Visible seals

A seal is what a reader draws on the page. It is an appearance and not part of the cryptography: omitting it leaves the signature invisible, and invisible is still valid.

->seal()                                   // drawn from the certificate
->sealFrom('/path/artwork.png')            // your own image

Placing it

use LSNepomuceno\Signet\Data\SealPlacement;
use LSNepomuceno\Signet\Enums\SealPage;

->seal(placement: new SealPlacement(x: 155, y: 250, width: 50, page: 2))
->seal(placement: new SealPlacement(x: 155, y: 250, width: 50))                  // the last page
->seal(placement: new SealPlacement(x: 155, y: 250, width: 50, page: SealPage::First))
->seal(placement: new SealPlacement(x: 155, y: 250, width: 50, onEveryPage: true))

Argument	Meaning
x, y	position, in PDF user units, from the bottom left
width, height	size. A height of 0 keeps the image's own ratio
page	Enums\SealPage or a 1-based number, in the order the page tree declares. SealPage::Last is the default
onEveryPage	the seal appears on every page, and wins over page

A page the document does not have raises SealPlacementException rather than clamping to the nearest one. Clamping puts a signature somewhere nobody asked for and nobody notices (0017).

Where the page actually is

Coordinates are measured from the region the reader displays, which is not always the sheet. Two entries decide it, and both turn up in the documents this matters most for: architectural drawings, engineering plots, anything printed at A1 or A0.

Entry	What it does	What the seal does about it
/CropBox (§7.7.3.3)	the region a viewer displays and prints, often inset from the sheet by a CAD or plotter export	x and y are measured from its corner, and it is intersected with /MediaBox as the clause requires
/UserUnit (§14.11.1)	multiplies every coordinate on the page, because a PDF unit is 1/72 inch and that caps a page at 200 inches	sizes and offsets are divided by it, so width: 120 is 120 points on paper

Nothing has to be passed for either: a page that declares neither behaves exactly as it did before they were read, byte for byte.

A seal outside the visible area raises

It does not get clamped to the edge, for the same reason a page that does not exist raises rather than resolving to the nearest one: a signed document with the seal somewhere nobody chose looks deliberate and is not (0017). The message names both rectangles, the one asked for and the one the page shows.

One signature, many pages

onEveryPage still produces one signature. The widget annotation goes on the first page, and every further page gets a stamp annotation drawing the same appearance, so the image is embedded once whatever the page count. A document of two hundred pages does not grow by two hundred JPEGs.

Drawing from the certificate

seal() with no image renders the signer's details:

use LSNepomuceno\Signet\Enums\FontSize;

->seal(
    fontSize: FontSize::Medium,     // Small, Medium, Large
    showExpiry: true,               // add the certificate's validity window
)

Defaults for every seal live in Config\SealConfig, so an application sets them once instead of at each call site:

use LSNepomuceno\Signet\Config\SealConfig;
use LSNepomuceno\Signet\Enums\ImageDriver;

new SealConfig(
    driver: ImageDriver::Gd,        // or ImageDriver::Imagick
    fontPath: '/path/font.ttf',
    fontSize: FontSize::Large,
    fontColor: '#16A085',
    background: null,               // an image behind the text
    transparent: true,
    textX: 160,
    textRows: [80, 150, 250],
);

Taking control of the layout

Data\SealLayout overrides the text and its geometry for a single signature, leaving the rest of the configuration alone:

use LSNepomuceno\Signet\Data\SealLayout;

->seal(layout: new SealLayout(
    lines: ['Signed by Lucas Nepomuceno', 'Contract 4471', '2026-08-18'],
    rows: [80, 150, 250],
    x: 160,
    color: '#1F2328',
    background: '/path/logo.png',
    transparent: true,
))

Replacing the renderer entirely

Contracts\SealRenderer is the seam. Implement it for a corporate logo with a layout of its own, a QR code linking to a validation page, or anything else, and pass it where the default is built.

public function fromImage(string $imagePath, ?SealLayout $layout = null);

The package deliberately stays out of the business of turning HTML into pixels: that is a large dependency for a signing library, and an application that needs it already has one.

Seals and accessibility

A signed document stays PDF/A conformant, and PDF/UA conformant too, seal or not. Both are measured with veraPDF rather than assumed (0025, 0032).

A visible seal used to cost PDF/UA two clauses, and no longer does. The widget is nested in a Form structure element, reached through an /OBJR, with /StructParent and a /ParentTree entry pointing back at it, and the field carries a /TU description holding the signer and the reason, which is what a screen reader announces where a sighted reader sees the seal (0113).

Only for a document that is already tagged. An untagged document has no structure tree to extend, and nothing here invents one: a document that was never accessible is not made to claim it is.

Seals in a template's field

When you sign into a field the document already declares, the field's own rectangle decides where the seal goes, so a SealPlacement cannot be combined with intoField(). See Signature fields.