Visual signature support

[zosocanuck]

I am testing this library/utility and noticed support for visual signatures, however when attempting to sign a sample PDF, the visual signature doesn't appear at least in the latest version of Adobe. Has this been tested?

[vanbroup]

There is a test case for visual signatures:

sign/pdfvisualsignature_test.go

I don't have tested myself this recently. Can you do a test based on the unit test (including) the file?

[karelbilek]

It doesn't show because the Rect is 0 0 0 0.

However even if I change the Rect I see nothing, I think because there is no reference to any other visual object...?

(when I change the rect, Acrobat says it's "visible signature" but then shows nothing)

[karelbilek]

Ahhh that's because it's AcroForm stuff, so I would also need to set appearance and /AP object... ugh no. AcroForms = hell. :D

[vanbroup]

If you have a working example it would be great to add this to the documentation!

[karelbilek]

I don't think it can be done just with this library; if I look at other PDFs with visual signatures (made by Acrobat I think), it has AP appearence streams, and I am not sure this library can do it.

Maybe if it is somehow used with conjunction with pdfcpu https://github.com/pdfcpu/pdfcpu ... but that gets me thinking it would be maybe better to add the signing functionality into pdfcpu

[vanbroup]

@karelbilek I’ve just released a new version with some improvements and new signature types. Unfortunately, it doesn’t include support for visible signatures yet. However, I believe we can add basic support for features like an image or handwritten name in the future. Before we can do this, I need to refactor some code to make it easier to add new objects to the document. Please understand that this is not a high priority and it might take some time before I can work on it.