function InfoBox(opt_opts) {

  opt_opts = opt_opts || {};

  google.maps.OverlayView.apply(this, arguments);

  // Standard options (in common with google.maps.InfoWindow):
  //
  this.content_ = opt_opts.content || "";
  this.disableAutoPan_ = opt_opts.disableAutoPan || false;
  this.maxWidth_ = opt_opts.maxWidth || 0;
  this.pixelOffset_ = opt_opts.pixelOffset || new google.maps.Size(0, 0);
  this.position_ = opt_opts.position || new google.maps.LatLng(0, 0);
  this.zIndex_ = opt_opts.zIndex || null;

  // Additional options (unique to InfoBox):
  //
  this.boxClass_ = opt_opts.boxClass || "infoBox";
  this.boxStyle_ = opt_opts.boxStyle || {};
  this.closeBoxMargin_ = opt_opts.closeBoxMargin || "2px";
  this.closeBoxURL_ = opt_opts.closeBoxURL || "http://www.google.com/intl/en_us/mapfiles/close.gif";
  if (opt_opts.closeBoxURL === "") {
    this.closeBoxURL_ = "";
  }
  this.infoBoxClearance_ = opt_opts.infoBoxClearance || new google.maps.Size(1, 1);

  if (typeof opt_opts.visible === "undefined") {
    if (typeof opt_opts.isHidden === "undefined") {
      opt_opts.visible = true;
    } else {
      opt_opts.visible = !opt_opts.isHidden;
    }
  }
  this.isHidden_ = !opt_opts.visible;

  this.alignBottom_ = opt_opts.alignBottom || false;
  this.pane_ = opt_opts.pane || "floatPane";
  this.enableEventPropagation_ = opt_opts.enableEventPropagation || false;

  this.div_ = null;
  this.closeListener_ = null;
  this.moveListener_ = null;
  this.contextListener_ = null;
  this.eventListeners_ = null;
  this.fixedWidthSet_ = null;
}

/* InfoBox extends OverlayView in the Google Maps API v3.
 */
InfoBox.prototype = new google.maps.OverlayView();

/**
 * Creates the DIV representing the InfoBox.
 * @private
 */
InfoBox.prototype.createInfoBoxDiv_ = function () {

  var i;
  var events;
  var bw;
  var me = this;

  // This handler prevents an event in the InfoBox from being passed on to the map.
  //
  var cancelHandler = function (e) {
    e.cancelBubble = true;
    if (e.stopPropagation) {
      e.stopPropagation();
    }
  };

  // This handler ignores the current event in the InfoBox and conditionally prevents
  // the event from being passed on to the map. It is used for the contextmenu event.
  //
  var ignoreHandler = function (e) {

    e.returnValue = false;

    if (e.preventDefault) {

      e.preventDefault();
    }

    if (!me.enableEventPropagation_) {

      cancelHandler(e);
    }
  };

  if (!this.div_) {

    this.div_ = document.createElement("div");

    this.setBoxStyle_();

    if (typeof this.content_.nodeType === "undefined") {
      this.div_.innerHTML = this.getCloseBoxImg_() + this.content_;
    } else {
      this.div_.innerHTML = this.getCloseBoxImg_();
      this.div_.appendChild(this.content_);
    }

    // Add the InfoBox DIV to the DOM
    this.getPanes()[this.pane_].appendChild(this.div_);

    this.addClickHandler_();

    if (this.div_.style.width) {

      this.fixedWidthSet_ = true;

    } else {

      if (this.maxWidth_ !== 0 && this.div_.offsetWidth > this.maxWidth_) {

        this.div_.style.width = this.maxWidth_;
        this.div_.style.overflow = "auto";
        this.fixedWidthSet_ = true;

      } else { // The following code is needed to overcome problems with MSIE

        bw = this.getBoxWidths_();

        this.div_.style.width = (this.div_.offsetWidth - bw.left - bw.right) + "px";
        this.fixedWidthSet_ = false;
      }
    }

    this.panBox_(this.disableAutoPan_);

    if (!this.enableEventPropagation_) {

      this.eventListeners_ = [];

