146 lines
3.8 KiB
JavaScript
146 lines
3.8 KiB
JavaScript
goog.provide('ol.proj.EPSG3857');
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goog.require('ol');
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goog.require('ol.math');
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goog.require('ol.proj.Projection');
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goog.require('ol.proj.Units');
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/**
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* @classdesc
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* Projection object for web/spherical Mercator (EPSG:3857).
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*
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* @constructor
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* @extends {ol.proj.Projection}
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* @param {string} code Code.
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* @private
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*/
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ol.proj.EPSG3857.Projection_ = function(code) {
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ol.proj.Projection.call(this, {
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code: code,
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units: ol.proj.Units.METERS,
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extent: ol.proj.EPSG3857.EXTENT,
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global: true,
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worldExtent: ol.proj.EPSG3857.WORLD_EXTENT,
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getPointResolution: function(resolution, point) {
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return resolution / ol.math.cosh(point[1] / ol.proj.EPSG3857.RADIUS);
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}
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});
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};
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ol.inherits(ol.proj.EPSG3857.Projection_, ol.proj.Projection);
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/**
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* Radius of WGS84 sphere
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*
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* @const
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* @type {number}
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*/
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ol.proj.EPSG3857.RADIUS = 6378137;
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/**
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* @const
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* @type {number}
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*/
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ol.proj.EPSG3857.HALF_SIZE = Math.PI * ol.proj.EPSG3857.RADIUS;
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/**
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* @const
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* @type {ol.Extent}
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*/
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ol.proj.EPSG3857.EXTENT = [
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-ol.proj.EPSG3857.HALF_SIZE, -ol.proj.EPSG3857.HALF_SIZE,
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ol.proj.EPSG3857.HALF_SIZE, ol.proj.EPSG3857.HALF_SIZE
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];
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/**
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* @const
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* @type {ol.Extent}
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*/
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ol.proj.EPSG3857.WORLD_EXTENT = [-180, -85, 180, 85];
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/**
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* Projections equal to EPSG:3857.
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*
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* @const
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* @type {Array.<ol.proj.Projection>}
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*/
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ol.proj.EPSG3857.PROJECTIONS = [
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new ol.proj.EPSG3857.Projection_('EPSG:3857'),
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new ol.proj.EPSG3857.Projection_('EPSG:102100'),
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new ol.proj.EPSG3857.Projection_('EPSG:102113'),
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new ol.proj.EPSG3857.Projection_('EPSG:900913'),
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new ol.proj.EPSG3857.Projection_('urn:ogc:def:crs:EPSG:6.18:3:3857'),
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new ol.proj.EPSG3857.Projection_('urn:ogc:def:crs:EPSG::3857'),
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new ol.proj.EPSG3857.Projection_('http://www.opengis.net/gml/srs/epsg.xml#3857')
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];
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/**
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* Transformation from EPSG:4326 to EPSG:3857.
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*
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* @param {Array.<number>} input Input array of coordinate values.
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* @param {Array.<number>=} opt_output Output array of coordinate values.
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* @param {number=} opt_dimension Dimension (default is `2`).
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* @return {Array.<number>} Output array of coordinate values.
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*/
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ol.proj.EPSG3857.fromEPSG4326 = function(input, opt_output, opt_dimension) {
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var length = input.length,
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dimension = opt_dimension > 1 ? opt_dimension : 2,
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output = opt_output;
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if (output === undefined) {
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if (dimension > 2) {
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// preserve values beyond second dimension
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output = input.slice();
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} else {
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output = new Array(length);
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}
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}
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var halfSize = ol.proj.EPSG3857.HALF_SIZE;
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for (var i = 0; i < length; i += dimension) {
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output[i] = halfSize * input[i] / 180;
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var y = ol.proj.EPSG3857.RADIUS *
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Math.log(Math.tan(Math.PI * (input[i + 1] + 90) / 360));
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if (y > halfSize) {
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y = halfSize;
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} else if (y < -halfSize) {
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y = -halfSize;
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}
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output[i + 1] = y;
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}
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return output;
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};
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/**
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* Transformation from EPSG:3857 to EPSG:4326.
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*
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* @param {Array.<number>} input Input array of coordinate values.
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* @param {Array.<number>=} opt_output Output array of coordinate values.
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* @param {number=} opt_dimension Dimension (default is `2`).
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* @return {Array.<number>} Output array of coordinate values.
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*/
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ol.proj.EPSG3857.toEPSG4326 = function(input, opt_output, opt_dimension) {
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var length = input.length,
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dimension = opt_dimension > 1 ? opt_dimension : 2,
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output = opt_output;
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if (output === undefined) {
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if (dimension > 2) {
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// preserve values beyond second dimension
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output = input.slice();
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} else {
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output = new Array(length);
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}
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}
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for (var i = 0; i < length; i += dimension) {
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output[i] = 180 * input[i] / ol.proj.EPSG3857.HALF_SIZE;
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output[i + 1] = 360 * Math.atan(
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Math.exp(input[i + 1] / ol.proj.EPSG3857.RADIUS)) / Math.PI - 90;
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}
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return output;
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};
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