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

  REQUIRES: jquery.js (verified for 1.3.2)

  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.
        
  AUTHOR: Larry Stevens.  This work is in the public domain,
          and 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);