function MM_swapImgRestore() { //v3.0
  var i,x,a=document.MM_sr; for(i=0;a&&i<a.length&&(x=a[i])&&x.oSrc;i++) x.src=x.oSrc;
}

function MM_preloadImages() { //v3.0
  var d=document; if(d.images){ if(!d.MM_p) d.MM_p=new Array();
    var i,j=d.MM_p.length,a=MM_preloadImages.arguments; for(i=0; i<a.length; i++)
    if (a[i].indexOf("#")!=0){ d.MM_p[j]=new Image; d.MM_p[j++].src=a[i];}}
}

function MM_findObj(n, d) { //v4.01
  var p,i,x;  if(!d) d=document; if((p=n.indexOf("?"))>0&&parent.frames.length) {
    d=parent.frames[n.substring(p+1)].document; n=n.substring(0,p);}
  if(!(x=d[n])&&d.all) x=d.all[n]; for (i=0;!x&&i<d.forms.length;i++) x=d.forms[i][n];
  for(i=0;!x&&d.layers&&i<d.layers.length;i++) x=MM_findObj(n,d.layers[i].document);
  if(!x && d.getElementById) x=d.getElementById(n); return x;
}

function MM_swapImage() { //v3.0
  var i,j=0,x,a=MM_swapImage.arguments; document.MM_sr=new Array; for(i=0;i<(a.length-2);i+=3)
   if ((x=MM_findObj(a[i]))!=null){document.MM_sr[j++]=x; if(!x.oSrc) x.oSrc=x.src; x.src=a[i+2];}
}

function sqftToBoxes( sourceId, updateId, sqftPerBox )
{
  source = document.getElementById(sourceId);
  update = document.getElementById(updateId);
  numSqft = source.value;

  if( !update || !source ) return;
  if( numSqft == '' ) return;
  if( isNaN(numSqft) ) { source.value = sqftPerBox; boxesToSqft(sourceId, updateId, sqftPerBox); numSqft = source.value; }
  if( numSqft == 0 ) { source.value = sqftPerBox; boxesToSqft(sourceId, updateId, sqftPerBox); numSqft = source.value; }

  numBoxes = Math.ceil(numSqft / sqftPerBox);
  update.value = numBoxes;

  update_cart_quantity( updateId, '' );
}

function boxesToSqft( sourceId, updateId, sqftPerBox )
{
  source = document.getElementById(sourceId);
  update = document.getElementById(updateId);
  numBoxes = source.value;

  if( !update || !source ) return;
  if( numBoxes == '' ) return;
  if( isNaN(numBoxes) ) { source.value = 1; numBoxes = source.value; }
  if( numBoxes == 0 ) { source.value = 1; numBoxes = source.value; }

  sqft = sqftPerBox * numBoxes;

  update.value =  sqft.toFixed(2);

  update_cart_quantity( sourceId, '' );
}

function update_cart_quantity( sourceId, formId )
{
  form = document.getElementById(formId);
  source = document.getElementById(sourceId);

  if( !form ) return;

  field = form.elements['cart_quantity[]'];
  field.value = source.value;

  // Shipping Calc Add-on Here
  ajs_shipping_num_units = document.getElementById('ajs_shipping_num_units');
  if( !ajs_shipping_num_units ) return;
  ajs_shipping_num_units.value = source.value;
}