Merge branch '540-fractional-zoom' into 'devel_12.1.x'

Resolve "partial zooming using mac mouse"

See merge request !461

frontend-js/src/main/js/map/canvas/OpenLayers/OpenLayerCanvas.js

@@ -77,7 +77,12 @@ function OpenLayerCanvas(element, options) {
       minZoom: options.minZoom,
       maxZoom: options.maxZoom,
       enableRotation: false
-    })
+    }),
+    interactions: ol.interaction.defaults({}).extend([
+      new ol.interaction.PinchZoom({
+        constrainResolution: true
+      })
+    ])
   });
   self.setOpenLayersMap(map);
   self.addCenterButton();