Merge pull request #9196 from ahocevar/pointresolution-scaleline

getPointResolution returns resolution in projection units

src/ol/control/ScaleLine.js

@@ -201,20 +201,12 @@ class ScaleLine extends Control {
       ProjUnits.METERS;
     let pointResolution =
         getPointResolution(projection, viewState.resolution, center, pointResolutionUnits);
-    if (projection.getUnits() != ProjUnits.DEGREES && projection.getMetersPerUnit()
-      && pointResolutionUnits == ProjUnits.METERS) {
-      pointResolution *= projection.getMetersPerUnit();
-    }
 
     let nominalCount = this.minWidth_ * pointResolution;
     let suffix = '';
     if (units == Units.DEGREES) {
       const metersPerDegree = METERS_PER_UNIT[ProjUnits.DEGREES];
-      if (projection.getUnits() == ProjUnits.DEGREES) {
-        nominalCount *= metersPerDegree;
-      } else {
-        pointResolution /= metersPerDegree;
-      }
+      nominalCount *= metersPerDegree;
       if (nominalCount < metersPerDegree / 60) {
         suffix = '\u2033'; // seconds
         pointResolution *= 3600;

src/ol/proj.js

@@ -188,6 +188,12 @@ export function getPointResolution(projection, resolution, point, opt_units) {
   const getter = projection.getPointResolutionFunc();
   if (getter) {
     pointResolution = getter(resolution, point);
+    if (opt_units && opt_units !== projection.getUnits()) {
+      const metersPerUnit = projection.getMetersPerUnit();
+      if (metersPerUnit) {
+        pointResolution = pointResolution * metersPerUnit / METERS_PER_UNIT[opt_units];
+      }
+    }
   } else {
     const units = projection.getUnits();
     if (units == Units.DEGREES && !opt_units || opt_units == Units.DEGREES) {

src/ol/proj/Projection.js

@@ -19,7 +19,7 @@ import {METERS_PER_UNIT} from './Units.js';
  * @property {function(number, import("../coordinate.js").Coordinate):number} [getPointResolution]
  * Function to determine resolution at a point. The function is called with a
  * `{number}` view resolution and an `{import("../coordinate.js").Coordinate}` as arguments, and returns
- * the `{number}` resolution at the passed coordinate. If this is `undefined`,
+ * the `{number}` resolution in projection units at the passed coordinate. If this is `undefined`,
  * the default {@link module:ol/proj#getPointResolution} function will be used.
  */
 

test/spec/ol/control/scaleline.test.js

@@ -1,8 +1,10 @@
 import Map from '../../../../src/ol/Map.js';
 import View from '../../../../src/ol/View.js';
 import ScaleLine, {render} from '../../../../src/ol/control/ScaleLine.js';
-import {fromLonLat} from '../../../../src/ol/proj.js';
+import {fromLonLat, clearAllProjections, addCommon} from '../../../../src/ol/proj.js';
 import Projection from '../../../../src/ol/proj/Projection.js';
+import proj4 from 'proj4';
+import {register} from '../../../../src/ol/proj/proj4.js';
 
 describe('ol.control.ScaleLine', function() {
   let map;
@@ -244,6 +246,25 @@ describe('ol.control.ScaleLine', function() {
   });
 
