OpenLayers v4.0.1 API - Class: Control

# Class: Control

This documentation is for OpenLayers v4.0.1. The latest is v.

## ol.control.Control

A control is a visible widget with a DOM element in a fixed position on the screen. They can involve user input (buttons), or be informational only; the position is determined using CSS. By default these are placed in the container with CSS class name `ol-overlaycontainer-stopevent`, but can use any outside DOM element.

This is the base class for controls. You can use it for simple custom controls by creating the element with listeners, creating an instance:

    var myControl = new ol.control.Control({element: myElement});

and then adding this to the map.

The main advantage of having this as a control rather than a simple separate DOM element is that preventing propagation is handled for you. Controls will also be `ol.Object`s in a `ol.Collection`, so you can use their methods.

You can also extend this base for your own control class. See examples/custom-controls for an example of how to do this.

#### new ol.control.Control(options)

src/ol/control/control.js, line 39

  Name | Type | Description
  --- | --- | ---

  `options`

  Control options.

  Name | Type | Description
  --- | --- | ---
  `element` | Element | undefined | The element is the control's container element. This only needs to be specified if you're developing a custom control.
  `render` | function | undefined | Function called when the control should be re-rendered. This is called in a requestAnimationFrame callback.
  `target` | Element | string | undefined | Specify a target if you want the control to be rendered outside of the map's viewport.

  ##### Fires:

  - `change` (ol.events.Event) - Generic change event. Triggered when the revision counter is increased.
  - `propertychange` (ol.Object.Event) - Triggered when a property is changed.

### Subclasses

- ol.control.Attribution
- ol.control.FullScreen
- ol.control.MousePosition
- ol.control.OverviewMap
- ol.control.Rotate
- ol.control.ScaleLine
- ol.control.Zoom
- ol.control.ZoomSlider
- ol.control.ZoomToExtent

### Extends

- ol.Object

### Methods

#### changed() inherited

src/ol/observable.js, line 58

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

#### dispatchEvent(event) inherited

src/ol/observable.js, line 75

  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` | Object | ol.events.Event | string | Event object.

#### get(key){*} inherited

src/ol/object.js, line 101

  Gets a value.

  Name | Type | Description
  --- | --- | ---
  `key` | string | Key name.

  ##### Returns:

  Value.

#### getKeys(){Array.<string>} inherited

src/ol/object.js, line 115

  Get a list of object property names.

  ##### Returns:

  List of property names.

#### getMap(){ol.Map}

src/ol/control/control.js, line 94

  Get the map associated with this control.

  ##### Returns:

  Map.

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

src/ol/object.js, line 125

  Get an object of all property names and values.

  ##### Returns:

  Object.

#### getRevision(){number} inherited

src/ol/observable.js, line 84

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

  ##### Returns:

  Revision.

#### on(type, listener, opt_this){ol.EventsKey|Array.<ol.EventsKey>} inherited

src/ol/observable.js, line 99

  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.
  `this` | Object | The object to use as `this` in `listener`.

  ##### 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, opt_this){ol.EventsKey|Array.<ol.EventsKey>} inherited

src/ol/observable.js, line 124

  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.
  `this` | Object | The object to use as `this` in `listener`.

  ##### 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

src/ol/object.js, line 150

  Sets a value.

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

#### setMap(map)

src/ol/control/control.js, line 107

  Remove the control from its current map and attach it to the new map. Subclasses may set up event handlers to get notified about changes to the map here.

  Name | Type | Description
  --- | --- | ---
  `map` | ol.Map | Map.

#### setProperties(values, opt_silent) inherited

src/ol/object.js, line 170

  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.

#### setTarget(target)

src/ol/control/control.js, line 138

  This function is used to set a target element for the control. It has no effect if it is called after the control has been added to the map (i.e. after `setMap` is called on the control). If no `target` is set in the options passed to the control constructor and if `setTarget` is not called then the control is added to the map's overlay container.

  Name | Type | Description
  --- | --- | ---
  `target` | Element | string | Target.

#### un(type, listener, opt_this) inherited

src/ol/observable.js, line 147

  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.
  `this` | Object | The object which was used as `this` by the `listener`.

#### unset(key, opt_silent) inherited

src/ol/object.js, line 184

  Unsets a property.

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