Merge pull request #41 from annarieger/projection-util-default-defs

Default CRS definitions for ProjectionUtil

src/ProjectionUtil/ProjectionUtil.js

@@ -1,6 +1,8 @@
 import proj4 from 'proj4';
 import { register } from 'ol/proj/proj4';
 
+import isEmpty from 'lodash/isEmpty';
+
 /**
  * Helper class for ol/proj4 projection handling.
  *
@@ -9,32 +11,92 @@ import { register } from 'ol/proj/proj4';
 export class ProjectionUtil {
 
   /**
-   * Registers custom crs definitions to the application.
+   * Default proj4 CRS definitions.
+   */
+  static defaultProj4CrsDefinitions = {
+    'EPSG:25832': '+proj=utm +zone=32 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs',
+    'EPSG:31466': '+proj=tmerc +lat_0=0 +lon_0=6 +k=1 +x_0=2500000 +y_0=0 +ellps=bessel +towgs84=598.1,73.7,418.2,0.202,0.045,-2.455,6.7 +units=m +no_defs',
+    'EPSG:31467': '+proj=tmerc +lat_0=0 +lon_0=9 +k=1 +x_0=3500000 +y_0=0 +ellps=bessel +towgs84=598.1,73.7,418.2,0.202,0.045,-2.455,6.7 +units=m +no_defs'
+  }
+
+  /**
+   * Default mappings for CRS identifiers (e.g. "urn:ogc:def:crs:EPSG::25832").
+   */
+  static defaultProj4CrsMappings = {
+    'urn:ogc:def:crs:EPSG::3857': 'EPSG:3857',
+    'urn:ogc:def:crs:EPSG::25832': 'EPSG:25832',
+    'urn:ogc:def:crs:EPSG::31466': 'EPSG:31466',
+    'urn:ogc:def:crs:EPSG::31467': 'EPSG:31467'
+  }
+
+  /**
+   * Registers custom CRS definitions to the application.
    *
-   * @param {Object} proj4CrsDefinitions The (custom) proj4 definition strings.
+   * @param {Object} customCrsDefs The custom `proj4` definition strings
+   *   which should be registered additionally to default avaliable CRS (s.
+   *   `defaultProj4CrsDefinitions` above) as well.
+   *   Further CRS definitions in proj4 format can be checked under
+   *   http://epsg.io (e.g. http://epsg.io/3426.proj4).
+   * @param {Boolean} registerDefaults Whether the default CRS should be
+   *   registered or not. Default is true.
    */
-  static initProj4Definitions(proj4CrsDefinitions) {
-    for (let [projCode, projDefinition] of Object.entries(proj4CrsDefinitions)) {
-      proj4.defs(projCode, projDefinition);
+  static initProj4Definitions(customCrsDefs, registerDefaults = true) {
+    let proj4CrsDefinitions;
+
+    if (registerDefaults) {
+      proj4CrsDefinitions = ProjectionUtil.defaultProj4CrsDefinitions;
+    }
+
+    if (!isEmpty(customCrsDefs)) {
+      Object.keys(customCrsDefs).forEach(crsKey => {
+        if (!(crsKey in proj4CrsDefinitions)) {
+          proj4CrsDefinitions[crsKey] = customCrsDefs[crsKey];
+        }
+      });
+    }
+
+    if (!isEmpty(proj4CrsDefinitions)) {
+      for (let [projCode, projDefinition] of Object.entries(proj4CrsDefinitions)) {
+        proj4.defs(projCode, projDefinition);
+      }
+      register(proj4);
     }
-    register(proj4);
   }
 
