QGIS API Documentation 3.39.0Master (3783037d301)

This class offers geometry processing methods. More...
#include <qgsinternalgeometryengine.h>
Public Member Functions  
QgsInternalGeometryEngine (const QgsGeometry &geometry)  
The caller is responsible that the geometry is available and unchanged for the whole lifetime of this object.  
QgsGeometry  applyDashPattern (const QVector< double > &pattern, Qgis::DashPatternLineEndingRule startRule=Qgis::DashPatternLineEndingRule::NoRule, Qgis::DashPatternLineEndingRule endRule=Qgis::DashPatternLineEndingRule::NoRule, Qgis::DashPatternSizeAdjustment adjustment=Qgis::DashPatternSizeAdjustment::ScaleBothDashAndGap, double patternOffset=0) const 
Applies a dash pattern to a geometry, returning a MultiLineString geometry which is the input geometry stroked along each line/ring with the specified pattern.  
QgsGeometry  convertToCurves (double distanceTolerance, double angleTolerance) const 
Attempts to convert a noncurved geometry into a curved geometry type (e.g.  
QgsGeometry  densifyByCount (int extraNodesPerSegment) const 
Densifies the geometry by adding the specified number of extra nodes within each segment of the geometry.  
QgsGeometry  densifyByDistance (double distance) const 
Densifies the geometry by adding regularly placed extra nodes inside each segment so that the maximum distance between any two nodes does not exceed the specified distance.  
QgsGeometry  extrude (double x, double y) const 
Will extrude a line or (segmentized) curve by a given offset and return a polygon representation of it.  
bool  isAxisParallelRectangle (double maximumDeviation, bool simpleRectanglesOnly=false) const 
Returns true if the geometry is a polygon that is almost an axisparallel rectangle.  
QString  lastError () const 
Returns an error string referring to the last error encountered.  
QgsGeometry  orientedMinimumBoundingBox (double &area, double &angle, double &width, double &height) const 
Returns the oriented minimum bounding box for the geometry, which is the smallest (by area) rotated rectangle which fully encompasses the geometry.  
QgsGeometry  orthogonalize (double tolerance=1.0E8, int maxIterations=1000, double angleThreshold=15.0) const 
Attempts to orthogonalize a line or polygon geometry by shifting vertices to make the geometries angles either right angles or flat lines.  
QgsGeometry  poleOfInaccessibility (double precision, double *distanceFromBoundary=nullptr) const 
Calculates the approximate pole of inaccessibility for a surface, which is the most distant internal point from the boundary of the surface.  
QVector< QgsPointXY >  randomPointsInPolygon (int count, const std::function< bool(const QgsPointXY &) > &acceptPoint, unsigned long seed=0, QgsFeedback *feedback=nullptr, int maxTriesPerPoint=0) 
Returns a list of count random points generated inside a polygon geometry (if acceptPoint is specified, and restrictive, the number of points returned may be less than count).  
QgsGeometry  roundWaves (double wavelength, double amplitude, bool strictWavelength=false) const 
Constructs rounded (sinelike) waves along the boundary of the geometry, with the specified wavelength and amplitude.  
QgsGeometry  roundWavesRandomized (double minimumWavelength, double maximumWavelength, double minimumAmplitude, double maximumAmplitude, unsigned long seed=0) const 
Constructs randomized rounded (sinelike) waves along the boundary of the geometry, with the specified wavelength and amplitude ranges.  
QgsGeometry  squareWaves (double wavelength, double amplitude, bool strictWavelength=false) const 
Constructs square waves along the boundary of the geometry, with the specified wavelength and amplitude.  
QgsGeometry  squareWavesRandomized (double minimumWavelength, double maximumWavelength, double minimumAmplitude, double maximumAmplitude, unsigned long seed=0) const 
Constructs randomized square waves along the boundary of the geometry, with the specified wavelength and amplitude ranges.  
QgsGeometry  taperedBuffer (double startWidth, double endWidth, int segments) const 
Calculates a tapered width buffer for a (multi)curve geometry.  
QgsGeometry  triangularWaves (double wavelength, double amplitude, bool strictWavelength=false) const 
Constructs triangular waves along the boundary of the geometry, with the specified wavelength and amplitude.  
QgsGeometry  triangularWavesRandomized (double minimumWavelength, double maximumWavelength, double minimumAmplitude, double maximumAmplitude, unsigned long seed=0) const 
Constructs randomized triangular waves along the boundary of the geometry, with the specified wavelength and amplitude ranges.  
QgsGeometry  variableWidthBuffer (int segments, const std::function< std::unique_ptr< double[] >(const QgsLineString *line) > &widthFunction) const 
Calculates a variable width buffer for a (multi)curve geometry.  
QgsGeometry  variableWidthBufferByM (int segments) const 
Calculates a variable width buffer using the mvalues from a (multi)line geometry.  
This class offers geometry processing methods.
The methods are available via QgsGeometry::[geometryfunction] and therefore this does not need to be accessed directly.
Definition at line 41 of file qgsinternalgeometryengine.h.

