Class: QgsPointLocator¶

class qgis.core.QgsPointLocator¶

Bases: PyQt5.QtCore.QObject

The class defines interface for querying point location:

query nearest vertices / edges to a point
query vertices / edges in rectangle
query areas covering a point

Works with one layer.

New in version 2.8.

QgsPointLocator(layer: QgsVectorLayer, destinationCrs: QgsCoordinateReferenceSystem = QgsCoordinateReferenceSystem(), transformContext: QgsCoordinateTransformContext = QgsCoordinateTransformContext(), extent: QgsRectangle = None) Construct point locator for a layer.

If a valid QgsCoordinateReferenceSystem is passed for destinationCrs then the locator will do the searches on data reprojected to the given CRS. For accurate reprojection it is important to set the correct transformContext if a destinationCrs is specified. This is usually taken from the current QgsProject.transformContext().

If extent is not None, the locator will index only a subset of the layer which falls within that extent.

Methods

cachedGeometryCount

Returns how many geometries are cached in the index

childEvent

connectNotify

customEvent

destinationCrs

Gets destination CRS - may be an invalid QgsCoordinateReferenceSystem if not doing OTF reprojection

destroyIndex

disconnectNotify

edgesInRect

Find edges within a specified rectangle Optional filter may discard unwanted matches.

extent

Gets extent of the area point locator covers - if None then it caches the whole layer

hasIndex

Indicate whether the data have been already indexed

init

Prepare the index for queries.

isIndexing

Returns True if the point locator is currently indexing the data.

isSignalConnected

layer

Gets associated layer

nearestArea

Find nearest area to the specified point - up to distance specified by tolerance Optional filter may discard unwanted matches.

nearestCentroid

Find nearest centroid to the specified point - up to distance specified by tolerance Optional filter may discard unwanted matches.

nearestEdge

Find nearest edge to the specified point - up to distance specified by tolerance Optional filter may discard unwanted matches.

nearestLineEndpoints

Find nearest line endpoint (start or end vertex) to the specified point - up to distance specified by tolerance Optional filter may discard unwanted matches.

nearestMiddleOfSegment

Find nearest middle of segment to the specified point - up to distance specified by tolerance Optional filter may discard unwanted matches.

nearestVertex

Find nearest vertex to the specified point - up to distance specified by tolerance Optional filter may discard unwanted matches.

pointInPolygon

Find out if the point is in any polygons

rebuildIndex

param maxFeaturesToIndex:

receivers

sender

senderSignalIndex

setExtent

Configure extent - if not None, it will index only that area

setRenderContext

Configure render context - if not None, it will use to index only visible feature

timerEvent

verticesInRect

Find vertices within a specified rectangle This method is either blocking or non blocking according to relaxed parameter passed Optional filter may discard unwanted matches.

waitForIndexingFinished

If the point locator has been initialized relaxedly and is currently indexing, this methods waits for the indexing to be finished

Signals

initFinished

pyqtSignal(*types, name: str = ..., revision: int = ..., arguments: Sequence = ...) -> PYQT_SIGNAL

Attributes

All

Area

Centroid

Edge

Invalid

LineEndpoint

MiddleOfSegment

Vertex

All = 31¶

Area = 4¶

Centroid = 8¶

Edge = 2¶

Invalid = 0¶

LineEndpoint = 32¶

class Match¶

Bases: sip.wrapper

construct invalid match

QgsPointLocator.Match(t: QgsPointLocator.Type, vl: QgsVectorLayer, fid: int, dist: float, pt: QgsPointXY, vertexIndex: int = 0, edgePoints: QgsPointXY = None)

QgsPointLocator.Match(QgsPointLocator.Match)

distance(self) → float¶

for vertex / edge match units depending on what class returns it (geom.cache: layer units, map canvas snapper: dest crs units)

Return type:: float

edgePoints(self) → Tuple[QgsPointXY, QgsPointXY]¶

Only for a valid edge match - obtain endpoints of the edge

Return type:: Tuple[QgsPointXY, QgsPointXY]

featureId(self) → int¶

The id of the feature to which the snapped geometry belongs.

