PDF documents can contain embedded file attachments—a powerful feature for bundling related files like spreadsheets, images, or supporting documents. The Attachment demo shows how to work with PDF attachments using PDFium VCL.
Overview
This demo provides complete attachment management including listing, extracting, adding, and deleting file attachments from PDF documents. It’s essential for document management systems that need to handle complex PDF files.
Key Features
- List Attachments – View all embedded files in a PDF
- Extract Attachments – Save attachments to disk
- Add Attachments – Embed new files into PDFs
- Delete Attachments – Remove attachments from PDFs
- View Details – See attachment names and sizes
PDFium DLL Requirements
Before running any PDFium VCL application, ensure the PDFium DLL files are installed:
pdfium32.dll/pdfium64.dll– Standard versions (~5-6 MB)pdfium32v8.dll/pdfium64v8.dll– With V8 JavaScript engine (~23-27 MB)
Installation: Run PDFiumVCL\DLLs\CopyDlls.bat as Administrator to automatically copy the DLLs to Windows system directories.
Listing Attachments
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procedure TFormMain.RefreshAttachmentList; var I: Integer; AttachmentName: string; AttachmentData: TBytes; SizeStr: string; begin ListBoxAttachments.Items.Clear; if not Pdf.Active then Exit; for I := 0 to Pdf.AttachmentCount - 1 do begin AttachmentName := Pdf.AttachmentName[I]; AttachmentData := Pdf.Attachment[I]; // Format size if Length(AttachmentData) >= 1024 * 1024 then SizeStr := Format('%.2f MB', [Length(AttachmentData) / (1024 * 1024)]) else if Length(AttachmentData) >= 1024 then SizeStr := Format('%.2f KB', [Length(AttachmentData) / 1024]) else SizeStr := Format('%d bytes', [Length(AttachmentData)]); ListBoxAttachments.Items.Add(Format('%s (%s)', [AttachmentName, SizeStr])); end; LogStatus(Format('Found %d attachment(s)', [Pdf.AttachmentCount])); end; |
Extracting Attachments
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procedure TFormMain.ButtonExtractAttachmentClick(Sender: TObject); var Index: Integer; AttachmentName: string; AttachmentData: TBytes; FileStream: TFileStream; begin Index := GetSelectedAttachmentIndex; if Index < 0 then begin LogStatus('Please select an attachment to extract.'); Exit; end; try AttachmentName := Pdf.AttachmentName[Index]; AttachmentData := Pdf.Attachment[Index]; SaveDialog.FileName := AttachmentName; if SaveDialog.Execute then begin FileStream := TFileStream.Create(SaveDialog.FileName, fmCreate); try if Length(AttachmentData) > 0 then FileStream.WriteBuffer(AttachmentData[0], Length(AttachmentData)); LogStatus('Extracted: ' + SaveDialog.FileName); finally FileStream.Free; end; end; except on E: Exception do LogStatus('Error extracting attachment: ' + E.Message); end; end; |
Adding Attachments
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procedure TFormMain.ButtonAddAttachmentClick(Sender: TObject); var AttachmentName: string; FileData: TBytes; FileStream: TFileStream; begin if not Pdf.Active then begin LogStatus('Please load or create a PDF document first.'); Exit; end; OpenDialog.Filter := 'All Files|*.*'; if OpenDialog.Execute then begin try // Read file into byte array FileStream := TFileStream.Create(OpenDialog.FileName, fmOpenRead); try SetLength(FileData, FileStream.Size); if FileStream.Size > 0 then FileStream.ReadBuffer(FileData[0], FileStream.Size); finally FileStream.Free; end; // Use filename as attachment name AttachmentName := ExtractFileName(OpenDialog.FileName); // Create attachment slot if Pdf.CreateAttachment(AttachmentName) then begin // Find the new attachment and set its data Pdf.Attachment[Pdf.AttachmentCount - 1] := FileData; LogStatus('Added attachment: ' + AttachmentName); RefreshAttachmentList; end else LogStatus('Failed to create attachment: ' + AttachmentName); except on E: Exception do LogStatus('Error adding attachment: ' + E.Message); end; end; end; |
Deleting Attachments
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procedure TFormMain.ButtonDeleteAttachmentClick(Sender: TObject); var Index: Integer; AttachmentName: string; begin Index := GetSelectedAttachmentIndex; if Index < 0 then begin LogStatus('Please select an attachment to delete.'); Exit; end; try AttachmentName := Pdf.AttachmentName[Index]; if MessageDlg(Format('Delete attachment "%s"?', [AttachmentName]), mtConfirmation, [mbYes, mbNo], 0) = mrYes then begin if Pdf.DeleteAttachment(Index) then begin LogStatus('Deleted attachment: ' + AttachmentName); RefreshAttachmentList; end else LogStatus('Failed to delete attachment.'); end; except on E: Exception do LogStatus('Error deleting attachment: ' + E.Message); end; end; |
