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80 lines
3.2 KiB
Plaintext
80 lines
3.2 KiB
Plaintext
/** \ingroup core
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* Utility class that construct a planar graph from the input vector
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* layers and provides shortest path search for tracing of existing
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* features.
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*
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* @note added in QGIS 2.14
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*/
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class QgsTracer : QObject
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{
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%TypeHeaderCode
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#include <qgstracer.h>
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%End
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public:
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QgsTracer();
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~QgsTracer();
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//! Get layers used for tracing
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QList<QgsVectorLayer*> layers() const;
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//! Set layers used for tracing
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void setLayers( const QList<QgsVectorLayer*> &layers );
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//! Get CRS used for tracing
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QgsCoordinateReferenceSystem destinationCrs() const;
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//! Set CRS used for tracing
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void setDestinationCrs( const QgsCoordinateReferenceSystem &crs );
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//! Get extent to which graph's features will be limited (empty extent means no limit)
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QgsRectangle extent() const;
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//! Set extent to which graph's features will be limited (empty extent means no limit)
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void setExtent( const QgsRectangle &extent );
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//! Get maximum possible number of features in graph. If the number is exceeded, graph is not created.
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int maxFeatureCount() const;
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//! Get maximum possible number of features in graph. If the number is exceeded, graph is not created.
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void setMaxFeatureCount( int count );
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//! Build the internal data structures. This may take some time
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//! depending on how big the input layers are. It is not necessary
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//! to call this method explicitly - it will be called by findShortestPath()
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//! if necessary.
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bool init();
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//! Whether the internal data structures have been initialized
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bool isInitialized() const;
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//! Whether there was an error during graph creation due to noding exception,
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//! indicating some input data topology problems
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//! @note added in QGIS 2.16
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bool hasTopologyProblem() const;
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//! Possible errors that may happen when calling findShortestPath()
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enum PathError
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{
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ErrNone, //!< No error
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ErrTooManyFeatures, //!< Max feature count threshold was reached while reading features
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ErrPoint1, //!< Start point cannot be joined to the graph
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ErrPoint2, //!< End point cannot be joined to the graph
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ErrNoPath, //!< Points are not connected in the graph
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};
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//! Given two points, find the shortest path and return points on the way.
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//! The optional "error" argument may receive error code (PathError enum) if it is not null
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//! @return array of points - trace of linestrings of other features (empty array one error)
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QVector<QgsPoint> findShortestPath( const QgsPoint &p1, const QgsPoint &p2, QgsTracer::PathError *error /Out/ = nullptr );
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//! Find out whether the point is snapped to a vertex or edge (i.e. it can be used for tracing start/stop)
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bool isPointSnapped( const QgsPoint &pt );
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protected:
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//! Allows derived classes to setup the settings just before the tracer is initialized.
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//! This allows the configuration to be set in a lazy way only when it is really necessary.
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//! Default implementation does nothing.
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virtual void configure();
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protected slots:
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//! Destroy the existing graph structure if any (de-initialize)
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void invalidateGraph();
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};
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