Class: ScaleLine

ol/control/ScaleLine~ScaleLine 


import ScaleLine from 'ol/control/ScaleLine.js';

A control displaying rough y-axis distances, calculated for the center of the viewport. For conformal projections (e.g. EPSG:3857, the default view projection in OpenLayers), the scale is valid for all directions. No scale line will be shown when the y-axis distance of a pixel at the viewport center cannot be calculated in the view projection. By default the scale line will show in the bottom left portion of the map, but this can be changed by using the css selector .ol-scale-line. When specifying bar as true, a scalebar will be rendered instead of a scaleline. For cartesian measurements of the scaleline, you need to set the getPointResolution method of your projection to simply return the input value, e.g. projection.setGetPointResolution(r => r);

new ScaleLine(options)

control/ScaleLine.js, line 78
Name Type Description
className string | undefined

CSS class name. The default is ol-scale-bar when configured with bar: true. Otherwise the default is ol-scale-line.
minWidth number (defaults to 64)

Minimum width in pixels at the OGC default dpi. The width will be adjusted to match the dpi used.
maxWidth number | undefined

Maximum width in pixels at the OGC default dpi. The width will be adjusted to match the dpi used.
render function | undefined

Function called when the control should be re-rendered. This is called in a requestAnimationFrame callback.
target HTMLElement | string | undefined

Specify a target if you want the control to be rendered outside of the map's viewport.
units Units (defaults to 'metric')

Units.
bar boolean (defaults to false)

Render scalebars instead of a line.
steps number (defaults to 4)

Number of steps the scalebar should use. Use even numbers for best results. Only applies when bar is true.
text boolean (defaults to false)

Render the text scale above of the scalebar. Only applies when bar is true.
dpi number | undefined

dpi of output device such as printer. Only applies when bar is true. If undefined the OGC default screen pixel size of 0.28mm will be assumed.
Fires:

Extends

Observable Properties

Name Type Settable ObjectEvent type Description
units Units yes change:units

The units to use in the scale line.

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.

getKeys(){Array.<string>} inherited

Object.js, line 148

Get a list of object property names.

Returns:
List of property names.

getMap(){Map | null} inherited

control/Control.js, line 104

Get the map associated with this control.

Returns:
Map.

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.

getUnits(){Units}

control/ScaleLine.js, line 198

Return the units to use in the scale line.

Returns:
The units to use in the scale line.

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.

setDpi(dpi)

control/ScaleLine.js, line 224

Specify the dpi of output device such as printer.

Name Type Description
dpi number | undefined

The dpi of output device.

setMap(map) inherited

control/Control.js, line 116

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

Name Type Description
map Map | null

Map.

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.

setTarget(target) inherited

control/Control.js, line 153

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 HTMLElement | string

Target.

setUnits(units)

control/ScaleLine.js, line 215

Set the units to use in the scale line.

Name Type Description
units Units

The units to use in the scale line.

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.