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248 lines
8.4 KiB
Plaintext
248 lines
8.4 KiB
Plaintext
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class QgsFeatureRequest
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{
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%TypeHeaderCode
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#include <qgsfeaturerequest.h>
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%End
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public:
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enum Flag
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{
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NoFlags,
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NoGeometry, //!< Geometry is not required. It may still be returned if e.g. required for a filter condition.
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SubsetOfAttributes, //!< Fetch only a subset of attributes (setSubsetOfAttributes sets this flag)
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ExactIntersect //!< Use exact geometry intersection (slower) instead of bounding boxes
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};
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typedef QFlags<QgsFeatureRequest::Flag> Flags;
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enum FilterType
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{
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FilterNone, //!< No filter is applied
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FilterRect, //!< Filter using a rectangle, no need to set NoGeometry
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FilterFid, //!< Filter using feature ID
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FilterExpression, //!< Filter using expression
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FilterFids //!< Filter using feature IDs
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};
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/**
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* @brief The OrderByClause class represents an order by clause for a QgsFeatureRequest
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*/
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class OrderByClause
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{
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public:
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/**
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* Creates a new OrderByClause for a QgsFeatureRequest
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*
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* @param expression The expression to use for ordering
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* @param ascending If the order should be ascending (1,2,3) or descending (3,2,1)
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* If thr order is ascending, by default nulls are last
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* If thr order is descending, by default nulls are first
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*/
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OrderByClause( const QString &expression, bool ascending = true );
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/**
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* Creates a new OrderByClause for a QgsFeatureRequest
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*
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* @param expression The expression to use for ordering
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* @param ascending If the order should be ascending (1,2,3) or descending (3,2,1)
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* @param nullsfirst If true, NULLS are at the beginning, if false, NULLS are at the end
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*/
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OrderByClause( const QString &expression, bool ascending, bool nullsfirst );
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/**
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* The expression
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* @return the expression
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*/
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QgsExpression expression() const;
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/**
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* Order ascending
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* @return If ascending order is requested
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*/
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bool ascending() const;
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/**
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* Set if ascending order is requested
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*/
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void setAscending( bool ascending );
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/**
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* Set if NULLS should be returned first
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* @return if NULLS should be returned first
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*/
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bool nullsFirst() const;
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/**
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* Set if NULLS should be returned first
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*/
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void setNullsFirst( bool nullsFirst );
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};
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/**
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* A special attribute that if set matches all attributes
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*/
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static const QString AllAttributes;
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//! construct a default request: for all features get attributes and geometries
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QgsFeatureRequest();
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//! construct a request with feature ID filter
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explicit QgsFeatureRequest( QgsFeatureId fid );
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//! construct a request with rectangle filter
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explicit QgsFeatureRequest( const QgsRectangle& rect );
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//! construct a request with a filter expression
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explicit QgsFeatureRequest( const QgsExpression& expr, const QgsExpressionContext& context = QgsExpressionContext() );
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FilterType filterType() const;
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//! Set rectangle from which features will be taken. Empty rectangle removes the filter.
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//!
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QgsFeatureRequest& setFilterRect( const QgsRectangle& rect );
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const QgsRectangle& filterRect() const;
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//! Set feature ID that should be fetched.
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QgsFeatureRequest& setFilterFid( qint64 fid );
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qint64 filterFid() const;
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//! Set feature ID that should be fetched.
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QgsFeatureRequest& setFilterFids( const QgsFeatureIds& fids );
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const QgsFeatureIds& filterFids() const;
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/** Set the filter expression. {@see QgsExpression}
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* @param expression expression string
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* @see filterExpression
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* @see setExpressionContext
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*/
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QgsFeatureRequest& setFilterExpression( const QString& expression );
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/** Returns the filter expression if set.
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* @see setFilterExpression
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* @see expressionContext
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*/
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QgsExpression* filterExpression() const;
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/** Modifies the existing filter expression to add an additional expression filter. The
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* filter expressions are combined using AND, so only features matching both
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* the existing expression and the additional expression will be returned.
