Abstract base class for spatial data provider implementations. More...

#include <qgsdataprovider.h>

Inheritance diagram for QgsDataProvider:

Collaboration diagram for QgsDataProvider:

Public Types
enum	DataCapability { NoDataCapabilities = 0, File = 1, Dir = 1 << 1, Database = 1 << 2, Net = 1 << 3 }

Signals
void	fullExtentCalculated ()
	This is emitted whenever the worker thread has fully calculated the PostGIS extents for this layer, and its event has been received by this provider.
void	dataChanged ()
	This is emitted whenever an asynchronous operation has finished and the data should be redrawn.
void	dataChanged (int changed)
	This is emitted whenever data or metadata (e.g.

Public Member Functions
	QgsDataProvider (QString const &uri="")
virtual	~QgsDataProvider ()
	We need this so the subclass destructors get called.
virtual QgsCoordinateReferenceSystem	crs ()=0
virtual void	setDataSourceUri (const QString &uri)
	Set the data source specification.
virtual QString	dataSourceUri () const
	Get the data source specification.
virtual QgsRectangle	extent ()=0
	Get the extent of the layer.
virtual bool	isValid ()=0
	Returns true if this is a valid layer.
virtual void	updateExtents ()
	Update the extents of the layer.
virtual bool	setSubsetString (QString subset, bool updateFeatureCount=true)
	Set the subset string used to create a subset of features in the layer.
virtual bool	supportsSubsetString ()
	provider supports setting of subset strings
virtual QString	subsetString ()
	Returns the subset definition string (typically sql) currently in use by the layer and used by the provider to limit the feature set.
virtual QStringList	subLayers () const
	Sub-layers handled by this provider, in order from bottom to top.
virtual QStringList	subLayerStyles () const
	Sub-layer styles for each sub-layer handled by this provider, in order from bottom to top.
virtual uint	subLayerCount () const
	return the number of layers for the current data source
virtual void	setLayerOrder (const QStringList &layers)
	Reorder the list of layer names to be rendered by this provider (in order from bottom to top)
virtual void	setSubLayerVisibility (const QString &name, bool vis)
	Set the visibility of the given sublayer name.
virtual QString	name () const =0
	return a provider name
virtual QString	description () const =0
	return description
virtual QString	fileVectorFilters () const
	return vector file filter string
virtual QString	fileRasterFilters () const
	return raster file filter string
virtual void	reloadData ()
	Reloads the data from the source.
virtual QDateTime	timestamp () const
	Time stamp of data source in the moment when data/metadata were loaded by provider.
virtual QDateTime	dataTimestamp () const
	Current time stamp of data source.
virtual QgsError	error () const
	Get current status error.

Protected Member Functions
void	appendError (const QgsErrorMessage &theMessage)
	Add error message.
void	setError (const QgsError &theError)
	Set error message.

Protected Attributes
QDateTime	mTimestamp
	Timestamp of data in the moment when the data were loaded by provider.
QgsError	mError
	Error.

Private Attributes
QString	mDataSourceURI
	Universal Resource Identifier for source data.

Detailed Description

Abstract base class for spatial data provider implementations.

Author: Gary E.Sherman

This object needs to inherit from QObject to enable event processing in the Postgres/PostGIS provider (QgsPostgresProvider). It is called here so that this vtable and the vtable for QgsPostgresProvider don't get misaligned - the QgsVectorLayer class factory (which refers to generic QgsVectorDataProvider's) depends on it.

Definition at line 44 of file qgsdataprovider.h.

Member Enumeration Documentation

enum QgsDataProvider::DataCapability

Enumerator:

NoDataCapabilities
File
Dir
Database
Net

Definition at line 52 of file qgsdataprovider.h.

Constructor & Destructor Documentation

QgsDataProvider::QgsDataProvider ( QString const & uri = "" )

inline

Definition at line 61 of file qgsdataprovider.h.

virtual QgsDataProvider::~QgsDataProvider ( )

inlinevirtual

We need this so the subclass destructors get called.

Definition at line 68 of file qgsdataprovider.h.

Member Function Documentation

void QgsDataProvider::appendError ( const QgsErrorMessage & theMessage )

inlineprotected

Add error message.

