Class: QgsSnappingUtils

class qgis.core.QgsSnappingUtils(parent: QObject = None, enableSnappingForInvisibleFeature: bool = True)

Bases: PyQt5.QtCore.QObject

Constructor for QgsSnappingUtils

This class has all the configuration of snapping and can return answers to snapping queries. Internally, it keeps a cache of QgsPointLocator instances for multiple layers.

Currently it supports the following queries: - snapToMap() - has multiple modes of operation - snapToCurrentLayer() For more complex queries it is possible to use locatorForLayer() method that returns point locator instance with layer’s indexed data.

Indexing strategy determines how fast the queries will be and how much memory will be used.

When working with map canvas, it may be useful to use derived class QgsMapCanvasSnappingUtils which keeps the configuration in sync with map canvas (e.g. current view, active layer).

New in version 2.8: Methods

childEvent
clearAllLocators Deletes all existing locators (e.g.
config The snapping configuration controls the behavior of this object
connectNotify
currentLayer The current layer used if mode is SnapCurrentLayer
customEvent
disconnectNotify
dump Gets extra information about the instance
indexingStrategy Find out which strategy is used for indexing - by default hybrid indexing is used
isSignalConnected
layers Query layers used for snapping
locatorForLayer Gets a point locator for the given layer.
mapSettings
prepareIndexProgress Called when finished indexing a layer.
prepareIndexStarting Called when starting to index - can be overridden and e.g.
receivers
sender
senderSignalIndex
setConfig The snapping configuration controls the behavior of this object
setCurrentLayer Sets current layer so that if mode is SnapCurrentLayer we know which layer to use
setEnableSnappingForInvisibleFeature Set if invisible features must be snapped or not.
setIndexingStrategy Sets a strategy for indexing geometry data - determines how fast and memory consuming the data structures will be
setMapSettings Assign current map settings to the utils - used for conversion between screen coords to map coords
snapToCurrentLayer Snap to current layer
snapToMap Snap to map according to the current configuration.
timerEvent
toggleEnabled Toggles the state of snapping

Signals

configChanged Emitted when the snapping settings object changes.

Attributes

IndexAlwaysFull
IndexExtent
IndexHybrid
IndexNeverFull
IndexAlwaysFull = 0
IndexExtent = 3
IndexHybrid = 2
IndexNeverFull = 1
class IndexingStrategy

Bases: int

class LayerConfig(l: QgsVectorLayer, t: Union[QgsPointLocator.Types, QgsPointLocator.Type], tol: float, u: QgsTolerance.UnitType)

Bases: sip.wrapper

Create a new configuration for a snapping layer.

```py snapper = QgsMapCanvasSnappingUtils(mapCanvas)

snapping_layer1 = QgsSnappingUtils.LayerConfig(layer1, QgsPointLocator.Vertex, 10, QgsTolerance.Pixels) snapping_layer2 = QgsSnappingUtils.LayerConfig(layer2, QgsPointLocator.Vertex and QgsPointLocator.Edge, 10, QgsTolerance.Pixels)

snapper.setLayers([snapping_layer1, snapping_layer2]) ```

Parameters:
  • l – The vector layer for which this configuration is
  • t – Which parts of the geometry should be snappable
  • tol – The tolerance radius in which the snapping will trigger
  • u – The unit in which the tolerance is specified

QgsSnappingUtils.LayerConfig(QgsSnappingUtils.LayerConfig)

layer
tolerance
type
unit
childEvent()
clearAllLocators(self)

Deletes all existing locators (e.g. when destination CRS has changed and we need to reindex)

config(self) → QgsSnappingConfig

The snapping configuration controls the behavior of this object

configChanged

Emitted when the snapping settings object changes. [signal]

connectNotify()
currentLayer(self) → QgsVectorLayer

The current layer used if mode is SnapCurrentLayer

customEvent()
disconnectNotify()
dump(self) → str

Gets extra information about the instance

New in version 2.14.

indexingStrategy(self) → QgsSnappingUtils.IndexingStrategy

Find out which strategy is used for indexing - by default hybrid indexing is used

isSignalConnected()
layers(self) → object

Query layers used for snapping

locatorForLayer(self, vl: QgsVectorLayer) → QgsPointLocator

Gets a point locator for the given layer. If such locator does not exist, it will be created

mapSettings(self) → QgsMapSettings
prepareIndexProgress(self, index: int)

Called when finished indexing a layer. When index == count the indexing is complete

prepareIndexStarting(self, count: int)

Called when starting to index - can be overridden and e.g. progress dialog can be provided

receivers()
sender()
senderSignalIndex()
setConfig(self, snappingConfig: QgsSnappingConfig)

The snapping configuration controls the behavior of this object

setCurrentLayer(self, layer: QgsVectorLayer)

Sets current layer so that if mode is SnapCurrentLayer we know which layer to use

setEnableSnappingForInvisibleFeature(self, enable: bool)

Set if invisible features must be snapped or not.

Parameters:enable – Enable or not this feature

New in version 3.2.

setIndexingStrategy(self, strategy: QgsSnappingUtils.IndexingStrategy)

Sets a strategy for indexing geometry data - determines how fast and memory consuming the data structures will be

setMapSettings(self, settings: QgsMapSettings)

Assign current map settings to the utils - used for conversion between screen coords to map coords

snapToCurrentLayer(self, point: QPoint, type: Union[QgsPointLocator.Types, QgsPointLocator.Type], filter: QgsPointLocator.MatchFilter = None) → QgsPointLocator.Match

Snap to current layer

snapToMap(self, point: QPoint, filter: QgsPointLocator.MatchFilter = None) → QgsPointLocator.Match

Snap to map according to the current configuration. Optional filter allows discarding unwanted matches.

snapToMap(self, pointMap: QgsPointXY, filter: QgsPointLocator.MatchFilter = None) -> QgsPointLocator.Match

timerEvent()
toggleEnabled(self)

Toggles the state of snapping

New in version 3.0.