SignatureCount property

Questa voce API conserva identificatori, firme, blocchi di codice e termini PDF nella forma originale.

Number of digital signature fields embedded in the document.

SignatureCount returns the number of signature dictionaries currently present in the document. PDFium enumerates AcroForm signature fields (PDF 1.7 spec section 12.8) — each entry corresponds to a /Sig field whose /V value is a signature dictionary (/Type /Sig) carrying the /Contents hex string and /ByteRange coverage.

The value is 0 when Active is False, when the PDF carries only empty signature placeholders that have not been filled yet, or when the file simply was not signed. Note that this is a document-level count: signature fields can be visually placed on any page but the count itself is global.

Use Signature[Index] to retrieve a single TPdfSignature record containing the raw PKCS#7 Content bytes, the Encoding string (adbe.pkcs7.detached, ETSI.CAdES.detached, etc.), the signer-supplied Reason / Time strings and the Permission level. PDFiumVCL exposes only inspection data; verifying the signature requires a third-party cryptography library to validate the PKCS#7 blob against the document byte range.

• A document with multiple signatures is sequentially signed (incremental update chain); each signature covers everything up to the byte range it was created against, so signature n validates the state at signing time, not necessarily the current state.
• SignatureCount is constant across SaveToFile as long as no new field is added; signing externally and saving via FPDF_SaveAsCopy preserves existing signatures byte-for-byte.
• Combine with FormFieldCount to see whether the document has additional non-signature interactive fields.

Signature, FormFieldCount, FormType