   describe('projections affect the scaleline', function() {
+
+    beforeEach(function() {
+      proj4.defs('Indiana-East', 'PROJCS["IN83-EF",GEOGCS["LL83",DATUM["NAD83",' +
+        'SPHEROID["GRS1980",6378137.000,298.25722210]],PRIMEM["Greenwich",0],' +
+        'UNIT["Degree",0.017453292519943295]],PROJECTION["Transverse_Mercator"],' +
+        'PARAMETER["false_easting",328083.333],' +
+        'PARAMETER["false_northing",820208.333],' +
+        'PARAMETER["scale_factor",0.999966666667],' +
+        'PARAMETER["central_meridian",-85.66666666666670],' +
+        'PARAMETER["latitude_of_origin",37.50000000000000],' +
+        'UNIT["Foot_US",0.30480060960122]]');
+      register(proj4);
+    });
+
+    afterEach(function() {
+      clearAllProjections();
+      addCommon();
+    });
+
     it('is rendered differently for different projections', function() {
       const ctrl = new ScaleLine();
       ctrl.setMap(map);
@@ -253,15 +274,47 @@ describe('ol.control.ScaleLine', function() {
         projection: 'EPSG:3857'
       }));
       map.renderSync();
-      const innerHtml3857 = ctrl.element.innerHTML;
+      expect(ctrl.element.innerText).to.be('2000 km');
       map.setView(new View({
         center: [7, 52],
         zoom: 2,
         projection: 'EPSG:4326'
       }));
       map.renderSync();
-      const innerHtml4326 = ctrl.element.innerHTML;
-      expect(innerHtml4326).to.not.be(innerHtml3857);
+      expect(ctrl.element.innerText).to.be('5000 km');
+      map.setView(new View({
+        center: fromLonLat([-85.685, 39.891], 'Indiana-East'),
+        zoom: 7,
+        projection: 'Indiana-East'
+      }));
+      map.renderSync();
+      expect(ctrl.element.innerText).to.be('100 km');
+    });
+
+    it('shows the same scale for different projections at higher resolutions', function() {
+      const ctrl = new ScaleLine();
+      ctrl.setMap(map);
+      map.setView(new View({
+        center: fromLonLat([-85.685, 39.891]),
+        zoom: 7,
+        projection: 'EPSG:3857'
+      }));
+      map.renderSync();
+      expect(ctrl.element.innerText).to.be('100 km');
+      map.setView(new View({
+        center: [-85.685, 39.891],
+        zoom: 7,
+        projection: 'EPSG:4326'
+      }));
+      map.renderSync();
+      expect(ctrl.element.innerText).to.be('100 km');
+      map.setView(new View({
+        center: fromLonLat([-85.685, 39.891], 'Indiana-East'),
+        zoom: 7,
+        projection: 'Indiana-East'
+      }));
+      map.renderSync();
+      expect(ctrl.element.innerText).to.be('100 km');
     });
 
     it('Projection\'s metersPerUnit affect scale for non-degree units', function() {
@@ -344,7 +397,7 @@ describe('ol.control.ScaleLine', function() {
       const ctrl = new ScaleLine();
       ctrl.setMap(map);
       map.setView(new View({
-        center: fromLonLat([7, 0]),
+        center: [7, 0],
         zoom: 2,
         projection: 'EPSG:4326'
       }));
@@ -362,7 +415,7 @@ describe('ol.control.ScaleLine', function() {
       });
       ctrl.setMap(map);
       map.setView(new View({
-        center: fromLonLat([7, 0]),
+        center: [7, 0],
         zoom: 2,
         projection: 'EPSG:4326'
       }));

test/spec/ol/proj.test.js

@@ -9,11 +9,12 @@ import {
   toLonLat,
   getTransform,
   getPointResolution,
-  getTransformFromProjections
+  getTransformFromProjections,
+  METERS_PER_UNIT
 } from '../../../src/ol/proj.js';
 import {register} from '../../../src/ol/proj/proj4.js';
 import {HALF_SIZE} from '../../../src/ol/proj/epsg3857.js';
-import {METERS_PER_UNIT} from '../../../src/ol/proj/epsg4326.js';
+import {METERS_PER_UNIT as metersPerDegree} from '../../../src/ol/proj/epsg4326.js';
 import Projection from '../../../src/ol/proj/Projection.js';
 
 
@@ -268,7 +269,7 @@ describe('ol.proj', function() {
       expect(pointResolution).to.roughlyEqual(0.615661, 1e-5);
     });
     it('returns the correct point resolution for EPSG:3857 with custom units', function() {
-      let pointResolution = getPointResolution('EPSG:3857', 1, [0, 0], 'degrees');
+      let pointResolution = getPointResolution('EPSG:3857', METERS_PER_UNIT['degrees'], [0, 0], 'degrees');
       expect(pointResolution).to.be(1);
       pointResolution = getPointResolution('EPSG:4326', 1, fromLonLat([0, 52]), 'degrees');
       expect(pointResolution).to.be(1);
@@ -600,7 +601,7 @@ describe('ol.proj', function() {
 
     it('returns value in meters', function() {
       const epsg4326 = getProjection('EPSG:4326');
-      expect(epsg4326.getMetersPerUnit()).to.eql(METERS_PER_UNIT);
+      expect(epsg4326.getMetersPerUnit()).to.eql(metersPerDegree);
     });
 
     it('works for proj4js projections without units', function() {