C# winform 打印当前窗体

private void btnPrint_Click(object sender, EventArgs e)
        {
            SendKeys.Send("%{PRTSC}");
            Application.DoEvents();
            this.printDocument1.Print();  
        }

        private void printDocument1_PrintPage(object sender, System.Drawing.Printing.PrintPageEventArgs e)
        {
            IDataObject iData = Clipboard.GetDataObject();
            Image img = (Image)iData.GetData(DataFormats.Bitmap);
            e.Graphics.DrawImage(img, 0, 0);
        }