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0c5063fee6
Automatically analyses to determine whether the string refers to a column or is an expression.
119 lines
3.9 KiB
Plaintext
119 lines
3.9 KiB
Plaintext
/** \ingroup core
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* \class QgsDataDefined
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* A container class for data source field mapping or expression.
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*/
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class QgsDataDefined
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{
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%TypeHeaderCode
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#include <qgsdatadefined.h>
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%End
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public:
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/**
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* Construct a new data defined object
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*
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* @param active Whether the current data defined is active
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* @param useexpr Whether to use expression instead of field
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* @param expr Expression string
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* @param field Field name string
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*/
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QgsDataDefined( bool active = false,
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bool useexpr = false,
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const QString& expr = QString(),
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const QString& field = QString() );
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/**
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* Construct a new data defined object, analysing the expression to determine
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* if it's a simple field reference or an expression.
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* @param expression can be null
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*/
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explicit QgsDataDefined( const QgsExpression * expression );
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/**
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* Construct a new data defined object, analysing the string to determine
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* if it's a simple field reference or an expression
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* @param string field reference or an expression, can be empty
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* @note added in QGIS 2.9
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*/
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explicit QgsDataDefined( const QString& string );
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/**
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* Copy constructor. Note that copies of data defined objects with expressions
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* will not be prepared.
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*/
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QgsDataDefined( const QgsDataDefined& other );
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virtual ~QgsDataDefined();
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/**Returns whether the data defined container is set to all the default
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* values, ie, disabled, with empty expression and no assigned field
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* @returns true if data defined container is set to default values
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* @note added in QGIS 2.7
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*/
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bool hasDefaultValues() const;
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bool isActive() const;
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void setActive( bool active );
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bool useExpression() const;
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void setUseExpression( bool use );
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QString expressionString() const;
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void setExpressionString( const QString& expr );
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// @note not available in python bindings
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//QMap<QString, QVariant> expressionParams() const;
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// @note not available in python bindings
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//void setExpressionParams( QMap<QString, QVariant> params );
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void insertExpressionParam( QString key, QVariant param );
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/** Prepares the expression using a vector layer
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* @param layer vector layer
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* @returns true if expression was successfully prepared
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*/
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bool prepareExpression( QgsVectorLayer* layer );
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/** Prepares the expression using a fields collection
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* @param fields
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* @returns true if expression was successfully prepared
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* @note added in QGIS 2.9
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*/
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bool prepareExpression( const QgsFields &fields );
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/** Returns whether the data defined object's expression is prepared
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* @returns true if expression is prepared
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*/
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bool expressionIsPrepared() const;
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QgsExpression* expression();
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QStringList referencedColumns( QgsVectorLayer* layer );
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QString field() const;
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void setField( const QString& field );
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// @note not available in python bindings
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//QMap< QString, QString > toMap();
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/**Returns a DOM element containing the properties of the data defined container.
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* @param document DOM document
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* @param elementName name for DOM element
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* @returns DOM element corresponding to data defined container
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* @note added in QGIS 2.7
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* @see setFromXmlElement
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*/
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QDomElement toXmlElement( QDomDocument &document, const QString &elementName ) const;
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/**Sets the properties of the data defined container from an XML element. Calling
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* this will overwrite all the current properties of the container.
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* @param element DOM element
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* @returns true if properties were successfully read from element
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* @note added in QGIS 2.7
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* @see toXmlElement
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*/
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bool setFromXmlElement( const QDomElement& element );
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bool operator==( const QgsDataDefined &other ) const;
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bool operator!=( const QgsDataDefined &other ) const;
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};
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