      // Cancel event propagation.
      //
      // Note: mousemove not included (to resolve Issue 152)
      events = ["mousedown", "mouseover", "mouseout", "mouseup",
      "click", "dblclick", "touchstart", "touchend", "touchmove"];

      for (i = 0; i < events.length; i++) {

        this.eventListeners_.push(google.maps.event.addDomListener(this.div_, events[i], cancelHandler));
      }
      
      // Workaround for Google bug that causes the cursor to change to a pointer
      // when the mouse moves over a marker underneath InfoBox.
      this.eventListeners_.push(google.maps.event.addDomListener(this.div_, "mouseover", function (e) {
        this.style.cursor = "default";
      }));
    }

    this.contextListener_ = google.maps.event.addDomListener(this.div_, "contextmenu", ignoreHandler);

    /**
     * This event is fired when the DIV containing the InfoBox's content is attached to the DOM.
     * @name InfoBox#domready
     * @event
     */
    google.maps.event.trigger(this, "domready");
  }
};

/**
 * Returns the HTML <IMG> tag for the close box.
 * @private
 */
InfoBox.prototype.getCloseBoxImg_ = function () {

  var img = "";

  if (this.closeBoxURL_ !== "") {

    img  = "<img";
    img += " src='" + this.closeBoxURL_ + "'";
    img += " align=right"; // Do this because Opera chokes on style='float: right;'
    img += " style='";
    img += " position: relative;"; // Required by MSIE
    img += " cursor: pointer;";
    img += " margin: " + this.closeBoxMargin_ + ";";
    img += "'>";
  }

  return img;
};

/**
 * Adds the click handler to the InfoBox close box.
 * @private
 */
InfoBox.prototype.addClickHandler_ = function () {

  var closeBox;

  if (this.closeBoxURL_ !== "") {

    closeBox = this.div_.firstChild;
    this.closeListener_ = google.maps.event.addDomListener(closeBox, "click", this.getCloseClickHandler_());

  } else {

    this.closeListener_ = null;
  }
};

/**
 * Returns the function to call when the user clicks the close box of an InfoBox.
 * @private
 */
InfoBox.prototype.getCloseClickHandler_ = function () {

  var me = this;

  return function (e) {

    // 1.0.3 fix: Always prevent propagation of a close box click to the map:
    e.cancelBubble = true;

    if (e.stopPropagation) {

      e.stopPropagation();
    }

    /**
     * This event is fired when the InfoBox's close box is clicked.
     * @name InfoBox#closeclick
     * @event
     */
    google.maps.event.trigger(me, "closeclick");

    me.close();
  };
};

/**
 * Pans the map so that the InfoBox appears entirely within the map's visible area.
 * @private
 */
InfoBox.prototype.panBox_ = function (disablePan) {

  var map;
  var bounds;
  var xOffset = 0, yOffset = 0;

  if (!disablePan) {

    map = this.getMap();

    if (map instanceof google.maps.Map) { // Only pan if attached to map, not panorama

      if (!map.getBounds().contains(this.position_)) {
      // Marker not in visible area of map, so set center
      // of map to the marker position first.
        map.setCenter(this.position_);
      }

      bounds = map.getBounds();

      var mapDiv = map.getDiv();
      var mapWidth = mapDiv.offsetWidth;
      var mapHeight = mapDiv.offsetHeight;
      var iwOffsetX = this.pixelOffset_.width;
      var iwOffsetY = this.pixelOffset_.height;
      var iwWidth = this.div_.offsetWidth;
      var iwHeight = this.div_.offsetHeight;
      var padX = this.infoBoxClearance_.width;
      var padY = this.infoBoxClearance_.height;
      var pixPosition = this.getProjection().fromLatLngToContainerPixel(this.position_);

      if (pixPosition.x < (-iwOffsetX + padX)) {
        xOffset = pixPosition.x + iwOffsetX - padX;
      } else if ((pixPosition.x + iwWidth + iwOffsetX + padX) > mapWidth) {
        xOffset = pixPosition.x + iwWidth + iwOffsetX + padX - mapWidth;
      }
      if (this.alignBottom_) {
        if (pixPosition.y < (-iwOffsetY + padY + iwHeight)) {
          yOffset = pixPosition.y + iwOffsetY - padY - iwHeight;
        } else if ((pixPosition.y + iwOffsetY + padY) > mapHeight) {
          yOffset = pixPosition.y + iwOffsetY + padY - mapHeight;
        }
      } else {
        if (pixPosition.y < (-iwOffsetY + padY)) {
          yOffset = pixPosition.y + iwOffsetY - padY;
        } else if ((pixPosition.y + iwHeight + iwOffsetY + padY) > mapHeight) {
          yOffset = pixPosition.y + iwHeight + iwOffsetY + padY - mapHeight;
        }
      }

      if (!(xOffset === 0 && yOffset === 0)) {

        // Move the map to the shifted center.
        //
        var c = map.getCenter();
        map.panBy(xOffset, yOffset);
      }
    }
  }
};

