Provide methods to transform coordinates and extents

CHANGELOG.md

@@ -6,6 +6,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- Include transform and transformExtent OL methods. #171
+- Add getCurrentViewExtentCoordinates instance function. #171
+
 ## [v2.1.0] - 2022-11-15
 
 ### Added

src/instance/instance.js

@@ -8,6 +8,7 @@ import defaults from './defaults';
 // Import instance methods.
 import addLayer, { getLayerByName } from './methods/layer';
 import addPopup from './methods/popup';
+import { getCurrentViewExtentCoordinates, transform, transformExtent } from './methods/projection';
 import { zoomToVectors, zoomToLayer } from './methods/zoom';
 import { addBehavior, attachBehavior, attachBehaviorsByWeight } from './methods/behavior';
 import { measureGeometry } from '../utils/measure';
@@ -57,6 +58,9 @@ const createInstance = ({ target, options = {} }) => {
     attachBehavior,
     attachBehaviorsByWeight,
     measureGeometry,
+    getCurrentViewExtentCoordinates,
+    transform,
+    transformExtent,
   };
 
   return instance;

src/instance/methods/projection.js

@@ -0,0 +1,17 @@
+import { transformExtent } from 'ol/proj';
+
+// Export OpenLayers transform functions
+export { transform, transformExtent } from 'ol/proj';
+
+/**
+ * Returns the map's current view extent in the specified projection coordinates.
+ * @param {import('ol/proj').ProjectionLike} source Source projection-like.
+ *     Defaults to 'EPSG:3857'.
+ * @param {import('ol/proj').ProjectionLike} destination Destination projection-like.
+ *     Defaults to 'EPSG:4326'.
+ * @return {import('ol/extent').Extent} The transformed extent.
+ */
+export function getCurrentViewExtentCoordinates(source = 'EPSG:3857', destination = 'EPSG:4326') {
+  const extent = this.map.getView().calculateExtent(this.map.getSize());
+  return transformExtent(extent, source, destination);
+}