getViewFromBoundingBox

src/map/view.js

@@ -266,10 +266,33 @@ function getBoundingBoxFromViewForEpsg3857(
 	};
 }
 
+function getViewFromBoundingBoxForEpsg3857(bbox) {
+	const {minLat, maxLat, minLon, maxLon} = bbox;
+	const bottomLeftEpsg3857 = projections.coordinates4326To3857({
+		lat: minLat,
+		lon: minLon,
+	});
+	const topRightEpsg3857 = projections.coordinates4326To3857({
+		lat: maxLat,
+		lon: maxLon,
+	});
+	const {x: xMin, y: yMin} = bottomLeftEpsg3857;
+	const {x: xMax, y: yMax} = topRightEpsg3857;
+
+	return {
+		center: {
+			lat: (maxLat + minLat) / 2,
+			lon: (maxLon + minLon) / 2,
+		},
+		boxRange: Math.max(xMax - xMin, yMax - yMin),
+	};
+}
+
 export default {
 	ensureViewIntegrity,
 	mergeViews,
 	getBoundingBoxFromViewForEpsg3857,
+	getViewFromBoundingBoxForEpsg3857,
 	getBoxRangeFromZoomLevel,
 	getNearestZoomLevelBoxRange,
 	getMapViewportRange,
@@ -284,6 +307,7 @@ export {
 	ensureViewIntegrity, //check use in ptr-state
 	mergeViews,
 	getBoundingBoxFromViewForEpsg3857,
+	getViewFromBoundingBoxForEpsg3857,
 	getBoxRangeFromZoomLevel,
 	getNearestZoomLevelBoxRange,
 	getMapViewportRange,

tests/map/view/getViewFromBoundingBoxForEpsg3857-test.js

@@ -0,0 +1,69 @@
+import {assert} from 'chai';
+import view, {getViewFromBoundingBoxForEpsg3857} from '../../../src/map/view';
+
+describe('getViewFromBoundingBoxForEpsg3857', function () {
+	// Expected values calculated here https://epsg.io/transform#s_srs=3857&t_srs=4326
+
+	it('returns expected view approximately', function () {
+		// given params
+		const bbox = {
+			minLat: 0,
+			maxLat: 90,
+			minLon: 0,
+			maxLon: 180,
+		};
+
+		// expected output params
+		const expectedCenter = {lat: 45, lon: 90};
+		const expectedBoxRange = 20000000; // 10000 km
+
+		// no optLat given
+		const output = view.getViewFromBoundingBoxForEpsg3857(bbox);
+
+		assert.equal(output.center.lat, expectedCenter.lat);
+		assert.equal(output.center.lon, expectedCenter.lon);
+		assert.approximately(output.boxRange, expectedBoxRange, 100000);
+	});
+
+	it('returns expected view approximately 2', function () {
+		// given params
+		const bbox = {
+			minLat: 50,
+			maxLat: 51,
+			minLon: 15,
+			maxLon: 16,
+		};
+
+		// expected output params
+		const expectedCenter = {lat: 50.5, lon: 15.5};
+		const expectedBoxRange = 180000; // 111km
+
+		// no optLat given
+		const output = view.getViewFromBoundingBoxForEpsg3857(bbox);
+
+		assert.equal(output.center.lat, expectedCenter.lat);
+		assert.equal(output.center.lon, expectedCenter.lon);
+		assert.approximately(output.boxRange, expectedBoxRange, 10000);
+	});
+
+	it('returns expected view approximately 3', function () {
+		// given params
+		const bbox = {
+			minLat: 50.01,
+			maxLat: 50.02,
+			minLon: 15.01,
+			maxLon: 15.02,
+		};
+
+		// expected output params
+		const expectedCenter = {lat: 50.015, lon: 15.015};
+		const expectedBoxRange = 1700; // 111km
+
+		// no optLat given
+		const output = view.getViewFromBoundingBoxForEpsg3857(bbox);
+
+		assert.equal(output.center.lat, expectedCenter.lat);
+		assert.equal(output.center.lon, expectedCenter.lon);
+		assert.approximately(output.boxRange, expectedBoxRange, 100);
+	});
+});