How to retrieve image data from Signature field?

[Ryan]

Question:

I'm using PDFNet for Windows Universal Apps and I am trying to collect form field data. I have a loop that goes through all the fields and get all the text, checkbox, radio, etc., but for signature annotation type, I am having trouble retrieving the data. 

Users will only be using freehand to sign the form into the signature box, so I'm looking for a way to collect that freehand signed data. Is that possible?

Answer:

The Value entry of a Digtial Signature field would be a cryptographic signature dictionary. Which is a much more complicated structure than the value entries of other fields. The freehand signature part of a digital signature is purely a graphical entity, and if present, is in the AP dictionary.

Widget widget = new Widget(field.GetSDFObj());
Obj ap = widget.GetAppearance();
if(ap == null) // no visual appearance.