TSLGPkgFeatureTable Class Reference

Inheritance diagram for TSLGPkgFeatureTable:

Detailed Description

This class encapsulates the functionality associated with a geopackage feature table.

It provides the ability to query vector data from the table, information about the table structure, and allows an application to access raw data from the table via the TSLGPkgFeatureIterator class.

Geometry queries can be filtered based on a supplied extent, or by directly providing an SQL statement to execute.

Public Member Functions
const char *	getAttributeColumnNameAt (int index) const
TSLGPkgFeatureIterator *	getFeatureIterator (double tmcPerMU, TSLDataHandler *dataHandler=NULL) const
TSLEntitySet *	getGeometryBySQL (const char *sqlStatement, double tmcPerMU, TSLGPkgFeatureCallback *featureCallback=NULL, TSLDataHandler *dataHandler=NULL, TSLMUExtent *extent=NULL) const
TSLEntitySet *	getGeometryByExtent (const TSLMUExtent &extent, double tmcPerMU, TSLGPkgFeatureCallback *featureCallback=NULL, TSLDataHandler *dataHandler=NULL) const
int	numberOfItems () const
int	numberOfAttributeColumns () const
Public Member Functions inherited from TSLGPkgContentTable
const char *	name () const
const char *	description () const
const TSLMUExtent &	getMUExtent () const
const char *	lastChange () const
const char *	identifier () const
const TSLGPkgMetadataContainer *	queryMetadata () const
const TSLCoordinateSystem *	querySpatialReferenceSystem () const
TSLGPkgContentTableTypeEnum	type () const

Member Function Documentation

getAttributeColumnNameAt()

const char * TSLGPkgFeatureTable::getAttributeColumnNameAt

(

int

index

)

const

Query the name of an attribute column.

The mandatory ID and Geometry columns are not excluded from this query.

Parameters

index

The index of the column to query.

Returns

the name of the column at the index provided, or NULL if the requested column does not exist.

getFeatureIterator()

TSLGPkgFeatureIterator * TSLGPkgFeatureTable::getFeatureIterator	(	double	tmcPerMU,
		TSLDataHandler *	dataHandler = NULL ) const

Returns an iterator that allows the application to iterate through the contents of the feature table.

The iterator is owned by the application and should be deleted when no longer required.

Parameters

tmcPerMU	The TMC->Map Unit scaling factor to use when converting the geometry to a TSLEntity.
dataHandler	An optional data handler. If provided, the iterator will populate the TSLDataSet of each geometry item returned from the iterator with any attribute columns present in the feature table. If the data handler provided does not contain definitions for any of the attribute columns present in the feature table they will be automatically added to the data handler.

getGeometryByExtent()

TSLEntitySet * TSLGPkgFeatureTable::getGeometryByExtent	(	const TSLMUExtent &	extent,
		double	tmcPerMU,
		TSLGPkgFeatureCallback *	featureCallback = NULL,
		TSLDataHandler *	dataHandler = NULL ) const

Returns all geometry in the feature table that intersects the given extent. If no geometry is within the extent, this method returns NULL.

The application owns the returned entity set.

Parameters

extent	The extent to return geometry for.
tmcPerMU	The scaling factor to use to use when converting geometry from the GeoPackage native format to MapLink entity geometry types. For data in lat/lon a value of approximately 5,000,000 is reasonable, while for data in a world-scale meter-based coordinate system a value of 50 is reasonable.
featureCallback	An optional callback that will be invoked for each geometry item read from the database. This can be used to alter the geometry as it is loaded from the GeoPackage.
dataHandler	An optional data handler. If provided, the iterator will populate the TSLDataSet of each geometry item returned from the iterator with any attribute columns present in the feature table. If the data handler provided does not contain definitions for any of the attribute columns present in the feature table they will be automatically added to the data handler.

getGeometryBySQL()

TSLEntitySet * TSLGPkgFeatureTable::getGeometryBySQL	(	const char *	sqlStatement,
		double	tmcPerMU,
		TSLGPkgFeatureCallback *	featureCallback = NULL,
		TSLDataHandler *	dataHandler = NULL,
		TSLMUExtent *	extent = NULL ) const

Executes the SQL statement contained in the parameter string and returns the matching geometry from this feature table as a TSLEntitySet. If the query returns with no results, NULL is returned.

The application owns the returned entity set.

Parameters

sqlStatement	The SQL statement to execute on the GeoPackage.
tmcPerMU	The scaling factor to use to use when converting geometry from the GeoPackage native format to MapLink entity geometry types. For data in lat/lon a value of approximately 5,000,000 is reasonable, while for data in a world-scale meter-based coordinate system a value of 50 is reasonable.
featureCallback	An optional callback that will be invoked for each geometry item read from the database. This can be used to alter the geometry as it is loaded from the GeoPackage.
dataHandler	An optional data handler. If provided, the iterator will populate the TSLDataSet of each geometry item returned from the iterator with any attribute columns present in the feature table. If the data handler provided does not contain definitions for any of the attribute columns present in the feature table they will be automatically added to the data handler.
extent	An optional query extent. If provided, only geometry that intersects the given extent will be returned.

numberOfAttributeColumns()

int TSLGPkgFeatureTable::numberOfAttributeColumns

(

)

const

Returns the number of columns in the feature table.

Each table has an mandatory ID column and a Geometry column. Additional column entries represent Attribute data describing the feature.

The contents of these columns may be queried via the feature iterator.

numberOfItems()

int TSLGPkgFeatureTable::numberOfItems

(

)

const

Returns the number of Items in the feature table.