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219 lines
8.1 KiB
Plaintext
219 lines
8.1 KiB
Plaintext
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class QgsDistanceArea
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{
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%TypeHeaderCode
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#include <qgsdistancearea.h>
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%End
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public:
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//! Constructor
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QgsDistanceArea();
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//! Destructor
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~QgsDistanceArea();
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//! Copy constructor
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QgsDistanceArea( const QgsDistanceArea &origDA );
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/** Sets whether coordinates must be projected to ellipsoid before measuring
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* @note for calculations to use the ellipsoid, both the ellipsoid mode must be true
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* and an ellipse must be set
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* @see setEllipsoid()
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* @see willUseEllipsoid()
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*/
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void setEllipsoidalMode( bool flag );
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/** Returns whether ellipsoidal calculations are enabled
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* @see willUseEllipsoid()
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* @see setEllipsoidalMode()
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*/
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bool ellipsoidalEnabled() const;
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/** Returns whether calculations will use the ellipsoid. Calculations will only use the
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* ellipsoid if ellipsoidalEnabled() is true and an ellipsoid has been set.
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* @note added in QGIS 2.14
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* @see ellipsoidalEnabled()
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* @see ellipsoid()
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*/
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bool willUseEllipsoid() const;
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//! sets source spatial reference system (by QGIS CRS)
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void setSourceCrs( long srsid );
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/**
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* Sets source spatial reference system (by QGIS CRS)
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* @note: missing in Python bindings in QGIS < 2.2
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*/
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void setSourceCrs( const QgsCoordinateReferenceSystem& srcCRS );
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//! sets source spatial reference system by authid
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void setSourceAuthId( const QString& authid );
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//! returns source spatial reference system
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//! @deprecated use sourceCrsId() instead
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long sourceCrs() const /Deprecated/;
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/** Returns the QgsCoordinateReferenceSystem::srsid() for the CRS used during calculations.
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* @see setSourceCrs()
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* @note added in QGIS 2.14
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*/
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long sourceCrsId() const;
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//! What sort of coordinate system is being used?
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bool geographic() const;
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/** Sets ellipsoid by its acronym. Calculations will only use the ellipsoid if
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* both the ellipsoid has been set and ellipsoidalEnabled() is true.
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* @returns true if ellipsoid was successfully set
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* @see ellipsoid()
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* @see setEllipsoidalMode()
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* @see willUseEllipsoid()
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*/
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bool setEllipsoid( const QString& ellipsoid );
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/** Sets ellipsoid by supplied radii. Calculations will only use the ellipsoid if
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* both the ellipsoid has been set and ellipsoidalEnabled() is true.
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* @returns true if ellipsoid was successfully set
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* @see ellipsoid()
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* @see setEllipsoidalMode()
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* @see willUseEllipsoid()
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*/
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// Inverse flattening is calculated with invf = a/(a-b)
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bool setEllipsoid( double semiMajor, double semiMinor );
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/** Returns ellipsoid's acronym. Calculations will only use the
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* ellipsoid if ellipsoidalEnabled() is true and an ellipsoid has been set.
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* @see setEllipsoid()
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* @see ellipsoidalEnabled()
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* @see willUseEllipsoid()
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*/
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QString ellipsoid() const;
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//! returns ellipsoid's semi major axis
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double ellipsoidSemiMajor() const;
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//! returns ellipsoid's semi minor axis
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double ellipsoidSemiMinor() const;
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//! returns ellipsoid's inverse flattening
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double ellipsoidInverseFlattening() const;
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/** General measurement (line distance or polygon area)
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* @deprecated use measureArea() or measureLength() methods instead, as this method
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* is unpredictable for geometry collections
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*/
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double measure( const QgsGeometry* geometry ) const /Deprecated/;
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/** Measures the area of a geometry.
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* @param geometry geometry to measure
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* @returns area of geometry. For geometry collections, non surface geometries will be ignored
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* @note added in QGIS 2.12
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* @see measureLength()
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* @see measurePerimeter()
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*/
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double measureArea( const QgsGeometry* geometry ) const;
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/** Measures the length of a geometry.
