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dc18b5b36b
- Closes https://hub.qgis.org/issues/14378 - Adds new virtual methods in QgsDataProvider(): enterUpdateMode() and leaveUpdateMode() and implement them in the OGR provider. Limited to shapefiles and tabfiles - Implements QgsOGRProvider:reloadData() - Robustify OGR provider methods so they don't crash if dataset re-opening fails.
405 lines
12 KiB
C++
405 lines
12 KiB
C++
/***************************************************************************
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qgsdataprovider.h - DataProvider Interface class
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--------------------------------------
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Date : 09-Sep-2003
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Copyright : (C) 2003 by Gary E.Sherman
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email : sherman at mrcc.com
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***************************************************************************
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* *
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* This program is free software; you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation; either version 2 of the License, or *
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* (at your option) any later version. *
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* *
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***************************************************************************/
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#ifndef QQGSDATAPROVIDER_H
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#define QQGSDATAPROVIDER_H
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#include <QDateTime>
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#include <QObject>
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#include <QString>
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#include <QStringList>
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//#include "qgsdataitem.h"
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#include "qgsdatasourceuri.h"
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#include "qgserror.h"
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typedef int dataCapabilities_t();
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class QgsRectangle;
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class QgsCoordinateReferenceSystem;
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/** \ingroup core
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* Abstract base class for spatial data provider implementations.
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* @author Gary E.Sherman
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*
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* This object needs to inherit from QObject to enable event
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* processing in the Postgres/PostGIS provider (QgsPostgresProvider).
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* It is called *here* so that this vtable and the vtable for
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* QgsPostgresProvider don't get misaligned -
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* the QgsVectorLayer class factory (which refers
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* to generic QgsVectorDataProvider's) depends on it.
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*/
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class CORE_EXPORT QgsDataProvider : public QObject
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{
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Q_OBJECT
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public:
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Q_ENUMS( DataCapability )
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enum DataCapability
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{
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NoDataCapabilities = 0,
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File = 1,
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Dir = 1 << 1,
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Database = 1 << 2,
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Net = 1 << 3 // Internet source
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};
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QgsDataProvider( QString const & uri = "" )
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: mDataSourceURI( uri )
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{}
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/**
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* We need this so the subclass destructors get called
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*/
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virtual ~QgsDataProvider() {}
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/** Get the QgsCoordinateReferenceSystem for this layer
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* @note Must be reimplemented by each provider.
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* If the provider isn't capable of returning
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* its projection an empty srs will be return, ti will return 0
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*/
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virtual QgsCoordinateReferenceSystem crs() = 0;
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/**
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* Set the data source specification. This may be a path or database
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* connection string
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* @param uri source specification
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*/
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virtual void setDataSourceUri( const QString & uri )
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{
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mDataSourceURI = uri;
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}
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/**
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* Get the data source specification. This may be a path or database
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* connection string
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* @param expandAuthConfig Whether to expand any assigned authentication configuration
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* @return data source specification
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* @note The default authentication configuration expansion is FALSE. This keeps credentials
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* out of layer data source URIs and project files. Expansion should be specifically done
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* only when needed within a provider
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*/
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virtual QString dataSourceUri( bool expandAuthConfig = false ) const
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{
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if ( expandAuthConfig && mDataSourceURI.contains( "authcfg" ) )
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{
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QgsDataSourceURI uri( mDataSourceURI );
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return uri.uri( expandAuthConfig );
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}
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else
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{
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return mDataSourceURI;
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}
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}
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/**
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* Get the extent of the layer
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* @return QgsRectangle containing the extent of the layer
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*/
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virtual QgsRectangle extent() = 0;
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/**
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* Returns true if this is a valid layer. It is up to individual providers
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* to determine what constitutes a valid layer
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*/
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virtual bool isValid() = 0;
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/**
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* Update the extents of the layer. Not implemented by default
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*/
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virtual void updateExtents()
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{
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// NOP by default
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}
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/**
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* Set the subset string used to create a subset of features in
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* the layer. This may be a sql where clause or any other string
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* that can be used by the data provider to create a subset.
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* Must be implemented in the dataprovider.
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*/
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virtual bool setSubsetString( const QString& subset, bool updateFeatureCount = true )
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{
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// NOP by default
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Q_UNUSED( subset );
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Q_UNUSED( updateFeatureCount );
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return false;
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}
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/** Provider supports setting of subset strings */
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virtual bool supportsSubsetString() { return false; }
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/**
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* Returns the subset definition string (typically sql) currently in
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* use by the layer and used by the provider to limit the feature set.
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* Must be overridden in the dataprovider, otherwise returns a null
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* QString.
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*/
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virtual QString subsetString()
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{
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return QString::null;
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}
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/**
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* Sub-layers handled by this provider, in order from bottom to top
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*
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* Sub-layers are used when the provider's source can combine layers
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* it knows about in some way before it hands them off to the provider.
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*/
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virtual QStringList subLayers() const
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{
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return QStringList(); // Empty
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}
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/**
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* Sub-layer styles for each sub-layer handled by this provider,
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* in order from bottom to top
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*
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* Sub-layer styles are used to abstract the way the provider's source can symbolise
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* layers in some way at the server, before it serves them to the provider.
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*/
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virtual QStringList subLayerStyles() const
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{
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return QStringList(); // Empty
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}
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/**
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* return the number of layers for the current data source
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*/
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virtual uint subLayerCount() const
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{
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return 0;
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}
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/**
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* Reorder the list of layer names to be rendered by this provider
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* (in order from bottom to top)
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* \note layers must have been previously added.
