robwilkerson · November 29, 2011 15:35 · Nov 29, 2011
diff --git a/location.js b/location.js
@@ -0,0 +1,52 @@
+/** 
+ * Computes the distance in miles between two sets of coordinates.
+ * 
+ * @param   object  from    object containing longitude and latitude members
+ * @param   object  to      object containing longitude and latitude members
+ * @return  number
+ */
+exports.distance = function( from, to ) {
+    // approx. dist in miles, nothern hemisphere
+    // http://www.meridianworlddata.com/Distance-Calculation.asp
+    try {
+        return Math.sqrt( Math.pow( 69.1 * ( to.latitude - from.latitude ), 2 ) + Math.pow( 53 * ( to.longitude - from.longitude ), 2 ) );
+    }
+    catch( e ) {
+        throw( e );
+    }
+};
+
+/** 
+ * Calculates the region for a mapView so that all points are dislayed.
+ * 
+ * @param   array   points  An array of objects with long/lat properties.
+ *                          Essentially, stripped down annotation objects.
+ * @return  object  a region object
+ */
+exports.region = function( points ) {
+    var region = {}; 
+    var delta  = 0.02;
+    var minLat = points[0].latitude, 
+        maxLat = points[0].latitude, 
+        minLon = points[0].longitude, 
+        maxLon = points[0].longitude;
+
+    for( var i = 0; i < points.length - 1; i++ ) {
+        minLat = Math.min( points[i + 1].latitude, minLat );
+        maxLat = Math.max( points[i + 1].latitude, maxLat );
+        minLon = Math.min( points[i + 1].longitude, minLon );
+        maxLon = Math.max( points[i + 1].longitude, maxLon );
+    }
+
+    // Define the zoom level
+    var deltaLat = maxLat - minLat;
+    var deltaLon = maxLon - minLon;
+    delta = Math.max( deltaLat, deltaLon ) * 0.25;
+
+
+    region.latitude  = maxLat - parseFloat( ( maxLat - minLat ) / 2 );
+    region.longitude = maxLon - parseFloat( ( maxLon - minLon ) / 2 );
+    region.latitudeDelta = region.longitudeDelta = delta;
+
+    return region;
+};