// written by dodo
// http://pure-essence.net/
// read more about it here http://regretless.com/scripts/basics.php?inverse_color

function HexToR(h) { 
	return parseInt((cutHex(h)).substring(0,2),16)
}
function HexToG(h) { 
	return parseInt((cutHex(h)).substring(2,4),16) 
}
function HexToB(h) {
	return parseInt((cutHex(h)).substring(4,6),16) 
}
function cutHex(h) { 
	return (h.charAt(0)=="#") ? h.substring(1,7) : h
}


var hexbase = "0123456789ABCDEFabcdef";
function DecToHex(number) {
	return hexbase.charAt((number>> 4)& 0xf)+ hexbase.charAt(number& 0xf);
}

var strValidChars = "0123456789ABCDEFabcdef";
function IsNumeric(strString)
//  check for valid numeric strings	
{
	var strChar;
	var blnResult = true;

	if (strString.length == 0) return false;

	//  test strString consists of valid characters listed above
	for (i = 0; i < strString.length && blnResult == true; i++)
	  {
	  strChar = strString.charAt(i);
	  if (strValidChars.indexOf(strChar) == -1)
		 {
		 blnResult = false;
		 }
	  }
	return blnResult;
}



function InverseColor(strColor) {
	if(IsNumeric(strColor) == false) {
		alert("Please enter a valid hex color code with no leading \"#\"!");
		return false;
	}
	var r = 255 - HexToR(strColor);
	var g = 255 - HexToG(strColor);
	var b = 255 - HexToB(strColor);

	var ans = "#"+DecToHex(r).toString()+DecToHex(g).toString()+DecToHex(b).toString();
	return ans;
}