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329 lines
11 KiB
Plaintext
329 lines
11 KiB
Plaintext
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class QgsVectorDataProvider : QgsDataProvider
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{
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%TypeHeaderCode
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#include <qgsvectordataprovider.h>
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%End
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public:
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// If you add to this, please also add to capabilitiesString()
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/**
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* enumeration with capabilities that providers might implement
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*/
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enum Capability
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{
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/** provider has no capabilities */
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NoCapabilities = 0,
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/** allows adding features */
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AddFeatures = 1,
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/** allows deletion of features */
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DeleteFeatures = 2,
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/** allows modification of attribute values */
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ChangeAttributeValues = 4,
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/** allows addition of new attributes (fields) */
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AddAttributes = 8,
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/** allows deletion of attributes (fields) */
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DeleteAttributes = 16,
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/** DEPRECATED - do not use */
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SaveAsShapefile = 32,
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/** allows creation of spatial index */
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CreateSpatialIndex = 64,
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/** fast access to features using their ID */
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SelectAtId = 128,
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/** allows modifications of geometries */
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ChangeGeometries = 256,
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/** DEPRECATED - do not use */
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SelectGeometryAtId = 512,
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/** DEPRECATED - do not use */
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RandomSelectGeometryAtId = 1024,
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/** DEPRECATED - do not use */
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SequentialSelectGeometryAtId = 2048,
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CreateAttributeIndex = 4096,
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/** allows user to select encoding */
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SelectEncoding = 8192,
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/** supports simplification of geometries on provider side according to a distance tolerance */
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SimplifyGeometries = 32768,
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/** supports topological simplification of geometries on provider side according to a distance tolerance */
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SimplifyGeometriesWithTopologicalValidation = 65536,
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};
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/** bitmask of all provider's editing capabilities */
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static const int EditingCapabilities;
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/**
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* Constructor of the vector provider
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* @param uri uniform resource locator (URI) for a dataset
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*/
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QgsVectorDataProvider( QString uri = QString() );
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/**
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* Destructor
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*/
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virtual ~QgsVectorDataProvider();
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/**
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* Return feature source object that can be used for querying provider's data. The returned feature source
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* is independent from provider - any changes to provider's state (e.g. change of subset string) will not be
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* reflected in the feature source, therefore it can be safely used for processing in background without
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* having to care about possible changes within provider that may happen concurrently. Also, even in the case
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* of provider being deleted, any feature source obtained from the provider will be kept alive and working
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* (they are independent and owned by the caller).
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*
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* Sometimes there are cases when some data needs to be shared between vector data provider and its feature source.
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* In such cases, the implementation must ensure that the data is not susceptible to run condition. For example,
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* if it is possible that both feature source and provider may need reading/writing to some shared data at the
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* same time, some synchronization mechanisms must be used (e.g. mutexes) to prevent data corruption.
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*
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* @note added in 2.4
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* @return new instance of QgsAbstractFeatureSource (caller is responsible for deleting it)
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*/
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virtual QgsAbstractFeatureSource* featureSource() const /Factory/;
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/**
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* Returns the permanent storage type for this layer as a friendly name.
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*/
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virtual QString storageType() const;
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/**
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* Query the provider for features specified in request.
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*/
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virtual QgsFeatureIterator getFeatures( const QgsFeatureRequest& request = QgsFeatureRequest() ) = 0;
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/**
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* Get feature type.
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* @return int representing the feature type
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*/
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virtual QGis::WkbType geometryType() const = 0;
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/**
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* Number of features in the layer
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* @return long containing number of features
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*/
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virtual long featureCount() const = 0;
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/**
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* Return a map of indexes with field names for this layer
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* @return map of fields
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* @see QgsFieldMap
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*/
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virtual const QgsFields &fields() const = 0;
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/**
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* Return a short comment for the data that this provider is
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* providing access to (e.g. the comment for postgres table).
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*/
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virtual QString dataComment() const;
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/**
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* Returns the minimum value of an attribute
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* @param index the index of the attribute
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*
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* Default implementation walks all numeric attributes and caches minimal
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* and maximal values. If provider has facilities to retrieve minimal
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* value directly, override this function.
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*/
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virtual QVariant minimumValue( int index );
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/**
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* Returns the maximum value of an attribute
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* @param index the index of the attribute
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*
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* Default implementation walks all numeric attributes and caches minimal
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* and maximal values. If provider has facilities to retrieve maximal
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* value directly, override this function.
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*/
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virtual QVariant maximumValue( int index );
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/**
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* Return unique values of an attribute
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* @param index the index of the attribute
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* @param uniqueValues values reference to the list to fill
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* @param limit maxmum number of the values to return (added in 1.4)
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*
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* Default implementation simply iterates the features
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*/
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virtual void uniqueValues( int index, QList<QVariant> &uniqueValues /Out/, int limit = -1 );
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/**
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* Returns the possible enum values of an attribute. Returns an empty stringlist if a provider does not support enum types
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* or if the given attribute is not an enum type.
