Class: Layer

ol/layer/Layer~Layer 


import Layer from 'ol/layer/Layer';

Base class from which all layer types are derived. This should only be instantiated in the case where a custom layer is be 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 module:ol/interaction/Select~Select use unmanaged layers internally. These unmanaged layers are associated with the map using module:ol/layer/Layer~Layer#setMap instead.

A generic change event is fired when the state of the source changes.

Please note that for performance reasons several layers might get rendered to the same HTML element, which will cause map.forEachLayerAtPixel() to give false positives. To avoid this, apply different className properties to the layers at creation time.

new Layer(options)

layer/Layer.js, line 99
Name Type Description
options

Layer options.

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 module:ol/extent~Extent

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

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

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

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

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

The maximum view zoom level (inclusive) at which this layer will be visible.
source module:ol/source/Source~Source

Source for this layer. If not provided to the constructor, the source can be set by calling layer.setSource(source) after construction.
map module:ol/PluggableMap~PluggableMap

Map.
render module:ol/layer/Layer~RenderFunction

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, *>

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

Subclasses

Extends

Observable Properties

Name Type Settable ol/Object.ObjectEvent type Description
extent module:ol/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 yes change:source

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

The visibility of the layer.
zIndex number yes change:zindex

The Z-index of the layer.

Methods

changed() inherited

Observable.js, line 70

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 module:ol/events/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.

getExtent(){module:ol/extent~Extent|undefined} inherited

layer/Base.js, line 183

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 195

Return the maximum resolution of the layer.

Returns:
The maximum resolution of the layer.

getMaxZoom(){number} inherited

layer/Base.js, line 225

Return the maximum zoom level of the layer.

Returns:
The maximum zoom level of the layer.

getMinResolution(){number} inherited

layer/Base.js, line 205

Return the minimum resolution of the layer.

Returns:
The minimum resolution of the layer.

getMinZoom(){number} inherited

layer/Base.js, line 215

Return the minimum zoom level of the layer.

Returns:
The minimum zoom level of the layer.

getOpacity(){number} inherited

layer/Base.js, line 235

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 81

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

Returns:
Revision.

getSource(){SourceType}

layer/Layer.js, line 194

Get the layer source.

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

getVisible(){boolean} inherited

layer/Base.js, line 253

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

Returns:
The visibility of the layer.

getZIndex(){number} inherited

layer/Base.js, line 264

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

Returns:
The Z-index of the layer.

on(type, listener){module:ol/events~EventsKey|Array.<module:ol/events~EventsKey>} inherited

Observable.js, line 155

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){module:ol/events~EventsKey|Array.<module:ol/events~EventsKey>} inherited

Observable.js, line 167

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, opt_silent) inherited

Object.js, line 203

Sets a value.

Name Type Description
key string

Key name.
value *

Value.
silent boolean

Update without triggering an event.

setExtent(extent) inherited

layer/Base.js, line 275

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

Name Type Description
extent module:ol/extent~Extent | undefined

The extent of the layer.

setMap(map)

layer/Layer.js, line 273

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, and the callback in module:ol/Map~Map#forEachLayerAtPixel will receive null as layer. 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 module:ol/Map~Map#addLayer instead.

Name Type Description
map module:ol/PluggableMap~PluggableMap

Map.

setMaxResolution(maxResolution) inherited

layer/Base.js, line 285

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 307

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 295

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 319

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 329

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, opt_silent) inherited

Object.js, line 223

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

Update without triggering an event.

setSource(source)

layer/Layer.js, line 316

Set the layer source.

Name Type Description
source SourceType

The layer source.

setVisible(visible) inherited

layer/Base.js, line 340

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 351

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 176

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, opt_silent) inherited

Object.js, line 247

Unsets a property.

Name Type Description
key string

Key name.
silent boolean

Unset without triggering an event.