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qgsdataprovider.h
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qgsdataprovider.h
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/***************************************************************************
qgsdataprovider.h - DataProvider Interface class
--------------------------------------
Date : 09-Sep-2003
Copyright : (C) 2003 by Gary E.Sherman
email : sherman at mrcc.com
***************************************************************************
* *
* This program is free software; you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation; either version 2 of the License, or *
* (at your option) any later version. *
* *
***************************************************************************/
#ifndef QQGSDATAPROVIDER_H
#define QQGSDATAPROVIDER_H
#include "qgis_core.h"
#include <QDateTime>
#include <QObject>
#include <QString>
#include <QStringList>
//#include "qgsdataitem.h"
#include "qgsdatasourceuri.h"
#include "qgslayermetadata.h"
#include "qgserror.h"
typedef int dataCapabilities_t(); // SIP_SKIP
class QgsRectangle;
class QgsCoordinateReferenceSystem;
/**
* \ingroup core
* Abstract base class for spatial data provider implementations.
*
* 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.
*/
class CORE_EXPORT QgsDataProvider : public QObject
{
#ifdef SIP_RUN
SIP_CONVERT_TO_SUBCLASS_CODE
if ( qobject_cast<QgsVectorDataProvider *>( sipCpp ) )
{
sipType = sipType_QgsVectorDataProvider;
}
else if ( qobject_cast<QgsRasterDataProvider *>( sipCpp ) )
{
sipType = sipType_QgsRasterDataProvider;
}
else if ( qobject_cast<QgsMeshDataProvider *>( sipCpp ) )
{
sipType = sipType_QgsMeshDataProvider;
}
else
{
sipType = 0;
}
SIP_END
#endif
Q_OBJECT
public:
enum DataCapability
{
NoDataCapabilities = 0,
File = 1,
Dir = 1 << 1,
Database = 1 << 2,
Net = 1 << 3 // Internet source
};
Q_ENUM( DataCapability )
/**
* Properties are used to pass custom configuration options into data providers.
* This enum defines a list of custom properties which can be used on different
* providers. It depends on the provider, which properties are supported.
* In addition to these default properties, providers can add their custom properties
* starting from CustomData.
*/
enum ProviderProperty
{
EvaluateDefaultValues, //!< Evaluate default values on provider side when calling QgsVectorDataProvider::defaultValue( int index ) rather than on commit.
CustomData = 3000 //!< Custom properties for 3rd party providers or very provider-specific properties which are not expected to be of interest for other providers can be added starting from this value up.
};
/**
* Setting options for creating vector data providers.
* \since QGIS 3.2
*/
struct ProviderOptions
{
};
/**
* Create a new dataprovider with the specified in the \a uri.
*
* Additional creation options are specified within the \a options value.
*/
QgsDataProvider( const QString &uri = QString(), const QgsDataProvider::ProviderOptions &options = QgsDataProvider::ProviderOptions() )
: mDataSourceURI( uri )
{
Q_UNUSED( options );
}
/**
* Returns the coordinate system for the data source.
* If the provider isn't capable of returning its projection then an invalid
* QgsCoordinateReferenceSystem will be returned.
*/
virtual QgsCoordinateReferenceSystem crs() const = 0;
/**
* Set the data source specification. This may be a path or database
* connection string
* \param uri source specification
*/
virtual void setDataSourceUri( const QString &uri )
{
mDataSourceURI = uri;
}
/**
* Get the data source specification. This may be a path or database
* connection string
* \param expandAuthConfig Whether to expand any assigned authentication configuration
* \returns data source specification
* \note The default authentication configuration expansion is FALSE. This keeps credentials
* out of layer data source URIs and project files. Expansion should be specifically done
* only when needed within a provider
*/
virtual QString dataSourceUri( bool expandAuthConfig = false ) const
{
if ( expandAuthConfig && mDataSourceURI.contains( QLatin1String( "authcfg" ) ) )
{
QgsDataSourceUri uri( mDataSourceURI );
return uri.uri( expandAuthConfig );
}
else
{
return mDataSourceURI;
}
}
/**
* Set the data source specification.
