// 事先需要安装foxit quick pdf library ,安装完成，把DebenuPDFLibraryDLL1811.pas文件添加你的项目文件内

// 把DebenuPDFLibraryDLL1811.dll动态库复制到你执行程序目录

// 执行调用指定打印机打印PDF文件
var
  PDFLibrary: TDebenuPDFLibraryDLL1811;
  UnlockResult: Integer;
  CustomPrinter:string;
  iPrintOptions: Integer;
begin
  PDFLibrary := TDebenuPDFLibraryDLL1811.Create(ExtractFilePath(Application.ExeName) + 'DebenuPDFLibraryDLL1811.dll');
    UnlockResult := PDFLibrary.UnlockKey('quick pdf key'); // 需要软件密钥,去网上找个破解的密钥
    if UnlockResult = 1 then
    begin
      PDFLibrary.LoadFromFile(Edit3.Text, '');
       CustomPrinter := PDFLibrary.NewCustomPrinter('Microsoft Print to PDF'); // 自定义打印机
      iPrintOptions := PDFLibrary.PrintOptions(0, 0, 'Hello World.pdf');
      PDFLibrary.PrintDocument(CustomPrinter, 1, 1, iPrintOptions);
//      PDFLibrary.PrintDocument(PDFLibrary.GetDefaultPrinterName, 1, 1, iPrintOptions); // 默认打印机打印
    begin
      ShowMessage('Invalid license key');
    end;
  finally
    PDFLibrary.Free;
  end;