explicit 
The caller is responsible that the geometry is available and unchanged for the whole lifetime of this object.
geometry 
Definition at line 40 of file qgsinternalgeometryengine.cpp.
QgsGeometry QgsInternalGeometryEngine::applyDashPattern  (  const QVector< double > &  pattern, 
Qgis::DashPatternLineEndingRule  startRule = Qgis::DashPatternLineEndingRule::NoRule , 

Qgis::DashPatternLineEndingRule  endRule = Qgis::DashPatternLineEndingRule::NoRule , 

Qgis::DashPatternSizeAdjustment  adjustment = Qgis::DashPatternSizeAdjustment::ScaleBothDashAndGap , 

double  patternOffset = 0 

)  const 
Applies a dash pattern to a geometry, returning a MultiLineString geometry which is the input geometry stroked along each line/ring with the specified pattern.
The startRule and endRule options can be set to control how the dash pattern is adjusted at line endings. If a startRule or endRule is set, the adjustment option defines whether both dash and gaps, or only dash or gap sizes are adjusted to apply the rules.
The patternOffset option specifies how far along the pattern the result should start at. The offset is applied AFTER any start/end rules are applied.
Definition at line 3131 of file qgsinternalgeometryengine.cpp.
QgsGeometry QgsInternalGeometryEngine::convertToCurves  (  double  distanceTolerance, 
double  angleTolerance  
)  const 
Attempts to convert a noncurved geometry into a curved geometry type (e.g.
LineString to CompoundCurve, Polygon to CurvePolygon).
The distanceTolerance specifies the maximum deviation allowed between the original location of vertices and where they would fall on the candidate curved geometry.
This method only consider a segments as suitable for replacing with an arc if the points are all regularly spaced on the candidate arc. The pointSpacingAngleTolerance parameter specifies the maximum angular deviation (in radians) allowed when testing for regular point spacing.
Definition at line 1763 of file qgsinternalgeometryengine.cpp.
QgsGeometry QgsInternalGeometryEngine::densifyByCount  (  int  extraNodesPerSegment  )  const 
Densifies the geometry by adding the specified number of extra nodes within each segment of the geometry.
If the geometry has z or m values present then these will be linearly interpolated at the added nodes. Curved geometry types are automatically segmentized by this routine.
Definition at line 800 of file qgsinternalgeometryengine.cpp.
QgsGeometry QgsInternalGeometryEngine::densifyByDistance  (  double  distance  )  const 
Densifies the geometry by adding regularly placed extra nodes inside each segment so that the maximum distance between any two nodes does not exceed the specified distance.
E.g. specifying a distance 3 would cause the segment [0 0] > [10 0] to be converted to [0 0] > [2.5 0] > [5 0] > [7.5 0] > [10 0], since 3 extra nodes are required on the segment and spacing these at 2.5 increments allows them to be evenly spaced over the segment. If the geometry has z or m values present then these will be linearly interpolated at the added nodes. Curved geometry types are automatically segmentized by this routine.
Definition at line 836 of file qgsinternalgeometryengine.cpp.
QgsGeometry QgsInternalGeometryEngine::extrude  (  double  x, 
double  y  
)  const 
Will extrude a line or (segmentized) curve by a given offset and return a polygon representation of it.
x  offset in x direction 
y  offset in y direction 
Definition at line 190 of file qgsinternalgeometryengine.cpp.
bool QgsInternalGeometryEngine::isAxisParallelRectangle  (  double  maximumDeviation, 
bool  simpleRectanglesOnly = false 

