Class: Layer

ol/layer/Layer~Layer 


import Layer from 'ol/layer/Layer.js';

Base class from which all layer types are derived. This should only be instantiated in the case where a custom layer is added to the map with a custom render function. Such a function can be specified in the options object, and is expected to return an HTML element.

A visual representation of raster or vector map data. Layers group together those properties that pertain to how the data is to be displayed, irrespective of the source of that data.

Layers are usually added to a map with map.addLayer(). Components like Draw use unmanaged layers internally. These unmanaged layers are associated with the map using layer.setMap() instead.

A generic change event is fired when the state of the source changes. A sourceready event is fired when the layer's source is ready.

new Layer(options)

layer/Layer.js, line 100
Name Type Description
className string (defaults to 'ol-layer')

A CSS class name to set to the layer element.
opacity number (defaults to 1)

Opacity (0, 1).
visible boolean (defaults to true)

Visibility.
extent Extent | undefined

The bounding extent for layer rendering. The layer will not be rendered outside of this extent.
zIndex number | undefined

The z-index for layer rendering. At rendering time, the layers will be ordered, first by Z-index and then by position. When undefined, a zIndex of 0 is assumed for layers that are added to the map's layers collection, or Infinity when the layer's setMap() method was used.
minResolution number | undefined

The minimum resolution (inclusive) at which this layer will be visible.
maxResolution number | undefined

The maximum resolution (exclusive) below which this layer will be visible.
minZoom number | undefined

The minimum view zoom level (exclusive) above which this layer will be visible.
maxZoom number | undefined

The maximum view zoom level (inclusive) at which this layer will be visible.
source SourceType | undefined

Source for this layer. If not provided to the constructor, the source can be set by calling layer.setSource(source) after construction.
map Map | null | undefined

Map.
render RenderFunction | undefined

Render function. Takes the frame state as input and is expected to return an HTML element. Will overwrite the default rendering for the layer.
properties Object.<string, *> | undefined

Arbitrary observable properties. Can be accessed with #get() and #set().
Fires:

Subclasses

Extends

Observable Properties

Name Type Settable ObjectEvent type Description
extent Extent | undefined yes change:extent

The layer extent.
maxResolution number yes change:maxresolution

The maximum resolution of the layer.
maxZoom number yes change:maxzoom

The maximum zoom level of the layer.
minResolution number yes change:minresolution

The minimum resolution of the layer.
minZoom number yes change:minzoom

The minimum zoom level of the layer.
opacity number yes change:opacity

The opacity of the layer.
source SourceType | null yes change:source

The layer source (or null if not yet set).
visible boolean yes change:visible

The value of the visible property of the layer.
zIndex number | undefined yes change:zindex

The Z-index of the layer.

Methods

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 135

Gets a value.

Name Type Description
key string

Key name.
Returns:
Value.

getAttributions(view){Array.<string>}

layer/Layer.js, line 341

Get the attributions of the source of this layer for the given view.

Name Type Description
view View | ViewStateLayerStateExtent | undefined

View or FrameState. Only required when the layer is not added to a map.
Returns:
Attributions for this layer at the given view.

getExtent(){Extent | undefined} inherited

layer/Base.js, line 207

Return the extent of the layer or undefined if it will be visible regardless of extent.

Returns:
The layer extent.

getKeys(){Array.<string>} inherited

Object.js, line 148

Get a list of object property names.

Returns:
List of property names.

getMaxResolution(){number} inherited

layer/Base.js, line 220

Return the maximum resolution of the layer. Returns Infinity if the layer has no maximum resolution set.

Returns:
The maximum resolution of the layer.

getMaxZoom(){number} inherited

layer/Base.js, line 253

Return the maximum zoom level of the layer. Returns Infinity if the layer has no maximum zoom set.

Returns:
The maximum zoom level of the layer.

getMinResolution(){number} inherited

layer/Base.js, line 231

Return the minimum resolution of the layer. Returns 0 if the layer has no minimum resolution set.

