Disabling some checkboxes of choice widget in buildForm()

Disabling some checkboxes of choice widget in buildForm()

I have a form widget of type "choice" which is being displayed as a list
of many checkboxes. Everything works great. So to stress it out: there is
ONE widget, with MANY checkboxes (and NOT several checkbox widgets).
Now, I want to disable some of those checkboxes. The data for that is
avaliable in the $options-Array.
Here is the buildForm()-function of my FooType.php
...
public function buildForm(FormBuilderInterface $builder, array $options)
{
$builder
->add('foo', 'choice', array('choices' =>
$options['choiceArray']['id'],
'multiple' => true,
'expanded' => true,
'disabled' =>
$options['choiceArray']['disabled']
// does not work (needs
a boolean)
'data' =>
$options['choiceArray']['checked'],
// works
'attr' =>
array('class' =>
'checkbox')))
;
}
...
My Twig-template looks like this:
{% for document in documentForm %}
<dd>{{ form_widget(document) }}</dd>
{% endfor %}
I can only disable ALL the checkboxes (by setting 'disabled' => true in
buildForm). And passing an array there does not work (as commented in the
snippet).
How can I disable some selected checkboxed (stored in
$options['choiceArray']['disabled']) of my choice widget?