Definition at line 333 of file qgsdataprovider.h.

virtual QgsCoordinateReferenceSystem QgsDataProvider::crs ( )

pure virtual

Get the QgsCoordinateReferenceSystem for this layer

Note: Must be reimplemented by each provider. If the provider isn't capable of returning its projection an empty srs will be return, ti will return 0

Referenced by QgsMapToolIdentify::identifyRasterLayer(), QgsVectorLayer::setCoordinateSystem(), and QgsRasterLayer::setDataProvider().

void QgsDataProvider::dataChanged ( )

signal

This is emitted whenever an asynchronous operation has finished and the data should be redrawn.

Note: added in 1.5

void QgsDataProvider::dataChanged ( int changed )

signal

This is emitted whenever data or metadata (e.g.

color table, extent) has changed

Parameters

changed binary combination of changes

Note: added in 1.7

virtual QString QgsDataProvider::dataSourceUri ( ) const

inlinevirtual

Get the data source specification.

This may be a path or database connection string

Returns: data source specification

Definition at line 94 of file qgsdataprovider.h.

Referenced by QgsRasterLayer::setDataProvider(), QgsVectorLayer::setDataProvider(), and QgsVectorLayer::setSubsetString().

virtual QDateTime QgsDataProvider::dataTimestamp ( ) const

inlinevirtual

Current time stamp of data source.

Reimplemented in QgsRasterDataProvider.

Definition at line 292 of file qgsdataprovider.h.

virtual QString QgsDataProvider::description ( ) const

pure virtual

return description

Return a terse string describing what the provider is.

Note

Instead of being pure virtual, might be better to generalize this behavior and presume that none of the sub-classes are going to do anything strange with regards to their name or description?

Referenced by QgsRasterLayer::metadata(), and QgsVectorLayer::metadata().

virtual QgsError QgsDataProvider::error ( ) const

inlinevirtual

Get current status error.

This error describes some principal problem for which provider cannot work and thus is not valid. It is not last error after accessing data by block(), identify() etc.

Definition at line 298 of file qgsdataprovider.h.

Referenced by QgsRasterLayer::setDataProvider().

virtual QgsRectangle QgsDataProvider::extent ( )

pure virtual

Get the extent of the layer.

Returns: QgsRectangle containing the extent of the layer

Implemented in QgsRasterDataProvider.

Referenced by QgsVectorLayer::extent(), and QgsVectorLayer::setDataProvider().

virtual QString QgsDataProvider::fileRasterFilters ( ) const

inlinevirtual

return raster file filter string

Returns a string suitable for a QFileDialog of raster file formats supported by the data provider. Naturally this will be an empty string for those data providers that do not deal with plain files, such as databases and servers.

Note

It'd be nice to eventually be raster/vector neutral.

Definition at line 279 of file qgsdataprovider.h.

virtual QString QgsDataProvider::fileVectorFilters ( ) const

inlinevirtual

return vector file filter string

Returns a string suitable for a QFileDialog of vector file formats supported by the data provider. Naturally this will be an empty string for those data providers that do not deal with plain files, such as databases and servers.

Note

It'd be nice to eventually be raster/vector neutral.

Definition at line 262 of file qgsdataprovider.h.

void QgsDataProvider::fullExtentCalculated ( )

signal

This is emitted whenever the worker thread has fully calculated the PostGIS extents for this layer, and its event has been received by this provider.

virtual bool QgsDataProvider::isValid ( )

pure virtual

Returns true if this is a valid layer.

It is up to individual providers to determine what constitutes a valid layer

Referenced by QgsVectorLayerImport::QgsVectorLayerImport(), QgsRasterChecker::runTest(), QgsRasterLayer::setDataProvider(), and QgsVectorLayer::setDataProvider().

virtual QString QgsDataProvider::name ( ) const

pure virtual

return a provider name

Essentially just returns the provider key. Should be used to build file dialogs so that providers can be shown with their supported types. Thus if more than one provider supports a given format, the user is able to select a specific provider to open that file.

Note

Instead of being pure virtual, might be better to generalize this behavior and presume that none of the sub-classes are going to do anything strange with regards to their name or description?

Referenced by QgsComposerMap::containsWMSLayer(), QgsVectorDataProvider::fieldNameIndex(), QgsVectorDataProvider::fieldNameMap(), QgsRasterLayerSaveAsDialog::on_mFormatComboBox_currentIndexChanged(), QgsProviderRegistry::provider(), and QgsRasterLayerSaveAsDialog::QgsRasterLayerSaveAsDialog().

virtual void QgsDataProvider::reloadData ( )

inlinevirtual

Reloads the data from the source.

