ol-ext/render/InseeGrid.js

A set of cool extensions for OpenLayers (ol) in node modules structure

/*	Copyright (c) 2017 Jean-Marc VIGLINO, 
  released under the CeCILL-B license (French BSD license)
  (http://www.cecill.info/licences/Licence_CeCILL-B_V1-en.txt).
*/

import proj4 from 'proj4'
import ol_Object from 'ol/Object'
import {ol_ext_inherits} from '../util/ext'
import {register as ol_proj_proj4_register} from 'ol/proj/proj4.js';
import {transform as ol_proj_transform} from 'ol/proj'
import {transformExtent as ol_proj_transformExtent} from 'ol/proj'
import ol_geom_Polygon from 'ol/geom/Polygon'

/**
 * French INSEE grids
 * @classdesc a class to compute French INSEE grids, ie. fix area (200x200m) square grid, 
 * based appon EPSG:3035
 *
 * @requires proj4
 * @constructor 
 * @extends {ol_Object}
 * @param {Object} [options]
 *  @param {number} [options.size] size grid size in meter, default 200 (200x200m)
 */
var ol_InseeGrid = function (options) {
  options = options || {};
  
  // Define EPSG:3035 if none
  if (!proj4.defs["EPSG:3035"]) {
    proj4.defs("EPSG:3035","+proj=laea +lat_0=52 +lon_0=10 +x_0=4321000 +y_0=3210000 +ellps=GRS80 +units=m +no_defs");
    ol_proj_proj4_register(proj4);
  }

  ol_Object.call (this, options);

  // Options
  var size = Math.max(200, Math.round((options.size||0)/200) * 200);
  this.set('size', size);
};
ol_ext_inherits (ol_InseeGrid, ol_Object);

/** Grid extent (in EPSG:3035)
 */
ol_InseeGrid.extent = [3200000,2000000,4300000,3140000];

/** Get the grid extent
 * @param {ol.proj.ProjLike} [proj='EPSG:3857']
 */
ol_InseeGrid.prototype.getExtent = function (proj) {
  return ol_proj_transformExtent(ol_InseeGrid.extent, proj||'EPSG:3035', 'EPSG:3857')
};

/** Get grid geom at coord
 * @param {ol.Coordinate} coord
 * @param {ol.proj.ProjLike} [proj='EPSG:3857']
 */
ol_InseeGrid.prototype.getGridAtCoordinate = function (coord, proj) {
  var c = ol_proj_transform(coord, proj||'EPSG:3857', 'EPSG:3035')
  var s = this.get('size');
  var x = Math.floor(c[0]/s) * s;
  var y = Math.floor(c[1]/s) * s;
  var geom = new ol_geom_Polygon([[[x,y],[x+s,y],[x+s,y+s],[x,y+s],[x,y]]]);
  geom.transform('EPSG:3035', proj||'EPSG:3857');
  return geom;
};

export default ol_InseeGrid