Return type:: int

hasArea(self) → bool¶

Returns True if the Match is an area

Return type:: bool

hasCentroid(self) → bool¶

Returns True if the Match is a centroid

Return type:: bool

hasEdge(self) → bool¶

Returns True if the Match is an edge

Return type:: bool

hasLineEndpoint(self) → bool¶

Returns True if the Match is a line endpoint (start or end vertex).

New in version 3.20.

Return type:: bool

hasMiddleSegment(self) → bool¶

Returns True if the Match is the middle of a segment

Return type:: bool

hasVertex(self) → bool¶

Returns True if the Match is a vertex

Return type:: bool

interpolatedPoint(self, destinationCrs: QgsCoordinateReferenceSystem = QgsCoordinateReferenceSystem()) → QgsPoint¶

Convenient method to return a point on an edge with linear interpolation of the Z value. The parameter destinationCrs depends of where the instance of this Match is created (geom.cache: layer CRS, map canvas snapper: dest CRS)

New in version 3.10.

Parameters:: destinationCrs (QgsCoordinateReferenceSystem = QgsCoordinateReferenceSystem()) –
Return type:: QgsPoint

isValid(self) → bool¶

Return type:: bool

layer(self) → QgsVectorLayer¶

The vector layer where the snap occurred. Will be None if the snap happened on an intersection.

Return type:: QgsVectorLayer

point(self) → QgsPointXY¶

for vertex / edge match coords depending on what class returns it (geom.cache: layer coords, map canvas snapper: dest coords)

Return type:: QgsPointXY

type(self) → QgsPointLocator.Type¶

Return type:: QgsPointLocator.Type

vertexIndex(self) → int¶

for vertex / edge match (first vertex of the edge)

Return type:: int

class MatchFilter¶

class MatchFilter(QgsPointLocator.MatchFilter)

Bases: sip.wrapper

acceptMatch(self, match: QgsPointLocator.Match) → bool¶

Parameters:: match (QgsPointLocator.Match) –
Return type:: bool

MiddleOfSegment = 16¶

class Type¶: Bases: int

class Types¶
class Types(Union[QgsPointLocator.Types, QgsPointLocator.Type])
class Types(QgsPointLocator.Types): Bases: sip.wrapper

Vertex = 1¶

cachedGeometryCount(self) → int¶

Returns how many geometries are cached in the index

New in version 2.14.

Return type:: int

childEvent(self, QChildEvent)¶

connectNotify(self, QMetaMethod)¶

customEvent(self, QEvent)¶

destinationCrs(self) → QgsCoordinateReferenceSystem¶

Gets destination CRS - may be an invalid QgsCoordinateReferenceSystem if not doing OTF reprojection

New in version 2.14.

Return type:: QgsCoordinateReferenceSystem

destroyIndex(self)¶

disconnectNotify(self, QMetaMethod)¶

edgesInRect(self, rect: QgsRectangle, filter: QgsPointLocator.MatchFilter = None, relaxed: bool = False) → List[QgsPointLocator.Match]¶

Find edges within a specified rectangle Optional filter may discard unwanted matches. This method is either blocking or non blocking according to relaxed parameter passed

edgesInRect(self, point: QgsPointXY, tolerance: float, filter: QgsPointLocator.MatchFilter = None, relaxed: bool = False) -> List[QgsPointLocator.Match] Override of edgesInRect that construct rectangle from a center point and tolerance This method is either blocking or non blocking according to relaxed parameter passed

Parameters:

rect (QgsRectangle) –
filter (QgsPointLocator.MatchFilter = None) –
relaxed (bool = False) –

Return type:

List[QgsPointLocator.Match]

extent(self) → QgsRectangle¶

Gets extent of the area point locator covers - if None then it caches the whole layer

New in version 2.14.

Return type:: QgsRectangle

hasIndex(self) → bool¶

Indicate whether the data have been already indexed

Return type:: bool

init(self, maxFeaturesToIndex: int = -1, relaxed: bool = False) → bool¶

Prepare the index for queries. Does nothing if the index already exists. If the number of features is greater than the value of maxFeaturesToIndex, creation of index is stopped to make sure we do not run out of memory. If maxFeaturesToIndex is -1, no limits are used.

This method is either blocking or non blocking according to relaxed parameter passed in the constructor. if True, index building will be done in another thread and init() method returns immediately. initFinished() signal will be emitted once the initialization is over.

Returns False if the creation of index is blocking and has been prematurely stopped due to the limit of features, otherwise True