Read Only Form Filling - PDFTron - pdftron

Question

I'm using WebViewer [1] from PDFTron to fill Form Fields in a PDF on Web [2]. There's a way to make some fields in Read Only Mode, so the user will not be able to add text to textfield, check the checkboxes?
I found this page on the documentation [3] but it seems that I can only set document in read only mode, instead I want only custom fields in read only, users will be able to fill some fields and not others.
I found also this page [4] on doc to set fields to readonly but in my case on WebViewer it doesn't work, in my browser the viewerLoaded events never get called; I tried to put the code in another part of the code but nothing happens.
Are there some hints or some working code that you guys use?
Thanks, Alberto
[1] https://www.pdftron.com/webviewer
[2] https://www.pdftron.com/pdf-sdk/form-filler
[3] https://www.pdftron.com/documentation/web/guides/annotations/annotation-permissions?searchTerm=readon#readonly-mode
[4] https://www.pdftron.com/documentation/web/guides/advanced/forms#set-fields-to-readonly

Answer 1

I managed to make it work with a modified version of this code [1]. The final result is:
$(document).on('documentLoaded', function() {
var docViewer = myWebViewer.getInstance().docViewer;
var annotManager = docViewer.getAnnotationManager();
annotManager.on('annotationChanged', function(e, annotations, action) {
// if the annotation change occurs because of an import then
// these are fields from inside the document
if (action === 'add' && e.imported) {
annotations.forEach(function(annot) {
if(annot.fieldName == 'read_only_field_name'){
annot.fieldFlags.set('ReadOnly', true);
}
});
}
});
});
[1] https://www.pdftron.com/documentation/web/guides/advanced/forms#set-fields-to-readonly