)  const 
Returns true
if the geometry is a polygon that is almost an axisparallel rectangle.
The maximumDeviation argument specifes the maximum angle (in degrees) that the polygon edges are allowed to deviate from axis parallel lines.
By default the check will permit polygons with more than 4 edges, so long as the overall shape of the polygon is an axisparallel rectangle (i.e. it is tolerant to rectangles with additional vertices added along the rectangle sides). If simpleRectanglesOnly is set to true
then the method will only return true
if the geometry is a simple rectangle consisting of 4 edges.
Definition at line 162 of file qgsinternalgeometryengine.cpp.
QString QgsInternalGeometryEngine::lastError  (  )  const 
Returns an error string referring to the last error encountered.
Definition at line 46 of file qgsinternalgeometryengine.cpp.
QgsGeometry QgsInternalGeometryEngine::orientedMinimumBoundingBox  (  double &  area, 
double &  angle,  
double &  width,  
double &  height  
)  const 
Returns the oriented minimum bounding box for the geometry, which is the smallest (by area) rotated rectangle which fully encompasses the geometry.
The area, angle of the long axis (clockwise in degrees from North), width and height of the rotated bounding box will also be returned.
If an error was encountered while creating the result, more information can be retrieved by calling lastError().
Definition at line 1799 of file qgsinternalgeometryengine.cpp.
QgsGeometry QgsInternalGeometryEngine::orthogonalize  (  double  tolerance = 1.0E8 , 
int  maxIterations = 1000 , 

double  angleThreshold = 15.0 

)  const 
Attempts to orthogonalize a line or polygon geometry by shifting vertices to make the geometries angles either right angles or flat lines.
This is an iterative algorithm which will loop until either the vertices are within a specified tolerance of right angles or a set number of maximum iterations is reached. The angle threshold parameter specifies how close to a right angle or straight line an angle must be before it is attempted to be straightened.
Definition at line 642 of file qgsinternalgeometryengine.cpp.
QgsGeometry QgsInternalGeometryEngine::poleOfInaccessibility  (  double  precision, 
double *  distanceFromBoundary = nullptr 

)  const 
Calculates the approximate pole of inaccessibility for a surface, which is the most distant internal point from the boundary of the surface.
This function uses the 'polylabel' algorithm (Vladimir Agafonkin, 2016), which is an iterative approach guaranteed to find the true pole of inaccessibility within a specified tolerance. More precise tolerances require more iterations and will take longer to calculate. Optionally, the distance to the polygon boundary from the pole can be stored.
Definition at line 381 of file qgsinternalgeometryengine.cpp.
QVector< QgsPointXY > QgsInternalGeometryEngine::randomPointsInPolygon  (  int  count, 
const std::function< bool(const QgsPointXY &) > &  acceptPoint,  
unsigned long  seed = 0 , 

QgsFeedback *  feedback = nullptr , 

int  maxTriesPerPoint = 0 

) 
Returns a list of count random points generated inside a polygon geometry (if acceptPoint is specified, and restrictive, the number of points returned may be less than count).
Optionally, a specific random seed can be used when generating points. If seed is 0, then a completely random sequence of points will be generated.
The acceptPoint function is used to filter result candidates. If the function returns false
, then the point will not be accepted and another candidate generated.
The optional feedback argument can be used to provide cancellation support during the point generation.
When acceptPoint is specified, maxTriesPerPoint defines how many attempts to perform before giving up generating a point.
Definition at line 1491 of file qgsinternalgeometryengine.cpp.
QgsGeometry QgsInternalGeometryEngine::roundWaves  (  double  wavelength, 
double  amplitude,  
bool  strictWavelength = false 

)  const 
Constructs rounded (sinelike) waves along the boundary of the geometry, with the specified wavelength and amplitude.
By default the wavelength argument is treated as a "maximum wavelength", where the actual wavelength will be dynamically adjusted so that an exact number of waves are created along the boundaries of the geometry. If strictWavelength is set to true
then the wavelength will be used exactly and an incomplete pattern may be used for the final waveform.
Definition at line 2776 of file qgsinternalgeometryengine.cpp.
QgsGeometry QgsInternalGeometryEngine::roundWavesRandomized  (  double  minimumWavelength, 
double  maximumWavelength,  
double  minimumAmplitude,  
double  maximumAmplitude,  
unsigned long  seed = 0 

)  const 
Constructs randomized rounded (sinelike) waves along the boundary of the geometry, with the specified wavelength and amplitude ranges.
The minimumWavelength and maximumWavelength arguments set the range for the randomized wavelength. This is evaluated for each individual waveform created along the geometry boundaries, so the resultant geometry will consist of many different wavelengths.
Similarly, the minimumAmplitude and maximumAmplitude arguments define the range for the randomized amplitude of the square components. Randomized amplitude values will be calculated individually for waves placed on each either side of the input geometry boundaries.
Optionally, a specific random seed can be used when generating points. If seed is 0, then a completely random sequence of points will be generated.
Definition at line 2815 of file qgsinternalgeometryengine.cpp.
QgsGeometry QgsInternalGeometryEngine::squareWaves  (  double  wavelength, 
double  amplitude,  
bool  strictWavelength = false 

