QGIS API Documentation 3.40.0-Bratislava (b56115d8743)
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Does vector analysis using the geos library and handles import, export, exception handling*. More...
#include <qgsgeos.h>
Public Member Functions | |
QgsGeos (const QgsAbstractGeometry *geometry, double precision=0, Qgis::GeosCreationFlags flags=Qgis::GeosCreationFlags()) | |
GEOS geometry engine constructor. | |
double | area (QString *errorMsg=nullptr) const override |
QgsAbstractGeometry * | buffer (double distance, int segments, Qgis::EndCapStyle endCapStyle, Qgis::JoinStyle joinStyle, double miterLimit, QString *errorMsg=nullptr) const override |
Buffers a geometry. | |
QgsAbstractGeometry * | buffer (double distance, int segments, QString *errorMsg=nullptr) const override |
QgsPoint * | centroid (QString *errorMsg=nullptr) const override |
Calculates the centroid of this. | |
std::unique_ptr< QgsAbstractGeometry > | clip (const QgsRectangle &rectangle, QString *errorMsg=nullptr) const |
Performs a fast, non-robust intersection between the geometry and a rectangle. | |
QgsGeometry | closestPoint (const QgsGeometry &other, QString *errorMsg=nullptr) const |
Returns the closest point on the geometry to the other geometry. | |
QgsAbstractGeometry * | combine (const QgsAbstractGeometry *geom, QString *errorMsg=nullptr, const QgsGeometryParameters ¶meters=QgsGeometryParameters()) const override |
Calculate the combination of this and geom. | |
QgsAbstractGeometry * | combine (const QVector< QgsAbstractGeometry * > &geomList, QString *errorMsg, const QgsGeometryParameters ¶meters=QgsGeometryParameters()) const override |
Calculate the combination of this and geometries. | |
QgsAbstractGeometry * | combine (const QVector< QgsGeometry > &, QString *errorMsg=nullptr, const QgsGeometryParameters ¶meters=QgsGeometryParameters()) const override |
Calculate the combination of this and geometries. | |
QgsAbstractGeometry * | concaveHull (double targetPercent, bool allowHoles=false, QString *errorMsg=nullptr) const |
Returns a possibly concave geometry that encloses the input geometry. | |
std::unique_ptr< QgsAbstractGeometry > | constrainedDelaunayTriangulation (QString *errorMsg=nullptr) const |
Returns a constrained Delaunay triangulation for the vertices of the geometry. | |
bool | contains (const QgsAbstractGeometry *geom, QString *errorMsg=nullptr) const override |
Checks if geom contains this. | |
bool | contains (double x, double y, QString *errorMsg=nullptr) const |
Returns true if the geometry contains the point at (x, y). | |
QgsAbstractGeometry * | convexHull (QString *errorMsg=nullptr) const override |
Calculate the convex hull of this. | |
bool | crosses (const QgsAbstractGeometry *geom, QString *errorMsg=nullptr) const override |
Checks if geom crosses this. | |
QgsGeometry | delaunayTriangulation (double tolerance=0.0, bool edgesOnly=false, QString *errorMsg=nullptr) const |
Returns the Delaunay triangulation for the vertices of the geometry. | |
QgsAbstractGeometry * | difference (const QgsAbstractGeometry *geom, QString *errorMsg=nullptr, const QgsGeometryParameters ¶meters=QgsGeometryParameters()) const override |
Calculate the difference of this and geom. | |
bool | disjoint (const QgsAbstractGeometry *geom, QString *errorMsg=nullptr) const override |
Checks if geom is disjoint from this. | |
double | distance (const QgsAbstractGeometry *geom, QString *errorMsg=nullptr) const override |
Calculates the distance between this and geom. | |
double | distance (double x, double y, QString *errorMsg=nullptr) const |
Returns the minimum distance from the geometry to the point at (x, y). | |
bool | distanceWithin (const QgsAbstractGeometry *geom, double maxdistance, QString *errorMsg=nullptr) const override |
Checks if geom is within maxdistance distance from this geometry. | |
QgsAbstractGeometry * | envelope (QString *errorMsg=nullptr) const override |
double | frechetDistance (const QgsAbstractGeometry *geom, QString *errorMsg=nullptr) const |
Returns the Fréchet distance between this geometry and geom, restricted to discrete points for both geometries. | |
double | frechetDistanceDensify (const QgsAbstractGeometry *geom, double densifyFraction, QString *errorMsg=nullptr) const |
Returns the Fréchet distance between this geometry and geom, restricted to discrete points for both geometries. | |
void | geometryChanged () override |
Should be called whenever the geometry associated with the engine has been modified and the engine must be updated to suit. | |
double | hausdorffDistance (const QgsAbstractGeometry *geom, QString *errorMsg=nullptr) const |
Returns the Hausdorff distance between this geometry and geom. | |
double | hausdorffDistanceDensify (const QgsAbstractGeometry *geom, double densifyFraction, QString *errorMsg=nullptr) const |
Returns the Hausdorff distance between this geometry and geom. | |
QgsAbstractGeometry * | interpolate (double distance, QString *errorMsg=nullptr) const override |
QgsAbstractGeometry * | intersection (const QgsAbstractGeometry *geom, QString *errorMsg=nullptr, const QgsGeometryParameters ¶meters=QgsGeometryParameters()) const override |
Calculate the intersection of this and geom. | |
bool | intersects (const QgsAbstractGeometry *geom, QString *errorMsg=nullptr) const override |
Checks if geom intersects this. | |
bool | isEmpty (QString *errorMsg=nullptr) const override |
bool | isEqual (const QgsAbstractGeometry *geom, QString *errorMsg=nullptr) const override |
