Please provide option to add PNG image as signature in the signature widget

[ghoshpushpendu]

Steps I Followed -

add Signature Placeholder
pyhanko sign addfields --field PAGE/X1,Y1,X2,Y2/NAME input.pdf output.pdf

Sign PDF
pyhanko sign addsig --field Sig1 pemder \ --key key.pem --cert cert.pem input.pdf output.pdf

This signs the PDF and create a rectangle with the signature.

But is there a way to add signature image like png there ?

[ghoshpushpendu]

I am new to python and a node js developer - so I think it ll take time for me to understand your code. @MatthiasValvekens

[MatthiasValvekens]

Yes, that's possible; see here: https://pyhanko.readthedocs.io/en/latest/cli-guide/config.html#styles-for-stamping-and-signature-appearances and https://pyhanko.readthedocs.io/en/latest/api-docs/pyhanko.stamp.html#pyhanko.stamp.BaseStampStyle.

In particular, note the following:

• The background entry in a style definition can take a PNG image as its argument (or even another PDF).
• You can leave the stamp-text empty.
• There's a background-opacity option (which is only documented in the API reference at this point, but it works in config as well) that allows you to have the background displayed with full opacity.

Combining these, it's possible to set up a signature appearance with only an image and no text:

stamp-styles:
    bitmap-notext:
        type: text
        stamp-text: ""
        background: image.png
        background-opacity: 1

Would that work for you?

[MatthiasValvekens]

@ghoshpushpendu Note: I've migrated this question to a discussion, since I try to keep the issue tracker reserved for development work (bugs and feature requests). I prefer to handle questions here in the discussion space :)

[ghoshpushpendu]

Pretty straight forward ... I missed .. sorry .. my bad.

[ghoshpushpendu]

But still seems like we have less control on the signing text and image position.

[MatthiasValvekens]

Actually, those can be controlled as well, but it's again not documented outside of the API reference (clearly I should do something about that 😅).

Here's an example showing how you can (to a degree) control the position of the background image and the text box. Note that text alignment within the text's bounding box is not something you can easily control right now, though.

bitmap-demo:
        type: text
        stamp-text: "Test Test Test\n%(ts)s"
        background: image.png
        background-opacity: 1
        background-layout:
          x-align: left
          margins:
            left: 10
            top: 10
            bottom: 10
        inner-content-layout:
          x-align: right
          margins:
            right: 10

The layout code is pretty primitive though, since fancy graphics isn't what pyHanko is about. If you want something really fancy, you might be better off generating the appearance using (for example) an SVG to PDF converter, and use background: svg-to-pdf-output.pdf to use the generated PDF as a background.

[ghoshpushpendu]

Hey I need a way to remove the Square around the signature ?

[MatthiasValvekens]

Did you try adding border-width: 0 to the style?

[OttomanZ]

@MatthiasValvekens Can you give a simple example of adding an image background to a stamp.TextBoxLayout Object ?

[OttomanZ]

I'm going to give a minimum reproduce-able example of what I'm trying to achieve using the API.

Old Code

pdf_signer = signers.PdfSigner(
                        signers.PdfSignatureMetadata(field_name=f'Signature{i}'), signer=self.signer, stamp_style=stamp.TextStampStyle(
                            stamp_text='Signed by: %(signer)s\nTime: %(ts)s', text_box_style=stamp.TextBoxStyle(font_size=20)
                        )
                    )

New Requested Code @MatthiasValvekens @ghoshpushpendu

I want to add a tick image to the left of text such as the following,

Please provide some code using the API

[MatthiasValvekens]

Hi @OttomanZ, there's some code in the tests to showcase how to use images:

pyHanko/pyhanko_tests/test_stamp.py

Lines 220 to 233 in b26c28c

	w = empty_page()
	long_text = '\n'.join(
	'Test test test test test test test test test '
	'on a bitmap background!'
	for _ in range(60)
	)
	style = TextStampStyle(
	stamp_text=long_text,
	background=PdfImage('pyhanko_tests/data/img/stamp-indexed.png'),
	)
	ts = TextStamp(w, style)
	ts.apply(0, x=30, y=120)

. You'll also want to set the opacity to 1, and play around with the alignment a little to make it look the way you want.

Having said that, pyHanko's appearance generation system is very, very primitive. If you want something more fancy, then your options are as follows:

• Delegate the appearance generation process to an external piece of software and import the result (if the output of the external tool is also PDF, this can work pretty well).
• Put together your own appearance generation logic using low-level PDF operations. Admittedly, this use case is poorly supported right now, but that's mostly because nobody asked so far. I would be happy to add a shut-up-I-know-what-I'm-doing hook to the appearance provisioning code.