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

#include <qgsgeometryanalyzer.h>

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

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::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().

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

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().

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

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().

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

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().

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().

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

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().

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

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

Public Member Functions

Private Member Functions

Detailed Description

Member Function Documentation