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* @param geometry geometry to measure
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* @returns length of geometry. For geometry collections, non curve geometries will be ignored. The units for the
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* returned distance can be retrieved by calling lengthUnits().
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* @note added in QGIS 2.12
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* @see lengthUnits()
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* @see measureArea()
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* @see measurePerimeter()
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*/
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double measureLength( const QgsGeometry* geometry ) const;
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/** Measures the perimeter of a polygon geometry.
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* @param geometry geometry to measure
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* @returns perimeter of geometry. For geometry collections, any non-polygon geometries will be ignored. The units for the
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* returned perimeter can be retrieved by calling lengthUnits().
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* @note added in QGIS 2.12
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* @see lengthUnits()
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* @see measureArea()
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* @see measurePerimeter()
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*/
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double measurePerimeter( const QgsGeometry *geometry ) const;
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/** Measures the length of a line with multiple segments.
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* @param points list of points in line
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* @returns length of line. The units for the returned length can be retrieved by calling lengthUnits().
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* @see lengthUnits()
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*/
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double measureLine( const QList<QgsPoint>& points ) const;
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/** Measures length of a line with one segment.
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* @param p1 start of line
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* @param p2 end of line
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* @returns distance between points. The units for the returned distance can be retrieved by calling lengthUnits().
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* @see lengthUnits()
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*/
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double measureLine( const QgsPoint& p1, const QgsPoint& p2 ) const;
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/** Returns the units of distance for length calculations made by this object.
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* @note added in QGIS 2.14
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*/
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QGis::UnitType lengthUnits() const;
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//! measures polygon area
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double measurePolygon( const QList<QgsPoint>& points ) const;
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//! compute bearing - in radians
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double bearing( const QgsPoint& p1, const QgsPoint& p2 ) const;
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static QString textUnit( double value, int decimals, QGis::UnitType u, bool isArea, bool keepBaseUnit = false );
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//! Helper for conversion between physical units
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void convertMeasurement( double &measure /In,Out/, QGis::UnitType &measureUnits /In,Out/, QGis::UnitType displayUnits, bool isArea ) const;
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/** Takes a length measurement calculated by this QgsDistanceArea object and converts it to a
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* different distance unit.
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* @param length length value calculated by this class to convert. It is assumed that the length
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* was calculated by this class, ie that its unit of length is equal lengthUnits().
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* @param toUnits distance unit to convert measurement to
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* @returns converted distance
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*/
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double convertLengthMeasurement( double length, QGis::UnitType toUnits ) const;
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protected:
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//! measures line distance, line points are extracted from WKB
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// @note available in python bindings
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// const unsigned char* measureLine( const unsigned char* feature, double* area, bool hasZptr = false ) const;
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//! measures polygon area and perimeter, vertices are extracted from WKB
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// @note not available in python bindings
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// const unsigned char* measurePolygon( const unsigned char* feature, double* area, double* perimeter, bool hasZptr = false ) const;
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/**
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calculates distance from two points on ellipsoid
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based on inverse Vincenty's formulae
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Points p1 and p2 are expected to be in degrees and in currently used ellipsoid
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@note if course1 is not NULL, bearing (in radians) from first point is calculated
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(the same for course2)
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@return distance in meters
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*/
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double computeDistanceBearing( const QgsPoint& p1, const QgsPoint& p2,
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double* course1 = NULL, double* course2 = NULL ) const;
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//! uses flat / planimetric / Euclidean distance
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double computeDistanceFlat( const QgsPoint& p1, const QgsPoint& p2 ) const;
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//! calculate distance with given coordinates (does not do a transform anymore)
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double computeDistance( const QList<QgsPoint>& points ) const;
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/**
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calculates area of polygon on ellipsoid
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algorithm has been taken from GRASS: gis/area_poly1.c
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*/
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double computePolygonArea( const QList<QgsPoint>& points ) const;
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double computePolygonFlatArea( const QList<QgsPoint>& points ) const;
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/**
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precalculates some values
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(must be called always when changing ellipsoid)
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*/
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void computeAreaInit();
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};
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