Class: QgsCurvePolygon

Curve polygon geometry type.

Class Hierarchy

Base classes

QgsSurface	Surface geometry type.
QgsAbstractGeometry	Abstract base class for all geometries.

Subclasses

QgsPolygon

Polygon geometry type.

Abstract Methods

vertexAngle

Returns approximate rotation angle for a vertex.

Methods

exteriorRing	Returns the curve polygon's exterior ring.
forceClockwise	Forces the polygon to respect the exterior ring is clockwise, interior rings are counter-clockwise convention.
forceCounterClockwise	Forces the polygon to respect the exterior ring is counter-clockwise, interior rings are clockwise convention.
forceRHR	Forces the geometry to respect the Right-Hand-Rule, in which the area that is bounded by the polygon is to the right of the boundary.
interiorRing	Retrieves an interior ring from the curve polygon.
numInteriorRings	Returns the number of interior rings contained with the curve polygon.
removeInteriorRing	Removes an interior ring from the polygon.
removeInteriorRings	Removes the interior rings from the polygon.
removeInvalidRings	Removes any interior rings which are not valid from the polygon.
roundness	Returns the roundness of the curve polygon.
setInteriorRings	Sets all interior rings (takes ownership)

Virtual Methods

In PyQGIS, only methods marked as virtual can be safely overridden in a Python subclass of QgsCurvePolygon. See the FAQ for more details.

addInteriorRing	Adds an interior ring to the geometry (takes ownership)
segmentize	Returns a geometry without curves.
setExteriorRing	Sets the exterior ring of the polygon.
surfaceToPolygon	Gets a polygon representation of this surface.
toPolygon	Returns a new polygon geometry corresponding to a segmentized approximation of the curve.

class qgis.core.QgsCurvePolygon

Bases: QgsSurface

virtual addInteriorRing(self, ring: QgsCurve | None)

Adds an interior ring to the geometry (takes ownership)

Parameters:

ring (Optional[QgsCurve])

exteriorRing(self) → QgsCurve | None

Returns the curve polygon’s exterior ring.

See also

interiorRing()

Return type:

Optional[QgsCurve]

forceClockwise(self)

Forces the polygon to respect the exterior ring is clockwise, interior rings are counter-clockwise convention.

This convention is used primarily by ESRI software.

See also

forceCounterClockwise()

Added in version 3.24.

forceCounterClockwise(self)

Forces the polygon to respect the exterior ring is counter-clockwise, interior rings are clockwise convention.

This convention matches the OGC Simple Features specification.

See also

forceClockwise()

Added in version 3.24.

forceRHR(self)

Forces the geometry to respect the Right-Hand-Rule, in which the area that is bounded by the polygon is to the right of the boundary. In particular, the exterior ring is oriented in a clockwise direction and the interior rings in a counter-clockwise direction.

Warning

Due to the conflicting definitions of the right-hand-rule in general use, it is recommended to use the explicit forceClockwise() or forceCounterClockwise() methods instead.

See also

forceClockwise()

See also

forceCounterClockwise()

Added in version 3.6.

interiorRing(self, i: int) → QgsCurve

Retrieves an interior ring from the curve polygon. The first interior ring has index 0.

Raises:

IndexError – if no interior ring with the specified index exists.

See also

numInteriorRings()

See also

exteriorRing()

Parameters:

i (int)

Return type:

QgsCurve

numInteriorRings(self) → int

Returns the number of interior rings contained with the curve polygon.

See also

interiorRing()

Return type:

int

removeInteriorRing(self, i: int) → bool

Removes an interior ring from the polygon. The first interior ring has index 0. The corresponding ring is removed from the polygon and deleted. It is not possible to remove the exterior ring using this method.

Raises:

IndexError – if no interior ring with the specified index exists.

See also

removeInteriorRings()

Parameters:

i (int)

Return type:

bool

removeInteriorRings(self, minimumAllowedArea: float = -1)

Removes the interior rings from the polygon. If the minimumAllowedArea parameter is specified then only rings smaller than this minimum area will be removed.

See also

removeInteriorRing()

Parameters:

minimumAllowedArea (float = -1)

removeInvalidRings(self)

Removes any interior rings which are not valid from the polygon.

For example, this removes unclosed rings and rings with less than 4 vertices.

roundness(self) → float

Returns the roundness of the curve polygon. The returned value is between 0 and 1.

Added in version 3.24.

Return type:

float

virtual segmentize(self, tolerance: float = M_PI_2 / 90, toleranceType: QgsAbstractGeometry.SegmentationToleranceType = QgsAbstractGeometry.MaximumAngle) → QgsAbstractGeometry | None

Returns a geometry without curves. Caller takes ownership

Parameters:

• tolerance (float = M_PI_2/90) – segmentation tolerance

• toleranceType (QgsAbstractGeometry.SegmentationToleranceType = QgsAbstractGeometry.MaximumAngle) – maximum segmentation angle or maximum difference between approximation and curve

Return type:

Optional[QgsAbstractGeometry]

virtual setExteriorRing(self, ring: QgsCurve | None)

Sets the exterior ring of the polygon. The CurvePolygon type will be updated to match the dimensionality of the exterior ring. For instance, setting a 2D exterior ring on a 3D CurvePolygon will drop the z dimension from the CurvePolygon and all interior rings.

Parameters:

ring (Optional[QgsCurve]) – new exterior ring. Ownership is transferred to the CurvePolygon.

See also

setInteriorRings()

See also

exteriorRing()

setInteriorRings(self, rings: Iterable[QgsCurve])

Sets all interior rings (takes ownership)

Parameters:

rings (Iterable[QgsCurve])

virtual surfaceToPolygon(self) → QgsPolygon | None

Gets a polygon representation of this surface. Ownership is transferred to the caller.

Return type:

Optional[QgsPolygon]

virtual toPolygon(self, tolerance: float = M_PI_2 / 90, toleranceType: QgsAbstractGeometry.SegmentationToleranceType = QgsAbstractGeometry.MaximumAngle) → QgsPolygon | None

Returns a new polygon geometry corresponding to a segmentized approximation of the curve.

Parameters:

• tolerance (float = M_PI_2/90) – segmentation tolerance

• toleranceType (QgsAbstractGeometry.SegmentationToleranceType = QgsAbstractGeometry.MaximumAngle) – maximum segmentation angle or maximum difference between approximation and curve

Return type:

Optional[QgsPolygon]

abstract vertexAngle(self, vertex: QgsVertexId) → float

Returns approximate rotation angle for a vertex. Usually average angle between adjacent segments.

Parameters:

vertex (QgsVertexId) – the vertex id

Return type:

float

Returns:

rotation in radians, clockwise from north