/*

 Automatic, anti-aliased rounded corners.

 

 By Steven Wittens

 Based on http://pro.html.it/esempio/nifty/

 

 Thanks to Jacob from Oddlabs.com for fixing two nasty bugs.

*/



function NiftyCheck() {

  if(!document.getElementById || !document.createElement) {

    return false;

  }

  var b = navigator.userAgent.toLowerCase();

  if (b.indexOf("msie 5") > 0 && b.indexOf("opera") == -1) {

    return false;

  }

  return true;

}



function Rounded(selector, bk, color, sizex, sizey) {

  var i;

  var v = getElementsBySelector(selector);

  var l = v.length;

  for (i = 0; i < l; i++) {

    AddTop(v[i], bk, color, sizex, sizey);

    AddBottom(v[i], bk, color, sizex, sizey);

  }

}



Math.sqr = function (x) {

  return x*x;

};



function Blend(a, b, alpha) {

  var ca = Array(

    parseInt('0x' + a.substring(1, 3)), 

    parseInt('0x' + a.substring(3, 5)), 

    parseInt('0x' + a.substring(5, 7))

  );

  var cb = Array(

    parseInt('0x' + b.substring(1, 3)), 

    parseInt('0x' + b.substring(3, 5)), 

    parseInt('0x' + b.substring(5, 7))

  );

  r = '0' + Math.round(ca[0] + (cb[0] - ca[0])*alpha).toString(16);

  g = '0' + Math.round(ca[1] + (cb[1] - ca[1])*alpha).toString(16);

  b = '0' + Math.round(ca[2] + (cb[2] - ca[2])*alpha).toString(16);

  return '#'

    + r.substring(r.length - 2)

    + g.substring(g.length - 2)

    + b.substring(b.length - 2);

}



function AddTop(el, bk, color, sizex, sizey) {

  var i, j;

  var d = document.createElement("div");

  d.style.backgroundColor = bk;

  d.className = "rounded";

  var lastarc = 0;

  for (i = 1; i <= sizey; i++) {

    var coverage, arc2, arc3;

    // Find intersection of arc with bottom of pixel row

    arc = Math.sqrt(1.0 - Math.sqr(1.0 - i / sizey)) * sizex;

    // Calculate how many pixels are bg, fg and blended.

    var n_bg = sizex - Math.ceil(arc);

    var n_fg = Math.floor(lastarc);

    var n_aa = sizex - n_bg - n_fg;

    // Create pixel row wrapper

    var x = document.createElement("div");

    var y = d;

    x.style.margin = "0px " + n_bg +"px";

    // Make a wrapper per anti-aliased pixel (at least one)

    for (j = 1; j <= n_aa; j++) {

      // Calculate coverage per pixel

      // (approximates circle by a line within the pixel)

      if (j == 1) {

        if (j == n_aa) {

          // Single pixel

          coverage = ((arc + lastarc) * .5) - n_fg;

        }

        else {

          // First in a run

          arc2 = Math.sqrt(1.0 - Math.sqr(1.0 - (n_bg + 1) / sizex)) * sizey;

          coverage = (arc2 - (sizey - i)) * (arc - n_fg - n_aa + 1) * .5;

        }

      }

      else if (j == n_aa) {

        // Last in a run

        arc2 = Math.sqrt(1.0 - Math.sqr((sizex - n_bg - j + 1) / sizex)) * sizey;

        coverage = 1.0 - (1.0 - (arc2 - (sizey - i))) * (1.0 - (lastarc - n_fg)) * .5;

      }

      else {

        // Middle of a run

        arc3 = Math.sqrt(1.0 - Math.sqr((sizex - n_bg - j) / sizex)) * sizey;

        arc2 = Math.sqrt(1.0 - Math.sqr((sizex - n_bg - j + 1) / sizex)) * sizey;

        coverage = ((arc2 + arc3) * .5) - (sizey - i);