Checks if this is equal to geom. | |
bool | isSimple (QString *errorMsg=nullptr) const override |
Determines whether the geometry is simple (according to OGC definition). | |
bool | isValid (QString *errorMsg=nullptr, bool allowSelfTouchingHoles=false, QgsGeometry *errorLoc=nullptr) const override |
Returns true if the geometry is valid. | |
std::unique_ptr< QgsAbstractGeometry > | largestEmptyCircle (double tolerance, const QgsAbstractGeometry *boundary=nullptr, QString *errorMsg=nullptr) const |
Constructs the Largest Empty Circle for a set of obstacle geometries, up to a specified tolerance. | |
double | length (QString *errorMsg=nullptr) const override |
double | lineLocatePoint (const QgsPoint &point, QString *errorMsg=nullptr) const |
Returns a distance representing the location along this linestring of the closest point on this linestring geometry to the specified point. | |
double | lineLocatePoint (double x, double y, QString *errorMsg=nullptr) const |
Returns a distance representing the location along this linestring of the closest point on this linestring geometry to the point at (x, y). | |
std::unique_ptr< QgsAbstractGeometry > | makeValid (Qgis::MakeValidMethod method=Qgis::MakeValidMethod::Linework, bool keepCollapsed=false, QString *errorMsg=nullptr) const |
Repairs the geometry using GEOS make valid routine. | |
std::unique_ptr< QgsAbstractGeometry > | maximumInscribedCircle (double tolerance, QString *errorMsg=nullptr) const |
Returns the maximum inscribed circle. | |
QgsGeometry | mergeLines (QString *errorMsg=nullptr) const |
Merges any connected lines in a LineString/MultiLineString geometry and converts them to single line strings. | |
double | minimumClearance (QString *errorMsg=nullptr) const |
Computes the minimum clearance of a geometry. | |
std::unique_ptr< QgsAbstractGeometry > | minimumClearanceLine (QString *errorMsg=nullptr) const |
Returns a LineString whose endpoints define the minimum clearance of a geometry. | |
std::unique_ptr< QgsAbstractGeometry > | minimumWidth (QString *errorMsg=nullptr) const |
Returns a linestring geometry which represents the minimum diameter of the geometry. | |
std::unique_ptr< QgsAbstractGeometry > | node (QString *errorMsg=nullptr) const |
Returns a (Multi)LineString representing the fully noded version of a collection of linestrings. | |
QgsAbstractGeometry * | offsetCurve (double distance, int segments, Qgis::JoinStyle joinStyle, double miterLimit, QString *errorMsg=nullptr) const override |
Offsets a curve. | |
bool | overlaps (const QgsAbstractGeometry *geom, QString *errorMsg=nullptr) const override |
Checks if geom overlaps this. | |
QgsPoint * | pointOnSurface (QString *errorMsg=nullptr) const override |
Calculate a point that is guaranteed to be on the surface of this. | |
void | prepareGeometry () override |
Prepares the geometry, so that subsequent calls to spatial relation methods are much faster. | |
QString | relate (const QgsAbstractGeometry *geom, QString *errorMsg=nullptr) const override |
Returns the Dimensional Extended 9 Intersection Model (DE-9IM) representation of the relationship between the geometries. | |
bool | relatePattern (const QgsAbstractGeometry *geom, const QString &pattern, QString *errorMsg=nullptr) const override |
Tests whether two geometries are related by a specified Dimensional Extended 9 Intersection Model (DE-9IM) pattern. | |
std::unique_ptr< QgsAbstractGeometry > | reshapeGeometry (const QgsLineString &reshapeWithLine, EngineOperationResult *errorCode, QString *errorMsg=nullptr) const |
Reshapes the geometry using a line. | |
std::unique_ptr< QgsAbstractGeometry > | sharedPaths (const QgsAbstractGeometry *other, QString *errorMsg=nullptr) const |
Find paths shared between the two given lineal geometries (this and other). | |
QgsGeometry | shortestLine (const QgsAbstractGeometry *other, QString *errorMsg=nullptr) const |
Returns the shortest line joining this geometry to the other geometry. | |
QgsGeometry | shortestLine (const QgsGeometry &other, QString *errorMsg=nullptr) const |
Returns the shortest line joining this geometry to the other geometry. | |
QgsAbstractGeometry * | simplify (double tolerance, QString *errorMsg=nullptr) const override |
std::unique_ptr< QgsAbstractGeometry > | simplifyCoverageVW (double tolerance, bool preserveBoundary, QString *errorMsg=nullptr) const |
Operates on a coverage (represented as a list of polygonal geometry with exactly matching edge geometry) to apply a Visvalingam–Whyatt simplification to the edges, reducing complexity in proportion with the provided tolerance, while retaining a valid coverage (no edges will cross or touch after the simplification). | |
std::unique_ptr< QgsAbstractGeometry > | singleSidedBuffer (double distance, int segments, Qgis::BufferSide side, Qgis::JoinStyle joinStyle, double miterLimit, QString *errorMsg=nullptr) const |
Returns a single sided buffer for a geometry. | |
EngineOperationResult | splitGeometry (const QgsLineString &splitLine, QVector< QgsGeometry > &newGeometries, bool topological, QgsPointSequence &topologyTestPoints, QString *errorMsg=nullptr, bool skipIntersectionCheck=false) const override |
Splits this geometry according to a given line. | |
std::unique_ptr< QgsAbstractGeometry > | subdivide (int maxNodes, QString *errorMsg=nullptr, const QgsGeometryParameters ¶meters=QgsGeometryParameters()) const |
Subdivides the geometry. | |
