// Contributors 
// Ilkka Huotari at http://www.editsite.net
// Mathieu 'p01' HENRI at http://www.p01.org/
// http://seky.nahory.net/2005/04/rounded-corners/
// Steven Wittens at http://www.acko.net/anti-aliased-nifty-corners
// Original Nifty Corners by Alessandro Fulciniti at http://pro.html.it/esempio/nifty/
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(className, sizex, sizey, sizex_b, sizey_b) {
    var bk;
    if (!NiftyCheck()) return;
    if (typeof(sizex_b) == 'undefined')
	sizex_b = sizex;
    if (typeof(sizey_b) == 'undefined')
	sizey_b = sizey;
    var v = getElements(className);
    var l = v.length;
    for (var i = 0; i < l; i++) {
	color = get_current_style(v[i],"background-color","transparent");
	bk = get_current_style(v[i].parentNode,"background-color","transparent");
	AddRounded(v[i], bk, color, sizex, sizey, true);
	AddRounded(v[i], bk, color, sizex_b, sizey_b, false);
    }
}

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))
		   );
    return '#' + ('0'+Math.round(ca[0] + (cb[0] - ca[0])*alpha).toString(16)).slice(-2).toString(16)
	+ ('0'+Math.round(ca[1] + (cb[1] - ca[1])*alpha).toString(16)).slice(-2).toString(16)
	+ ('0'+Math.round(ca[2] + (cb[2] - ca[2])*alpha).toString(16)).slice(-2).toString(16);

    return '#' + ('0'+Math.round(ca[0] + (cb[0] - ca[0])*alpha).toString(16)).slice(-2).toString(16)
	+ ('0'+Math.round(ca[1] + (cb[1] - ca[1])*alpha).toString(16)).slice(-2).toString(16)
	+ ('0'+Math.round(ca[2] + (cb[2] - ca[2])*alpha).toString(16)).slice(-2).toString(16);
}

function AddRounded(el, bk, color, sizex, sizey, top) {
    if (!sizex && !sizey)
	return;
    var i, j;
    var d = document.createElement("div");
    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";
	x.style.height='1px';
	x.style.overflow='hidden';
	// 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((sizex - n_bg - j + 1) / sizex)) * sizey;
		    coverage = (arc2 - (sizey - i)) * (arc - n_fg - n_aa + 1) * .5;
		    // Coverage is incorrect. Why?
		    coverage = 0;
		}
	    }
	    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);
	    if (top)
		y.appendChild(x);
	    else
		y.insertBefore(x, y.firstChild);
	    y = x;
	    var x = document.createElement("div");
	    x.style.height='1px';
	    x.style.overflow='hidden';
	    x.style.margin = "0px 1px";
	}
	x.style.backgroundColor = color;
	if (top)
	    y.appendChild(x);
	else
	    y.insertBefore(x, y.firstChild);
	lastarc = arc;
    }
    if (top)
	el.insertBefore(d, el.firstChild);
    else
	el.appendChild(d);
}

function getElements(className) {
    var elements = [];
    var el = document.getElementsByTagName('DIV');  
    var regexp=new RegExp("\\b"+className+"\\b");
    for (var i = 0; i < el.length; i++) 
	{
	    if (regexp.test(el[i].className)) 
		elements.push(el[i]);
	}
    return elements;
}

function get_current_style(element,property,not_accepted)
{
    var ee,i,val,apr;
    try
	{
	    var cs=document.defaultView.getComputedStyle(element,'');
	    val=cs.getPropertyValue(property);
	}
    catch(ee)
	{
	    if(element.currentStyle)
		{
		    apr=property.split("-");
		    for(i=1;i<apr.length;i++) apr[i]=apr[i].toUpperCase();
		    apr=apr.join("");
		    val=element.currentStyle.getAttribute(apr);
		}
	}
    if((val.indexOf("rgba") > -1 || val==not_accepted) && element.parentNode)
	{
	    if(element.parentNode != document) 
		val=get_current_style(element.parentNode,property,not_accepted);
	    else
		val = '#FFFFFF';
	}
    if (val.indexOf("rgb") > -1 && val.indexOf("rgba") == -1)
	val = rgb2hex(val);
    if (val.length == 4)
	val = '#'+val.substring(1,1)+val.substring(1,1)+val.substring(2,1)+val.substring(2,1)+val.substring(3,1)+val.substring(3,1);
    return val;
}

function rgb2hex(value)
{
    var x = 255;
    var hex = '';
    var i;
    var regexp=/([0-9]+)[, ]+([0-9]+)[, ]+([0-9]+)/;
    var array=regexp.exec(value);
    for(i=1;i<4;i++) hex += ('0'+parseInt(array[i]).toString(16)).slice(-2);
    return '#'+hex;
}