Snap~Snap

import Snap from 'ol/interaction/Snap.js';

Handles snapping of vector features while modifying or drawing them. The features can come from a VectorSource or Collection Any interaction object that allows the user to interact with the features using the mouse can benefit from the snapping, as long as it is added before.

The snap interaction modifies map browser event coordinate and pixel properties to force the snap to occur to any interaction that uses them.

Example:

import Snap from 'ol/interaction/Snap.js';

const snap = new Snap({
  source: source
});

map.addInteraction(snap);

new Snap(options) interaction/Snap.js, line 320

Name	Type	Description
`features`	Collection<Feature> \| undefined	Snap to these features. Either this option or source should be provided.
`source`	VectorSource \| undefined	Snap to features from this source. Either this option or features should be provided
`edge`	boolean (defaults to true)	Snap to edges.
`vertex`	boolean (defaults to true)	Snap to vertices.
`intersection`	boolean (defaults to false)	Snap to intersections between segments.
`pixelTolerance`	number (defaults to 10)	Pixel tolerance for considering the pointer close enough to a segment or vertex for snapping.
`segmenters`	Segmenters \| undefined	Custom segmenters by `Type`. By default, the following segmenters are used: `Point`: A one-dimensional segment (e.g. `[[10, 20]]`) representing the point. `LineString`: One two-dimensional segment (e.g. `[[10, 20], [30, 40]]`) for each segment of the linestring. `Polygon`: One two-dimensional segment for each segment of the exterior ring and the interior rings. `Circle`: One two-dimensional segment for each segment of a regular polygon with 32 points representing the circle circumference. `GeometryCollection`: All segments of the contained geometries. `MultiPoint`: One one-dimensional segment for each point. `MultiLineString`: One two-dimensional segment for each segment of the linestrings. `MultiPolygon`: One two-dimensional segment for each segment of the polygons.

Fires:

change (BaseEvent) - Generic change event. Triggered when the revision counter is increased.
change:active (ObjectEvent)
error (BaseEvent) - Generic error event. Triggered when an error occurs.
propertychange (ObjectEvent) - Triggered when a property is changed.
snap (SnapEvent) - Triggered upon snapping to vertex or edge
unsnap (SnapEvent) - Triggered if no longer snapped

Extends

PointerInteraction

Observable Properties

Name	Type	Settable	ObjectEvent type	Description
`active`	boolean	yes	`change:active`	`true` if the interaction is active, `false` otherwise.

Methods

addFeature(feature, register) interaction/Snap.js, line 446

Add a feature to the collection of features that we may snap to.

Name	Type	Description
`feature`	Feature	Feature.
`register`	boolean \| undefined	Whether to listen to the feature change or not Defaults to `true`.

changed() inherited Observable.js, line 68

Increases the revision counter and dispatches a 'change' event.

dispatchEvent(event){boolean | undefined} inherited events/Target.js, line 85

Dispatches an event and calls all listeners listening for events of this type. The event parameter can either be a string or an Object with a type property.

Name	Type	Description
`event`	BaseEvent \| string	Event object.

Returns:

false if anyone called preventDefault on the event object or if any of the listeners returned false.

get(key){*} inherited Object.js, line 136

Gets a value.

Name	Type	Description
`key`	string	Key name.

Returns:

Value.

getActive(){boolean} inherited interaction/Interaction.js, line 82

Return whether the interaction is currently active.

Returns:

true if the interaction is active, false otherwise.

getKeys(){Array.<string>} inherited Object.js, line 149

Get a list of object property names.

Returns:

List of property names.

getMap(){Map | null} inherited interaction/Interaction.js, line 91

Get the map associated with this interaction.

Returns:

Map.

getPointerCount(){number} inherited interaction/Pointer.js, line 95

Returns the current number of pointers involved in the interaction, e.g. 2 when two fingers are used.

Returns:

The number of pointers.

getProperties(){NoInfer.<Properties>} inherited Object.js, line 158

Get an object of all property names and values.

Returns:

Object.

getRevision(){number} inherited Observable.js, line 79

Get the version number for this object. Each time the object is modified, its version number will be incremented.

Returns:

Revision.

handleEvent(evt){boolean} interaction/Snap.js, line 578

Name	Type	Description
`evt`	MapBrowserEvent	Map browser event.

Returns:

false to stop event propagation.

on(type, listener){EventsKey | Array<EventsKey>} inherited Observable.js, line 152

Listen for a certain type of event.

Name	Type	Description
`type`	string \| Array.<string>	The event type or array of event types.
`listener`	function	The listener function.

Returns:

Unique key for the listener. If called with an array of event types as the first argument, the return will be an array of keys.

once(type, listener){EventsKey | Array<EventsKey>} inherited Observable.js, line 164

Listen once for a certain type of event.

Name	Type	Description
`type`	string \| Array.<string>	The event type or array of event types.
`listener`	function	The listener function.

Returns:

Unique key for the listener. If called with an array of event types as the first argument, the return will be an array of keys.

removeFeature(feature, unlisten) interaction/Snap.js, line 666

Remove a feature from the collection of features that we may snap to.

Name	Type	Description
`feature`	Feature	Feature
`unlisten`	boolean \| undefined	Whether to unlisten to the feature change or not. Defaults to `true`.

set(key, value, silent) inherited Object.js, line 218

Sets a value.

Name	Type	Description
`key`	string	Key name.
`value`	*	Value.
`silent`	boolean \| undefined	Update without triggering an event.

setActive(active) inherited interaction/Interaction.js, line 111

Activate or deactivate the interaction.

Name	Type	Description
`active`	boolean	Active.

setProperties(values, silent) inherited Object.js, line 238

Sets a collection of key-value pairs. Note that this changes any existing properties and adds new ones (it does not remove any existing properties).

Name	Type	Description
`values`	Partial.<NoInfer.<Properties>>	Values.
`silent`	boolean \| undefined	Update without triggering an event.

un(type, listener) inherited Observable.js, line 173

Unlisten for a certain type of event.

Name	Type	Description
`type`	string \| Array.<string>	The event type or array of event types.
`listener`	function	The listener function.

unset(key, silent) inherited Object.js, line 262

Unsets a property.

Name	Type	Description
`key`	string	Key name.
`silent`	boolean \| undefined	Unset without triggering an event.