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* @param index the index of the attribute
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* @param enumList reference to the list to fill
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* @note: added in version 1.2
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*/
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virtual void enumValues( int index, QStringList& enumList /Out/ );
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/**
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* Adds a list of features
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* @return true in case of success and false in case of failure
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*/
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virtual bool addFeatures( QList<QgsFeature> &flist /In,Out/ );
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/**
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* Deletes one or more features
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* @param id list containing feature ids to delete
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* @return true in case of success and false in case of failure
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*/
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virtual bool deleteFeatures( const QSet<qint64> &id );
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/**
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* Adds new attributes
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* @param attributes list of new attributes
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* @return true in case of success and false in case of failure
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* @note added in 1.2
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*/
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virtual bool addAttributes( const QList<QgsField> &attributes );
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/**
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* Deletes existing attributes
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* @param attributes a set containing indices of attributes
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* @return true in case of success and false in case of failure
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*/
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virtual bool deleteAttributes( const QSet<int> &attributes );
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/**
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* Changes attribute values of existing features.
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* @param attr_map a map containing changed attributes
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* @return true in case of success and false in case of failure
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*/
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virtual bool changeAttributeValues( const QMap<qint64, QMap<int, QVariant> > &attr_map );
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/**
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* Returns the default value for field specified by @c fieldId
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*/
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virtual QVariant defaultValue( int fieldId );
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/**
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* Changes geometries of existing features
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* @param geometry_map A QgsGeometryMap whose index contains the feature IDs
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* that will have their geometries changed.
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* The second map parameter being the new geometries themselves
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* @return True in case of success and false in case of failure
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*/
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virtual bool changeGeometryValues( QMap<qint64, QgsGeometry> & geometry_map );
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/**
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* Creates a spatial index on the datasource (if supported by the provider type).
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* @return true in case of success
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*/
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virtual bool createSpatialIndex();
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/**Create an attribute index on the datasource*/
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virtual bool createAttributeIndex( int field );
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/** Returns a bitmask containing the supported capabilities
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Note, some capabilities may change depending on whether
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a spatial filter is active on this provider, so it may
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be prudent to check this value per intended operation.
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*/
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virtual int capabilities() const;
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/**
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* Returns the above in friendly format.
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*/
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QString capabilitiesString() const;
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/**
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* Set encoding used for accessing data from layer
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*/
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virtual void setEncoding( const QString& e );
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/**
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* Get encoding which is used for accessing data
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*/
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QString encoding() const;
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/**
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* Returns the index of a field name or -1 if the field does not exist
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*/
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int fieldNameIndex( const QString& fieldName ) const;
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/**
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* Return a map where the key is the name of the field and the value is its index
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*/
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QMap<QString, int> fieldNameMap() const;
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/**
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* Return list of indexes to fetch all attributes in nextFeature()
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*/
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QList<int> attributeIndexes();
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/**
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* Return list of indexes of fields that make up the primary key
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* @note added in 2.0
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*/
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virtual QList<int> pkAttributeIndexes();
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/**
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* Return list of indexes to names for QgsPalLabeling fix
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*/
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virtual QHash<int, QString> palAttributeIndexNames() const;
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/**
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* check if provider supports type of field
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* @note added in 1.2
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*/
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bool supportedType( const QgsField &field ) const;
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struct NativeType
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{
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NativeType( QString typeDesc, QString typeName, QVariant::Type type, int minLen = 0, int maxLen = 0, int minPrec = 0, int maxPrec = 0 );
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QString mTypeDesc;
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QString mTypeName;
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QVariant::Type mType;
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int mMinLen;
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int mMaxLen;
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int mMinPrec;
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int mMaxPrec;
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};
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/**
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* Returns the names of the supported types
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* @note added in 1.2
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*/
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const QList< QgsVectorDataProvider::NativeType > &nativeTypes() const;
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/** Returns true if the provider is strict about the type of inserted features
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(e.g. no multipolygon in a polygon layer)
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@note: added in version 1.4*/
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bool doesStrictFeatureTypeCheck() const;
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/** Returns a list of available encodings */
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static const QStringList &availableEncodings();
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/**
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* Provider has errors to report
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* @note added in 1.7
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*/
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bool hasErrors();
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/**
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* Clear recorded errors
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* @note added in 1.7
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*/
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void clearErrors();
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/**
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* Get recorded errors
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* @note added in 1.7
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*/
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QStringList errors();
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/**
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* It returns false by default.
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* Must be implemented by providers that support saving and loading styles to db returning true
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*/
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virtual bool isSaveAndLoadStyleToDBSupported();
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static QVariant convertValue( QVariant::Type type, QString value );
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protected:
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void clearMinMaxCache();
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void fillMinMaxCache();
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void pushError( QString msg );
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};
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