Accessing Attachment Properties
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// Number of attachments Count := Pdf.AttachmentCount; // Attachment name at index Name := Pdf.AttachmentName[Index]; // Attachment data as byte array Data := Pdf.Attachment[Index]; // Set attachment data Pdf.Attachment[Index] := NewData; // Create new attachment Success := Pdf.CreateAttachment('filename.txt'); // Delete attachment Success := Pdf.DeleteAttachment(Index); |
Creating a New Document with Attachments
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procedure CreatePdfWithAttachments; var Pdf: TPdf; FileData: TBytes; FileStream: TFileStream; begin Pdf := TPdf.Create(nil); try // Create new document Pdf.CreateDocument; Pdf.Active := True; // Add a page Pdf.AddPage(1, 595, 842); Pdf.PageNumber := 1; Pdf.AddText('Document with Attachments', 'Arial', 18, 50, 750, clBlack, $FF, 0.0); // Add first attachment FileStream := TFileStream.Create('data.csv', fmOpenRead); try SetLength(FileData, FileStream.Size); FileStream.ReadBuffer(FileData[0], FileStream.Size); finally FileStream.Free; end; if Pdf.CreateAttachment('data.csv') then Pdf.Attachment[0] := FileData; // Add second attachment FileStream := TFileStream.Create('readme.txt', fmOpenRead); try SetLength(FileData, FileStream.Size); FileStream.ReadBuffer(FileData[0], FileStream.Size); finally FileStream.Free; end; if Pdf.CreateAttachment('readme.txt') then Pdf.Attachment[1] := FileData; // Save Pdf.SaveAs('document_with_attachments.pdf'); finally Pdf.Active := False; Pdf.Free; end; end; |
Saving Document After Modifications
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procedure TFormMain.ButtonSaveDocumentClick(Sender: TObject); var CurrentFileName, TempFileName: string; WasActive: Boolean; begin SaveDialog.Filter := 'PDF Files|*.pdf|All Files|*.*'; SaveDialog.DefaultExt := 'pdf'; if SaveDialog.Execute then begin try CurrentFileName := Pdf.FileName; WasActive := Pdf.Active; // If saving to the same file, use temporary file if WasActive and SameText(CurrentFileName, SaveDialog.FileName) then begin TempFileName := SaveDialog.FileName + '.tmp'; if Pdf.SaveAs(TempFileName) then begin // Close, delete old, rename new Pdf.Active := False; if DeleteFile(CurrentFileName) then begin if RenameFile(TempFileName, SaveDialog.FileName) then begin // Reload Pdf.FileName := SaveDialog.FileName; Pdf.Active := True; LogStatus('Document saved successfully.'); end; end; end; end else begin // Save to different file if Pdf.SaveAs(SaveDialog.FileName) then LogStatus('Document saved: ' + ExtractFileName(SaveDialog.FileName)) else LogStatus('Failed to save document.'); end; except on E: Exception do LogStatus('Error saving document: ' + E.Message); end; end; end; |
Displaying Attachment Details
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procedure TFormMain.ListBoxAttachmentsClick(Sender: TObject); var Index: Integer; AttachmentName: string; AttachmentData: TBytes; begin Index := GetSelectedAttachmentIndex; if Index >= 0 then begin AttachmentName := Pdf.AttachmentName[Index]; AttachmentData := Pdf.Attachment[Index]; MemoDetails.Lines.Clear; MemoDetails.Lines.Add('Name: ' + AttachmentName); MemoDetails.Lines.Add('Size: ' + IntToStr(Length(AttachmentData)) + ' bytes'); MemoDetails.Lines.Add('Index: ' + IntToStr(Index)); // Try to detect file type from extension if EndsText('.txt', AttachmentName) or EndsText('.csv', AttachmentName) then MemoDetails.Lines.Add('Type: Text file') else if EndsText('.pdf', AttachmentName) then MemoDetails.Lines.Add('Type: PDF document') else if EndsText('.jpg', AttachmentName) or EndsText('.png', AttachmentName) then MemoDetails.Lines.Add('Type: Image file') else MemoDetails.Lines.Add('Type: Binary file'); end; end; |
Use Cases
- Document Packages – Bundle main document with supporting files
- Form Submissions – Attach evidence or supporting documents to forms
- Technical Manuals – Include CAD files, spreadsheets, or source code
- Legal Documents – Attach exhibits and appendices
- Archive Management – Extract attachments for processing
Conclusion
The Attachment demo shows how PDFium VCL provides complete control over PDF file attachments. Whether you’re building a document management system or processing PDF forms with embedded files, these APIs make it straightforward.
The ability to add, extract, and delete attachments programmatically opens up many possibilities for document automation and processing workflows.
Manage PDF attachments with ease using Delphi PDFium VCL.