QgsAbstractGeometry * | symDifference (const QgsAbstractGeometry *geom, QString *errorMsg=nullptr, const QgsGeometryParameters ¶meters=QgsGeometryParameters()) const override |
Calculate the symmetric difference of this and geom. | |
bool | touches (const QgsAbstractGeometry *geom, QString *errorMsg=nullptr) const override |
Checks if geom touches this. | |
std::unique_ptr< QgsAbstractGeometry > | unionCoverage (QString *errorMsg=nullptr) const |
Optimized union algorithm for polygonal inputs that are correctly noded and do not overlap. | |
Qgis::CoverageValidityResult | validateCoverage (double gapWidth, std::unique_ptr< QgsAbstractGeometry > *invalidEdges, QString *errorMsg=nullptr) const |
Analyze a coverage (represented as a collection of polygonal geometry with exactly matching edge geometry) to find places where the assumption of exactly matching edges is not met. | |
QgsGeometry | voronoiDiagram (const QgsAbstractGeometry *extent=nullptr, double tolerance=0.0, bool edgesOnly=false, QString *errorMsg=nullptr) const |
Creates a Voronoi diagram for the nodes contained within the geometry. | |
bool | within (const QgsAbstractGeometry *geom, QString *errorMsg=nullptr) const override |
Checks if geom is within this. | |
Public Member Functions inherited from QgsGeometryEngine | |
virtual | ~QgsGeometryEngine ()=default |
void | setLogErrors (bool enabled) |
Sets whether warnings and errors encountered during the geometry operations should be logged. | |
Static Public Member Functions | |
static Qgis::GeometryOperationResult | addPart (QgsGeometry &geometry, GEOSGeometry *newPart) |
Adds a new island polygon to a multipolygon feature. | |
static geos::unique_ptr | asGeos (const QgsAbstractGeometry *geometry, double precision=0, Qgis::GeosCreationFlags flags=Qgis::GeosCreationFlags()) |
Returns a geos geometry - caller takes ownership of the object (should be deleted with GEOSGeom_destroy_r) | |
static geos::unique_ptr | asGeos (const QgsGeometry &geometry, double precision=0, Qgis::GeosCreationFlags flags=Qgis::GeosCreationFlags()) |
Returns a geos geometry - caller takes ownership of the object (should be deleted with GEOSGeom_destroy_r) | |
static QgsPoint | coordSeqPoint (const GEOSCoordSequence *cs, int i, bool hasZ, bool hasM) |
static std::unique_ptr< QgsAbstractGeometry > | fromGeos (const GEOSGeometry *geos) |
Create a geometry from a GEOSGeometry. | |
static std::unique_ptr< QgsPolygon > | fromGeosPolygon (const GEOSGeometry *geos) |
static QgsGeometry | geometryFromGeos (const geos::unique_ptr &geos) |
Creates a new QgsGeometry object, feeding in a geometry in GEOS format. | |
static QgsGeometry | geometryFromGeos (GEOSGeometry *geos) |
Creates a new QgsGeometry object, feeding in a geometry in GEOS format. | |
static QgsGeometry | polygonize (const QVector< const QgsAbstractGeometry * > &geometries, QString *errorMsg=nullptr) |
Creates a GeometryCollection geometry containing possible polygons formed from the constituent linework of a set of geometries. | |
Additional Inherited Members | |
Public Types inherited from QgsGeometryEngine | |
enum | EngineOperationResult { Success = 0 , NothingHappened = 1000 , MethodNotImplemented , EngineError , NodedGeometryError , InvalidBaseGeometry , InvalidInput , SplitCannotSplitPoint } |
Success or failure of a geometry operation. More... | |
Protected Member Functions inherited from QgsGeometryEngine | |
QgsGeometryEngine (const QgsAbstractGeometry *geometry) | |
void | logError (const QString &engineName, const QString &message) const |
Logs an error message encountered during an operation. | |
Protected Attributes inherited from QgsGeometryEngine | |
const QgsAbstractGeometry * | mGeometry = nullptr |
bool | mLogErrors = true |
Does vector analysis using the geos library and handles import, export, exception handling*.
QgsGeos::QgsGeos | ( | const QgsAbstractGeometry * | geometry, |
double | precision = 0 , |
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Qgis::GeosCreationFlags | flags = Qgis::GeosCreationFlags() |
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GEOS geometry engine constructor.
geometry | The geometry |
precision | The precision of the grid to which to snap the geometry vertices. If 0, no snapping is performed. |
flags | GEOS creation flags (since QGIS 3.40) |
Definition at line 177 of file qgsgeos.cpp.
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Adds a new island polygon to a multipolygon feature.
geometry | geometry to add part to |
newPart | part to add. Ownership is NOT transferred. |
Definition at line 267 of file qgsgeos.cpp.
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Implements QgsGeometryEngine.
Definition at line 1007 of file qgsgeos.cpp.
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static |
Returns a geos geometry - caller takes ownership of the object (should be deleted with GEOSGeom_destroy_r)
geometry | geometry to convert to GEOS representation |
precision | The precision of the grid to which to snap the geometry vertices. If 0, no snapping is performed. |
flags | GEOS creation flags (since QGIS 3.40) |
Definition at line 1799 of file qgsgeos.cpp.
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static |
Returns a geos geometry - caller takes ownership of the object (should be deleted with GEOSGeom_destroy_r)
geometry | geometry to convert to GEOS representation |
precision | The precision of the grid to which to snap the geometry vertices. If 0, no snapping is performed. |
flags | GEOS creation flags (since QGIS 3.40) |
Definition at line 257 of file qgsgeos.cpp.
