Simplify meters per unit handling

externs/olx.js

@@ -429,6 +429,7 @@ olx.OverlayOptions.prototype.autoPanMargin;
  *     extent: (ol.Extent|undefined),
  *     axisOrientation: (string|undefined),
  *     global: (boolean|undefined),
+ *     metersPerUnit: (number|undefined),
  *     worldExtent: (ol.Extent|undefined),
  *     getPointResolution: (function(number, ol.Coordinate):number|undefined) }}
  * @api
@@ -476,6 +477,15 @@ olx.ProjectionOptions.prototype.axisOrientation;
 olx.ProjectionOptions.prototype.global;
 
 
+/**
+ * The meters per unit for the SRS. If not provided, the `units` are used to get
+ * the meters per unit from the {@link ol.proj.METERS_PER_UNIT} lookup table.
+ * @type {number|undefined}
+ * @api
+ */
+olx.ProjectionOptions.prototype.metersPerUnit;
+
+
 /**
  * The world extent for the SRS.
  * @type {ol.Extent|undefined}

src/ol/proj/epsg4326projection.js

@@ -3,6 +3,7 @@ goog.provide('ol.proj.EPSG4326');
 goog.require('ol.proj');
 goog.require('ol.proj.Projection');
 goog.require('ol.proj.Units');
+goog.require('ol.sphere.WGS84');
 
 
 
@@ -27,6 +28,7 @@ ol.proj.EPSG4326_ = function(code, opt_axisOrientation) {
     extent: ol.proj.EPSG4326.EXTENT,
     axisOrientation: opt_axisOrientation,
     global: true,
+    metersPerUnit: ol.proj.EPSG4326.METERS_PER_UNIT,
     worldExtent: ol.proj.EPSG4326.EXTENT
   });
 };
@@ -50,6 +52,13 @@ ol.proj.EPSG4326_.prototype.getPointResolution = function(resolution, point) {
 ol.proj.EPSG4326.EXTENT = [-180, -90, 180, 90];
 
 
+/**
+ * @const
+ * @type {number}
+ */
+ol.proj.EPSG4326.METERS_PER_UNIT = Math.PI * ol.sphere.WGS84.radius / 180;
+
+
 /**
  * Projections equal to EPSG:4326.
  *

src/ol/proj/proj.js

@@ -143,6 +143,12 @@ ol.proj.Projection = function(options) {
    */
   this.defaultTileGrid_ = null;
 
+  /**
+   * @private
+   * @type {number|undefined}
+   */
+  this.metersPerUnit_ = options.metersPerUnit;
+
   var projections = ol.proj.projections_;
   var code = options.code;
   goog.asserts.assert(code !== undefined,
@@ -155,16 +161,11 @@ ol.proj.Projection = function(options) {
         if (def.axis !== undefined && options.axisOrientation === undefined) {
           this.axisOrientation_ = def.axis;
         }
+        if (options.metersPerUnit === undefined) {
+          this.metersPerUnit_ = def.to_meter;
+        }
         if (options.units === undefined) {
-          var units = def.units;
-          if (def.to_meter !== undefined) {
-            if (units === undefined ||
-                ol.proj.METERS_PER_UNIT[units] === undefined) {
-              units = def.to_meter.toString();
-              ol.proj.METERS_PER_UNIT[units] = def.to_meter;
-            }
-          }
-          this.units_ = units;
+          this.units_ = def.units;
         }
         var currentCode, currentDef, currentProj, proj4Transform;
         for (currentCode in projections) {
@@ -227,12 +228,13 @@ ol.proj.Projection.prototype.getUnits = function() {
 
 /**
  * Get the amount of meters per unit of this projection.  If the projection is
- * not configured with a units identifier, the return is `undefined`.
+ * not configured with `metersPerUnit` or a units identifier, the return is
+ * `undefined`.
  * @return {number|undefined} Meters.
  * @api stable
  */
 ol.proj.Projection.prototype.getMetersPerUnit = function() {
-  return ol.proj.METERS_PER_UNIT[this.units_];
+  return this.metersPerUnit_ || ol.proj.METERS_PER_UNIT[this.units_];
 };
 
 

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

@@ -554,7 +554,8 @@ describe('ol.proj', function() {
 
     it('returns value in meters', function() {
       var epsg4326 = ol.proj.get('EPSG:4326');
-      expect(epsg4326.getMetersPerUnit()).to.eql(111194.87428468118);
+      expect(epsg4326.getMetersPerUnit()).to.eql(
+          ol.proj.EPSG4326.METERS_PER_UNIT);
     });
 
     it('works for proj4js projections without units', function() {
@@ -582,6 +583,7 @@ describe('ol.proj', function() {
 
 
 goog.require('ol.proj');
+goog.require('ol.proj.EPSG4326');
 goog.require('ol.proj.Projection');
 goog.require('ol.proj.Units');
 goog.require('ol.proj.common');

test/spec/ol/reproj/reproj.test.js

@@ -31,7 +31,8 @@ describe('ol.reproj', function() {
       var resolution3857 = ol.reproj.calculateSourceResolution(
           proj3857, proj4326, point4326, resolution4326);
       expect(resolution3857).not.to.be(resolution4326);
-      expect(resolution3857).to.roughlyEqual(555974.3714343394, 1e-6);
+      expect(resolution3857).to.roughlyEqual(
+          5 * proj4326.getMetersPerUnit(), 1e-4);
 
       var result = ol.reproj.calculateSourceResolution(
           proj4326, proj3857, point3857, resolution3857);