Showing a Google Map in a modal created with Twitter Bootstrap

I'm trying to insert a Google map into a modal using Twitter Bootstrap. The modal shows up with the shape of the map present, but only part of the map is displayed, the rest is gray. Upon resizing the screen the map always shows up correctly, although centered in the wrong place.

I've searched and found suggestions such as calling the map's resize event, or setting the max-width of the map image to none, but none of these suggestions have helped so far. It seems like the map is failing to figure out it's correct size as long as it's in an element that's hidden.

JS

function initialize() {
  var mapOptions = {
    center: new google.maps.LatLng(51.219987, 4.396237),
    zoom: 12,
    mapTypeId: google.maps.MapTypeId.ROADMAP
  };
  var map = new google.maps.Map(document.getElementById("mapCanvas"),
    mapOptions);
  var marker = new google.maps.Marker({
    position: new google.maps.LatLng(51.219987, 4.396237)
  });
  marker.setMap(map);
}

HTML

<div class="modal hide fade" id="myModal">
  <div class="modal-header">
    <button type="button" class="close" data-dismiss="modal">×</button>
    <h3></h3>
  </div>
  <div class="modal-body">
    <div id="mapCanvas" style="width: 500px; height: 400px"></div>
  </div>
  <div class="modal-footer">
    <a href="#" class="btn" data-dismiss="modal">Close</a>
  </div>
</div>

I'm using Twitter Bootstrap v2.0.4. I need some help because I'm failing to trigger the resize event correctly or editing the css so that the Google map is left alone.

Google Maps indeed displays "Grey" area's when it's placed inside a dynamic element (for example: One that resizes, fades etc.). You're right about triggering the "resize" function, which should be called once the animation is complete (the shown.bs.modal event in Bootstrap 3 or the shown event in Bootstrap 2):

$("#myModal").on("shown.bs.modal", function () {
    google.maps.event.trigger(map, "resize");
});

In Bootstrap 2, you will do:

$('#myModal').on('shown', function () {
    google.maps.event.trigger(map, "resize");
});

(where map is the variable name of your map (see Google Maps documentation for further details), and #myModal the ID from your element).

UPDATE 2018-05-22

With a new renderer release in version 3.32 of Maps JavaScript API the resize event is no longer a part of Map class.

The documentation states

When the map is resized, the map center is fixed

• The full-screen control now preserves center.

• There is no longer any need to trigger the resize event manually.

source: https://developers.google.com/maps/documentation/javascript/new-renderer

google.maps.event.trigger(map, "resize"); doesn't have any effect starting from version 3.32

For me, it works like this (Boostrap 3):

$("#contact-modal").on("shown.bs.modal", function () {
    google.maps.event.trigger(map, "resize");
});

Showing the map correctly and centered

I wanted to point out a few modifications I made, based on the original answer, to make it work with Bootstrap 3 (check about modals usage).

// Resize map to show on a Bootstrap's modal
$('#map-modal').on('shown.bs.modal', function() {
  var currentCenter = map.getCenter();  // Get current center before resizing
  google.maps.event.trigger(map, "resize");
  map.setCenter(currentCenter); // Re-set previous center
});

In this case, I also take care of recentering the map, based on this question suggested in Jan-Henk's comment to the first answer.

When using Bootstrap 3 you need to use what is provided within their documentation i.e. instead of 'shown' use 'shown.bs.modal'

Example:

 $('#modal').on('shown.bs.modal', function () { 
     initialiseMap();
 });

The accepted answer does, indeed, work in this case where the contents of the div are local. Unfortunately, I had the same problem showing a map that was included as part of remote data. Getting the handle of the map and calling resize did not correctly center my map. Here is how I fixed the issue in my remote data situation.

Include a script tag as part of your remote data with a function to initialize the map

<script type="text/javascript">
    function renderMap() {
        var point = new google.maps.LatLng(51.219987, 4.396237);
        var map = new google.maps.Map(document.getElementById('map'), {
            mapTypeId: google.maps.MapTypeId.ROADMAP,
            zoom: 13,
            center: point
        });
        var marker = new google.maps.Marker({ position: point, map: map, icon: 'http://www.google.com/intl/en_us/mapfiles/ms/icons/red-dot.png' });
    }
</script>

Call the function in the shown event of the dialog on the main page

<script type="text/javascript">

    $(document).ready(function () {
        $('#dlgReportInfo').on('shown', function () {
            renderMap();
        });
    })
</script>

This way, the map is already sized in the dialog before you initialize it. Hopefully this will help out any others with a similar situation.