/*
  VERSION: Drop Shadow jQuery Plugin 1.6  12-13-2007

  REQUIRES: jquery.js (1.2.6 or later)

  SYNTAX: $(selector).dropShadow(options);  // Creates new drop shadows
          $(selector).redrawShadow();       // Redraws shadows on elements
          $(selector).removeShadow();       // Removes shadows from elements
          $(selector).shadowId();           // Returns an existing shadow's ID

  OPTIONS:

    left    : integer (default = 4)
    top     : integer (default = 4)
    blur    : integer (default = 2)
    opacity : decimal (default = 0.5)
    color   : string (default = "black")
    swap    : boolean (default = false)

  The left and top parameters specify the distance and direction, in  pixels, to
  offset the shadow. Zero values position the shadow directly behind the element.
  Positive values shift the shadow to the right and down, while negative values
  shift the shadow to the left and up.

  The blur parameter specifies the spread, or dispersion, of the shadow. Zero
  produces a sharp shadow, one or two produces a normal shadow, and  three or four
  produces a softer shadow. Higher values increase the processing load.

  The opacity parameter  should be a decimal value, usually less than one. You can
  use a value  higher than one in special situations, e.g. with extreme blurring.

  Color is specified in the usual manner, with a color name or hex value. The
  color parameter  does not apply with transparent images.

  The swap parameter reverses the stacking order of the original and the shadow.
  This can be used for special effects, like an embossed or engraved look.

  EXPLANATION:

  This jQuery plug-in adds soft drop shadows behind page elements. It is only
  intended for adding a few drop shadows to mostly stationary objects, like a
  page heading, a photo, or content containers.

  The shadows it creates are not bound to the original elements, so they won't
  move or change size automatically if the original elements change. A window
  resize event listener is assigned, which should re-align the shadows in many
  cases, but if the elements otherwise move or resize you will have to handle
  those events manually. Shadows can be redrawn with the redrawShadow() method
  or removed with the removeShadow() method. The redrawShadow() method uses the
  same options used to create the original shadow. If you want to change the
  options, you should remove the shadow first and then create a new shadow.

  The dropShadow method returns a jQuery collection of the new shadow(s). If
  further manipulation is required, you can store it in a variable like this:

    var myShadow = $("#myElement").dropShadow();

  You can also read the ID of the shadow from the original element at a later
  time. To get a shadow's ID, either read the shadowId attribute of the
  original element or call the shadowId() method. For example:

    var myShadowId = $("#myElement").attr("shadowId");  or
    var myShadowId = $("#myElement").shadowId();

  If the original element does not already have an ID assigned, a random ID will
  be generated for the shadow. However, if the original does have an ID, the
  shadow's ID will be the original ID and "_dropShadow". For example, if the
  element's ID is "myElement", the shadow's ID would be "myElement_dropShadow".

  If you have a long piece of text and the user resizes the  window so that the
  text wraps or unwraps, the shape of the text changes and the words are no
  longer in the same positions. In that case, you can either preset the height
  and width, so that it becomes a fixed box, or you can shadow each word
  separately, like this:

    <h1><span>Your</span> <span>Page</span> <span>Title</span></h1>

    $("h1 span").dropShadow();

  The dropShadow method attempts to determine whether the selected elements have
  transparent backgrounds. If you want to shadow the content inside an element,
  like text or a transparent image, it must not have a background-color or
  background-image style. If the element has a solid background it will create a
  rectangular  shadow around the outside box.

  The shadow elements are positioned absolutely one layer below the original
  element, which is positioned relatively (unless it's already absolute).

  *** All shadows have the "dropShadow" class, for selecting with CSS or jQuery.

  ISSUES:

    1)  Limited styling of shadowed elements by ID. Because IDs must be unique,
        and the shadows have their own ID, styles applied by ID won't transfer
        to the shadows. Instead, style elements by class or use inline styles.
    2)  Sometimes shadows don't align properly. Elements may need to be wrapped
        in container elements, margins or floats changed, etc. or you may just
        have to tweak the left and top offsets to get them to align. For example,
        with draggable objects, you have to wrap them inside two divs. Make the
        outer div draggable and set the inner div's position to relative. Then
        you can create a shadow on the element inside the inner div.
    3)  If the user changes font sizes it will throw the shadows off. Browsers
        do not expose an event for font size changes. The only known way to
        detect a user font size change is to embed an invisible text element and
        then continuously poll for changes in size.
    4)  Safari support is shaky, and may require even more tweaks/wrappers, etc.

    The bottom line is that this is a gimick effect, not PFM, and if you push it
    too hard or expect it to work in every possible situation on every browser,
    you will be disappointed. Use it sparingly, and don't use it for anything
    critical. Otherwise, have fun with it!

