Google Maps v3 OverlayView.getProjection() - google-maps

Question

I cannot seem to figure out why the object returned by getProjection() is undefined. Here is my code:
// Handles the completion of the rectangle
var ne = recBounds.getNorthEast();
var sw = recBounds.getSouthWest();
$("#map_tools_selat").attr( 'value', sw.lat() );
$("#map_tools_nwlat").attr( 'value', ne.lat() );
$("#map_tools_selng").attr( 'value', ne.lng() );
$("#map_tools_nwlng").attr( 'value', sw.lng() );
// Set Zoom Level
$("#map_tools_zoomlevel").attr( 'value', HAR.map.getZoom()+1 );
document.getElementById("map_tools_centerLat").value = HAR.map.getCenter().lat();
document.getElementById("map_tools_centerLong").value = HAR.map.getCenter().lng();
// All this junk below is for getting pixel coordinates for a lat/lng =/
MyOverlay.prototype = new google.maps.OverlayView();
MyOverlay.prototype.onAdd = function() { }
MyOverlay.prototype.onRemove = function() { }
MyOverlay.prototype.draw = function() { }
function MyOverlay(map) { this.setMap(map); }
var overlay = new MyOverlay(HAR.map);
var projection = overlay.getProjection();
// END - all the junk
var p = projection.fromLatLngToContainerPixel(recBounds.getCenter());
alert(p.x+", "+p.y);
My error is: Cannot call method 'fromLatLngToContainerPixel' of undefined

Answer 1

Actually, i the reason why this happens is because the projection object is created after the map is idle after panning / zooming. So, a better solution is to listen on the idle event of the google.maps.Map object, and get a reference to the projection there:
// Create your map and overlay
var map;
MyOverlay.prototype = new google.maps.OverlayView();
MyOverlay.prototype.onAdd = function() { }
MyOverlay.prototype.onRemove = function() { }
MyOverlay.prototype.draw = function() { }
function MyOverlay(map) { this.setMap(map); }
var overlay = new MyOverlay(map);
var projection;
// Wait for idle map
google.maps.event.addListener(map, 'idle', function() {
// Get projection
projection = overlay.getProjection();
})

Answer 2

I kind of figured out what was going on. Even though it is still not crystal clear why this happens, I know that I had to instantiate the variable "overlay" right after instantiating my google map (HAR.map). So I practically moved that code snippet into my HAR class and now i use:
HAR.canvassOverlay.getProjection().fromLatLngToContainerPixel( recBounds.getCenter() );
So now, every time I create a map via my class "HAR" I also have a parallel OverlayView object within my class.
The Error could have been with losing scope of my class object, but I think it was more of the map event "projection_changed" not being fired. I got a hint from the map API docs for map class, under method getProjection():
"Returns the current Projection. If the map is not yet initialized (i.e. the mapType is still null) then the result is null. Listen to projection_changed and check its value to ensure it is not null."
If you are getting the similar issue, make sure that you assign your overlayView.setMAP( YOUR_MAP_OBJECT ) closely after instantiating the map object.