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overridevirtual |
Implements QgsGeometryEngine.
Definition at line 2079 of file qgsgeos.cpp.
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overridevirtual |
Calculates the centroid of this.
May return a \c nullptr
.
Implements QgsGeometryEngine.
Definition at line 2141 of file qgsgeos.cpp.
std::unique_ptr< QgsAbstractGeometry > QgsGeos::clip | ( | const QgsRectangle & | rectangle, |
QString * | errorMsg = nullptr |
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) | const |
Performs a fast, non-robust intersection between the geometry and a rectangle.
The returned geometry may be invalid.
Definition at line 327 of file qgsgeos.cpp.
QgsGeometry QgsGeos::closestPoint | ( | const QgsGeometry & | other, |
QString * | errorMsg = nullptr |
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) | const |
Returns the closest point on the geometry to the other geometry.
Definition at line 3051 of file qgsgeos.cpp.
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overridevirtual |
Calculate the combination of this and geom.
geom | geometry to perform the operation |
errorMsg | Error message returned by GEOS |
parameters | can be used to specify parameters which control the union results (since QGIS 3.28) |
Implements QgsGeometryEngine.
Definition at line 468 of file qgsgeos.cpp.
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overridevirtual |
Calculate the combination of this and geometries.
geomList | list of geometries to perform the operation |
errorMsg | Error message returned by GEOS |
parameters | can be used to specify parameters which control the combination results (since QGIS 3.28) |
Implements QgsGeometryEngine.
Definition at line 473 of file qgsgeos.cpp.
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overridevirtual |
Calculate the combination of this and geometries.
geometries | list of geometries to perform the operation |
errorMsg | Error message returned by GEOS |
parameters | can be used to specify parameters which control the combination results (since QGIS 3.28) |
Implements QgsGeometryEngine.
Definition at line 505 of file qgsgeos.cpp.
QgsAbstractGeometry * QgsGeos::concaveHull | ( | double | targetPercent, |
bool | allowHoles = false , |
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QString * | errorMsg = nullptr |
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) | const |
Returns a possibly concave geometry that encloses the input geometry.
The result is a single polygon, line or point.
It will not contain holes unless the optional allowHoles argument is specified as true.
One can think of a concave hull as a geometry obtained by "shrink-wrapping" a set of geometries. This is different to the convex hull, which is more like wrapping a rubber band around the geometries. It is slower to compute than the convex hull but generally has a smaller area and represents a more natural boundary for the input geometry. The target_percent is the percentage of area of the convex hull the solution tries to approach.
A target_percent of 1 gives the same result as the convex hull. A target_percent between 0 and 0.99 produces a result that should have a smaller area than the convex hull.
This method requires a QGIS build based on GEOS 3.11 or later.
QgsNotSupportedException | on QGIS builds based on GEOS 3.10 or earlier. |
Definition at line 2228 of file qgsgeos.cpp.
std::unique_ptr< QgsAbstractGeometry > QgsGeos::constrainedDelaunayTriangulation | ( | QString * | errorMsg = nullptr | ) | const |
Returns a constrained Delaunay triangulation for the vertices of the geometry.
An empty geometry will be returned if the triangulation could not be calculated.
This method requires a QGIS build based on GEOS 3.11 or later.
QgsNotSupportedException | on QGIS builds based on GEOS 3.10 or earlier. |
Definition at line 3309 of file qgsgeos.cpp.
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overridevirtual |
Checks if geom contains this.
Implements QgsGeometryEngine.
Definition at line 902 of file qgsgeos.cpp.
bool QgsGeos::contains | ( | double | x, |
double | y, | ||
QString * | errorMsg = nullptr |
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) | const |
Returns true
if the geometry contains the point at (x, y).
This method is more efficient than creating a temporary QgsPoint object to test for containment.
Definition at line 714 of file qgsgeos.cpp.
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overridevirtual |
Calculate the convex hull of this.
Implements QgsGeometryEngine.
Definition at line 2212 of file qgsgeos.cpp.
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static |
Definition at line 1762 of file qgsgeos.cpp.
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overridevirtual |
Checks if geom crosses this.
Implements QgsGeometryEngine.
Definition at line 887 of file qgsgeos.cpp.
QgsGeometry QgsGeos::delaunayTriangulation | ( | double | tolerance = 0.0 , |
bool | edgesOnly = false , |
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QString * | errorMsg = nullptr |
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) | const |
Returns the Delaunay triangulation for the vertices of the geometry.
The tolerance parameter specifies an optional snapping tolerance which can be used to improve the robustness of the triangulation. If edgesOnly is true
than line string boundary geometries will be returned instead of polygons. An empty geometry will be returned if the diagram could not be calculated.
Definition at line 3286 of file qgsgeos.cpp.
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overridevirtual |
Calculate the difference of this and geom.
geom | geometry to perform the operation |
errorMsg | Error message returned by GEOS |
parameters | can be used to specify parameters which control the difference results (since QGIS 3.28) |
Implements QgsGeometryEngine.
Definition at line 322 of file qgsgeos.cpp.
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overridevirtual |
Checks if geom is disjoint from this.
Implements QgsGeometryEngine.
Definition at line 935 of file qgsgeos.cpp.
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overridevirtual |
Calculates the distance between this and geom.
Implements QgsGeometryEngine.
Definition at line 581 of file qgsgeos.cpp.
double QgsGeos::distance | ( | double | x, |
double | y, | ||
QString * | errorMsg = nullptr |
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) | const |
Returns the minimum distance from the geometry to the point at (x, y).