*
* \since QGIS 3.0
*/
void setUri( const QgsDataSourceUri &uri )
{
mDataSourceURI = uri.uri( true );
}
/**
* Get the data source specification.
*
* \since QGIS 3.0
*/
QgsDataSourceUri uri() const
{
return QgsDataSourceUri( mDataSourceURI );
}
/**
* Returns the extent of the layer
* \returns QgsRectangle containing the extent of the layer
*/
virtual QgsRectangle extent() const = 0;
/**
* Returns true if this is a valid layer. It is up to individual providers
* to determine what constitutes a valid layer.
*/
virtual bool isValid() const = 0;
/**
* Update the extents of the layer. Not implemented by default.
*/
virtual void updateExtents()
{
// NOP by default
}
/**
* 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.
*/
virtual bool setSubsetString( const QString &subset, bool updateFeatureCount = true )
{
// NOP by default
Q_UNUSED( subset );
Q_UNUSED( updateFeatureCount );
return false;
}
/**
* Returns true if the provider supports setting of subset strings.
*/
virtual bool supportsSubsetString() const { return false; }
/**
* 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.
*/
virtual QString subsetString() const
{
return QString();
}
/**
* 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.
*
* \see SUBLAYER_SEPARATOR
*/
virtual QStringList subLayers() const
{
return QStringList(); // Empty
}
/**
* String sequence used for separating components of sublayers strings.
* \see subLayers()
* \since QGIS 3.0
*/
static QString SUBLAYER_SEPARATOR;
/**
* 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.
*/
virtual QStringList subLayerStyles() const
{
return QStringList(); // Empty
}
/**
* return the number of layers for the current data source
*/
virtual uint subLayerCount() const
{
return 0;
}
/**
* 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.
*/
virtual void setLayerOrder( const QStringList &layers )
{
//prevent unused var warnings
if ( layers.count() < 1 )
{
return;
}
// NOOP
}
/**
* Set the visibility of the given sublayer name
*/
virtual void setSubLayerVisibility( const QString &name, bool vis )
{
//prevent unused var warnings
if ( name.isEmpty() || !vis )
{
return;
}
// NOOP
}
/**
* 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?
*
*/
virtual QString name() const = 0;
/**
* 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?
*
*/
virtual QString description() const = 0;
/**
* 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.
*/
virtual QString fileVectorFilters() const
{
return QLatin1String( "" );
}
/**
* 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.
*/
virtual QString fileRasterFilters() const
{
return QLatin1String( "" );
}
/**
* Reloads the data from the source. Needs to be implemented by providers with data caches to
* synchronize with changes in the data source
*/
virtual void reloadData() {}
//! Time stamp of data source in the moment when data/metadata were loaded by provider
virtual QDateTime timestamp() const { return mTimestamp; }
//! Current time stamp of data source
virtual QDateTime dataTimestamp() const { return QDateTime(); }
/**
* 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.
*/
virtual QgsError error() const { return mError; }
/**
* Invalidate connections corresponding to specified name
* \since QGIS 2.16
*/
virtual void invalidateConnections( const QString &connection ) { Q_UNUSED( connection ); }
/**
* Enter update mode.
*
* This is aimed at providers that can open differently the connection to
* the datasource, according it to be in update mode or in read-only mode.
* A call to this method shall be balanced with a call to leaveUpdateMode(),
* if this method returns true.
*
* Most providers will have an empty implementation for that method.
*
* For backward compatibility, providers that implement enterUpdateMode() should
* still make sure to allow editing operations to work even if enterUpdateMode()
* is not explicitly called.
*
* Several successive calls to enterUpdateMode() can be done. So there is
* a concept of stack of calls that must be handled by the provider. Only the first
* call to enterUpdateMode() will really turn update mode on.
*
* \returns true in case of success (or no-op implementation), false in case of failure.
*
* \since QGIS 2.16
*/
virtual bool enterUpdateMode() { return true; }
/**
* Leave update mode.
*
* This is aimed at providers that can open differently the connection to
* the datasource, according it to be in update mode or in read-only mode.
