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.
bool	eventLayer (QgsVectorLayer lineLayer, QgsVectorLayer eventLayer, int lineField, int eventField, QList< int > &unlocatedFeatureIds, const QString &outputLayer, const QString &outputFormat, int locationField1, int locationField2=-1, int offsetField=-1, double offsetScale=1.0, bool forceSingleGeometry=false, QgsVectorDataProvider memoryProvider=0, QProgressDialog p=0)
	Creates an event layer (multipoint or multiline) by locating features from a (non-spatial) event table along the features of a line layer.
QgsGeometry *	locateBetweenMeasures (double fromMeasure, double toMeasure, QgsGeometry *lineGeom)
	Returns linear reference geometry as a multiline (or 0 if no match).
QgsGeometry *	locateAlongMeasure (double measure, QgsGeometry *lineGeom)
	Returns linear reference geometry.

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)
void	addEventLayerFeature (QgsFeature &feature, QgsGeometry geom, QgsGeometry lineGeom, QgsVectorFileWriter *fileWriter, QgsFeatureList &memoryFeatures, int offsetField=-1, double offsetScale=1.0, bool forceSingleType=false)
void	createOffsetGeometry (QgsGeometry geom, QgsGeometry lineGeom, double offset)
	Create geometry offset relative to line geometry.
QgsPoint	createPointOffset (double x, double y, double dist, QgsGeometry *lineGeom) const
const unsigned char *	locateBetweenWkbString (const unsigned char *ptr, QgsMultiPolyline &result, double fromMeasure, double toMeasure)
const unsigned char *	locateAlongWkbString (const unsigned char *ptr, QgsMultiPoint &result, double measure)

Static Private Member Functions
static bool	clipSegmentByRange (double x1, double y1, double m1, double x2, double y2, double m2, double range1, double range2, QgsPoint &pt1, QgsPoint &pt2, bool &secondPointClipped)
static void	locateAlongSegment (double x1, double y1, double m1, double x2, double y2, double m2, double measure, bool &pt1Ok, QgsPoint &pt1, bool &pt2Ok, QgsPoint &pt2)

Detailed Description

The QGis class provides vector geometry analysis functions.

Definition at line 36 of file qgsgeometryanalyzer.h.

Member Function Documentation

void QgsGeometryAnalyzer::addEventLayerFeature	(	QgsFeature &	feature,
		QgsGeometry *	geom,
		QgsGeometry *	lineGeom,
		QgsVectorFileWriter *	fileWriter,
		QgsFeatureList &	memoryFeatures,
		int	offsetField = `-1`,
		double	offsetScale = `1.0`,
		bool	forceSingleType = `false`
	)

private

Definition at line 1035 of file qgsgeometryanalyzer.cpp.

References QgsVectorFileWriter::addFeature(), QgsGeometry::asGeometryCollection(), QgsFeature::attribute(), createOffsetGeometry(), and QgsFeature::setGeometry().

Referenced by eventLayer().

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 752 of file qgsgeometryanalyzer.cpp.

References bufferFeature(), QgsMapLayer::crs(), QgsVectorLayer::dataProvider(), dissolveFeature(), QgsVectorDataProvider::encoding(), QgsVectorLayer::featureCount(), QgsVectorLayer::getFeatures(), QgsFeatureIterator::nextFeature(), QgsVectorLayer::pendingFields(), QgsDebugMsg, 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 858 of file qgsgeometryanalyzer.cpp.

References QgsVectorFileWriter::addFeature(), QgsFeature::attribute(), QgsFeature::attributes(), QgsGeometry::buffer(), QgsGeometry::combine(), QgsFeature::geometry(), QgsFeature::setAttributes(), 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 239 of file qgsgeometryanalyzer.cpp.

References QgsVectorFileWriter::addFeature(), QgsFeature::attributes(), QgsGeometry::centroid(), QgsFeature::geometry(), QgsFeature::setAttributes(), 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 146 of file qgsgeometryanalyzer.cpp.

References centroidFeature(), QgsMapLayer::crs(), QgsVectorLayer::dataProvider(), QgsVectorDataProvider::encoding(), QgsVectorLayer::featureCount(), QgsVectorLayer::getFeatures(), QgsFeatureIterator::nextFeature(), QgsVectorLayer::pendingFields(), QgsDebugMsg, QgsVectorLayer::selectedFeaturesIds(), and QGis::WKBPoint.

bool QgsGeometryAnalyzer::clipSegmentByRange	(	double	x1,
		double	y1,
		double	m1,
		double	x2,
		double	y2,
		double	m2,
		double	range1,
		double	range2,
		QgsPoint &	pt1,
		QgsPoint &	pt2,
		bool &	secondPointClipped
	)

staticprivate

Definition at line 1355 of file qgsgeometryanalyzer.cpp.

References QgsPoint::setX(), and QgsPoint::setY().

Referenced by locateBetweenWkbString().

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

private

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

Definition at line 569 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 385 of file qgsgeometryanalyzer.cpp.

References QgsFields::append(), convexFeature(), QgsGeometry::convexHull(), QgsMapLayer::crs(), QgsVectorLayer::dataProvider(), dissolveFeature(), QgsVectorDataProvider::encoding(), QgsVectorLayer::featureCount(), QgsVectorLayer::getFeatures(), QgsFeatureIterator::nextFeature(), QgsDebugMsg, QgsVectorLayer::selectedFeaturesIds(), QgsFeature::setAttributes(), QgsFeature::setGeometry(), simpleMeasure(), and QGis::WKBPolygon.

void QgsGeometryAnalyzer::createOffsetGeometry	(	QgsGeometry *	geom,
		QgsGeometry *	lineGeom,
		double	offset
	)

private

Create geometry offset relative to line geometry.

Parameters

geom	the geometry to modify
lineGeom	the line geometry to which the feature is referenced
offset	the offset value in layer unit. Negative values mean offset towards left, positive values offset to the right side

Definition at line 1081 of file qgsgeometryanalyzer.cpp.

References QgsGeometry::asGeometryCollection(), createPointOffset(), QgsGeometry::fromGeos(), QgsGeometry::isMultipart(), QGis::Line, QGis::Point, QgsGeometry::type(), QgsPoint::x(), and QgsPoint::y().

Referenced by addEventLayerFeature().

QgsPoint QgsGeometryAnalyzer::createPointOffset	(	double	x,
		double	y,
		double	dist,
		QgsGeometry *	lineGeom
	)		const

private

Definition at line 1154 of file qgsgeometryanalyzer.cpp.

References QgsGeometry::closestSegmentWithContext(), QgsGeometry::vertexAt(), QgsPoint::x(), and QgsPoint::y().

Referenced by createOffsetGeometry().

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 595 of file qgsgeometryanalyzer.cpp.

References QgsMapLayer::crs(), QgsVectorLayer::dataProvider(), dissolveFeature(), QgsVectorDataProvider::encoding(), QgsVectorLayer::featureCount(), QgsVectorDataProvider::geometryType(), QgsVectorLayer::getFeatures(), QgsFeatureIterator::nextFeature(), QgsVectorLayer::pendingFields(), QgsVectorLayer::selectedFeaturesIds(), QgsFeature::setAttributes(), and QgsFeature::setGeometry().

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

private

Helper function to dissolve feature(s)

Definition at line 729 of file qgsgeometryanalyzer.cpp.

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

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

bool QgsGeometryAnalyzer::eventLayer	(	QgsVectorLayer *	lineLayer,
		QgsVectorLayer *	eventLayer,
		int	lineField,
		int	eventField,
		QList< int > &	unlocatedFeatureIds,
		const QString &	outputLayer,
		const QString &	outputFormat,
		int	locationField1,
		int	locationField2 = `-1`,
		int	offsetField = `-1`,
		double	offsetScale = `1.0`,
		bool	forceSingleGeometry = `false`,
		QgsVectorDataProvider *	memoryProvider = `0`,
		QProgressDialog *	p = `0`
	)

Creates an event layer (multipoint or multiline) by locating features from a (non-spatial) event table along the features of a line layer.

Note that currently (until QgsGeometry supports m-values) the z-coordinate of the line layer is used for linear referencing

Parameters

lineLayer	layer with the line geometry
eventLayer	layer with features and location field
lineField	join index in line layer
eventField	join index in event layer
outputLayer	name of output file (can be empty if a memory layer is used)
outputFormat	name of output format (can be empty if a memory provider is used to store the results)
unlocatedFeatureIds	out: ids of event features where linear referencing was not successful
locationField1	attribute index of location field in event layer
locationField2	attribute index of location end field (or -1 for point layer)
offsetField	attribute index for offset field. Negative offset value = offset to left side, positive value = offset to right side
offsetScale	factor to scale offset
forceSingleGeometry	force layer to single point/line type. Feature attributes are copied in case of multiple matches
memoryProvider	memory provider to write output to (can be 0 if output is written to a file)
p	progress dialog or 0 if no progress dialog should be shown

Definition at line 910 of file qgsgeometryanalyzer.cpp.

