsGeometry::wkbSize().

Referenced by buffer(), convexHull(), and dissolve().

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

src/analysis/vector/qgsgeometryanalyzer.h
src/analysis/vector/qgsgeometryanalyzer.cpp


Public Member Functions
bool	simplify (QgsVectorLayer layer, const QString &shapefileName, double tolerance, bool onlySelectedFeatures=false, QProgressDialog p=0)
	Simplify vector layer using (a modified) Douglas-Peucker algorithm and write it to a new shape file.
bool	centroids (QgsVectorLayer layer, const QString &shapefileName, bool onlySelectedFeatures=false, QProgressDialog p=0)
	Calculate the true centroids, or 'center of mass' for a vector layer and write it to a new shape file.
bool	extent (QgsVectorLayer layer, const QString &shapefileName, bool onlySelectedFeatures=false, QProgressDialog p=0)
	Create a polygon based on the extent of all (selected) features and write it to a new shape file.
bool	buffer (QgsVectorLayer layer, const QString &shapefileName, double bufferDistance, bool onlySelectedFeatures=false, bool dissolve=false, int bufferDistanceField=-1, QProgressDialog p=0)
	Create buffers for a vector layer and write it to a new shape file.
bool	convexHull (QgsVectorLayer layer, const QString &shapefileName, bool onlySelectedFeatures=false, int uniqueIdField=-1, QProgressDialog p=0)
	Create convex hull(s) of a vector layer and write it to a new shape file.
bool	dissolve (QgsVectorLayer layer, const QString &shapefileName, bool onlySelectedFeatures=false, int uniqueIdField=-1, QProgressDialog p=0)
	Dissolve a vector layer and write it to a new shape file.
Private Member Functions
QList< double >	simpleMeasure (QgsGeometry *geometry)
double	perimeterMeasure (QgsGeometry *geometry, QgsDistanceArea &measure)
void	simplifyFeature (QgsFeature &f, QgsVectorFileWriter *vfw, double tolerance)
	Helper function to simplify an individual feature.
void	centroidFeature (QgsFeature &f, QgsVectorFileWriter *vfw)
	Helper function to get the cetroid of an individual feature.
void	bufferFeature (QgsFeature &f, int nProcessedFeatures, QgsVectorFileWriter vfw, bool dissolve, QgsGeometry *dissolveGeometry, double bufferDistance, int bufferDistanceField)
	Helper function to buffer an individual feature.
void	convexFeature (QgsFeature &f, int nProcessedFeatures, QgsGeometry **dissolveGeometry)
	Helper function to get the convex hull of feature(s).
void	dissolveFeature (QgsFeature &f, int nProcessedFeatures, QgsGeometry **dissolveGeometry)
	Helper function to dissolve feature(s).

QgsGeometryAnalyzer Class Reference [QGIS analysis library.]

Public Member Functions

Private Member Functions

Detailed Description

Member Function Documentation

QgsGeometryAnalyzer Class Reference
[QGIS analysis library.]