Delphi code snippet for overlaying one page from a PDF onto another page in a different PDF

Overlay one page onto another (stitch PDFs)

procedure TForm2.btnOverlayClick(Sender: TObject);
var
  FileA: Integer;
  FileB: Integer;
  CapturedPageID: Integer;
  PageHeight: Double;
  PageWidth: Double;
  Path: AnsiString;
begin
  DPL := TDebenuPDFLibrary1114.Create;
  try
    UnlockResult := DPL.UnlockKey('...'); // Insert trial or paid license key here
    if UnlockResult = 1 then
    begin
    // You can only use the DrawCapturedPage function if the captured page is in the same
    // document, so first we'll need to merge the two pages that we wish to overlay together
    // into one document.
    if dlgOpen.Execute then
      begin
         DPL.LoadFromFile(dlgOpen.FileName, '');
         FileA := DPL.SelectedDocument();
      end;
      if dlgOpen.Execute then
      begin
         DPL.LoadFromFile(dlgOpen.FileName, '');
         FileB := DPL.SelectedDocument();
      end;
      // After merging FileB is automatically deleted, leaving only FileB which is now a combination of FileA and FileB
      DPL.SelectDocument(FileA);
      DPL.MergeDocument(FileB);

      // Capture the second page in the merged document
      CapturedPageID := DPL.CapturePage(2);
      // Now select the first page and retrieve its height and width
      DPL.SelectDocument(FileA);
      DPL.SelectPage(1);
      PageHeight := DPL.PageHeight();
      PageWidth := DPL.PageWidth();
      // Draw the captured page onto the currently selected page
      DPL.DrawCapturedPage(CapturedPageID, 0, PageHeight, PageWidth, PageHeight);

      // Save the stitched file to disk
    if dlgSave.Execute then
      begin
        Path := dlgSave.FileName;
      end;
      DPL.SaveToFile(Path);
    end;
  finally
    DPL.Free;
  end;
end;