References QgsVectorDataProvider::addAttributes(), addEventLayerFeature(), QgsVectorDataProvider::addFeatures(), QgsFeature::attribute(), QgsMapLayer::crs(), QgsVectorLayer::dataProvider(), QgsVectorDataProvider::encoding(), QgsFeature::geometry(), QgsVectorLayer::getFeatures(), QgsFeature::id(), QgsMapLayer::isValid(), locateAlongMeasure(), locateBetweenMeasures(), QgsFeatureIterator::nextFeature(), QgsFeatureRequest::NoGeometry, QgsVectorLayer::pendingFeatureCount(), QgsVectorLayer::pendingFields(), QgsFeatureRequest::setSubsetOfAttributes(), QgsFields::toList(), QGis::WKBLineString, QGis::WKBMultiLineString, QGis::WKBMultiPoint, 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 262 of file qgsgeometryanalyzer.cpp.

References QgsFields::append(), QgsVectorLayer::boundingBoxOfSelected(), QgsMapLayer::crs(), QgsVectorLayer::dataProvider(), QgsVectorDataProvider::encoding(), QgsVectorLayer::extent(), QgsGeometry::fromRect(), QgsFeature::setAttributes(), QgsFeature::setGeometry(), QGis::WKBPolygon, and QgsRectangle::xMinimum().

QgsGeometry * QgsGeometryAnalyzer::locateAlongMeasure	(	double	measure,
		QgsGeometry *	lineGeom
	)

Returns linear reference geometry.

Unlike the PostGIS function, this method always returns multipoint or 0 if no match (not geometry collection). Currently, the z-coordinates are considered to be the measures (no support for m-values in QGIS)

Definition at line 1223 of file qgsgeometryanalyzer.cpp.

References QgsGeometry::asWkb(), QgsGeometry::fromMultiPoint(), locateAlongWkbString(), QGis::WKBLineString25D, and QGis::WKBMultiLineString25D.

Referenced by eventLayer().

void QgsGeometryAnalyzer::locateAlongSegment	(	double	x1,
		double	y1,
		double	m1,
		double	x2,
		double	y2,
		double	m2,
		double	measure,
		bool &	pt1Ok,
		QgsPoint &	pt1,
		bool &	pt2Ok,
		QgsPoint &	pt2
	)

staticprivate

Definition at line 1450 of file qgsgeometryanalyzer.cpp.

References qgsDoubleNear(), QgsPoint::setX(), and QgsPoint::setY().

Referenced by locateAlongWkbString().

const unsigned char * QgsGeometryAnalyzer::locateAlongWkbString	(	const unsigned char *	ptr,
		QgsMultiPoint &	result,
		double	measure
	)

private

Definition at line 1319 of file qgsgeometryanalyzer.cpp.

References locateAlongSegment().

Referenced by locateAlongMeasure().

QgsGeometry * QgsGeometryAnalyzer::locateBetweenMeasures	(	double	fromMeasure,
		double	toMeasure,
		QgsGeometry *	lineGeom
	)

Returns linear reference geometry as a multiline (or 0 if no match).

Currently, the z-coordinates are considered to be the measures (no support for m-values in QGIS)

Definition at line 1179 of file qgsgeometryanalyzer.cpp.

References QgsGeometry::asWkb(), QgsGeometry::fromMultiPolyline(), locateBetweenWkbString(), QGis::WKBLineString25D, and QGis::WKBMultiLineString25D.

Referenced by eventLayer().

const unsigned char * QgsGeometryAnalyzer::locateBetweenWkbString	(	const unsigned char *	ptr,
		QgsMultiPolyline &	result,
		double	fromMeasure,
		double	toMeasure
	)

private

Definition at line 1267 of file qgsgeometryanalyzer.cpp.

References clipSegmentByRange().

Referenced by locateBetweenMeasures().

double QgsGeometryAnalyzer::perimeterMeasure	(	QgsGeometry *	geometry,
		QgsDistanceArea &	measure
	)

private

Definition at line 357 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 334 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 30 of file qgsgeometryanalyzer.cpp.

References QgsMapLayer::crs(), QgsVectorLayer::dataProvider(), QgsVectorDataProvider::encoding(), QgsVectorLayer::featureCount(), QgsVectorDataProvider::geometryType(), QgsVectorLayer::getFeatures(), QgsFeatureIterator::nextFeature(), QgsVectorLayer::pendingFields(), QgsVectorLayer::selectedFeaturesIds(), and simplifyFeature().

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

private

Helper function to simplify an individual feature.

Definition at line 123 of file qgsgeometryanalyzer.cpp.

References QgsVectorFileWriter::addFeature(), QgsFeature::attributes(), QgsFeature::geometry(), QgsFeature::setAttributes(), QgsFeature::setGeometry(), and QgsGeometry::simplify().

Referenced by simplify().

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

/tmp/buildd/qgis-2.2.0+wheezy1/src/analysis/vector/qgsgeometryanalyzer.h
/tmp/buildd/qgis-2.2.0+wheezy1/src/analysis/vector/qgsgeometryanalyzer.cpp

Public Member Functions

Private Member Functions

Static Private Member Functions

Detailed Description

Member Function Documentation