GMaps.prototype.drawOverlay = function(options) {
  var overlay = new google.maps.OverlayView(),
      auto_show = true;

  overlay.setMap(this.map);

  if (options.auto_show != null) {
    auto_show = options.auto_show;
  }

  overlay.onAdd = function() {
    var el = document.createElement('div');

    el.style.borderStyle = "none";
    el.style.borderWidth = "0px";
    el.style.position = "absolute";
    el.style.zIndex = 100;
    el.innerHTML = options.content;

    overlay.el = el;

    if (!options.layer) {
      options.layer = 'overlayLayer';
    }
    
    var panes = this.getPanes(),
        overlayLayer = panes[options.layer],
        stop_overlay_events = ['contextmenu', 'DOMMouseScroll', 'dblclick', 'mousedown'];

    overlayLayer.appendChild(el);

    for (var ev = 0; ev < stop_overlay_events.length; ev++) {
      (function(object, name) {
        google.maps.event.addDomListener(object, name, function(e){
          if (navigator.userAgent.toLowerCase().indexOf('msie') != -1 && document.all) {
            e.cancelBubble = true;
            e.returnValue = false;
          }
          else {
            e.stopPropagation();
          }
        });
      })(el, stop_overlay_events[ev]);
    }

    if (options.click) {
      google.maps.event.addDomListener(overlay.el, 'click', function() {
        options.click.apply(overlay, [overlay]);
      });
    }

    google.maps.event.trigger(this, 'ready');
  };

  overlay.draw = function() {
    var projection = this.getProjection(),
        pixel = projection.fromLatLngToDivPixel(new google.maps.LatLng(options.lat, options.lng));

    options.horizontalOffset = options.horizontalOffset || 0;
    options.verticalOffset = options.verticalOffset || 0;

    var el = overlay.el,
        content = el.children[0],
        content_height = content.clientHeight,
        content_width = content.clientWidth;

    switch (options.verticalAlign) {
      case 'top':
        el.style.top = (pixel.y - content_height + options.verticalOffset) + 'px';
        break;
      default:
      case 'middle':
        el.style.top = (pixel.y - (content_height / 2) + options.verticalOffset) + 'px';
        break;
      case 'bottom':
        el.style.top = (pixel.y + options.verticalOffset) + 'px';
        break;
    }

    switch (options.horizontalAlign) {
      case 'left':
        el.style.left = (pixel.x - content_width + options.horizontalOffset) + 'px';
        break;
      default:
      case 'center':
        el.style.left = (pixel.x - (content_width / 2) + options.horizontalOffset) + 'px';
        break;
      case 'right':
        el.style.left = (pixel.x + options.horizontalOffset) + 'px';
        break;
    }

    el.style.display = auto_show ? 'block' : 'none';

    if (!auto_show) {
      options.show.apply(this, [el]);
    }
  };

  overlay.onRemove = function() {
    var el = overlay.el;

    if (options.remove) {
      options.remove.apply(this, [el]);
    }
    else {
      overlay.el.parentNode.removeChild(overlay.el);
      overlay.el = null;
    }
  };

  this.overlays.push(overlay);
  return overlay;
};

GMaps.prototype.removeOverlay = function(overlay) {
  for (var i = 0; i < this.overlays.length; i++) {
    if (this.overlays[i] === overlay) {
      this.overlays[i].setMap(null);
      this.overlays.splice(i, 1);

      break;
    }
  }
};

GMaps.prototype.removeOverlays = function() {
  for (var i = 0, item; item = this.overlays[i]; i++) {
    item.setMap(null);
  }

  this.overlays = [];
};
