Tryanks/pdfsign
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Add initial support for signature appearance

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This commit is contained in:
Paul van Brouwershaven
2024-12-16 15:05:27 +01:00
parent e5cdb61bea
commit b9112bb85b
10 changed files with 335 additions and 122 deletions
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40
sign/pdfcatalog.go
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@@ -10,7 +10,7 @@ func (context *SignContext) createCatalog() ([]byte, error) {
// Start the catalog object
catalog_buffer.WriteString("<<\n")
catalog_buffer.WriteString(" /Type /Catalog")
catalog_buffer.WriteString(" /Type /Catalog\n")
// (Optional; PDF 1.4) The version of the PDF specification to which
// the document conforms (for example, 1.4) if later than the version
@@ -49,33 +49,45 @@ func (context *SignContext) createCatalog() ([]byte, error) {
// Add Pages and Names references if they exist
if foundPages {
pages := root.Key("Pages").GetPtr()
catalog_buffer.WriteString(" /Pages " + strconv.Itoa(int(pages.GetID())) + " " + strconv.Itoa(int(pages.GetGen())) + " R")
catalog_buffer.WriteString(" /Pages " + strconv.Itoa(int(pages.GetID())) + " " + strconv.Itoa(int(pages.GetGen())) + " R\n")
}
if foundNames {
names := root.Key("Names").GetPtr()
catalog_buffer.WriteString(" /Names " + strconv.Itoa(int(names.GetID())) + " " + strconv.Itoa(int(names.GetGen())) + " R")
catalog_buffer.WriteString(" /Names " + strconv.Itoa(int(names.GetID())) + " " + strconv.Itoa(int(names.GetGen())) + " R\n")
}
// Start the AcroForm dictionary with /NeedAppearances
catalog_buffer.WriteString(" /AcroForm << /Fields [")
catalog_buffer.WriteString(" /AcroForm <<\n")
catalog_buffer.WriteString(" /Fields [")
// Add existing signatures to the AcroForm dictionary
for i, sig := range context.SignData.ExistingSignatures {
for i, sig := range context.existingSignatures {
if i > 0 {
catalog_buffer.WriteString(" ")
}
catalog_buffer.WriteString(strconv.Itoa(int(sig.ObjectId)) + " 0 R")
catalog_buffer.WriteString(strconv.Itoa(int(sig.objectId)) + " 0 R")
}
// Add the visual signature field to the AcroForm dictionary
if len(context.SignData.ExistingSignatures) > 0 {
if len(context.existingSignatures) > 0 {
catalog_buffer.WriteString(" ")
}
catalog_buffer.WriteString(strconv.Itoa(int(context.VisualSignData.ObjectId)) + " 0 R")
catalog_buffer.WriteString(strconv.Itoa(int(context.VisualSignData.objectId)) + " 0 R")
catalog_buffer.WriteString("]") // close Fields array
catalog_buffer.WriteString("]\n") // close Fields array
catalog_buffer.WriteString(" /NeedAppearances false")
// (Optional; deprecated in PDF 2.0) A flag specifying whether
// to construct appearance streams and appearance
// dictionaries for all widget annotations in the document (see
// 12.7.4.3, "Variable text"). Default value: false. A PDF writer
// shall include this key, with a value of true, if it has not
// provided appearance streams for all visible widget
// annotations present in the document.
// if context.SignData.Visible {
// catalog_buffer.WriteString(" /NeedAppearances true")
// } else {
// catalog_buffer.WriteString(" /NeedAppearances false")
// }
// Signature flags (Table 225)
//
@@ -100,14 +112,14 @@ func (context *SignContext) createCatalog() ([]byte, error) {
// Set SigFlags and Permissions based on Signature Type
switch context.SignData.Signature.CertType {
case CertificationSignature, ApprovalSignature, TimeStampSignature:
catalog_buffer.WriteString(" /SigFlags 3")
catalog_buffer.WriteString(" /SigFlags 3\n")
case UsageRightsSignature:
catalog_buffer.WriteString(" /SigFlags 1")
catalog_buffer.WriteString(" /SigFlags 1\n")
}
// Finalize the AcroForm and Catalog object
catalog_buffer.WriteString(" >>\n") // Close AcroForm
catalog_buffer.WriteString(">>\n") // Close Catalog
catalog_buffer.WriteString(" >>\n") // Close AcroForm
catalog_buffer.WriteString(">>\n") // Close Catalog
return catalog_buffer.Bytes(), nil
}