gistfile1.rb

## template

gmaps("markers" => {"data" => @json}, "map_options" => {:type => 'HYBRID', "processing" => "json", "auto_adjust" => true, "zoom" => 10})


## javascript


 function drawItems(theBounds) {
    var url = '/within.json/?sw_y=' + theBounds.getSouthWest().lng() + 
                           '&sw_x=' + theBounds.getSouthWest().lat() + 
                           '&ne_y=' + theBounds.getNorthEast().lng() +
                           '&ne_x=' + theBounds.getNorthEast().lat();
    $.get(url, function(newItemData) {
      Gmaps.map.replaceMarkers(newItemData);
    }); 
  }
   Gmaps.map.callback = function() {
      google.maps.event.addListener(Gmaps.map.map, "dragend", function() {
        var bounds = Gmaps.map.map.getBounds();
        drawItems(bounds);
      }); 
    };  


## controller


def within
      # Only pull venues within the visible bounds of the map
      if (params[:sw_y] && params[:sw_x] && params[:ne_y] && params[:ne_x])
        bounds = [ [params[:sw_x].to_f, params[:sw_y].to_f], 
          [params[:ne_x].to_f, params[:ne_y].to_f] ]
        @venues_within_bounds = Spot.within(bounds)
      else
        @venues_within_bounds = Spot.all
      end   
  
      respond_to do |format|
        format.html # index.html.erb
        format.json { 
          @data = @venues_within_bounds #collect { |v| 
          render :json => @data                                                                                                                                                                                                              
      }   
      end 
end 

## within template:

@data.to_gmaps4rails