////////////////////////////////////////////////////////////
//global variables that can be used by ALL the function son this page.
var inputs;
var imgFalse = '/images/tests/buttons/box_unchecked.gif';
var imgTrue = '/images/tests/buttons/box_checked.gif';

function init() {
    replaceChecks();
}
function replaceChecks() {

    //get all the input fields on the page
    inputs = document.getElementsByTagName('input');

    //cycle trough the input fields
    for(var i=0; i < inputs.length; i++) {

        //check if the input is a checkbox
        if(inputs[i].getAttribute('type') == 'checkbox') {

            //create a new image
            var img = document.createElement('img');

            //check if the checkbox is checked
            if(inputs[i].checked) {
                img.src = imgTrue;
            } else {
                img.src = imgFalse;
            }

            //set image ID and onclick action
            img.id = 'checkImage'+i;
            //set image
            img.onclick = new Function('checkChange('+i+')');
            //place image in front of the checkbox
            inputs[i].parentNode.insertBefore(img, inputs[i]);

            //hide the checkbox
            inputs[i].style.display='none';
        }
    }
}
//change the checkbox status and the replacement image
// use this for graphical elements to select all checkboxes
function checkChange(i) {
   if(inputs[i].checked) {
       inputs[i].checked = '';
       document.getElementById('checkImage'+i).src=imgFalse;
   } else {
       inputs[i].checked = 'checked';
       document.getElementById('checkImage'+i).src=imgTrue;
   }
}

window.onload = init;