)  const 
Constructs square waves along the boundary of the geometry, with the specified wavelength and amplitude.
By default the wavelength argument is treated as a "maximum wavelength", where the actual wavelength will be dynamically adjusted so that an exact number of square waves are created along the boundaries of the geometry. If strictWavelength is set to true
then the wavelength will be used exactly and an incomplete pattern may be used for the final waveform.
Definition at line 2360 of file qgsinternalgeometryengine.cpp.
QgsGeometry QgsInternalGeometryEngine::squareWavesRandomized  (  double  minimumWavelength, 
double  maximumWavelength,  
double  minimumAmplitude,  
double  maximumAmplitude,  
unsigned long  seed = 0 

)  const 
Constructs randomized square waves along the boundary of the geometry, with the specified wavelength and amplitude ranges.
The minimumWavelength and maximumWavelength arguments set the range for the randomized wavelength. This is evaluated for each individual square waveform created along the geometry boundaries, so the resultant geometry will consist of many different wavelengths.
Similarly, the minimumAmplitude and maximumAmplitude arguments define the range for the randomized amplitude of the square components. Randomized amplitude values will be calculated individiually for squares placed on each either side of the input geometry boundaries.
Optionally, a specific random seed can be used when generating points. If seed is 0, then a completely random sequence of points will be generated.
Definition at line 2399 of file qgsinternalgeometryengine.cpp.
QgsGeometry QgsInternalGeometryEngine::taperedBuffer  (  double  startWidth, 
double  endWidth,  
int  segments  
)  const 
Calculates a tapered width buffer for a (multi)curve geometry.
The buffer begins at a width of startWidth at the start of each curve, and ends at a width of endWidth. Note that unlike QgsGeometry::buffer() methods, startWidth and endWidth are the diameter of the buffer at these points, not the radius.
The segments argument specifies the number of segments to approximate quartercircle curves in the buffer.
Non (multi)curve input geometries will return a null output geometry.
Definition at line 1178 of file qgsinternalgeometryengine.cpp.
QgsGeometry QgsInternalGeometryEngine::triangularWaves  (  double  wavelength, 
double  amplitude,  
bool  strictWavelength = false 

)  const 
Constructs triangular waves along the boundary of the geometry, with the specified wavelength and amplitude.
By default the wavelength argument is treated as a "maximum wavelength", where the actual wavelength will be dynamically adjusted so that an exact number of triangular waves are created along the boundaries of the geometry. If strictWavelength is set to true
then the wavelength will be used exactly and an incomplete pattern may be used for the final waveform.
Definition at line 2064 of file qgsinternalgeometryengine.cpp.
QgsGeometry QgsInternalGeometryEngine::triangularWavesRandomized  (  double  minimumWavelength, 
double  maximumWavelength,  
double  minimumAmplitude,  
double  maximumAmplitude,  
unsigned long  seed = 0 

)  const 
Constructs randomized triangular waves along the boundary of the geometry, with the specified wavelength and amplitude ranges.
The minimumWavelength and maximumWavelength arguments set the range for the randomized wavelength. This is evaluated for each individual triangular waveform created along the geometry boundaries, so the resultant geometry will consist of many different wavelengths.
Similarly, the minimumAmplitude and maximumAmplitude arguments define the range for the randomized amplitude of the triangular components. Randomized amplitude values will be calculated individiually for triangles placed on each either side of the input geometry boundaries.
Optionally, a specific random seed can be used when generating points. If seed is 0, then a completely random sequence of points will be generated.
Definition at line 2103 of file qgsinternalgeometryengine.cpp.
QgsGeometry QgsInternalGeometryEngine::variableWidthBuffer  (  int  segments, 
const std::function< std::unique_ptr< double[] >(const QgsLineString *line) > &  widthFunction  
)  const 
Calculates a variable width buffer for a (multi)curve geometry.
The width of the buffer at each node in the input linestrings is calculated by calling the specified widthFunction, which must return an array of the buffer widths for every node in the line.
The segments argument specifies the number of segments to approximate quartercircle curves in the buffer.
Non (multi)curve input geometries will return a null output geometry.
Definition at line 1046 of file qgsinternalgeometryengine.cpp.
QgsGeometry QgsInternalGeometryEngine::variableWidthBufferByM  (  int  segments  )  const 
Calculates a variable width buffer using the mvalues from a (multi)line geometry.
The segments argument specifies the number of segments to approximate quartercircle curves in the buffer.
Non (multi)line input geometries will return a null output geometry.
Definition at line 1211 of file qgsinternalgeometryengine.cpp.