This method is more efficient than creating a temporary QgsPoint object to test distance.
Definition at line 627 of file qgsgeos.cpp.
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Checks if geom is within maxdistance distance from this geometry.
Implements QgsGeometryEngine.
Definition at line 656 of file qgsgeos.cpp.
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overridevirtual |
Implements QgsGeometryEngine.
Definition at line 2168 of file qgsgeos.cpp.
double QgsGeos::frechetDistance | ( | const QgsAbstractGeometry * | geom, |
QString * | errorMsg = nullptr |
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) | const |
Returns the Fréchet distance between this geometry and geom, restricted to discrete points for both geometries.
The Fréchet distance is a measure of similarity between curves that takes into account the location and ordering of the points along the curves. Therefore it is often better than the Hausdorff distance.
This method requires a QGIS build based on GEOS 3.7 or later.
QgsNotSupportedException | on QGIS builds based on GEOS 3.6 or earlier. |
Definition at line 803 of file qgsgeos.cpp.
double QgsGeos::frechetDistanceDensify | ( | const QgsAbstractGeometry * | geom, |
double | densifyFraction, | ||
QString * | errorMsg = nullptr |
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) | const |
Returns the Fréchet distance between this geometry and geom, restricted to discrete points for both geometries.
The Fréchet distance is a measure of similarity between curves that takes into account the location and ordering of the points along the curves. Therefore it is often better than the Hausdorff distance.
This function accepts a densifyFraction argument. The function performs a segment densification before computing the discrete Fréchet distance. The densifyFraction parameter sets the fraction by which to densify each segment. Each segment will be split into a number of equal-length subsegments, whose fraction of the total length is closest to the given fraction.
This method can be used when the default approximation provided by frechetDistance() is not sufficient. Decreasing the densifyFraction parameter will make the distance returned approach the true Fréchet distance for the geometries.
This method requires a QGIS build based on GEOS 3.7 or later.
QgsNotSupportedException | on QGIS builds based on GEOS 3.6 or earlier. |
Definition at line 826 of file qgsgeos.cpp.
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static |
Create a geometry from a GEOSGeometry.
geos | GEOSGeometry. Ownership is NOT transferred. |
Definition at line 1568 of file qgsgeos.cpp.
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static |
Definition at line 1669 of file qgsgeos.cpp.
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overridevirtual |
Should be called whenever the geometry associated with the engine has been modified and the engine must be updated to suit.
Implements QgsGeometryEngine.
Definition at line 282 of file qgsgeos.cpp.
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static |
Creates a new QgsGeometry object, feeding in a geometry in GEOS format.
Definition at line 192 of file qgsgeos.cpp.
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static |
Creates a new QgsGeometry object, feeding in a geometry in GEOS format.
This class will take ownership of the buffer.
Definition at line 185 of file qgsgeos.cpp.
double QgsGeos::hausdorffDistance | ( | const QgsAbstractGeometry * | geom, |
QString * | errorMsg = nullptr |
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) | const |
Returns the Hausdorff distance between this geometry and geom.
This is basically a measure of how similar or dissimilar 2 geometries are.
This algorithm is an approximation to the standard Hausdorff distance. This approximation is exact or close enough for a large subset of useful cases. Examples of these are:
If the default approximate provided by this method is insufficient, use hausdorffDistanceDensify() instead.
Definition at line 757 of file qgsgeos.cpp.
double QgsGeos::hausdorffDistanceDensify | ( | const QgsAbstractGeometry * | geom, |
double | densifyFraction, | ||
QString * | errorMsg = nullptr |
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) | const |
Returns the Hausdorff distance between this geometry and geom.
This is basically a measure of how similar or dissimilar 2 geometries are.
This function accepts a densifyFraction argument. The function performs a segment densification before computing the discrete Hausdorff distance. The densifyFraction parameter sets the fraction by which to densify each segment. Each segment will be split into a number of equal-length subsegments, whose fraction of the total length is closest to the given fraction.
This method can be used when the default approximation provided by hausdorffDistance() is not sufficient. Decreasing the densifyFraction parameter will make the distance returned approach the true Hausdorff distance for the geometries.
Definition at line 780 of file qgsgeos.cpp.
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overridevirtual |
Implements QgsGeometryEngine.
Definition at line 2126 of file qgsgeos.cpp.
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overridevirtual |
Calculate the intersection of this and geom.
geom | geometry to perform the operation |
errorMsg | Error message returned by GEOS |
parameters | can be used to specify parameters which control the intersection results (since QGIS 3.28) |
Implements QgsGeometryEngine.
Definition at line 317 of file qgsgeos.cpp.
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overridevirtual |
Checks if geom intersects this.
Implements QgsGeometryEngine.
Definition at line 849 of file qgsgeos.cpp.
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overridevirtual |
Implements QgsGeometryEngine.
Definition at line 2422 of file qgsgeos.cpp.
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Checks if this is equal to geom.
If both are Null geometries, \c false
is returned.
Implements QgsGeometryEngine.
Definition at line 2402 of file qgsgeos.cpp.
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Determines whether the geometry is simple (according to OGC definition).
Implements QgsGeometryEngine.
Definition at line 2436 of file qgsgeos.cpp.
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overridevirtual |
Returns true
if the geometry is valid.
If the geometry is invalid, errorMsg will be filled with the reported geometry error.
The allowSelfTouchingHoles argument specifies whether self-touching holes are permitted. OGC validity states that self-touching holes are NOT permitted, whilst other vendor validity checks (e.g. ESRI) permit self-touching holes.
