Add ol.proj.EPSG21781

src/ol/proj/epsg21781projection.exports

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+@exportSymbol ol.proj.EPSG21781
+@exportSymbol ol.proj.EPSG21781.add

src/ol/proj/epsg21781projection.js

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+goog.provide('ol.proj.EPSG21781');
+
+goog.require('goog.asserts');
+goog.require('ol.Projection');
+goog.require('ol.ProjectionUnits');
+goog.require('ol.proj');
+goog.require('ol.proj.EPSG4326');
+
+
+
+/**
+ * @constructor
+ * @extends {ol.Projection}
+ */
+ol.proj.EPSG21781 = function() {
+  goog.base(this, {
+    code: 'EPSG:21781',
+    units: ol.ProjectionUnits.METERS,
+    extent: ol.proj.EPSG21781.EXTENT,
+    global: false
+  });
+};
+goog.inherits(ol.proj.EPSG21781, ol.Projection);
+
+
+/**
+ * @const
+ * @type {ol.Extent}
+ */
+ol.proj.EPSG21781.EXTENT = [485869.5728, 837076.5648, 76443.1884, 299941.7864];
+
+
+/**
+ * FIXME empty description for jsdoc
+ */
+ol.proj.EPSG21781.add = function() {
+  ol.proj.addEquivalentProjections(ol.proj.EPSG4326.PROJECTIONS);
+  var epsg21781 = new ol.proj.EPSG21781();
+  ol.proj.addProjection(epsg21781);
+  ol.proj.addEquivalentTransforms(
+      ol.proj.EPSG4326.PROJECTIONS,
+      [epsg21781],
+      ol.proj.EPSG21781.fromEPSG4326,
+      ol.proj.EPSG21781.toEPSG4326);
+};
+
+
+/**
+ * Transformation from EPSG:4326 to EPSG:21781.
+ *
+ * @see http://www.swisstopo.admin.ch/internet/swisstopo/en/home/products/software/products/skripts.html
+ *
+ * @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.
+ */
+ol.proj.EPSG21781.fromEPSG4326 = function(input, opt_output, opt_dimension) {
+  var n = input.length;
+  var dimension = goog.isDef(opt_dimension) ? opt_dimension : 2;
+  var output;
+  if (goog.isDef(opt_output)) {
+    output = opt_output;
+  } else {
+    if (dimension > 2) {
+      output = input.slice();
+    } else {
+      output = new Array(n);
+    }
+  }
+  goog.asserts.assert(dimension >= 2);
+  goog.asserts.assert(output.length % dimension === 0);
+  var auxLat, auxLon, i;
+  for (i = 0; i < n; i += dimension) {
+    auxLat = 36 * input[i + 1] / 100 - 16.902866;
+    auxLon = 36 * input[i] / 100 - 2.67825;
+    output[i] = 600072.37 +
+        211455.93 * auxLon -
+        10938.51 * auxLon * auxLat -
+        0.36 * auxLon * auxLat * auxLat -
+        44.54 * auxLon * auxLon * auxLon;
+    output[i + 1] = 200147.07 +
+        308807.95 * auxLat +
+        3745.25 * auxLon * auxLon +
+        76.63 * auxLat * auxLat -
+        194.56 * auxLon * auxLon * auxLat +
+        119.79 * auxLat * auxLat * auxLat;
+  }
+  return output;
+};
+
+
+/**
+ * Transformation from EPSG:21781 to EPSG:4326.
+ *
+ * @see http://www.swisstopo.admin.ch/internet/swisstopo/en/home/products/software/products/skripts.html
+ *
+ * @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.
+ */
+ol.proj.EPSG21781.toEPSG4326 = function(input, opt_output, opt_dimension) {
+  var n = input.length;
+  var dimension = goog.isDef(opt_dimension) ? opt_dimension : 2;
+  var output;
+  if (goog.isDef(opt_output)) {
+    output = opt_output;
+  } else {
+    if (dimension > 2) {
+      output = input.slice();
+    } else {
+      output = new Array(n);
+    }
+  }
+  goog.asserts.assert(dimension >= 2);
+  goog.asserts.assert(output.length % dimension === 0);
+  var auxX, auxY, i;
+  for (i = 0; i < n; i += dimension) {
+    auxY = (input[i] - 600000) / 1000000;
+    auxX = (input[i + 1] - 200000) / 1000000;
+    output[i] = 100 * (2.6779094 +
+        4.728982 * auxY +
+        0.791484 * auxY * auxX +
+        0.1306 * auxY * auxX * auxX -
+        0.0436 * auxY * auxY * auxY) / 36;
+    output[i + 1] = 100 * (16.9023892 +
+        3.238272 * auxX -
+        0.270978 * auxY * auxY -
+        0.002528 * auxX * auxX -
+        0.0447 * auxY * auxY * auxX -
+        0.014 * auxX * auxX * auxX) / 36;
+  }
+  return output;
+};
+
+
+/**
+ * @inheritDoc
+ */
+ol.proj.EPSG21781.prototype.getPointResolution = function(resolution, point) {
+  return resolution;
+};

test/spec/ol/proj/epsg21781projection.test.js

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+goog.provide('ol.test.proj.EPSG21781');
+
+
+describe('ol.proj.EPSG21781', function() {
+
+  var epsg21781;
+  beforeEach(function() {
+    ol.proj.EPSG21781.add();
+    epsg21781 = ol.proj.get('EPSG:21781');
+    expect(epsg21781).to.be.an(ol.Projection);
+  });
+
+  it('does not lose too much accuracy when round-tripping', function() {
+    var extent = epsg21781.getExtent();
+    var roundTripped, x, y;
+    for (x = extent[0]; x < extent[1]; x += 50000) {
+      for (y = extent[2]; y < extent[3]; y += 50000) {
+        roundTripped = ol.proj.EPSG21781.fromEPSG4326(
+            ol.proj.EPSG21781.toEPSG4326([x, y]));
+        expect(roundTripped).to.be.an(Array);
+        expect(roundTripped).to.have.length(2);
+        expect(roundTripped[0]).to.roughlyEqual(x, 1e1);
+        expect(roundTripped[1]).to.roughlyEqual(y, 1e1);
+      }
+    }
+  });
+
+  it('transforms from EPSG:21781 to EPSG:4326', function() {
+    var wgs84 = ol.proj.transform(
+        [660389.515487, 185731.630396], 'EPSG:21781', 'EPSG:4326');
+    expect(wgs84).to.be.an(Array);
+    expect(wgs84).to.have.length(2);
+    expect(wgs84[0]).to.roughlyEqual(8.23, 1e-3);
+    expect(wgs84[1]).to.roughlyEqual(46.82, 1e-3);
+  });
+
+  it('transforms from EPSG:4326 to EPSG:21781', function() {
+    var ch1903 = ol.proj.transform([8.23, 46.82], 'EPSG:4326', 'EPSG:21781');
+    expect(ch1903).to.be.an(Array);
+    expect(ch1903).to.have.length(2);
+    expect(ch1903[0]).to.roughlyEqual(660389.515487, 1);
+    expect(ch1903[1]).to.roughlyEqual(185731.630396, 1);
+  });
+
+});
+
+
+goog.require('ol.Projection');
+goog.require('ol.proj');
+goog.require('ol.proj.EPSG21781');