How to add ACROFORM_FIELD_SIG without cordinate

[sagarprostartme]

How can I implement a digital signature field in a dynamically generated PDF document using either Dompdf or TCPDF when the content is within a table structure, and the content itself is dynamic? The examples I've found so far require specifying coordinates for placing the signature field, which becomes complex with dynamic content in a table. Any insights or alternative approaches?
#2155

[sagarprostartme]

Is there any way where i can add add $cpdf->addFormField(Cpdf::ACROFORM_FIELD_SIG, 'Signature1') in html directly

[bsweeney]

I would attach your script to a callback that triggers based on an element's identifier. That elements can also block off some space for the signature field.

With the following HTML:

<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.</p>
<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.</p>
<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.</p>
<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.</p>
<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.</p>
<div id="signature" style="height: 200px; background-color: #00cccc33"></div>
<hr>
<p>Dompdf and Co.</p>

You can add a signature that's contained within the "signature" div using the following:

$dompdf = new Dompdf();
$dompdf->loadHtml($html);
$dompdf->setCallbacks([
    [
        'event' => 'end_frame',
        'f' => function ($frame, $canvas, $fontMetrics) {
            $node = $frame->get_node();
            if ($node->hasAttributes() && ($id = $node->attributes->getNamedItem("id")) !== null && $id->nodeValue === "signature") {
                $bbox = $frame->get_border_box();
                $w = $bbox["w"];
                $h = $bbox["h"];
                $x1 = $bbox["x"];
                $x2 = $x1 + $bbox["w"];
                $y1 = $canvas->get_height() - $bbox["y"] - $h;
                $y2 = $y1 + $bbox["h"];
                
                $cpdf = $canvas->get_cpdf();
                $cpdf->addForm(Dompdf\Cpdf::ACROFORM_SIG_SIGNATURESEXISTS);
                $cpdf->setStrokeColor(\Dompdf\Css\Color::parse('green'));
                //$canvas->rectangle($x1, $y1, $w, $h, \Dompdf\Css\Color::parse('black'), 5); // to show visibility
                $cpdf->rectangle($x1, $y1, $w, $h);
                $fieldSigId = $cpdf->addFormField(Dompdf\Cpdf::ACROFORM_FIELD_SIG, 'Signature1', $x1, $y1, $x2, $y2);
            }
        }
    ]
]);
$dompdf->render();