If errorLoc is specified, it will be set to the geometry of the error location.
Implements QgsGeometryEngine.
Definition at line 2339 of file qgsgeos.cpp.
std::unique_ptr< QgsAbstractGeometry > QgsGeos::largestEmptyCircle | ( | double | tolerance, |
const QgsAbstractGeometry * | boundary = nullptr , |
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QString * | errorMsg = nullptr |
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) | const |
Constructs the Largest Empty Circle for a set of obstacle geometries, up to a specified tolerance.
The Largest Empty Circle is the largest circle which has its center in the convex hull of the obstacles (the boundary), and whose interior does not intersect with any obstacle. The circle center is the point in the interior of the boundary which has the farthest distance from the obstacles (up to tolerance). The circle is determined by the center point and a point lying on an obstacle indicating the circle radius. The implementation uses a successive-approximation technique over a grid of square cells covering the obstacles and boundary. The grid is refined using a branch-and-bound algorithm. Point containment and distance are computed in a performant way by using spatial indexes. Returns a two-point linestring, with one point at the center of the inscribed circle and the other on the boundary of the inscribed circle.
This method requires a QGIS build based on GEOS 3.9 or later.
QgsNotSupportedException | on QGIS builds based on GEOS 3.8 or earlier. |
Definition at line 2808 of file qgsgeos.cpp.
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overridevirtual |
Implements QgsGeometryEngine.
Definition at line 1024 of file qgsgeos.cpp.
double QgsGeos::lineLocatePoint | ( | const QgsPoint & | point, |
QString * | errorMsg = nullptr |
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) | const |
Returns a distance representing the location along this linestring of the closest point on this linestring geometry to the specified point.
Ie, the returned value indicates how far along this linestring you need to traverse to get to the closest location where this linestring comes to the specified point.
point | point to seek proximity to |
errorMsg | error messages emitted, if any |
Definition at line 3153 of file qgsgeos.cpp.
double QgsGeos::lineLocatePoint | ( | double | x, |
double | y, | ||
QString * | errorMsg = nullptr |
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) | const |
Returns a distance representing the location along this linestring of the closest point on this linestring geometry to the point at (x, y).
Ie, the returned value indicates how far along this linestring you need to traverse to get to the closest location where this linestring comes to the specified point.
This method is more efficient than creating a temporary QgsPoint object to locate.
Definition at line 3184 of file qgsgeos.cpp.
std::unique_ptr< QgsAbstractGeometry > QgsGeos::makeValid | ( | Qgis::MakeValidMethod | method = Qgis::MakeValidMethod::Linework , |
bool | keepCollapsed = false , |
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QString * | errorMsg = nullptr |
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) | const |
Repairs the geometry using GEOS make valid routine.
The method and keepCollapsed arguments require builds based on GEOS 3.10 or later.
QgsNotSupportedException | on QGIS builds based on GEOS 3.9 or earlier when the method is not Qgis::MakeValidMethod::Linework or the keepCollapsed option is set. |
Definition at line 198 of file qgsgeos.cpp.
std::unique_ptr< QgsAbstractGeometry > QgsGeos::maximumInscribedCircle | ( | double | tolerance, |
QString * | errorMsg = nullptr |
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) | const |
Returns the maximum inscribed circle.
Constructs the Maximum Inscribed Circle for a polygonal geometry, up to a specified tolerance. The Maximum Inscribed Circle is determined by a point in the interior of the area which has the farthest distance from the area boundary, along with a boundary point at that distance. In the context of geography the center of the Maximum Inscribed Circle is known as the Pole of Inaccessibility. A cartographic use case is to determine a suitable point to place a map label within a polygon. The radius length of the Maximum Inscribed Circle is a measure of how "narrow" a polygon is. It is the distance at which the negative buffer becomes empty. The class supports polygons with holes and multipolygons. The implementation uses a successive-approximation technique over a grid of square cells covering the area geometry. The grid is refined using a branch-and-bound algorithm. Point containment and distance are computed in a performant way by using spatial indexes. Returns a two-point linestring, with one point at the center of the inscribed circle and the other on the boundary of the inscribed circle.
This method requires a QGIS build based on GEOS 3.9 or later.
QgsNotSupportedException | on QGIS builds based on GEOS 3.8 or earlier. |
Definition at line 2792 of file qgsgeos.cpp.
QgsGeometry QgsGeos::mergeLines | ( | QString * | errorMsg = nullptr | ) | const |
Merges any connected lines in a LineString/MultiLineString geometry and converts them to single line strings.
errorMsg | if specified, will be set to any reported GEOS errors |
Definition at line 3031 of file qgsgeos.cpp.
double QgsGeos::minimumClearance | ( | QString * | errorMsg = nullptr | ) | const |
Computes the minimum clearance of a geometry.
The minimum clearance is the smallest amount by which a vertex could be moved to produce an invalid polygon, a non-simple linestring, or a multipoint with repeated points. If a geometry has a minimum clearance of 'eps', it can be said that:
If the minimum clearance cannot be defined for a geometry (such as with a single point, or a multipoint whose points are identical) a value of infinity will be returned.
If an error occurs while calculating the clearance NaN will be returned.
This method requires a QGIS build based on GEOS 3.6 or later.
QgsNotSupportedException | on QGIS builds based on GEOS 3.5 or earlier. |
Definition at line 2844 of file qgsgeos.cpp.
std::unique_ptr< QgsAbstractGeometry > QgsGeos::minimumClearanceLine | ( | QString * | errorMsg = nullptr | ) | const |
Returns a LineString whose endpoints define the minimum clearance of a geometry.