/**
 * Sets the style of the InfoBox by setting the style sheet and applying
 * other specific styles requested.
 * @private
 */
InfoBox.prototype.setBoxStyle_ = function () {

  var i, boxStyle;

  if (this.div_) {

    // Apply style values from the style sheet defined in the boxClass parameter:
    this.div_.className = this.boxClass_;

    // Clear existing inline style values:
    this.div_.style.cssText = "";

    // Apply style values defined in the boxStyle parameter:
    boxStyle = this.boxStyle_;
    for (i in boxStyle) {

      if (boxStyle.hasOwnProperty(i)) {

        this.div_.style[i] = boxStyle[i];
      }
    }

    // Fix for iOS disappearing InfoBox problem.
    // See http://stackoverflow.com/questions/9229535/google-maps-markers-disappear-at-certain-zoom-level-only-on-iphone-ipad
    this.div_.style.WebkitTransform = "translateZ(0)";

    // Fix up opacity style for benefit of MSIE:
    //
    if (typeof this.div_.style.opacity !== "undefined" && this.div_.style.opacity !== "") {
      // See http://www.quirksmode.org/css/opacity.html
      this.div_.style.MsFilter = "\"progid:DXImageTransform.Microsoft.Alpha(Opacity=" + (this.div_.style.opacity * 100) + ")\"";
      this.div_.style.filter = "alpha(opacity=" + (this.div_.style.opacity * 100) + ")";
    }

    // Apply required styles:
    //
    this.div_.style.position = "absolute";
    this.div_.style.visibility = 'hidden';
    if (this.zIndex_ !== null) {

      this.div_.style.zIndex = this.zIndex_;
    }
  }
};

/**
 * Get the widths of the borders of the InfoBox.
 * @private
 * @return {Object} widths object (top, bottom left, right)
 */
InfoBox.prototype.getBoxWidths_ = function () {

  var computedStyle;
  var bw = {top: 0, bottom: 0, left: 0, right: 0};
  var box = this.div_;

  if (document.defaultView && document.defaultView.getComputedStyle) {

    computedStyle = box.ownerDocument.defaultView.getComputedStyle(box, "");

    if (computedStyle) {

      // The computed styles are always in pixel units (good!)
      bw.top = parseInt(computedStyle.borderTopWidth, 10) || 0;
      bw.bottom = parseInt(computedStyle.borderBottomWidth, 10) || 0;
      bw.left = parseInt(computedStyle.borderLeftWidth, 10) || 0;
      bw.right = parseInt(computedStyle.borderRightWidth, 10) || 0;
    }

  } else if (document.documentElement.currentStyle) { // MSIE

    if (box.currentStyle) {

      // The current styles may not be in pixel units, but assume they are (bad!)
      bw.top = parseInt(box.currentStyle.borderTopWidth, 10) || 0;
      bw.bottom = parseInt(box.currentStyle.borderBottomWidth, 10) || 0;
      bw.left = parseInt(box.currentStyle.borderLeftWidth, 10) || 0;
      bw.right = parseInt(box.currentStyle.borderRightWidth, 10) || 0;
    }
  }

  return bw;
};

/**
 * Invoked when <tt>close</tt> is called. Do not call it directly.
 */
InfoBox.prototype.onRemove = function () {

  if (this.div_) {

    this.div_.parentNode.removeChild(this.div_);
    this.div_ = null;
  }
};

/**
 * Draws the InfoBox based on the current map projection and zoom level.
 */
InfoBox.prototype.draw = function () {

  this.createInfoBoxDiv_();

  var pixPosition = this.getProjection().fromLatLngToDivPixel(this.position_);

  this.div_.style.left = (pixPosition.x + this.pixelOffset_.width) + "px";
  
  if (this.alignBottom_) {
    this.div_.style.bottom = -(pixPosition.y + this.pixelOffset_.height) + "px";
  } else {
    this.div_.style.top = (pixPosition.y + this.pixelOffset_.height) + "px";
  }

  if (this.isHidden_) {

    this.div_.style.visibility = "hidden";