   /**
-   * Registers custom crs mappings to allow automatic crs detection. Sometimes
+   * Registers custom CRS mappings to allow automatic CRS detection. Sometimes
    * FeatureCollections returned by the GeoServer may be associated with
-   * crs identifiers (e.g. "urn:ogc:def:crs:EPSG::25832") that aren't
-   * supported by proj4 and/or ol per default. Add appropriate
-   * mappings to allow automatic crs detection by ol here.
+   * CRS identifiers (e.g. "urn:ogc:def:crs:EPSG::25832") that aren't
+   * supported by `proj4` and `OpenLayers` per default. Add appropriate
+   * mappings to allow automatic CRS detection by `OpenLayers` here.
    *
-   * @param {Object} proj4CrsMappings The crs mappings.
+   * @param {Object} customCrsMappings The custom CRS mappings which will be
+   *   added additionally to the by default avaliable (s. `defaultProj4CrsMappings`
+   *   above).
+   * @param {Boolean} useDefaultMappings Whether the default CRS should be mapped
+   *   as well or not. Default is true.
    */
-  static initProj4DefinitionMappings(proj4CrsMappings) {
-    for (let [aliasProjCode, projCode] of Object.entries(proj4CrsMappings)) {
-      proj4.defs(aliasProjCode, proj4.defs(projCode));
+  static initProj4DefinitionMappings(customCrsMappings, useDefaultMappings = true) {
+    let proj4CrsMappings;
+
+    if (useDefaultMappings) {
+      proj4CrsMappings = ProjectionUtil.defaultProj4CrsMappings;
+    }
+
+    if (!isEmpty(customCrsMappings)) {
+      Object.keys(customCrsMappings).forEach(crsKey => {
+        if (!(crsKey in proj4CrsMappings)) {
+          proj4CrsMappings[crsKey] = customCrsMappings[crsKey];
+        }
+      });
     }
-  }
 
+    if (!isEmpty(proj4CrsMappings)) {
+      for (let [aliasProjCode, projCode] of Object.entries(proj4CrsMappings)) {
+        proj4.defs(aliasProjCode, proj4.defs(projCode));
+      }
+    }
+  }
 }
 
 export default ProjectionUtil;

src/ProjectionUtil/ProjectionUtil.spec.js

@@ -6,15 +6,6 @@ import ProjectionUtil from './ProjectionUtil.js';
 
 describe('ProjectionUtil', () => {
 
-  const testCrsDefinition = {
-    'EPSG:25832': '+proj=utm +zone=32 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs'
-  };
-
-  const testCrsMappings = {
-    'urn:ogc:def:crs:EPSG::3857': 'EPSG:3857',
-    'urn:ogc:def:crs:EPSG::25832': 'EPSG:25832'
-  };
-
   describe('Basic test', () => {
     it('is defined', () => {
       expect(ProjectionUtil).not.toBeUndefined();
@@ -29,9 +20,10 @@ describe('ProjectionUtil', () => {
       it('it registers the given CRS definitions in proj4 and ol', () => {
         OlProj4.register = jest.fn();
         const proj4Spy = jest.spyOn(proj4, 'defs');
+        const length = Object.keys(ProjectionUtil.defaultProj4CrsDefinitions).length;
 
-        ProjectionUtil.initProj4Definitions(testCrsDefinition);
-        expect(proj4Spy).toHaveBeenCalled();
+        ProjectionUtil.initProj4Definitions();
+        expect(proj4Spy).toHaveBeenCalledTimes(length);
         expect(OlProj4.register).toHaveBeenCalled();
 
         proj4Spy.mockReset();
@@ -45,14 +37,14 @@ describe('ProjectionUtil', () => {
       });
       it('it registers the given CRS mappings in proj4', () => {
         const proj4Spy = jest.spyOn(proj4, 'defs');
+        const length = Object.keys(ProjectionUtil.defaultProj4CrsMappings).length;
 
-        ProjectionUtil.initProj4DefinitionMappings(testCrsMappings);
-        expect(proj4Spy).toHaveBeenCalledTimes(4);
+        ProjectionUtil.initProj4DefinitionMappings(ProjectionUtil.defaultProj4CrsMappings);
+        expect(proj4Spy).toHaveBeenCalledTimes(length * 2);
 
         proj4Spy.mockReset();
         proj4Spy.mockRestore();
       });
     });
   });
-
 });