Subgroup: Curve

Class: QgsCurve¶

class qgis.core.QgsCurve¶

Bases: qgis._core.QgsAbstractGeometry

Abstract base class for curved geometry type

New in version 2.10: Methods

`addMValue`	Adds a measure to the geometry, initialized to a preset value.
`addToPainterPath`	Adds a curve to a painter path.
`addZValue`	Adds a z-dimension to the geometry, initialized to a preset value.
`adjacentVertices`
`area`	Returns the area of the geometry.
`asGml2`	Returns a GML2 representation of the geometry.
`asGml3`	Returns a GML3 representation of the geometry.
`asJson`	Returns a GeoJSON representation of the geometry.
`asQPolygonF`	Returns a QPolygonF representing the points.
`asWkb`	Returns a WKB representation of the geometry.
`asWkt`	Returns a WKT representation of the geometry.
`boundary`
`boundingBox`
`calculateBoundingBox`
`centroid`	Returns the centroid of the geometry
`childCount`
`childGeometry`
`childPoint`
`clear`	Clears the geometry, ie reset it to a null geometry
`clearCache`
`clone`
`closestSegment`	Searches for the closest segment of the geometry to a given point.
`convertTo`	Converts the geometry to a specified type.
`coordinateSequence`
`createEmptyWithSameType`
`curveToLine`	Returns a new line string geometry corresponding to a segmentized approximation of the curve.
`deleteVertex`	Deletes a vertex within the geometry
`dimension`	Returns the inherent dimension of the geometry.
`draw`	Draws the geometry using the specified QPainter.
`drawAsPolygon`	Draws the curve as a polygon on the specified QPainter.
`dropMValue`	Drops any measure values which exist in the geometry.
`dropZValue`	Drops any z-dimensions which exist in the geometry.
`endPoint`	Returns the end point of the curve.
`equals`	Checks whether this curve exactly equals another curve.
`fromWkb`	Sets the geometry from a WKB string.
`fromWkt`	Sets the geometry from a WKT string.
`geometryType`	Returns a unique string representing the geometry type.
`hasChildGeometries`
`hasCurvedSegments`	Returns true if the geometry contains curved segments
`insertVertex`	Inserts a vertex into the geometry
`is3D`	Returns true if the geometry is 3D and contains a z-value.
`isClosed`	Returns true if the curve is closed.
`isEmpty`	Returns true if the geometry is empty
`isMeasure`	Returns true if the geometry contains m values.
`isRing`	Returns true if the curve is a ring.
`length`	Returns the length of the geometry.
`moveVertex`	Moves a vertex within the geometry
`nCoordinates`	Returns the number of nodes contained in the geometry
`nextVertex`
`numPoints`	Returns the number of points in the curve.
`partCount`
`perimeter`	Returns the perimeter of the geometry.
`pointAt`	Returns the point and vertex id of a point within the curve.
`points`	Returns a list of points within the curve.
`removeDuplicateNodes`	Removes duplicate nodes from the geometry, wherever removing the nodes does not result in a degenerate geometry.
`reversed`	Returns a reversed copy of the curve, where the direction of the curve has been flipped.
`ringCount`
`segmentLength`	Returns the length of the segment of the geometry which begins at `startVertex`.
`segmentize`	Returns a geometry without curves.
`setZMTypeFromSubGeometry`
`snappedToGrid`	Makes a new geometry with all the points or vertices snapped to the closest point of the grid.
`startPoint`	Returns the starting point of the curve.
`sumUpArea`	Sums up the area of the curve by iterating over the vertices (shoelace formula).
`toCurveType`
`transform`	Transforms the geometry using a coordinate transform
`vertexAngle`	Returns approximate angle at a vertex.
`vertexAt`
`vertexCount`
`vertexNumberFromVertexId`
`vertices`	Returns Java-style iterator for traversal of vertices of the geometry
`wkbType`	Returns the WKB type of the geometry.
`wktTypeStr`	Returns the WKT type string of the geometry.
`xAt`	Returns the x-coordinate of the specified node in the line string.
`yAt`	Returns the y-coordinate of the specified node in the line string.

Attributes

`MaximumAngle`
`MaximumDifference`

addToPainterPath(self, path: QPainterPath)¶: Adds a curve to a painter path.

adjacentVertices(self, vertex: QgsVertexId) → Tuple[QgsVertexId, QgsVertexId]¶

asQPolygonF(self) → QPolygonF¶: Returns a QPolygonF representing the points.

boundary(self) → QgsAbstractGeometry¶

boundingBox(self) → QgsRectangle¶

calculateBoundingBox()¶

childCount(self) → int¶

childGeometry()¶

childPoint(self, index: int) → QgsPoint¶

clearCache(self)¶

clone(self) → QgsCurve¶

coordinateSequence(self) → object¶

createEmptyWithSameType()¶

curveToLine(self, tolerance: float = M_PI_2/90, toleranceType: QgsAbstractGeometry.SegmentationToleranceType = QgsAbstractGeometry.MaximumAngle) → QgsLineString¶

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

Parameters:	tolerance – segmentation tolerance toleranceType – maximum segmentation angle or maximum difference between approximation and curve

Uses a MaximumAngle tolerance of 1 degrees by default (360 segments in a full circle)

drawAsPolygon(self, p: QPainter)¶

Draws the curve as a polygon on the specified QPainter.

Parameters:	p – destination QPainter

endPoint(self) → QgsPoint¶: Returns the end point of the curve.

See also

startPoint()

equals(self, other: QgsCurve) → bool¶: Checks whether this curve exactly equals another curve.

New in version 3.0.

hasChildGeometries()¶

isClosed(self) → bool¶: Returns true if the curve is closed.

isRing(self) → bool¶: Returns true if the curve is a ring.

nextVertex(self, id: QgsVertexId) → Tuple[bool, QgsPoint]¶

numPoints(self) → int¶: Returns the number of points in the curve.

partCount(self) → int¶

pointAt(self, node: int) → Tuple[bool, QgsPoint, QgsVertexId.VertexType]¶

Returns the point and vertex id of a point within the curve.

Parameters:	node – node number, where the first node is 0 point – will be set to point at corresponding node in the curve type – will be set to the vertex type of the node
Returns:	true if node exists within the curve

points(self) → object¶: Returns a list of points within the curve.

reversed(self) → QgsCurve¶: Returns a reversed copy of the curve, where the direction of the curve has been flipped.

New in version 2.14.

ringCount(self, part: int = 0) → int¶

segmentize(self, tolerance: float = M_PI_2/90, toleranceType: QgsAbstractGeometry.SegmentationToleranceType = QgsAbstractGeometry.MaximumAngle) → QgsCurve¶

Returns a geometry without curves. Caller takes ownership

Parameters:	tolerance – segmentation tolerance toleranceType – maximum segmentation angle or maximum difference between approximation and curve*

setZMTypeFromSubGeometry()¶

startPoint(self) → QgsPoint¶: Returns the starting point of the curve.

See also

endPoint()

sumUpArea(self) → float¶: Sums up the area of the curve by iterating over the vertices (shoelace formula).

toCurveType(self) → QgsCurve¶

vertexAt(self, id: QgsVertexId) → QgsPoint¶

vertexCount(self, part: int = 0, ring: int = 0) → int¶

vertexNumberFromVertexId(self, id: QgsVertexId) → int¶

xAt(self, index: int) → float¶

Returns the x-coordinate of the specified node in the line string.

Parameters:	index – index of node, where the first node in the line is 0
Returns:	x-coordinate of node, or 0.0 if index is out of bounds