  } else {

    this.div_.style.visibility = "visible";
  }
};

/**
 * Sets the options for the InfoBox. Note that changes to the <tt>maxWidth</tt>,
 *  <tt>closeBoxMargin</tt>, <tt>closeBoxURL</tt>, and <tt>enableEventPropagation</tt>
 *  properties have no affect until the current InfoBox is <tt>close</tt>d and a new one
 *  is <tt>open</tt>ed.
 * @param {InfoBoxOptions} opt_opts
 */
InfoBox.prototype.setOptions = function (opt_opts) {
  if (typeof opt_opts.boxClass !== "undefined") { // Must be first

    this.boxClass_ = opt_opts.boxClass;
    this.setBoxStyle_();
  }
  if (typeof opt_opts.boxStyle !== "undefined") { // Must be second

    this.boxStyle_ = opt_opts.boxStyle;
    this.setBoxStyle_();
  }
  if (typeof opt_opts.content !== "undefined") {

    this.setContent(opt_opts.content);
  }
  if (typeof opt_opts.disableAutoPan !== "undefined") {

    this.disableAutoPan_ = opt_opts.disableAutoPan;
  }
  if (typeof opt_opts.maxWidth !== "undefined") {

    this.maxWidth_ = opt_opts.maxWidth;
  }
  if (typeof opt_opts.pixelOffset !== "undefined") {

    this.pixelOffset_ = opt_opts.pixelOffset;
  }
  if (typeof opt_opts.alignBottom !== "undefined") {

    this.alignBottom_ = opt_opts.alignBottom;
  }
  if (typeof opt_opts.position !== "undefined") {

    this.setPosition(opt_opts.position);
  }
  if (typeof opt_opts.zIndex !== "undefined") {

    this.setZIndex(opt_opts.zIndex);
  }
  if (typeof opt_opts.closeBoxMargin !== "undefined") {

    this.closeBoxMargin_ = opt_opts.closeBoxMargin;
  }
  if (typeof opt_opts.closeBoxURL !== "undefined") {

    this.closeBoxURL_ = opt_opts.closeBoxURL;
  }
  if (typeof opt_opts.infoBoxClearance !== "undefined") {

    this.infoBoxClearance_ = opt_opts.infoBoxClearance;
  }
  if (typeof opt_opts.isHidden !== "undefined") {

    this.isHidden_ = opt_opts.isHidden;
  }
  if (typeof opt_opts.visible !== "undefined") {

    this.isHidden_ = !opt_opts.visible;
  }
  if (typeof opt_opts.enableEventPropagation !== "undefined") {

    this.enableEventPropagation_ = opt_opts.enableEventPropagation;
  }

  if (this.div_) {

    this.draw();
  }
};

/**
 * Sets the content of the InfoBox.
 *  The content can be plain text or an HTML DOM node.
 * @param {string|Node} content
 */
InfoBox.prototype.setContent = function (content) {
  this.content_ = content;

  if (this.div_) {

    if (this.closeListener_) {

      google.maps.event.removeListener(this.closeListener_);
      this.closeListener_ = null;
    }

    // Odd code required to make things work with MSIE.
    //
    if (!this.fixedWidthSet_) {

      this.div_.style.width = "";
    }

    if (typeof content.nodeType === "undefined") {
      this.div_.innerHTML = this.getCloseBoxImg_() + content;
    } else {
      this.div_.innerHTML = this.getCloseBoxImg_();
      this.div_.appendChild(content);
    }

    // Perverse code required to make things work with MSIE.
    // (Ensures the close box does, in fact, float to the right.)
    //
    if (!this.fixedWidthSet_) {
      this.div_.style.width = this.div_.offsetWidth + "px";
      if (typeof content.nodeType === "undefined") {
        this.div_.innerHTML = this.getCloseBoxImg_() + content;
      } else {
        this.div_.innerHTML = this.getCloseBoxImg_();
        this.div_.appendChild(content);
      }
    }

    this.addClickHandler_();
  }

  /**
   * This event is fired when the content of the InfoBox changes.
   * @name InfoBox#content_changed
   * @event
   */
  google.maps.event.trigger(this, "content_changed");
};

