Center/Set Zoom of Map to cover all visible Markers?

Question

I am setting multiple markers on my map and I can set statically the zoom levels and the center but what I want is, to cover all the markers and zoom as much as possible hav

Answer 1

The size of array must be greater than zero. Οtherwise you will have unexpected results.

function zoomeExtends(){
  var bounds = new google.maps.LatLngBounds();
  if (markers.length>0) { 
      for (var i = 0; i < markers.length; i++) {
         bounds.extend(markers[i].getPosition());
        }    
        myMap.fitBounds(bounds);
    }
}

Answer 2

You need to use the fitBounds() method.

var markers = [];//some array
var bounds = new google.maps.LatLngBounds();
for (var i = 0; i < markers.length; i++) {
 bounds.extend(markers[i]);
}

map.fitBounds(bounds);

---

Documentation from developers.google.com/maps/documentation/javascript:

fitBounds(bounds[, padding])

Parameters:

`bounds`:  [`LatLngBounds`][1]|[`LatLngBoundsLiteral`][1]
`padding` (optional):  number|[`Padding`][1]

Return Value: None

Sets the viewport to contain the given bounds.
Note: When the map is set to display: none, the fitBounds function reads the map's size as 0x0, and therefore does not do anything. To change the viewport while the map is hidden, set the map to visibility: hidden, thereby ensuring the map div has an actual size.

Answer 3

There is this MarkerClusterer client side utility available for google Map as specified here on Google Map developer Articles, here is brief on what's it's usage:

There are many approaches for doing what you asked for:

• Grid based clustering
• Distance based clustering
• Viewport Marker Management
• Fusion Tables
• Marker Clusterer
• MarkerManager

You can read about them on the provided link above.

Marker Clusterer uses Grid Based Clustering to cluster all the marker wishing the grid. Grid-based clustering works by dividing the map into squares of a certain size (the size changes at each zoom) and then grouping the markers into each grid square.

Before Clustering

After Clustering

I hope this is what you were looking for & this will solve your problem :)

Answer 4

To extend the given answer with few useful tricks:

var markers = //some array;
var bounds = new google.maps.LatLngBounds();
for(i=0;i<markers.length;i++) {
   bounds.extend(markers[i].getPosition());
}

//center the map to a specific spot (city)
map.setCenter(center); 

//center the map to the geometric center of all markers
map.setCenter(bounds.getCenter());

map.fitBounds(bounds);

//remove one zoom level to ensure no marker is on the edge.
map.setZoom(map.getZoom()-1); 

// set a minimum zoom 
// if you got only 1 marker or all markers are on the same address map will be zoomed too much.
if(map.getZoom()> 15){
  map.setZoom(15);
}

//Alternatively this code can be used to set the zoom for just 1 marker and to skip redrawing.
//Note that this will not cover the case if you have 2 markers on the same address.
if(count(markers) == 1){
    map.setMaxZoom(15);
    map.fitBounds(bounds);
    map.setMaxZoom(Null)
}

UPDATE:
Further research in the topic show that fitBounds() is a asynchronic and it is best to make Zoom manipulation with a listener defined before calling Fit Bounds.
Thanks @Tim, @xr280xr, more examples on the topic : SO:setzoom-after-fitbounds

google.maps.event.addListenerOnce(map, 'bounds_changed', function(event) {
  this.setZoom(map.getZoom()-1);

  if (this.getZoom() > 15) {
    this.setZoom(15);
  }
});
map.fitBounds(bounds);