Needs to be implemented by providers with data caches to synchronize with changes in the data source

Definition at line 286 of file qgsdataprovider.h.

Referenced by QgsRasterLayer::reload(), and QgsVectorLayer::reload().

virtual void QgsDataProvider::setDataSourceUri ( const QString & uri )

inlinevirtual

Set the data source specification.

This may be a path or database connection string

Parameters

uri	source specification

Definition at line 84 of file qgsdataprovider.h.

void QgsDataProvider::setError ( const QgsError & theError )

inlineprotected

Set error message.

Definition at line 336 of file qgsdataprovider.h.

virtual void QgsDataProvider::setLayerOrder ( const QStringList & layers )

inlinevirtual

Reorder the list of layer names to be rendered by this provider (in order from bottom to top)

Note: layers must have been previously added.

Definition at line 195 of file qgsdataprovider.h.

Referenced by QgsRasterLayer::setLayerOrder().

virtual void QgsDataProvider::setSubLayerVisibility	(	const QString &	name,
		bool	vis
	)

inlinevirtual

Set the visibility of the given sublayer name.

Definition at line 209 of file qgsdataprovider.h.

Referenced by QgsRasterLayer::setSubLayerVisibility().

virtual bool QgsDataProvider::setSubsetString	(	QString	subset,
		bool	updateFeatureCount = `true`
	)

inlinevirtual

Set the subset string used to create a subset of features in the layer.

This may be a sql where clause or any other string that can be used by the data provider to create a subset. Must be implemented in the dataprovider.

Definition at line 129 of file qgsdataprovider.h.

Referenced by QgsVectorLayer::setSubsetString().

virtual uint QgsDataProvider::subLayerCount ( ) const

inlinevirtual

return the number of layers for the current data source

Definition at line 184 of file qgsdataprovider.h.

virtual QStringList QgsDataProvider::subLayers ( ) const

inlinevirtual

Sub-layers handled by this provider, in order from bottom to top.

Sub-layers are used when the provider's source can combine layers it knows about in some way before it hands them off to the provider.

Reimplemented in QgsRasterDataProvider.

Definition at line 162 of file qgsdataprovider.h.

virtual QStringList QgsDataProvider::subLayerStyles ( ) const

inlinevirtual

Sub-layer styles for each sub-layer handled by this provider, in order from bottom to top.

Sub-layer styles are used to abstract the way the provider's source can symbolise layers in some way at the server, before it serves them to the provider.

Definition at line 175 of file qgsdataprovider.h.

virtual QString QgsDataProvider::subsetString ( )

inlinevirtual

Returns the subset definition string (typically sql) currently in use by the layer and used by the provider to limit the feature set.

Must be overridden in the dataprovider, otherwise returns a null QString.

Definition at line 150 of file qgsdataprovider.h.

Referenced by QgsVectorLayer::subsetString().

virtual bool QgsDataProvider::supportsSubsetString ( )

inlinevirtual

provider supports setting of subset strings

Note: added in 1.4

Definition at line 142 of file qgsdataprovider.h.

virtual QDateTime QgsDataProvider::timestamp ( ) const

inlinevirtual

Time stamp of data source in the moment when data/metadata were loaded by provider.

Reimplemented in QgsRasterDataProvider.

Definition at line 289 of file qgsdataprovider.h.

virtual void QgsDataProvider::updateExtents ( )

inlinevirtual

Update the extents of the layer.

Not implemented by default

Definition at line 117 of file qgsdataprovider.h.

Referenced by QgsVectorLayer::commitChanges(), and QgsVectorLayer::extent().

Member Data Documentation

QString QgsDataProvider::mDataSourceURI

private

Universal Resource Identifier for source data.

This could be a file, database, or server address.

Definition at line 344 of file qgsdataprovider.h.

QgsError QgsDataProvider::mError

protected

Error.

Definition at line 330 of file qgsdataprovider.h.

QDateTime QgsDataProvider::mTimestamp

protected

Timestamp of data in the moment when the data were loaded by provider.

Definition at line 327 of file qgsdataprovider.h.

Referenced by QgsRasterDataProvider::timestamp().

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

/tmp/buildd/qgis-2.0.1/src/core/qgsdataprovider.h

Public Types

Signals

Public Member Functions

Protected Member Functions

Protected Attributes

Private Attributes

Detailed Description

Member Enumeration Documentation

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation