C# ถามเรื่องการ capture หน้าจอครับ เวลารันผ่าน server แล้วมัน capture ได้หน้าดำ

public class GD
        {
            [DllImport("user32.dll", CharSet = CharSet.Auto)]
            public static extern IntPtr FindWindowEx(IntPtr parent /*HWND*/, IntPtr next /*HWND*/, string sClassName, IntPtr sWindowTitle);

            [DllImport("user32.dll", ExactSpelling = true, CharSet = CharSet.Auto)]
            public static extern IntPtr GetWindow(IntPtr hWnd, int uCmd);

            [DllImport("user32.Dll")]
            public static extern void GetClassName(int h, StringBuilder s, int nMaxCount);

            [DllImport("user32.dll")]
            private static extern bool PrintWindow(IntPtr hwnd, IntPtr hdcBlt, uint nFlags);

            public const int GW_CHILD = 5;
            public const int GW_HWNDNEXT = 2;

            public void CapDisplay()
            {
                int heightsize;
                int widthsize;
                int screenHeight;
                int screenWidth;
                bool chkWriteURL = true, chkShowGuides = false, IsDTDDocument = true;

                Cursor.Current = Cursors.WaitCursor;

                SHDocVw.WebBrowser m_browser = null;
                SHDocVw.ShellWindows shellWindows = shellWindows = new SHDocVw.ShellWindowsClass();

                //Find first availble browser window.
                //Application can easily be modified to loop through and capture all open windows.
                string filename;
                foreach (SHDocVw.WebBrowser browser in shellWindows)
                {
                    filename = Path.GetFileNameWithoutExtension(browser.FullName).ToLower();
                    if (filename.Equals("iexplore"))
                    {
                        m_browser = browser;
                        break;
                    }
                    if (filename.Equals("firefox"))
                    {
                        m_browser = browser;
                        break;
                    }
                }
                if (m_browser == null)
                {
                    MessageBox.Show("No Browser Open");
                    return;
                }

                //Assign Browser Document
                mshtml.IHTMLDocument2 myDoc = (mshtml.IHTMLDocument2)m_browser.Document;
                mshtml.IHTMLDocument3 doc3 = (mshtml.IHTMLDocument3)myDoc;


                //URL Location
                string myLocalLink = myDoc.url;
                int URLExtraHeight = 0;
                int URLExtraLeft = 0;

                //Adjustment variable for capture size.
                //if (chkWriteURL.Checked == true)
                //    URLExtraHeight = 25;

                //TrimHeight and TrimLeft trims off some captured IE graphics.
                int trimHeight = 3;
                int trimLeft = 3;

                //Use UrlExtra height to carry trimHeight.
                URLExtraHeight = URLExtraHeight - trimHeight;
                URLExtraLeft = URLExtraLeft - trimLeft;
                if (!IsDTDDocument)
                {
                    myDoc.body.setAttribute("scroll", "yes", 0);

                    //Get Browser Window Height
                    heightsize = (int)myDoc.body.getAttribute("scrollHeight", 0);
                    widthsize = (int)myDoc.body.getAttribute("scrollWidth", 0);

                    //Get Screen Height
                    screenHeight = (int)myDoc.body.getAttribute("clientHeight", 0);
                    screenWidth = (int)myDoc.body.getAttribute("clientWidth", 0);
                }
                else
                {
                    doc3.documentElement.setAttribute("scroll", "Yes", 0);

                    //Get Browser Window Height
                    heightsize = (int)doc3.documentElement.getAttribute("scrollHeight", 0);
                    widthsize = (int)doc3.documentElement.getAttribute("scrollWidth", 0);

                    //Get Screen Height
                    screenHeight = (int)doc3.documentElement.getAttribute("clientHeight", 0);
                    screenWidth = (int)doc3.documentElement.getAttribute("clientWidth", 0);

                }
                //Get bitmap to hold screen fragment.
                Bitmap bm = new Bitmap(screenWidth, screenHeight, System.Drawing.Imaging.PixelFormat.Format16bppRgb555);

                //Create a target bitmap to draw into.
                Bitmap bm2 = new Bitmap(widthsize + URLExtraLeft, heightsize + URLExtraHeight - trimHeight, System.Drawing.Imaging.PixelFormat.Format16bppRgb555);
                Graphics g2 = Graphics.FromImage(bm2);

                Graphics g = null;
                IntPtr hdc;
                System.Drawing.Image screenfrag = null;
                int brwTop = 0;
                int brwLeft = 0;
                int myPage = 0;
                IntPtr myIntptr = (IntPtr)m_browser.HWND;
                //Get inner browser window.
                int hwndInt = myIntptr.ToInt32();
                IntPtr hwnd = myIntptr;
                hwnd = GetWindow(hwnd, GW_CHILD);
                StringBuilder sbc = new StringBuilder(256);

                //Get Browser "Document" Handle
                while (hwndInt != 0)
                {
                    hwndInt = hwnd.ToInt32();
                    GetClassName(hwndInt, sbc, 256);
                    if (sbc.ToString().IndexOf("Shell DocObject View", 0) > -1) //IE6
                    {
                        hwnd = FindWindowEx(hwnd, IntPtr.Zero, "Internet Explorer_Server", IntPtr.Zero);
                        break;
                    }
                    if (sbc.ToString().IndexOf("TabWindowClass", 0) > -1) //IE7
                    {
                        hwnd = FindWindowEx(hwnd, IntPtr.Zero, "Shell DocObject View", IntPtr.Zero);
                        hwnd = FindWindowEx(hwnd, IntPtr.Zero, "Internet Explorer_Server", IntPtr.Zero);
                        break;
                    }
                    if (sbc.ToString().IndexOf("Frame Tab", 0) > -1) // IE8
                    {
                        hwnd = FindWindowEx(hwnd, IntPtr.Zero, "TabWindowClass", IntPtr.Zero);
                        hwnd = FindWindowEx(hwnd, IntPtr.Zero, "Shell DocObject View", IntPtr.Zero);
                        hwnd = FindWindowEx(hwnd, IntPtr.Zero, "Internet Explorer_Server", IntPtr.Zero);
                        break;
                    }
                    hwnd = GetWindow(hwnd, GW_HWNDNEXT);
                }

                //Get Screen Height (for bottom up screen drawing)
                while ((myPage * screenHeight) < heightsize)
                {
                    if (!IsDTDDocument)
                        myDoc.body.setAttribute("scrollTop", (screenHeight - 5) * myPage, 0);
                    else
                        doc3.documentElement.setAttribute("scrollTop", (screenHeight - 5) * myPage, 0);
                    ++myPage;
                }
                //Rollback the page count by one
                --myPage;

                int myPageWidth = 0;

                while ((myPageWidth * screenWidth) < widthsize)
                {
                    if (!IsDTDDocument)
                        myDoc.body.setAttribute("scrollLeft", (screenWidth - 5) * myPageWidth, 0);
                    else
                        doc3.documentElement.setAttribute("scrollLeft", (screenWidth - 5) * myPageWidth, 0);
                    if (!IsDTDDocument)
                        brwLeft = (int)myDoc.body.getAttribute("scrollLeft", 0);
                    else
                        brwLeft = (int)doc3.documentElement.getAttribute("scrollLeft", 0);
                    for (int i = myPage; i >= 0; --i)
                    {
                        //Shoot visible window
                        g = Graphics.FromImage(bm);
                        hdc = g.GetHdc();
                        if (!IsDTDDocument)
                            myDoc.body.setAttribute("scrollTop", (screenHeight - 5) * i, 0);
                        else
                            doc3.documentElement.setAttribute("scrollTop", (screenHeight - 5) * i, 0);

                        if (!IsDTDDocument)
                            brwTop = (int)myDoc.body.getAttribute("scrollTop", 0);
                        else
                            brwTop = (int)doc3.documentElement.getAttribute("scrollTop", 0);
                        PrintWindow(hwnd, hdc, 0);
                        g.ReleaseHdc(hdc);
                        g.Flush();
                        screenfrag = System.Drawing.Image.FromHbitmap(bm.GetHbitmap());
                        g2.DrawImage(screenfrag, brwLeft + URLExtraLeft, brwTop + URLExtraHeight);
                    }
                    ++myPageWidth;
                }

                //Draw Standard Resolution Guides
                if (chkShowGuides == true)
                {
                    // Create pen.
                    int myWidth = 1;
                    Pen myPen = new Pen(Color.Navy, myWidth);
                    Pen myShadowPen = new Pen(Color.NavajoWhite, myWidth);
                    // Create coordinates of points that define line.
                    float x1 = -(float)myWidth - 1 + URLExtraLeft;
                    float y1 = -(float)myWidth - 1 + URLExtraHeight;

                    float x600 = 600.0F + (float)myWidth + 1;
                    float y480 = 480.0F + (float)myWidth + 1;

                    float x2 = 800.0F + (float)myWidth + 1;
                    float y2 = 600.0F + (float)myWidth + 1;

                    float x3 = 1024.0F + (float)myWidth + 1;
                    float y3 = 768.0F + (float)myWidth + 1;

                    float x1280 = 1280.0F + (float)myWidth + 1;
                    float y1024 = 1024.0F + (float)myWidth + 1;

                    // Draw line to screen.
                    g2.DrawRectangle(myPen, x1, y1, x600 + myWidth, y480 + myWidth);
                    g2.DrawRectangle(myPen, x1, y1, x2 + myWidth, y2 + myWidth);
                    g2.DrawRectangle(myPen, x1, y1, x3 + myWidth, y3 + myWidth);
                    g2.DrawRectangle(myPen, x1, y1, x1280 + myWidth, y1024 + myWidth);

                    // Create font and brush.
                    Font drawFont = new Font("Arial", 12);
                    SolidBrush drawBrush = new SolidBrush(Color.Navy);
                    SolidBrush drawBrush2 = new SolidBrush(Color.NavajoWhite);

                    // Set format of string.
                    StringFormat drawFormat = new StringFormat();
                    drawFormat.FormatFlags = StringFormatFlags.FitBlackBox;
                    // Draw string to screen.
                    g2.DrawString("600 x 480", drawFont, drawBrush, 5, y480 - 20 + URLExtraHeight, drawFormat);
                    g2.DrawString("800 x 600", drawFont, drawBrush, 5, y2 - 20 + URLExtraHeight, drawFormat);
                    g2.DrawString("1024 x 768", drawFont, drawBrush, 5, y3 - 20 + URLExtraHeight, drawFormat);
                    g2.DrawString("1280 x 1024", drawFont, drawBrush, 5, y1024 - 20 + URLExtraHeight, drawFormat);
                }

                //Write URL
                if (chkWriteURL == true)
                { //Backfill URL paint location
                    SolidBrush whiteBrush = new SolidBrush(Color.White);
                    Rectangle fillRect = new Rectangle(0, 0, widthsize, URLExtraHeight + 2);
                    Region fillRegion = new Region(fillRect);
                    g2.FillRegion(whiteBrush, fillRegion);

                    SolidBrush drawBrushURL = new SolidBrush(Color.Black);
                    Font drawFont = new Font("Arial", 12);
                    StringFormat drawFormat = new StringFormat();
                    drawFormat.FormatFlags = StringFormatFlags.FitBlackBox;

                    g2.DrawString(myLocalLink, drawFont, drawBrushURL, 0, 0, drawFormat);
                }

                //Reduce Resolution Size
                double myResolution = Convert.ToDouble(1) * 0.01;
                int finalWidth = (int)((widthsize + URLExtraLeft));
                int finalHeight = (int)((heightsize + URLExtraHeight));
                Bitmap finalImage = new Bitmap(finalWidth, finalHeight, System.Drawing.Imaging.PixelFormat.Format16bppRgb555);
                Graphics gFinal = Graphics.FromImage((System.Drawing.Image)finalImage);
                gFinal.DrawImage(bm2, 0, 0, finalWidth, finalHeight);

                //Get Time Stamp
                DateTime myTime = DateTime.Now;
                String format = "MM.dd.hh.mm.ss";

                //Create Directory to save image to.
                Directory.CreateDirectory("C:\\IECapture");

                //Write Image.
                EncoderParameters eps = new EncoderParameters(1);
                long myQuality = Convert.ToInt64(200);
                eps.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, myQuality);
                ImageCodecInfo ici = GetEncoderInfo("image/jpeg");
                finalImage.Save(@"c:\\IECapture\Captured_" + myTime.ToString(format) + ".jpg", ici, eps);


                //Clean Up.
                myDoc = null;
                g.Dispose();
                g2.Dispose();
                gFinal.Dispose();
                bm.Dispose();
                bm2.Dispose();
                finalImage.Dispose();

                Cursor.Current = Cursors.Default;

            }

            private static ImageCodecInfo GetEncoderInfo(String mimeType)
            {
                int j;
                ImageCodecInfo[] encoders;
                encoders = ImageCodecInfo.GetImageEncoders();
                for (j = 0; j < encoders.Length; ++j)
                {
                    if (encoders[j].MimeType == mimeType)
                        return encoders[j];
                }
                return null;
            }

            private void lnkOpenCapture_LinkClicked(object sender, System.Windows.Forms.LinkLabelLinkClickedEventArgs e)
            {
                Process.Start("explorer.exe", "C:\\IECapture");
            }
        }

        protected void Button1_Click(object sender, EventArgs e)
        {
            GD g = new GD();
            g.CapDisplay();
        }