/*==========================================================================#
# * Function for adding a Filter to an Input Field                          #
# * @param  : [filterType  ] Type of filter 0=>Alpha, 1=>Num, 2=>AlphaNum   #
# * @param  : [evt         ] The Event Object                               #
# * @param  : [allowDecimal] To allow Decimal Point set this to true        #
# * @param  : [allowCustom ] Custom Characters that are to be allowed       #
#==========================================================================*/
function filterInput(filterType, evt, allowDecimal, allowCustom){
    var keyCode, Char, inputField, filter = '';
    var alpha = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
    var num   = '0123456789';
	var spec   = '.';
    // Get the Key Code of the Key pressed if possible else - allow
    if(window.event){
        keyCode = window.event.keyCode;
        evt = window.event;
    }else if (evt)keyCode = evt.which;
    else return true;
    // Setup the allowed Character Set
    if(filterType == 0) filter = alpha;
    else if(filterType == 1) filter = num;
    else if(filterType == 2) filter = alpha + num;
	else if(filterType == 3) filter = num+spec;
    if(allowCustom)filter += allowCustom;
    if(filter == '')return true;
    // Get the Element that triggered the Event
    inputField = evt.srcElement ? evt.srcElement : evt.target || evt.currentTarget;
    // If the Key Pressed is a CTRL key like Esc, Enter etc - allow
    if((keyCode==null) || (keyCode==0) || (keyCode==8) || (keyCode==9) || (keyCode==13) || (keyCode==27) )return true;
    // Get the Pressed Character
    Char = String.fromCharCode(keyCode);
    // If the Character is a number - allow
    if((filter.indexOf(Char) > -1)) return true;
    // Else if Decimal Point is allowed and the Character is '.' - allow
    else if(filterType == 1 && allowDecimal && (Char == '.') && inputField.value.indexOf('.') == -1)return true;
    else return false;
}