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*/
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virtual void setLayerOrder( const QStringList &layers )
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{
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//prevent unused var warnings
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if ( layers.count() < 1 )
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{
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return;
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}
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// NOOP
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}
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/**
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* Set the visibility of the given sublayer name
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*/
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virtual void setSubLayerVisibility( const QString &name, bool vis )
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{
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//prevent unused var warnings
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if ( name.isEmpty() || !vis )
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{
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return;
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}
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// NOOP
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}
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/** Return a provider name
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*
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* Essentially just returns the provider key. Should be used to build file
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* dialogs so that providers can be shown with their supported types. Thus
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* if more than one provider supports a given format, the user is able to
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* select a specific provider to open that file.
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*
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* @note
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*
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* Instead of being pure virtual, might be better to generalize this
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* behavior and presume that none of the sub-classes are going to do
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* anything strange with regards to their name or description?
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*
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*/
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virtual QString name() const = 0;
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/** Return description
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*
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* Return a terse string describing what the provider is.
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*
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* @note
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*
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* Instead of being pure virtual, might be better to generalize this
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* behavior and presume that none of the sub-classes are going to do
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* anything strange with regards to their name or description?
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*
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*/
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virtual QString description() const = 0;
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/** Return vector file filter string
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*
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* Returns a string suitable for a QFileDialog of vector file formats
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* supported by the data provider. Naturally this will be an empty string
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* for those data providers that do not deal with plain files, such as
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* databases and servers.
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*
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* @note It'd be nice to eventually be raster/vector neutral.
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*/
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virtual QString fileVectorFilters() const
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{
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return "";
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}
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/** Return raster file filter string
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*
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* Returns a string suitable for a QFileDialog of raster file formats
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* supported by the data provider. Naturally this will be an empty string
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* for those data providers that do not deal with plain files, such as
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* databases and servers.
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*
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* @note It'd be nice to eventually be raster/vector neutral.
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*/
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virtual QString fileRasterFilters() const
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{
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return "";
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}
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/** Reloads the data from the source. Needs to be implemented by providers with data caches to
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* synchronize with changes in the data source
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*/
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virtual void reloadData() {}
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/** Time stamp of data source in the moment when data/metadata were loaded by provider */
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virtual QDateTime timestamp() const { return mTimestamp; }
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/** Current time stamp of data source */
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virtual QDateTime dataTimestamp() const { return QDateTime(); }
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/** Get current status error. This error describes some principal problem
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* for which provider cannot work and thus is not valid. It is not last error
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* after accessing data by block(), identify() etc.
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*/
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virtual QgsError error() const { return mError; }
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/** Invalidate connections corresponding to specified name
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* @note added in QGIS 2.16
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*/
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virtual void invalidateConnections( const QString& connection ) { Q_UNUSED( connection ); }
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/** Enter update mode.
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*
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* This is aimed at providers that can open differently the connection to
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* the datasource, according it to be in update mode or in read-only mode.
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* A call to this method shall be balanced with a call to leaveUpdateMode(),
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* if this method returns true.
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*
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* Most providers will have an empty implementation for that method.
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*
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* For backward compatibility, providers that implement enterUpdateMode() should
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* still make sure to allow editing operations to work even if enterUpdateMode()
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* is not explicitly called.
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*
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* Several successive calls to enterUpdateMode() can be done. So there is
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* a concept of stack of calls that must be handled by the provider. Only the first
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* call to enterUpdateMode() will really turn update mode on.
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*
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* @return true in case of success (or no-op implementation), false in case of failure.
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*
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* @note added in QGIS 2.16
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*/
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virtual bool enterUpdateMode() { return true; }
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/** Leave update mode.
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*
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* This is aimed at providers that can open differently the connection to
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* the datasource, according it to be in update mode or in read-only mode.
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* This method shall be balanced with a succesful call to enterUpdateMode().
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*
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* Most providers will have an empty implementation for that method.
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*
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* Several successive calls to enterUpdateMode() can be done. So there is
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* a concept of stack of calls that must be handled by the provider. Only the last
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* call to leaveUpdateMode() will really turn update mode off.
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*
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* @return true in case of success (or no-op implementation), false in case of failure.
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*
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* @note added in QGIS 2.16
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*/
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virtual bool leaveUpdateMode() { return true; }
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signals:
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/**
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* This is emitted whenever the worker thread has fully calculated the
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* PostGIS extents for this layer, and its event has been received by this
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* provider.
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*/
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void fullExtentCalculated();
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/**
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* This is emitted whenever an asynchronous operation has finished
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* and the data should be redrawn
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*
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* When emitted from a QgsVectorDataProvider, any cached information such as
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* feature ids should be invalidated.
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*/
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void dataChanged();
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/**
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* This is emitted whenever data or metadata (e.g. color table, extent) has changed
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* @param changed binary combination of changes
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*/
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void dataChanged( int changed );
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protected:
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/**
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* Timestamp of data in the moment when the data were loaded by provider.
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*/
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QDateTime mTimestamp;
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/** \brief Error */
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QgsError mError;
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/** Add error message */
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void appendError( const QgsErrorMessage & theMessage ) { mError.append( theMessage );}
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/** Set error message */
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void setError( const QgsError & theError ) { mError = theError;}
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private:
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/**
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* Universal Resource Identifier for source data.
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* This could be a file, database, or server address.
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*/
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QString mDataSourceURI;
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};
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#endif
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