openlayers/src/ol/proj/projection.js

Build tools and sources for developing OpenLayers based mapping applications

goog.provide('ol.proj.Projection');

goog.require('ol');
goog.require('ol.proj.Units');
goog.require('ol.proj.proj4');


/**
 * @classdesc
 * Projection definition class. One of these is created for each projection
 * supported in the application and stored in the {@link ol.proj} namespace.
 * You can use these in applications, but this is not required, as API params
 * and options use {@link ol.ProjectionLike} which means the simple string
 * code will suffice.
 *
 * You can use {@link ol.proj.get} to retrieve the object for a particular
 * projection.
 *
 * The library includes definitions for `EPSG:4326` and `EPSG:3857`, together
 * with the following aliases:
 * * `EPSG:4326`: CRS:84, urn:ogc:def:crs:EPSG:6.6:4326,
 *     urn:ogc:def:crs:OGC:1.3:CRS84, urn:ogc:def:crs:OGC:2:84,
 *     http://www.opengis.net/gml/srs/epsg.xml#4326,
 *     urn:x-ogc:def:crs:EPSG:4326
 * * `EPSG:3857`: EPSG:102100, EPSG:102113, EPSG:900913,
 *     urn:ogc:def:crs:EPSG:6.18:3:3857,
 *     http://www.opengis.net/gml/srs/epsg.xml#3857
 *
 * If you use proj4js, aliases can be added using `proj4.defs()`; see
 * [documentation](https://github.com/proj4js/proj4js). To set an alternative
 * namespace for proj4, use {@link ol.proj.setProj4}.
 *
 * @constructor
 * @param {olx.ProjectionOptions} options Projection options.
 * @struct
 * @api stable
 */
ol.proj.Projection = function(options) {

  /**
   * @private
   * @type {string}
   */
  this.code_ = options.code;

  /**
   * @private
   * @type {ol.proj.Units}
   */
  this.units_ = /** @type {ol.proj.Units} */ (options.units);

  /**
   * @private
   * @type {ol.Extent}
   */
  this.extent_ = options.extent !== undefined ? options.extent : null;

  /**
   * @private
   * @type {ol.Extent}
   */
  this.worldExtent_ = options.worldExtent !== undefined ?
      options.worldExtent : null;

  /**
   * @private
   * @type {string}
   */
  this.axisOrientation_ = options.axisOrientation !== undefined ?
      options.axisOrientation : 'enu';

  /**
   * @private
   * @type {boolean}
   */
  this.global_ = options.global !== undefined ? options.global : false;

  /**
   * @private
   * @type {boolean}
   */
  this.canWrapX_ = !!(this.global_ && this.extent_);

  /**
  * @private
  * @type {function(number, ol.Coordinate):number|undefined}
  */
  this.getPointResolutionFunc_ = options.getPointResolution;

  /**
   * @private
   * @type {ol.tilegrid.TileGrid}
   */
  this.defaultTileGrid_ = null;

  /**
   * @private
   * @type {number|undefined}
   */
  this.metersPerUnit_ = options.metersPerUnit;

  var code = options.code;
  ol.DEBUG && console.assert(code !== undefined,
      'Option "code" is required for constructing instance');
  if (ol.ENABLE_PROJ4JS) {
    var proj4js = ol.proj.proj4.get();
    if (typeof proj4js == 'function') {
      var def = proj4js.defs(code);
      if (def !== undefined) {
        if (def.axis !== undefined && options.axisOrientation === undefined) {
          this.axisOrientation_ = def.axis;
        }
        if (options.metersPerUnit === undefined) {
          this.metersPerUnit_ = def.to_meter;
        }
        if (options.units === undefined) {
          this.units_ = def.units;
        }
      }
    }
  }

};


/**
 * @return {boolean} The projection is suitable for wrapping the x-axis
 */
ol.proj.Projection.prototype.canWrapX = function() {
  return this.canWrapX_;
};


/**
 * Get the code for this projection, e.g. 'EPSG:4326'.
 * @return {string} Code.
 * @api stable
 */
ol.proj.Projection.prototype.getCode = function() {
  return this.code_;
};


/**
 * Get the validity extent for this projection.
 * @return {ol.Extent} Extent.
 * @api stable
 */
ol.proj.Projection.prototype.getExtent = function() {
  return this.extent_;
};


/**
 * Get the units of this projection.
 * @return {ol.proj.Units} Units.
 * @api stable
 */
ol.proj.Projection.prototype.getUnits = function() {
  return this.units_;
};


/**
 * Get the amount of meters per unit of this projection.  If the projection is
 * not configured with `metersPerUnit` or a units identifier, the return is
 * `undefined`.
 * @return {number|undefined} Meters.
 * @api stable
 */
ol.proj.Projection.prototype.getMetersPerUnit = function() {
  return this.metersPerUnit_ || ol.proj.Units.METERS_PER_UNIT[this.units_];
};


/**
 * Get the world extent for this projection.
 * @return {ol.Extent} Extent.
 * @api
 */
ol.proj.Projection.prototype.getWorldExtent = function() {
  return this.worldExtent_;
};


/**
 * Get the axis orientation of this projection.
 * Example values are:
 * enu - the default easting, northing, elevation.
 * neu - northing, easting, up - useful for "lat/long" geographic coordinates,
 *     or south orientated transverse mercator.
 * wnu - westing, northing, up - some planetary coordinate systems have
 *     "west positive" coordinate systems
 * @return {string} Axis orientation.
 */
ol.proj.Projection.prototype.getAxisOrientation = function() {
  return this.axisOrientation_;
};


/**
 * Is this projection a global projection which spans the whole world?
 * @return {boolean} Whether the projection is global.
 * @api stable
 */
ol.proj.Projection.prototype.isGlobal = function() {
  return this.global_;
};


/**
* Set if the projection is a global projection which spans the whole world
* @param {boolean} global Whether the projection is global.
* @api stable
*/
ol.proj.Projection.prototype.setGlobal = function(global) {
  this.global_ = global;
  this.canWrapX_ = !!(global && this.extent_);
};


/**
 * @return {ol.tilegrid.TileGrid} The default tile grid.
 */
ol.proj.Projection.prototype.getDefaultTileGrid = function() {
  return this.defaultTileGrid_;
};


/**
 * @param {ol.tilegrid.TileGrid} tileGrid The default tile grid.
 */
ol.proj.Projection.prototype.setDefaultTileGrid = function(tileGrid) {
  this.defaultTileGrid_ = tileGrid;
};


/**
 * Set the validity extent for this projection.
 * @param {ol.Extent} extent Extent.
 * @api stable
 */
ol.proj.Projection.prototype.setExtent = function(extent) {
  this.extent_ = extent;
  this.canWrapX_ = !!(this.global_ && extent);
};


/**
 * Set the world extent for this projection.
 * @param {ol.Extent} worldExtent World extent
 *     [minlon, minlat, maxlon, maxlat].
 * @api
 */
ol.proj.Projection.prototype.setWorldExtent = function(worldExtent) {
  this.worldExtent_ = worldExtent;
};


/**
 * Set the getPointResolution function for this projection.
 * @param {function(number, ol.Coordinate):number} func Function
 * @api
 */
ol.proj.Projection.prototype.setGetPointResolution = function(func) {
  this.getPointResolutionFunc_ = func;
};


/**
 * Get the custom point resolution function for this projection (if set).
 * @return {function(number, ol.Coordinate):number|undefined} The custom point
 * resolution function (if set).
 */
ol.proj.Projection.prototype.getPointResolutionFunc = function() {
  return this.getPointResolutionFunc_;
};