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node_modules/ol/src/proj/epsg3857.js

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+/**
+ * @module ol/proj/epsg3857
+ */
+import Projection from './Projection.js';
+import Units from './Units.js';
+import {cosh} from '../math.js';
+
+/**
+ * Radius of WGS84 sphere
+ *
+ * @const
+ * @type {number}
+ */
+export const RADIUS = 6378137;
+
+/**
+ * @const
+ * @type {number}
+ */
+export const HALF_SIZE = Math.PI * RADIUS;
+
+/**
+ * @const
+ * @type {import("../extent.js").Extent}
+ */
+export const EXTENT = [-HALF_SIZE, -HALF_SIZE, HALF_SIZE, HALF_SIZE];
+
+/**
+ * @const
+ * @type {import("../extent.js").Extent}
+ */
+export const WORLD_EXTENT = [-180, -85, 180, 85];
+
+/**
+ * Maximum safe value in y direction
+ * @const
+ * @type {number}
+ */
+export const MAX_SAFE_Y = RADIUS * Math.log(Math.tan(Math.PI / 2));
+
+/**
+ * @classdesc
+ * Projection object for web/spherical Mercator (EPSG:3857).
+ */
+class EPSG3857Projection extends Projection {
+  /**
+   * @param {string} code Code.
+   */
+  constructor(code) {
+    super({
+      code: code,
+      units: Units.METERS,
+      extent: EXTENT,
+      global: true,
+      worldExtent: WORLD_EXTENT,
+      getPointResolution: function (resolution, point) {
+        return resolution / cosh(point[1] / RADIUS);
+      },
+    });
+  }
+}
+
+/**
+ * Projections equal to EPSG:3857.
+ *
+ * @const
+ * @type {Array<import("./Projection.js").default>}
+ */
+export const PROJECTIONS = [
+  new EPSG3857Projection('EPSG:3857'),
+  new EPSG3857Projection('EPSG:102100'),
+  new EPSG3857Projection('EPSG:102113'),
+  new EPSG3857Projection('EPSG:900913'),
+  new EPSG3857Projection('http://www.opengis.net/def/crs/EPSG/0/3857'),
+  new EPSG3857Projection('http://www.opengis.net/gml/srs/epsg.xml#3857'),
+];
+
+/**
+ * Transformation from EPSG:4326 to EPSG:3857.
+ *
+ * @param {Array<number>} input Input array of coordinate values.
+ * @param {Array<number>} [opt_output] Output array of coordinate values.
+ * @param {number} [opt_dimension] Dimension (default is `2`).
+ * @return {Array<number>} Output array of coordinate values.
+ */
+export function fromEPSG4326(input, opt_output, opt_dimension) {
+  const length = input.length;
+  const dimension = opt_dimension > 1 ? opt_dimension : 2;
+  let output = opt_output;
+  if (output === undefined) {
+    if (dimension > 2) {
+      // preserve values beyond second dimension
+      output = input.slice();
+    } else {
+      output = new Array(length);
+    }
+  }
+  for (let i = 0; i < length; i += dimension) {
+    output[i] = (HALF_SIZE * input[i]) / 180;
+    let y = RADIUS * Math.log(Math.tan((Math.PI * (+input[i + 1] + 90)) / 360));
+    if (y > MAX_SAFE_Y) {
+      y = MAX_SAFE_Y;
+    } else if (y < -MAX_SAFE_Y) {
+      y = -MAX_SAFE_Y;
+    }
+    output[i + 1] = y;
+  }
+  return output;
+}
+
+/**
+ * Transformation from EPSG:3857 to EPSG:4326.
+ *
+ * @param {Array<number>} input Input array of coordinate values.
+ * @param {Array<number>} [opt_output] Output array of coordinate values.
+ * @param {number} [opt_dimension] Dimension (default is `2`).
+ * @return {Array<number>} Output array of coordinate values.
+ */
+export function toEPSG4326(input, opt_output, opt_dimension) {
+  const length = input.length;
+  const dimension = opt_dimension > 1 ? opt_dimension : 2;
+  let output = opt_output;
+  if (output === undefined) {
+    if (dimension > 2) {
+      // preserve values beyond second dimension
+      output = input.slice();
+    } else {
+      output = new Array(length);
+    }
+  }
+  for (let i = 0; i < length; i += dimension) {
+    output[i] = (180 * input[i]) / HALF_SIZE;
+    output[i + 1] =
+      (360 * Math.atan(Math.exp(input[i + 1] / RADIUS))) / Math.PI - 90;
+  }
+  return output;
+}