  AUTHOR: Larry Stevens (McLars@eyebulb.com) This work is in the public domain,
          and it is not supported in any way. Use it at your own risk.
*/


(function($){

  var dropShadowZindex = 1;  //z-index counter

  $.fn.dropShadow = function(options)
  {
    // Default options
    var opt = $.extend({
      left: 4,
      top: 4,
      blur: 2,
      opacity: .5,
      color: "black",
      swap: false
      }, options);
    var jShadows = $([]);  //empty jQuery collection

    // Loop through original elements
    this.not(".dropShadow").each(function()
    {
      var jthis = $(this);
      var shadows = [];
      var blur = (opt.blur <= 0) ? 0 : opt.blur;
      var opacity = (blur == 0) ? opt.opacity : opt.opacity / (blur * 8);
      var zOriginal = (opt.swap) ? dropShadowZindex : dropShadowZindex + 1;
      var zShadow = (opt.swap) ? dropShadowZindex + 1 : dropShadowZindex;

      // Create ID for shadow
      var shadowId;
      if (this.id) {
        shadowId = this.id + "_dropShadow";
      }
      else {
        shadowId = "ds" + (1 + Math.floor(9999 * Math.random()));
      }

      // Modify original element
      $.data(this, "shadowId", shadowId); //store id in expando
      $.data(this, "shadowOptions", options); //store options in expando
      jthis
        .attr("shadowId", shadowId)
        .css("zIndex", zOriginal);
      if (jthis.css("position") != "absolute") {
        jthis.css({
          position: "relative",
          zoom: 1 //for IE layout
        });
      }

      // Create first shadow layer
      bgColor = jthis.css("backgroundColor");
      if (bgColor == "rgba(0, 0, 0, 0)") bgColor = "transparent";  //Safari
      if (bgColor != "transparent" || jthis.css("backgroundImage") != "none"
          || this.nodeName == "SELECT"
          || this.nodeName == "INPUT"
          || this.nodeName == "TEXTAREA") {
        shadows[0] = $("<div></div>")
          .css("background", opt.color);
      }
      else {
        shadows[0] = jthis
          .clone()
          .removeAttr("id")
          .removeAttr("name")
          .removeAttr("shadowId")
          .css("color", opt.color);
      }
      shadows[0]
        .addClass("dropShadow")
        .css({
          height: jthis.outerHeight(),
          left: blur,
          opacity: opacity,
          position: "absolute",
          top: blur,
          width: jthis.outerWidth(),
          zIndex: zShadow
        });

      // Create other shadow layers
      var layers = (8 * blur) + 1;
      for (i = 1; i < layers; i++) {
        shadows[i] = shadows[0].clone();
      }

      // Position layers
      var i = 1;
      var j = blur;
      while (j > 0) {
        shadows[i].css({left: j * 2, top: 0});           //top
        shadows[i + 1].css({left: j * 4, top: j * 2});   //right
        shadows[i + 2].css({left: j * 2, top: j * 4});   //bottom
        shadows[i + 3].css({left: 0, top: j * 2});       //left
        shadows[i + 4].css({left: j * 3, top: j});       //top-right
        shadows[i + 5].css({left: j * 3, top: j * 3});   //bottom-right
        shadows[i + 6].css({left: j, top: j * 3});       //bottom-left
        shadows[i + 7].css({left: j, top: j});           //top-left
        i += 8;
        j--;
      }

      // Create container
      var divShadow = $("<div></div>")
        .attr("id", shadowId)
        .addClass("dropShadow")
        .css({
          left: jthis.position().left + opt.left - blur,
          marginTop: jthis.css("marginTop"),
          marginRight: jthis.css("marginRight"),
          marginBottom: jthis.css("marginBottom"),
          marginLeft: jthis.css("marginLeft"),
          position: "absolute",
          top: jthis.position().top + opt.top - blur,
          zIndex: zShadow
        });

      // Add layers to container
      for (i = 0; i < layers; i++) {
        divShadow.append(shadows[i]);
      }

      // Add container to DOM
      jthis.after(divShadow);

      // Add shadow to return set
      jShadows = jShadows.add(divShadow);

      // Re-align shadow on window resize
      $(window).resize(function()
      {
        try {
          divShadow.css({
            left: jthis.position().left + opt.left - blur,
            top: jthis.position().top + opt.top - blur
          });
        }
        catch(e){}
      });

      // Increment z-index counter
      dropShadowZindex += 2;

    });  //end each

    return this.pushStack(jShadows);
  };


  $.fn.redrawShadow = function()
  {
    // Remove existing shadows
    this.removeShadow();

    // Draw new shadows
    return this.each(function()
    {
      var shadowOptions = $.data(this, "shadowOptions");
      $(this).dropShadow(shadowOptions);
    });
  };


  $.fn.removeShadow = function()
  {
    return this.each(function()
    {
      var shadowId = $(this).shadowId();
      $("div#" + shadowId).remove();
    });
  };


  $.fn.shadowId = function()
  {
    return $.data(this[0], "shadowId");
  };


  $(function()
  {
    // Suppress printing of shadows
    var noPrint = "<style type='text/css' media='print'>";
    noPrint += ".dropShadow{visibility:hidden;}</style>";
    $("head").append(noPrint);
  });

})(jQuery);