proj4js/lib/Proj.js

var extend = require('./extend');
var common = require('./common');
var defs = require('./defs');
var constants = require('./constants/index');
var datum = require('./datum');
var projections = require('./projections/index');
var wkt = require('./wkt');
var projStr = require('./projString');

function Projection(srsCode) {
  if (!(this instanceof Projection)) {
    return new Projection(srsCode);
  }
  this.srsCodeInput = srsCode;
  this.x0 = 0;
  this.y0 = 0;
  var obj;
  if (typeof srsCode === 'string') {
    //check to see if this is a WKT string
    if (srsCode in defs) {
      this.deriveConstants(defs[srsCode]);
      extend(this, defs[srsCode]);
    }
    else if ((srsCode.indexOf('GEOGCS') >= 0) || (srsCode.indexOf('GEOCCS') >= 0) || (srsCode.indexOf('PROJCS') >= 0) || (srsCode.indexOf('LOCAL_CS') >= 0)) {
      obj = wkt(srsCode);
      this.deriveConstants(obj);
      extend(this, obj);
      //this.loadProjCode(this.projName);
    }
    else if (srsCode[0] === '+') {
      obj = projStr(srsCode);
      this.deriveConstants(obj);
      extend(this, obj);
    }
  }
  else {
    this.deriveConstants(srsCode);
    extend(this, srsCode);
  }

  this.initTransforms(this.projName);
}
Projection.projections = projections;
Projection.projections.start();
Projection.prototype = {
  /**
   * Function: initTransforms
   *    Finalize the initialization of the Proj object
   *
   */
  initTransforms: function(projName) {
    var ourProj = Projection.projections.get(projName);
    if (ourProj) {
      extend(this, ourProj);
      this.init();
    }
    else {
      throw ("unknown projection " + projName);
    }
  },

  deriveConstants: function(self) {
    // DGR 2011-03-20 : nagrids -> nadgrids
    if (self.nadgrids && self.nadgrids.length === 0) {
      self.nadgrids = null;
    }
    if (self.nadgrids) {
      self.grids = self.nadgrids.split(",");
      var g = null,
        l = self.grids.length;
      if (l > 0) {
        for (var i = 0; i < l; i++) {
          g = self.grids[i];
          var fg = g.split("@");
          if (fg[fg.length - 1] === "") {
            //..reportError("nadgrids syntax error '" + self.nadgrids + "' : empty grid found");
            continue;
          }
          self.grids[i] = {
            mandatory: fg.length === 1, //@=> optional grid (no error if not found)
            name: fg[fg.length - 1],
            grid: constants.grids[fg[fg.length - 1]] //FIXME: grids loading ...
          };
          if (self.grids[i].mandatory && !self.grids[i].grid) {
            //..reportError("Missing '" + self.grids[i].name + "'");
          }
        }
      }
      // DGR, 2011-03-20: grids is an array of objects that hold
      // the loaded grids, its name and the mandatory informations of it.
    }
    if (self.datumCode && self.datumCode !== 'none') {
      var datumDef = constants.Datum[self.datumCode];
      if (datumDef) {
        self.datum_params = datumDef.towgs84 ? datumDef.towgs84.split(',') : null;
        self.ellps = datumDef.ellipse;
        self.datumName = datumDef.datumName ? datumDef.datumName : self.datumCode;
      }
    }
    if (!self.a) { // do we have an ellipsoid?
      var ellipse = constants.Ellipsoid[self.ellps] ? constants.Ellipsoid[self.ellps] : constants.Ellipsoid.WGS84;
      extend(self, ellipse);
    }
    if (self.rf && !self.b) {
      self.b = (1.0 - 1.0 / self.rf) * self.a;
    }
    if (self.rf === 0 || Math.abs(self.a - self.b) < common.EPSLN) {
      self.sphere = true;
      self.b = self.a;
    }
    self.a2 = self.a * self.a; // used in geocentric
    self.b2 = self.b * self.b; // used in geocentric
    self.es = (self.a2 - self.b2) / self.a2; // e ^ 2
    self.e = Math.sqrt(self.es); // eccentricity
    if (self.R_A) {
      self.a *= 1 - self.es * (common.SIXTH + self.es * (common.RA4 + self.es * common.RA6));
      self.a2 = self.a * self.a;
      self.b2 = self.b * self.b;
      self.es = 0;
    }
    self.ep2 = (self.a2 - self.b2) / self.b2; // used in geocentric
    if (!self.k0) {
      self.k0 = 1.0; //default value
    }
    //DGR 2010-11-12: axis
    if (!self.axis) {
      self.axis = "enu";
    }

    self.datum = datum(self);
  }
};
module.exports = Projection;