C#：有没有办法将窗口保存为PDF？

Document document = new Document();
PdfWriter writer = PdfWriter.GetInstance(document, new FileStream("output.pdf", FileMode.Create));
document.Open();

PdfDocument document = new PdfDocument();
document.Info.Title = "My PDF";
PdfPage page = document.AddPage();
XGraphics gfx = XGraphics.FromPdfPage(page);

PdfContentByte cb = writer.DirectContent;
cb.SaveState();
cb.SetPdfVersion(PdfWriter.PDF_VERSION_1_7);
cb.CreateGraphics(PageSize.A4.Width, PageSize.A4.Height);
cb.Rectangle(0, 0, PageSize.A4.Width, PageSize.A4.Height);
cb.Clip();
cb.NewPath();
Graphics2D g2 = new PdfGraphics2D(cb, PageSize.A4.Width, PageSize.A4.Height);
yourForm.Paint(g2);
g2.Dispose();
cb.RestoreState();

XGraphics gfx = XGraphics.FromPdfPage(page);
gfx.DrawImage(yourForm.BackgroundImage, 0, 0, page.Width, page.Height);
gfx.DrawString("Hello, World!", new XFont("Arial", 12), XBrushes.Black, new XRect(10, 10, page.Width, page.Height), XStringFormats.TopLeft);

document.Close();

document.Save("output.pdf");
document.Close();