final PropertyValue value = collection.getItem(whichElement);
if (value.canEvalPercentage()) {
int base = 0;
if (fobj instanceof SimplePageMaster) {
final SimplePageMaster spm = (SimplePageMaster) fobj;
base = spm.traitPageHeight();
} else {
base = context.widthContainingBlock();
}
final float percent = value.evalPercentage();
return Math.round(base * percent / WKConstants.PERCENT_CONVERSION);