Fix offline zoom issue and document zoom level differences

Google Maps and OSM Maps use different zoom levels for the same
view ranges. This is better documented. Additionally, this change
fixes zooming out causing zoom in (Issue #1485).

1 files changed, 7 insertions, 5 deletions

diff --git a/main/src/cgeo/geocaching/maps/mapsforge/MapsforgeMapController.java b/main/src/cgeo/geocaching/maps/mapsforge/MapsforgeMapController.java
index db81609..5aaecc8 100644
--- a/main/src/cgeo/geocaching/maps/mapsforge/MapsforgeMapController.java
+++ b/main/src/cgeo/geocaching/maps/mapsforge/MapsforgeMapController.java
@@ -26,13 +26,15 @@ public class MapsforgeMapController implements MapControllerImpl {
         mapController.setCenter((GeoPoint) geoPoint);
     }
 
+    /**
+     * Set the map zoom level to mapzoom-1 or maxZoomLevel, whichever is least
+     * mapzoom-1 is used to be compatible with Google Maps zoom levels
+     */
     @Override
     public void setZoom(int mapzoom) {
-        int mfzoom = mapzoom - 1;
-        if (mfzoom > maxZoomLevel) {
-            mfzoom = maxZoomLevel;
-        }
-        mapController.setZoom(mfzoom);
+        // Google Maps and OSM Maps use different zoom levels for the same view.
+        // All OSM Maps zoom levels are offset by 1 so they match Google Maps.
+        mapController.setZoom(Math.min(mapzoom - 1, maxZoomLevel));
     }
 
     @Override