Returns:
The minimum resolution of the layer.

getMinZoom(){number} inherited

layer/Base.js, line 242

Return the minimum zoom level of the layer. Returns -Infinity if the layer has no minimum zoom set.

Returns:
The minimum zoom level of the layer.

getOpacity(){number} inherited

layer/Base.js, line 263

Return the opacity of the layer (between 0 and 1).

Returns:
The opacity of the layer.

getProperties(){Object.<string, *>} inherited

Object.js, line 157

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.

getSource(){SourceType | null}

layer/Layer.js, line 209

Get the layer source.

Returns:
The layer source (or null if not yet set).

getVisible(){boolean} inherited

layer/Base.js, line 282

Return the value of this layer's visible property. To find out whether the layer is visible on a map, use isVisible() instead.

Returns:
The value of the visible property of the layer.

getZIndex(){number | undefined} inherited

layer/Base.js, line 293

Return the Z-index of the layer, which is used to order layers before rendering. Returns undefined if the layer is unmanaged.

Returns:
The Z-index of the layer.

isVisible(view){boolean}

layer/Layer.js, line 300

The layer is visible on the map view, i.e. within its min/max resolution or zoom and extent, not set to visible: false, and not inside a layer group that is set to visible: false.

Name Type Description
view View | ViewStateLayerStateExtent | undefined

View or FrameState. Only required when the layer is not added to a map.
Returns:
The layer is visible in the map view.

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.

set(key, value, silent) inherited

Object.js, line 215

Sets a value.

Name Type Description
key string

Key name.
value *

Value.
silent boolean | undefined

Update without triggering an event.

setExtent(extent) inherited

layer/Base.js, line 313

Set the extent at which the layer is visible. If undefined, the layer will be visible at all extents.

Name Type Description
extent Extent | undefined

The extent of the layer.

setMap(map)

layer/Layer.js, line 436

Sets the layer to be rendered on top of other layers on a map. The map will not manage this layer in its layers collection. This is useful for temporary layers. To remove an unmanaged layer from the map, use #setMap(null).

To add the layer to a map and have it managed by the map, use addLayer instead.

Name Type Description
map Map | null

Map.

setMaxResolution(maxResolution) inherited

layer/Base.js, line 323

Set the maximum resolution at which the layer is visible.

Name Type Description
maxResolution number

The maximum resolution of the layer.

setMaxZoom(maxZoom) inherited

layer/Base.js, line 345

Set the maximum zoom (exclusive) at which the layer is visible. Note that the zoom levels for layer visibility are based on the view zoom level, which may be different from a tile source zoom level.

Name Type Description
maxZoom number

The maximum zoom of the layer.

setMinResolution(minResolution) inherited

layer/Base.js, line 333

Set the minimum resolution at which the layer is visible.

Name Type Description
minResolution number

The minimum resolution of the layer.

setMinZoom(minZoom) inherited

layer/Base.js, line 357

Set the minimum zoom (inclusive) at which the layer is visible. Note that the zoom levels for layer visibility are based on the view zoom level, which may be different from a tile source zoom level.

Name Type Description
minZoom number

The minimum zoom of the layer.

setOpacity(opacity) inherited

layer/Base.js, line 367

Set the opacity of the layer, allowed values range from 0 to 1.

Name Type Description
opacity number

The opacity of the layer.

setProperties(values, silent) inherited

Object.js, line 235

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 Object.<string, *>

Values.
silent boolean | undefined

Update without triggering an event.

setSource(source)

layer/Layer.js, line 484

Set the layer source.

Name Type Description
source SourceType | null

The layer source.

setVisible(visible) inherited

layer/Base.js, line 378

Set the visibility of the layer (true or false).

Name Type Description
visible boolean

The visibility of the layer.

setZIndex(zindex) inherited

layer/Base.js, line 389

Set Z-index of the layer, which is used to order layers before rendering. The default Z-index is 0.

Name Type Description
zindex number

The z-index of the layer.

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 259

Unsets a property.

Name Type Description
key string

Key name.
silent boolean | undefined

Unset without triggering an event.