* This method shall be balanced with a successful call to enterUpdateMode().
*
* Most providers will have an empty implementation for that method.
*
* Several successive calls to enterUpdateMode() can be done. So there is
* a concept of stack of calls that must be handled by the provider. Only the last
* call to leaveUpdateMode() will really turn update mode off.
*
* \returns true in case of success (or no-op implementation), false in case of failure.
*
* \since QGIS 2.16
*/
virtual bool leaveUpdateMode() { return true; }
/**
* Allows setting arbitrary properties on the provider.
* It depends on the provider which properties are supported.
*
* \since QGIS 2.16
*/
void setProviderProperty( ProviderProperty property, const QVariant &value );
/**
* Allows setting arbitrary properties on the provider.
* It depends on the provider which properties are supported.
*
* \since QGIS 2.16
*/
void setProviderProperty( int property, const QVariant &value ); // SIP_SKIP
/**
* Get the current value of a certain provider property.
* It depends on the provider which properties are supported.
*
* \since QGIS 2.16
*/
QVariant providerProperty( ProviderProperty property, const QVariant &defaultValue = QVariant() ) const;
/**
* Get the current value of a certain provider property.
* It depends on the provider which properties are supported.
*
* \since QGIS 2.16
*/
QVariant providerProperty( int property, const QVariant &defaultValue ) const; // SIP_SKIP
/**
* Set whether the provider will listen to datasource notifications
* If set, the provider will issue notify signals.
*
* The default implementation does nothing.
*
* \see notify
*
* \since QGIS 3.0
*/
virtual void setListening( bool isListening );
#ifndef SIP_RUN
/**
* Stores settings related to the context in which a preview job runs.
* \note Not available in Python bindings
* \since QGIS 3.0
*/
struct PreviewContext
{
//! Previous rendering time for the layer, in ms
double lastRenderingTimeMs = -1;
//! Default maximum allowable render time, in ms
double maxRenderingTimeMs = MAXIMUM_LAYER_PREVIEW_TIME_MS;
};
#endif
/**
* Returns whether the layer must be rendered in preview jobs.
*
* The \a context argument gives useful information which can be used
* to determine whether the layer should be rendered or not.
*
* The base implementation returns true if lastRenderingTimeMs <= maxRenderingTimeMs.
*
* \since QGIS 3.0
*
* \note not available in Python bindings
*/
virtual bool renderInPreview( const QgsDataProvider::PreviewContext &context ); // SIP_SKIP
/**
* Returns layer metadata collected from the provider's source.
*
* Individual data providers must implement this method if they support collecting metadata.
*
* \see writeLayerMetadata()
* \since QGIS 3.0
*/
virtual QgsLayerMetadata layerMetadata() const { return QgsLayerMetadata(); }
/**
* Writes layer \a metadata to the underlying provider source. Support depends
* on individual provider capabilities.
*
* Returns true if metadata was successfully written to the data provider.
* \see layerMetadata()
* \since QGIS 3.0
*/
virtual bool writeLayerMetadata( const QgsLayerMetadata &metadata ) { Q_UNUSED( metadata ); return false; }
signals:
/**
* 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 fullExtentCalculated();
/**
* This is emitted whenever an asynchronous operation has finished
* and the data should be redrawn
*
* When emitted from a QgsVectorDataProvider, any cached information such as
* feature ids should be invalidated.
*/
void dataChanged();
/**
* Emitted when datasource issues a notification
*
* \see setListening
*
* \since QGIS 3.0
*/
void notify( const QString &msg );
protected:
/**
* Timestamp of data in the moment when the data were loaded by provider.
*/
QDateTime mTimestamp;
//! \brief Error
QgsError mError;
//! Add error message
void appendError( const QgsErrorMessage &message ) { mError.append( message ); }
//! Set error message
void setError( const QgsError &error ) { mError = error;}
private:
/**
* Universal Resource Identifier for source data.
* This could be a file, database, or server address.
*/
QString mDataSourceURI;
QMap< int, QVariant > mProviderProperties;
};
#endif