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* @note added in QGIS 2.14
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*/
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QgsFeatureRequest& combineFilterExpression( const QString& expression );
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/** Returns the expression context used to evaluate filter expressions.
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* @note added in QGIS 2.12
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* @see setExpressionContext
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*/
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QgsExpressionContext* expressionContext();
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/** Sets the expression context used to evaluate filter expressions.
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* @note added in QGIS 2.12
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* @see expressionContext
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*/
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QgsFeatureRequest& setExpressionContext( const QgsExpressionContext& context );
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/**
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* Disables filter conditions.
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* The spatial filter (filterRect) will be kept in place.
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*
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* @return The object the method is called on for chaining
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*
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* @note Added in 2.12
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*/
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QgsFeatureRequest& disableFilter();
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/**
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* Adds a new OrderByClause
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*
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* @param expression The expression to use for ordering
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* @param ascending If the order should be ascending (1,2,3) or descending (3,2,1)
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* If the order is ascending, by default nulls are last
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* If the order is descending, by default nulls are first
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*
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* @added in QGIS 2.14
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*/
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QgsFeatureRequest& addOrderBy( const QString &expression, bool ascending = true );
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/**
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* Adds a new OrderByClause, appending it as the least important one.
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*
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* @param expression The expression to use for ordering
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* @param ascending If the order should be ascending (1,2,3) or descending (3,2,1)
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* @param nullsfirst If true, NULLS are at the beginning, if false, NULLS are at the end
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*
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* @added in QGIS 2.14
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*/
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QgsFeatureRequest& addOrderBy( const QString &expression, bool ascending, bool nullsfirst );
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/**
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* Return a list of order by clauses specified for this feature request.
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*/
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QList<QgsFeatureRequest::OrderByClause> orderBys() const;
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/**
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* Set a list of order by clauses.
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*/
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void setOrderBys(const QList<QgsFeatureRequest::OrderByClause>& orderBys );
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/** Set the maximum number of features to request.
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* @param limit maximum number of features, or -1 to request all features.
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* @see limit()
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* @note added in QGIS 2.14
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*/
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QgsFeatureRequest& setLimit( long limit );
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/** Returns the maximum number of features to request, or -1 if no limit set.
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* @see setLimit
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* @note added in QGIS 2.14
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*/
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long limit() const;
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//! Set flags that affect how features will be fetched
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QgsFeatureRequest& setFlags( const Flags& flags );
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const Flags& flags() const;
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//! Set a subset of attributes that will be fetched. Empty list means that all attributes are used.
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//! To disable fetching attributes, reset the FetchAttributes flag (which is set by default)
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QgsFeatureRequest& setSubsetOfAttributes( const QgsAttributeList& attrs );
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const QgsAttributeList& subsetOfAttributes() const;
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//! Set a subset of attributes by names that will be fetched
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QgsFeatureRequest& setSubsetOfAttributes( const QStringList& attrNames, const QgsFields& fields );
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//! Set a simplification method for geometries that will be fetched
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//! @note added in 2.2
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QgsFeatureRequest& setSimplifyMethod( const QgsSimplifyMethod& simplifyMethod );
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//! Get simplification method for geometries that will be fetched
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//! @note added in 2.2
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const QgsSimplifyMethod& simplifyMethod() const;
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/**
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* Check if a feature is accepted by this requests filter
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*
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* @param feature The feature which will be tested
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*
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* @return true, if the filter accepts the feature
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*
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* @note added in 2.1
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*/
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bool acceptFeature( const QgsFeature& feature );
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};
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/** Base class that can be used for any class that is capable of returning features
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* @note added in 2.4
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*/
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class QgsAbstractFeatureSource
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{
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%TypeHeaderCode
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#include <qgsfeaturerequest.h>
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%End
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public:
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virtual ~QgsAbstractFeatureSource();
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virtual QgsFeatureIterator getFeatures( const QgsFeatureRequest& request ) = 0;
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protected:
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void iteratorOpened( QgsAbstractFeatureIterator* it );
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void iteratorClosed( QgsAbstractFeatureIterator* it );
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};
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