Count and output number of markers bound by circle radius - google-maps-api-3

Question

I have a map thats populated with markers of places from a fusion table. I'm taking the users location and displaying a circle of radius 10 miles from their location. Here is my code - http://connormccarra.com/sandbox/map/. How can I use the api to count the number of markers bound by the circle and output that number in the footer?
Cheers!
Relevant code:
var map;
function Initialize() {
var MapOptions = {
zoom: 7,
center: new google.maps.LatLng(53.4125694, -8.245014),
mapTypeId: google.maps.MapTypeId.ROADMAP,
sensor: true
};
map = new google.maps.Map(document.getElementById("map_canvas"), MapOptions);
var layer = new google.maps.FusionTablesLayer({
query: {
select: 'Address',
from: '1OPU6utSjRYwJSFK-EXdaGmt2KgLTq2loVIjS3AA'
}
});
layer.setMap(map);
// Try HTML5 geolocation
if(navigator.geolocation) {
navigator.geolocation.getCurrentPosition(function(position) {
var pos = new google.maps.LatLng(position.coords.latitude,
position.coords.longitude);
var marker = new google.maps.Marker({
map: map,
position: pos,
content: 'You are here!'
});
// Add circle overlay and bind to marker
var circle = new google.maps.Circle({
map: map,
radius: 16093, // 10 miles in metres
fillColor: '#AA0000'
});
circle.bindTo('center', marker, 'position');
map.setCenter(pos);
}, function() {
handleNoGeolocation(true);
});
} else {
// Browser doesn't support Geolocation
handleNoGeolocation(false);
}
}
function handleNoGeolocation(errorFlag) {
if (errorFlag) {
var content = 'Error: The Geolocation service failed.';
} else {
var content = 'Error: Your browser doesn\'t support geolocation.';
}
var options = {
map: map,
position: new google.maps.LatLng(60, 105),
content: content
};
var count = mgr.getMarkerCount(circle);
document.getElementById("Address").innerHTML += count + "<BR>";
google.maps.event.addDomListener(window, 'load', initialize);
//Maps API loaded, now load customizations
var element = document.createElement('script');
element.src = 'template.js';
element.type = 'text/javascript';
var scripts = document.getElementsByTagName('script')[0];
scripts.parentNode.insertBefore(element, scripts);
}

Answer 1

The markers created by a FusionTableLayer are not real markers, there is no way to get them as a kind of list to filter them(you can't get any details for the markers, except you click them).
But you may request the FusionTableAPI with a spatial condition(via AJAX, jsonp is supported).
The syntax for the query:
SELECT COUNT() from tableId
WHERE ST_INTERSECTS('Address',CIRCLE(LATLNG(lat,lng),10000))
How to send a query : https://developers.google.com/fusiontables/docs/v1/sql-reference
Demo(using data of another FusionTable because your table is protected):
http://jsfiddle.net/doktormolle/bAtgf/

Answer 2

Simplest way: use the geometry library computeDistanceBetween method. If the distance from the user's location is less than 10 miles, the marker is in the circle.

Answer 3

I suggest you first fetch all the coordinates of your FusionTablesLayer.
Here is an example which was used in the sidebar
http://www.geocodezip.com/v3_FusionTables_AfricaMap_kml_sidebar.html
Then using a loop statement you can use the computeDistanceBetween function.
Detect If Marker is Within Circle Overlay