Question

I can currently place static points in the map window:

var latlng = new GLatLng(lat, lng);
map.addOverlay(new GMarker(latlng, markerOptions));

And I know how to get the bounds of the window. I can also code a page that will take the bounds and return the points that are inside them in any format.

The problems I have now:

1. Does the moveend event capture all moves, including zoom changes? Or do I need to watch for that event separately?
2. How should I call my external datasource? (should I just do a JQuery $.get request?)
3. What should that datasource return?
4. How do I display that data on the map?

Answer 1

I’m using this in one of my sites. I think it’s exactly what you are looking for. But be warned “gmaps-utility-library” plugins have some buggy/bad code so it’s a good idea to go over it and double check if everything is working as it should (I haven’t encountered any bugs in marker manager but in some other plugins from that library).

Here’s reference and examples.

Even if you want to code your own this one is probably a good starting point.

EDIT

My answer for 3-4:

It really depends on situation. If it’s static (you just need to manage a lot points on map > 300) then you could serve all points together with the page where the map is located in (as JavaScript array for example). If user interacts with data then probably it’s better to use AJAX. If you use jQuery (or any other JS library) in your site then use ajax function from that library if not then go with the one which comes from gmaps. It’s because it’s nice to use same AJAX function in whole site instead of using 2 which does the same job.

If you are taking AJAX path you have 2 options:

1. Load all markers for whole map in one request.
2. Load markers that shows up on user screen + small margin.

If you expect that user wants to see the big picture or that he will want to see all/most of the points then go for option 1 + marker manager (like the one I recommended or your own similar).

If there’s really a lot of points and user will never be interested in most of them then go for option 2 + manager or just this simple algorithm: Clear map -> Request points for map window bounds + magin / (Cache) -> Draw points -> Repeat for each move/zoom.

From personal experience (I’ve used both AJAX options) marker manager does quite nice job, can handle a lot points and overall user experience is a lot smoother then loading points for just viewport. Requesting new points and drawing them on map is quite laggy/choppy. Of course it depends on amount of points.