If the geometry has no minimum clearance, an empty LineString will be returned.
This method requires a QGIS build based on GEOS 3.6 or later.
QgsNotSupportedException | on QGIS builds based on GEOS 3.5 or earlier. |
Definition at line 2862 of file qgsgeos.cpp.
std::unique_ptr< QgsAbstractGeometry > QgsGeos::minimumWidth | ( | QString * | errorMsg = nullptr | ) | const |
Returns a linestring geometry which represents the minimum diameter of the geometry.
The minimum diameter is defined to be the width of the smallest band that contains the geometry, where a band is a strip of the plane defined by two parallel lines. This can be thought of as the smallest hole that the geometry can be moved through, with a single rotation.
This method requires a QGIS build based on GEOS 3.6 or later.
QgsNotSupportedException | on QGIS builds based on GEOS 3.5 or earlier. |
Definition at line 2828 of file qgsgeos.cpp.
std::unique_ptr< QgsAbstractGeometry > QgsGeos::node | ( | QString * | errorMsg = nullptr | ) | const |
Returns a (Multi)LineString representing the fully noded version of a collection of linestrings.
The noding preserves all of the input nodes, and introduces the least possible number of new nodes. The resulting linework is dissolved (duplicate lines are removed).
The input geometry type should be a (Multi)LineString.
Definition at line 2878 of file qgsgeos.cpp.
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overridevirtual |
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overridevirtual |
Checks if geom overlaps this.
Implements QgsGeometryEngine.
Definition at line 897 of file qgsgeos.cpp.
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overridevirtual |
Calculate a point that is guaranteed to be on the surface of this.
May return a \c nullptr
.
Implements QgsGeometryEngine.
Definition at line 2183 of file qgsgeos.cpp.
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static |
Creates a GeometryCollection geometry containing possible polygons formed from the constituent linework of a set of geometries.
The input geometries must be fully noded (i.e. nodes exist at every common intersection of the geometries). The easiest way to ensure this is to first unary union these geometries by calling combine() on the set of input geometries and then pass the result to polygonize(). An empty geometry will be returned in the case of errors.
Definition at line 3213 of file qgsgeos.cpp.
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overridevirtual |
Prepares the geometry, so that subsequent calls to spatial relation methods are much faster.
This should be called for any geometry which is used for multiple relation tests against other geometries.
Implements QgsGeometryEngine.
Definition at line 289 of file qgsgeos.cpp.
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overridevirtual |
Returns the Dimensional Extended 9 Intersection Model (DE-9IM) representation of the relationship between the geometries.
geom | geometry to relate to |
errorMsg | destination storage for any error message |
Implements QgsGeometryEngine.
Definition at line 940 of file qgsgeos.cpp.
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overridevirtual |
Tests whether two geometries are related by a specified Dimensional Extended 9 Intersection Model (DE-9IM) pattern.
geom | geometry to relate to |
pattern | DE-9IM pattern for match |
errorMsg | destination storage for any error message |
true
if geometry relationship matches with pattern Implements QgsGeometryEngine.
Definition at line 976 of file qgsgeos.cpp.
std::unique_ptr< QgsAbstractGeometry > QgsGeos::reshapeGeometry | ( | const QgsLineString & | reshapeWithLine, |
EngineOperationResult * | errorCode, | ||
QString * | errorMsg = nullptr |
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) | const |
Reshapes the geometry using a line.
reshapeWithLine | the line used to reshape lines or polygons |
errorCode | if specified, provides result of operation (success or reason of failure) |
errorMsg | if specified, provides more details about failure |
Definition at line 2914 of file qgsgeos.cpp.
std::unique_ptr< QgsAbstractGeometry > QgsGeos::sharedPaths | ( | const QgsAbstractGeometry * | other, |
QString * | errorMsg = nullptr |
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) | const |
Find paths shared between the two given lineal geometries (this and other).
Returns a GeometryCollection having two elements:
Returns nullptr
on exception.
Definition at line 2894 of file qgsgeos.cpp.
QgsGeometry QgsGeos::shortestLine | ( | const QgsAbstractGeometry * | other, |
QString * | errorMsg = nullptr |
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) | const |
Returns the shortest line joining this geometry to the other geometry.
Definition at line 3105 of file qgsgeos.cpp.
QgsGeometry QgsGeos::shortestLine | ( | const QgsGeometry & | other, |
QString * | errorMsg = nullptr |
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) | const |
Returns the shortest line joining this geometry to the other geometry.
Definition at line 3095 of file qgsgeos.cpp.
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overridevirtual |
Implements QgsGeometryEngine.
Definition at line 2111 of file qgsgeos.cpp.
std::unique_ptr< QgsAbstractGeometry > QgsGeos::simplifyCoverageVW | ( | double | tolerance, |
bool | preserveBoundary, | ||
QString * | errorMsg = nullptr |
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) | const |
Operates on a coverage (represented as a list of polygonal geometry with exactly matching edge geometry) to apply a Visvalingam–Whyatt simplification to the edges, reducing complexity in proportion with the provided tolerance, while retaining a valid coverage (no edges will cross or touch after the simplification).
Geometries never disappear, but they may be simplified down to just a triangle. Also, some invalid geoms (such as Polygons which have too few non-repeated points) will be returned unchanged.
If the input dataset is not a valid coverage due to overlaps, it will still be simplified, but invalid topology such as crossing edges will still be invalid.
tolerance | A tolerance parameter in linear units. |
preserveBoundary | Set to true to preserve the outside edges of the coverage without simplification, or false to allow them to be simplified. |
errorMsg |
This method requires a QGIS build based on GEOS 3.12 or later.
