Change map opacity outside circle of Google Maps JavaScript API v3

Question

So I\'m currently putting a circle on my map:

    var optionsCercle = {
        center: latlang,
        map: map,
        radius: 1000,
        fillOpacity:         


        

Answer 1

{-Lat, (Long-180)%180, 20037508.34-Radius} workes well for me, Thx to Bahram Ardalan. Here my Code:

lat = 53;
lng = 10;
distance = 10 * 1000; // 10km

new google.maps.Circle({
                strokeColor: '#FF0000',
                strokeOpacity: 0.8,
                strokeWeight: 2,
                fillColor: '#FF0000',
                fillOpacity: 0.35,
                map: this.map,
                center: {lat: -1 * lat, lng: (lng - 180 ) % 180},
                radius: 20037508.34 - distance