      }

      

      x.style.backgroundColor = Blend(bk, color, coverage);

      y.appendChild(x);

      y = x;

      var x = document.createElement("div");

      x.style.margin = "0px 1px";

    }

    x.style.backgroundColor = color;

    y.appendChild(x);

    lastarc = arc;

  }

  el.insertBefore(d, el.firstChild);

}



function AddBottom(el, bk, color, sizex, sizey) {

  var i, j;

  var d = document.createElement("div");

  d.className = "rounded";

  d.style.backgroundColor = bk;

  var lastarc = 0;

  for (i = 1; i <= sizey; i++) {

    var coverage, arc2, arc3;

    // Find intersection of arc with bottom of pixel row

    arc = Math.sqrt(1.0 - Math.sqr(1.0 - i / sizey)) * sizex;

    // Calculate how many pixels are bg, fg and blended.

    var n_bg = sizex - Math.ceil(arc);

    var n_fg = Math.floor(lastarc);

    var n_aa = sizex - n_bg - n_fg;

    // Create pixel row wrapper

    var x = document.createElement("div");

    var y = d;

    x.style.margin = "0px " + n_bg + "px";

    // Make a wrapper per anti-aliased pixel (at least one)

    for (j = 1; j <= n_aa; j++) {

      // Calculate coverage per pixel

      // (approximates circle by a line within the pixel)

      if (j == 1) {

        if (j == n_aa) {

          // Single pixel

          coverage = ((arc + lastarc) * .5) - n_fg;

        }

        else {

          // First in a run

          arc2 = Math.sqrt(1.0 - Math.sqr(1.0 - (n_bg + 1) / sizex)) * sizey;

          coverage = (arc2 - (sizey - i)) * (arc - n_fg - n_aa + 1) * .5;

        }

      }

      else if (j == n_aa) {

        // Last in a run

        arc2 = Math.sqrt(1.0 - Math.sqr((sizex - n_bg - j + 1) / sizex)) * sizey;

        coverage = 1.0 - (1.0 - (arc2 - (sizey - i))) * (1.0 - (lastarc - n_fg)) * .5;

      }

      else {

        // Middle of a run

        arc3 = Math.sqrt(1.0 - Math.sqr((sizex - n_bg - j) / sizex)) * sizey;

        arc2 = Math.sqrt(1.0 - Math.sqr((sizex - n_bg - j + 1) / sizex)) * sizey;

        coverage = ((arc2 + arc3) * .5) - (sizey - i);

      }

      

      x.style.backgroundColor = Blend(bk, color, coverage);

      y.insertBefore(x, y.firstChild);

      y = x;

      var x = document.createElement("div");

      x.style.margin = "0px 1px";

    }

    x.style.backgroundColor = color;

    y.insertBefore(x, y.firstChild);

    lastarc = arc;

  }

  el.appendChild(d);

}



function getElementsBySelector(selector) {

  var i;

  var s = [];

  var selid = "";

  var selclass = "";

  var tag = selector;

  var objlist = [];

  if (selector.indexOf(" ") > 0) {  //descendant selector like "tag#id tag"

    s = selector.split(" ");

    var fs = s[0].split("#");

    if (fs.length == 1) {

      return objlist;

    }

    return document.getElementById(fs[1]).getElementsByTagName(s[1]);

  }

  if (selector.indexOf("#") > 0) { //id selector like "tag#id"

    s = selector.split("#");

    tag = s[0];

    selid = s[1];

  }

  if (selid != "") {

    objlist.push(document.getElementById(selid));

    return objlist;

  }

  if (selector.indexOf(".") > 0) {  //class selector like "tag.class"

    s = selector.split(".");

    tag = s[0];

    selclass = s[1];

  }

  var v = document.getElementsByTagName(tag);  // tag selector like "tag"

  if (selclass == "") {

    return v;

  }

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

    if (v[i].className == selclass) {

      objlist.push(v[i]);

    }

  }

  return objlist;

}