QgsNotSupportedException | on QGIS builds based on GEOS 3.11 or earlier. |
Definition at line 2296 of file qgsgeos.cpp.
std::unique_ptr< QgsAbstractGeometry > QgsGeos::singleSidedBuffer | ( | double | distance, |
int | segments, | ||
Qgis::BufferSide | side, | ||
Qgis::JoinStyle | joinStyle, | ||
double | miterLimit, | ||
QString * | errorMsg = nullptr |
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) | const |
Returns a single sided buffer for a geometry.
The buffer is only applied to one side of the geometry.
distance | buffer distance |
segments | for round joins, number of segments to approximate quarter-circle |
side | side of geometry to buffer (0 = left, 1 = right) |
joinStyle | join style for corners ( Round (1) / Miter (2) / Bevel (3) ) |
miterLimit | limit on the miter ratio used for very sharp corners |
errorMsg | error messages emitted, if any |
nullptr
if buffer could not be calculated Definition at line 2765 of file qgsgeos.cpp.
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overridevirtual |
Splits this geometry according to a given line.
splitLine | the line that splits the geometry | |
[out] | newGeometries | list of new geometries that have been created with the split |
topological | true if topological editing is enabled | |
[out] | topologyTestPoints | points that need to be tested for topological completeness in the dataset |
[out] | errorMsg | error messages emitted, if any |
skipIntersectionCheck | set to true to skip the potentially expensive initial intersection check. Only set this flag if an intersection test has already been performed by the caller! |
Reimplemented from QgsGeometryEngine.
Definition at line 1040 of file qgsgeos.cpp.
std::unique_ptr< QgsAbstractGeometry > QgsGeos::subdivide | ( | int | maxNodes, |
QString * | errorMsg = nullptr , |
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const QgsGeometryParameters & | parameters = QgsGeometryParameters() |
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) | const |
Subdivides the geometry.
The returned geometry will be a collection containing subdivided parts from the original geometry, where no part has more then the specified maximum number of nodes (maxNodes).
This is useful for dividing a complex geometry into less complex parts, which are better able to be spatially indexed and faster to perform further operations such as intersects on. The returned geometry parts may not be valid and may contain self-intersections.
The minimum allowed value for maxNodes is 8.
Curved geometries are not supported.
maxNodes | Maximum nodes used |
errorMsg | Error message returned by GEOS |
parameters | can be used to specify parameters which control the subdivision results (since QGIS 3.28) |
Definition at line 448 of file qgsgeos.cpp.
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overridevirtual |
Calculate the symmetric difference of this and geom.
geom | geometry to perform the operation |
errorMsg | Error message returned by GEOS |
parameters | can be used to specify parameters which control the difference results (since QGIS 3.28) |
Implements QgsGeometryEngine.
Definition at line 539 of file qgsgeos.cpp.
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overridevirtual |
Checks if geom touches this.
Implements QgsGeometryEngine.
Definition at line 882 of file qgsgeos.cpp.
std::unique_ptr< QgsAbstractGeometry > QgsGeos::unionCoverage | ( | QString * | errorMsg = nullptr | ) | const |
Optimized union algorithm for polygonal inputs that are correctly noded and do not overlap.
It may generate an error (returns nullptr
) for inputs that do not satisfy this constraint, however this is not guaranteed.
The input geometry is the polygonal coverage to union, stored in a geometry collection. All members must be POLYGON or MULTIPOLYGON.
Definition at line 2321 of file qgsgeos.cpp.
Qgis::CoverageValidityResult QgsGeos::validateCoverage | ( | double | gapWidth, |
std::unique_ptr< QgsAbstractGeometry > * | invalidEdges, | ||
QString * | errorMsg = nullptr |
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) | const |
Analyze a coverage (represented as a collection of polygonal geometry with exactly matching edge geometry) to find places where the assumption of exactly matching edges is not met.
The input geometry is the polygonal coverage to access, stored in a geometry collection. All members must be POLYGON or MULTIPOLYGON.
gapWidth | The maximum width of gaps to detect. |
invalidEdges | When there are invalidities in the coverage, this pointer will be set with a geometry collection of the same length as the input, with a MULTILINESTRING of the error edges for each invalid polygon, or an EMPTY where the polygon is a valid participant in the coverage. Pass nullptr if you do not want the invalid edges returned. |
errorMsg |
This method requires a QGIS build based on GEOS 3.12 or later.
QgsNotSupportedException | on QGIS builds based on GEOS 3.11 or earlier. |
Definition at line 2251 of file qgsgeos.cpp.
QgsGeometry QgsGeos::voronoiDiagram | ( | const QgsAbstractGeometry * | extent = nullptr , |
double | tolerance = 0.0 , |
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bool | edgesOnly = false , |
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QString * | errorMsg = nullptr |
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) | const |
Creates a Voronoi diagram for the nodes contained within the geometry.
Returns the Voronoi polygons for the nodes contained within the geometry. If extent is specified then it will be used as a clipping envelope for the diagram. If no extent is set then the clipping envelope will be automatically calculated. In either case the diagram will be clipped to the larger of the provided envelope OR the envelope surrounding all input nodes. The tolerance parameter specifies an optional snapping tolerance which can be used to improve the robustness of the diagram calculation. If edgesOnly is true
than line string boundary geometries will be returned instead of polygons. An empty geometry will be returned if the diagram could not be calculated.
Definition at line 3253 of file qgsgeos.cpp.
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overridevirtual |
Checks if geom is within this.
Implements QgsGeometryEngine.
Definition at line 892 of file qgsgeos.cpp.