def register_widget_annotation(self, writer: BasePdfFileWriter,
sig_field_ref):
annot_dict = self.annot_dict
if annot_dict is not self:
annot_ref = writer.add_object(annot_dict)
self['/Kids'] = generic.ArrayObject([annot_ref])
else:
annot_ref = sig_field_ref
writer.register_annotation(self.page_ref, annot_ref)
def _prepare_sig_field(sig_field_name,
root,
update_writer: BasePdfFileWriter,
existing_fields_only=False,
lock_sig_flags=True,
**kwargs):
"""
Returns a tuple of a boolean and a reference to a signature field.
The boolean is ``True`` if the field was created, and ``False`` otherwise.
"""
if sig_field_name is None: # pragma: nocover
raise ValueError
try:
form = root['/AcroForm']
try:
fields = form['/Fields']
except KeyError:
raise ValueError('/AcroForm has no /Fields')
candidates = enumerate_sig_fields_in(fields, with_name=sig_field_name)
sig_field_ref = None
try:
field_name, value, sig_field_ref = next(candidates)
if value is not None:
raise SigningError(
'Signature field with name %s appears to be filled already.'
% sig_field_name)
except StopIteration:
if existing_fields_only:
raise SigningError(
'No empty signature field with name %s found.' %
sig_field_name)
form_created = False
except KeyError:
# we have to create the form
if existing_fields_only:
raise SigningError('This file does not contain a form.')
# no AcroForm present, so create one
form = generic.DictionaryObject()
root[pdf_name('/AcroForm')] = update_writer.add_object(form)
fields = generic.ArrayObject()
form[pdf_name('/Fields')] = fields
# now we need to mark the root as updated
update_writer.update_root()
form_created = True
sig_field_ref = None
if sig_field_ref is not None:
return False, sig_field_ref
# no signature field exists, so create one
# default: grab a reference to the first page
page_ref = update_writer.find_page_for_modification(0)[0]
sig_form_kwargs = {'include_on_page': page_ref}
sig_form_kwargs.update(**kwargs)
sig_field = SignatureFormField(sig_field_name, **sig_form_kwargs)
created, sig_field_ref = _insert_or_get_field_at(
update_writer,
fields,
path=sig_field_name.split('.'),
field_obj=sig_field)
update_writer.register_annotation(page_ref, sig_field_ref)
# make sure /SigFlags is present. If not, create it
sig_flags = 3 if lock_sig_flags else 1
form.setdefault(pdf_name('/SigFlags'), generic.NumberObject(sig_flags))
# if a field was added to an existing form, register an extra update
if not form_created:
update_writer.update_container(fields)
return True, sig_field_ref