How can I determine if a signature field is signed using the PDFNet SDK?

Q: How can I determine if a signature field is signed using the PDFNet SDK?

To do this, you can determine if an ink or stamp annotation exists within a signature field which is what happens when a user inserts a signature in the PDFTron WebViewer for instance.

The sample code below in Python shows how to do this.

# Iterate over all fields
itr = doc.GetFieldIterator()
while itr.HasNext():

# Examine all signature widgets
if itr.Current().GetType() == Field.e_signature and itr.Current().IsAnnot():
signature_found = False

print("Signature field name: " + itr.Current().GetName())

print(“Traversing all annotations in the document…”)
page_num = 1
page_itr = doc.GetPageIterator()

sig_widget = Annot(itr.Current().GetSDFObj())
sig_widget_rect = sig_widget.GetRect()

# Iterate through all annotations in the document
while page_itr.HasNext():
page_num = page_num + 1
page = page_itr.Current()
num_annots = page.GetNumAnnots()
i = 0
while i < num_annots:
annot = page.GetAnnot(i)
if not annot.IsValid():

if annot.GetType() == Annot.e_Ink or annot.GetType() == Annot.e_Stamp:

# Check if ink or stamp annotation is in signature field widget
ink_rect = annot.GetRect()
if (sig_widget_rect.Contains(ink_rect.x1, ink_rect.y1) or
sig_widget_rect.Contains(ink_rect.x1, ink_rect.y2) or
sig_widget_rect.Contains(ink_rect.x2, ink_rect.y1) or
sig_widget_rect.Contains(ink_rect.x2, ink_rect.y2)):
signature_found = True

# Check if ink or signature widget overlaps with stamp or ink annotation
if (ink_rect.Contains(sig_widget_rect.x1, sig_widget_rect.y1) or
ink_rect.Contains(sig_widget_rect.x1, sig_widget_rect.y2) or
ink_rect.Contains(sig_widget_rect.x2, sig_widget_rect.y1) or
ink_rect.Contains(sig_widget_rect.x2, sig_widget_rect.y2)):
signature_found = True

i = i + 1

if signature_found:
print(“Signature found”)
print(“No signature found”)



Note that this will register any ink annotation or stamp annotation within a signature widget as being the signature even if it was not meant for that particular field. This will, however, detect any signature field that is missing a signature annotation that is not a stamp or ink.

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A: The short answer is that you’ll need to manually identify if a signature actually exists within the signature widget itself.