/**
 * Sets the geographic location of the InfoBox.
 * @param {LatLng} latlng
 */
InfoBox.prototype.setPosition = function (latlng) {

  this.position_ = latlng;

  if (this.div_) {

    this.draw();
  }

  /**
   * This event is fired when the position of the InfoBox changes.
   * @name InfoBox#position_changed
   * @event
   */
  google.maps.event.trigger(this, "position_changed");
};

/**
 * Sets the zIndex style for the InfoBox.
 * @param {number} index
 */
InfoBox.prototype.setZIndex = function (index) {

  this.zIndex_ = index;

  if (this.div_) {

    this.div_.style.zIndex = index;
  }

  /**
   * This event is fired when the zIndex of the InfoBox changes.
   * @name InfoBox#zindex_changed
   * @event
   */
  google.maps.event.trigger(this, "zindex_changed");
};

/**
 * Sets the visibility of the InfoBox.
 * @param {boolean} isVisible
 */
InfoBox.prototype.setVisible = function (isVisible) {

  this.isHidden_ = !isVisible;
  if (this.div_) {
    this.div_.style.visibility = (this.isHidden_ ? "hidden" : "visible");
  }
};

/**
 * Returns the content of the InfoBox.
 * @returns {string}
 */
InfoBox.prototype.getContent = function () {

  return this.content_;
};

/**
 * Returns the geographic location of the InfoBox.
 * @returns {LatLng}
 */
InfoBox.prototype.getPosition = function () {

  return this.position_;
};

/**
 * Returns the zIndex for the InfoBox.
 * @returns {number}
 */
InfoBox.prototype.getZIndex = function () {

  return this.zIndex_;
};

/**
 * Returns a flag indicating whether the InfoBox is visible.
 * @returns {boolean}
 */
InfoBox.prototype.getVisible = function () {

  var isVisible;

  if ((typeof this.getMap() === "undefined") || (this.getMap() === null)) {
    isVisible = false;
  } else {
    isVisible = !this.isHidden_;
  }
  return isVisible;
};

/**
 * Shows the InfoBox. [Deprecated; use <tt>setVisible</tt> instead.]
 */
InfoBox.prototype.show = function () {

  this.isHidden_ = false;
  if (this.div_) {
    this.div_.style.visibility = "visible";
  }
};

/**
 * Hides the InfoBox. [Deprecated; use <tt>setVisible</tt> instead.]
 */
InfoBox.prototype.hide = function () {

  this.isHidden_ = true;
  if (this.div_) {
    this.div_.style.visibility = "hidden";
  }
};

/**
 * Adds the InfoBox to the specified map or Street View panorama. If <tt>anchor</tt>
 *  (usually a <tt>google.maps.Marker</tt>) is specified, the position
 *  of the InfoBox is set to the position of the <tt>anchor</tt>. If the
 *  anchor is dragged to a new location, the InfoBox moves as well.
 * @param {Map|StreetViewPanorama} map
 * @param {MVCObject} [anchor]
 */
InfoBox.prototype.open = function (map, anchor) {

  var me = this;

  if (anchor) {

    this.position_ = anchor.getPosition();
    this.moveListener_ = google.maps.event.addListener(anchor, "position_changed", function () {
      me.setPosition(this.getPosition());
    });
  }

  this.setMap(map);

  if (this.div_) {

    this.panBox_();
  }
};

/**
 * Removes the InfoBox from the map.
 */
InfoBox.prototype.close = function () {

  var i;

  if (this.closeListener_) {

    google.maps.event.removeListener(this.closeListener_);
    this.closeListener_ = null;
  }

  if (this.eventListeners_) {
    
    for (i = 0; i < this.eventListeners_.length; i++) {

      google.maps.event.removeListener(this.eventListeners_[i]);
    }
    this.eventListeners_ = null;
  }

  if (this.moveListener_) {

    google.maps.event.removeListener(this.moveListener_);
    this.moveListener_ = null;
  }

  if (this.contextListener_) {

    google.maps.event.removeListener(this.contextListener_);
    this.contextListener_ = null;
  }

  this.setMap(null);
};