var map = new GMap2(document.getElementById("map_canvas"));
map.setCenter(new GLatLng(37.4419, -122.1419), 13);

var bounds = map.getBounds();
var southWest = bounds.getSouthWest();
var northEast = bounds.getNorthEast();

3 Answers

• Accepted Answer

  Hello,

  I've made a function which can count the boundaries from the center point and deltas.

  /**
   * Get the screen boundaries as latitude and longitude values 
   */
  function getMapBounds(region) {
      var b = {};
      b.northWest = {}; b.northEast = {};
      b.southWest = {}; b.southEast = {};
  
      b.northWest.lat = parseFloat(region.latitude) + 
          parseFloat(region.latitudeDelta) / 2.0;
      b.northWest.lng = parseFloat(region.longitude) - 
          parseFloat(region.longitudeDelta) / 2.0;
  
      b.southWest.lat = parseFloat(region.latitude) - 
          parseFloat(region.latitudeDelta) / 2.0;
      b.southWest.lng = parseFloat(region.longitude) - 
          parseFloat(region.longitudeDelta) / 2.0;
  
      b.northEast.lat = parseFloat(region.latitude) + 
          parseFloat(region.latitudeDelta) / 2.0;
      b.northEast.lng = parseFloat(region.longitude) + 
          parseFloat(region.longitudeDelta) / 2.0;
  
      b.southEast.lat = parseFloat(region.latitude) - 
          parseFloat(region.latitudeDelta) / 2.0;
      b.southEast.lng = parseFloat(region.longitude) + 
          parseFloat(region.longitudeDelta) / 2.0;
  
      return b;
  }
  

  You can use it like this:

  var bounds = getMapBounds(e);
  
  var a = Ti.Map.createAnnotation({
      latitude: bounds.southWest.lat,
      longitude: bounds.southWest.lng,
      pincolor: Ti.Map.ANNOTATION_RED,
      animate: false,
  });
  
  mapview.addAnnotation(a);
  

• Okay, there's an answer, but it ain't easy…

  We have support for a regionChanged event (shown here in our documentation). You have four properties of note on that event - the x/y coordinates on which the map is centered, and the "longitudeDelta" and "latitudeDelta". With this information, you can calculate the currently visible region of the map:

  latitudeDelta

  The amount of north-to-south distance (measured in degrees) to use for the span. Unlike longitudinal distances, which vary based on the latitude, one degree of latitude is approximately 111 kilometers (69 miles) at all times.

  longitudeDelta

  The amount of east-to-west distance (measured in degrees) to use for the span. The number of kilometers spanned by a longitude range varies based on the current latitude. For example, one degree of longitude spans a distance of approximately 111 kilometers (69 milies) at the equator but shrinks to 0 kilometers at the poles.

  You'll have to use this information to calculate the viewable area of the map. A quick Google search reveals a site which should help calculate the length of a degree of lat/long. That JavaScript (check it out in view source) ought to run fine in Titanium to perform the calculation.

  You have the primordial material to make this work, but will have to do some math - your solution would be very helpful to the community if you want to post it back here.

• Hmmm…I found this post…and while it's a possible alternative I would think that there should be an exposed method to the Google Map API for Bounds.

  https://developer.appcelerator.com/question/19881/near-me-functionality