Google Maps "center_changed" is firing my function more than once

Question

Just as the Title implies, I just added a "center_changed" listener to my map and the function is running more than once. I'm assuming it's because the center of the map is changing a bunch of times before the map comes to a rest, but I thought that that's what "drag" was for and that "center_changed only fires once after it comes to a rest??? The only reason I know its firing a bunch of times is because I have a drop shadow on the icon and it gets darker and darker over about two seconds before its completely black. If anyone needs my code, its below.

         google.maps.event.addListener(map, 'center_changed', function() {
    var zoomLevel = map.getZoom();
        if (zoomLevel > 7) {
            clearAll();
            addmarker1();
            addmarker2();
            addmarker3();
            addmarker4();
                    }
        else {
            clearAll();
            }   
            });

Answer 1

These two functions fire only after your map comes to a rest

If you want your function to execute only when user drags(not programmatically) then use...

       google.maps.event.addListener(map, 'dragend', function(){...}

But if you want your function to execute even when dragged, zoom changed programmatically(e.g. setZoom , fitBounds), then use...

       google.maps.event.addListener(map, 'idle', function(){...}