Externs
This directory contains externs files, which tell the Closure compiler about symbols and properties that it should not rename.
oli.js
These are special externs that belong to OpenLayers, and this document explains their purpose and how they are used.
Prevent class properties from being renamed
For events, we make properties available to the application. Methods can be made available by just marking them with the @api annotation directly where they are defined; properties should also be added to oli.js:
/**
* @interface
*/
oli.MapBrowserEvent = function() {};
/**
* @type {ol.Coordinate}
*/
oli.MapBrowserEvent.prototype.coordinate;
In the source file (src/ol/MapBrowserEvent.js), the class needs to implement this interface:
/**
* ...
* @constructor
* @implements {oli.MapBrowserEvent}
*/
ol.MapBrowserEvent = function(type, map, originalEvent, opt_frameState) {
// ...
/**
* @type {ol.Coordinate}
* @api
*/
this.coordinate = map.getEventCoordinate(this.originalEvent);
// ...
};
Override methods in custom classes
For custom subclasses in applications, which can be created using ol.inherits, the API may want to make certain methods available to override. In addition to marking such methods as @api, they should also be added to an interface in oli.js:
/**
* @interface
*/
oli.control.Control = function() {};
/**
* @param {ol.PluggableMap} map Map.
* @return {undefined} Undefined.
*/
oli.control.Control.prototype.setMap = function(map) {};
This interface must be implemented by the class in the source file (src/ol/control/control.js):
/**
* ...
* @constructor
* @implements {oli.control.Control}
*/
ol.control.Control = function(options) {
// ...
};
// ...
/**
* Application subclasses may override this.
* @param {ol.PluggableMap} map Map.
* @api
*/
ol.control.Control.prototype.setMap = function(map) {
// ...
};
See Custom controls example for an example of how this can be used.