mORMot Open Source

  obPDF := TPdfDocumentGDI.Create;
  try
    obPDF.UseOptionalContent := True;
    obNonPrintableLayer := obPDF.CreateOptionalContentGroup(nil, 'Non-Printable', True, False);
    try
      obPDF.AddPage;

      obPDF.VCLCanvasBeginMarkedContent(obNonPrintableLayer);

      c := obPDF.VCLCanvas;
      c.Font.Name := 'Times new roman';
      c.Font.Size := 32;
      c.Font.Style := [fsBold, fsItalic];
      c.Font.Color := clNavy;
      c.TextOut(100, 100, 'Hello 1');

      obPDF.VclCanvasEndMarkedContent;

      c.TextOut(40, 40, 'Hello 2');

      obPDF.SaveToFile(ChangeFileExt(ExeVersion.ProgramFileName, '.pdf'));
  finally
    obPDF.Free;
  end;

function TPdfDocument.CreateOptionalContentGroup(ParentContentGroup: TPdfOptionalContentGroup; const Title: string; Visible: boolean; PrintLayer: boolean = True): TPdfOptionalContentGroup;
var
  Dico, DicoD, DicU, DicASEntry, DicPr: TPdfDictionary;
  Arr, ArrOCGs, ArrAS: TPdfArray;
  i: integer;

  function FindParentContentGroupArray(Current: TPdfArray): TPdfArray;
  var
    i: integer;
  begin
    Result := nil;
    if Current = nil then
      exit;
    for i := 0 to Current.ItemCount - 1 do
      if Current.Items[i] = ParentContentGroup then
      begin
        if (i < Current.ItemCount - 1) and Current.Items[i + 1].InheritsFrom(TPdfArray) then
          Result := TPdfArray(Current.Items[i + 1])
        else
        begin
          Result := TPdfArray.Create(FXRef);
          Current.InsertItem(i + 1, Result);
        end;
        exit;
      end;
    for i := 0 to Current.ItemCount - 1 do
      if Current.Items[i].InheritsFrom(TPdfArray) then
      begin
        Result := FindParentContentGroupArray(TPdfArray(Current.Items[i]));
        if Result <> nil then
          exit;
      end;
  end;

begin
  if FUseOptionalContent then
  begin
    Result := TPdfOptionalContentGroup.Create(FXRef);
    FXRef.AddObject(Result);
    Result.AddItem('Type', 'OCG');
    Result.AddItemTextString('Name', Title);

    Dico := FRoot.Data.PdfDictionaryByName('OCProperties');

    if not PrintLayer then
    begin
      DicU := TPdfDictionary.Create(FXRef);
      DicPr := TPdfDictionary.Create(FXRef);
      DicPr.AddItem('PrintState', 'OFF');
      DicU.AddItem('Print', DicPr);
      Result.AddItem('Usage', DicU);
    end;

    if Dico <> nil then
    begin
      DicoD := Dico.PdfDictionaryByName('D');
      if DicoD <> nil then
      begin

        Arr := DicoD.PdfArrayByName('Order');
        if ParentContentGroup <> nil then
          Arr := FindParentContentGroupArray(Arr);
        if Arr <> nil then
          Arr.AddItem(Result);

        if not Visible then
        begin
          Arr := DicoD.PdfArrayByName('OFF');
          if Arr <> nil then
            Arr.AddItem(Result);
        end;

        if not PrintLayer then
        begin
          ArrAS := DicoD.PdfArrayByName('AS');
          if ArrAS = nil then
          begin
            ArrAS := TPdfArray.Create(FXRef);
            DicASEntry := TPdfDictionary.Create(FXRef);
            DicASEntry.AddItem('Event', 'Print');
            DicASEntry.AddItem('Category', TPdfArray.CreateNames(FXRef, ['Print']));
            ArrOCGs := TPdfArray.Create(FXRef);
            ArrOCGs.AddItem(Result);
            DicASEntry.AddItem('OCGs', ArrOCGs);
            ArrAS.AddItem(DicASEntry);
            DicoD.AddItem('AS', ArrAS);
          end
          else
          begin
            for i := 0 to ArrAS.ItemCount - 1 do
            begin
              if TPdfName(TPdfDictionaryElement(TPdfDictionary(ArrAS.Items[i]).ValueByName('Event'))).Value = 'Print' then
              begin
                ArrOCGs := TPdfArray(TPdfDictionary(ArrAS.Items[i]).ValueByName('OCGs'));
                if ArrOCGs <> nil then
                  ArrOCGs.AddItem(Result);
              end;
            end;
          end;

        end;
        Arr := Dico.PdfArrayByName('OCGs');
        if Arr <> nil then
          Arr.AddItem(Result);
      end;

    end;
  end
  else
    Result := nil;
end;