how to print Rich text box contents on any device contenxt with proper formatting?

i would like to print the rich text box contents with formatting to any device context, for example I would li开发者_运维技巧ke to print on panel or any other control which is associated to actual print device.

I am simulating print preview using panel by drawing some contents from a custom designed form, rich text content is one among the content of that form

is there any best solution to address this??

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below is code that prints an rtf control's contents to the printer. i could be adapted to print to any old dc fairly easy. the language is powerbasic, but it could be easily translated in to C, pascal or whatever:

SUB PrintRichTextBox (  hWnd as LONG, hInst as LONG, rtfEdit as LONG, LM as Single, _
                        RM as Single, TM as Single, BM as Single )
   '
   '  Purpose:
   '           Prints the contents of an RTF text box given it's handle, the
   '           calling program's handle(s), and the page margins.
   '
   '  Parameters:
   '           hWnd     = Parent window (used for print common dlg)
   '           hInst    = Instance of calling program
   '           rtfEdit  = Handle of rich edit control
   '           LM       = Left Margin in inches
   '           RM       = Right Margin in inches
   '           TM       = Top Margin in inches
   '           BM       = Bottom Margin in inches
   '
   Dim fr as FORMATRANGE
   Dim rDocInfo as DOCINFO
   Dim iTextOut as LONG
   Dim iTextAmt as LONG
   Dim pd as PRINTDLGAPI
   Dim zString as ASCIIZ * 200
   Dim iWidthTwips&
   Dim iHeightTwips&

   '- Setup the print common dialog
   pd.lStructSize = len(pd)
   pd.hwndOwner = hWnd
   pd.hDevMode = %NULL
   pd.hDevNames = %NULL
   pd.nFromPage = 0
   pd.nToPage = 0
   pd.nMinPage = 0
   pd.nMaxPage = 0
   pd.nCopies = 0
   pd.hInstance = hInst
   pd.Flags = %PD_RETURNDC or %PD_NOPAGENUMS or %PD_PRINTSETUP
   pd.lpfnSetupHook = %NULL
   pd.lpPrintSetupTemplateName = %NULL
   pd.lpfnPrintHook = %NULL
   pd.lpPrintTemplateName = %NULL

   if PrintDlg(pd) then

      SetCursor LoadCursor( %NULL, BYVAL %IDC_WAIT )

      '- Fill format range structure
      '
      '  NOTE:
      '     This gave me fits. I was looking at the book from
      '     Microsoft Press called Programming the Windows 95
      '     Iterface. It said (via example) that the
      '     Rectagle was defined in Pixels. This didn't work right.
      '     The SDK, however, said the measurements needed to be
      '     in Twips! This seems to work fine.
      '
      '
      fr.hdc = pd.hDC
      fr.hdcTarget = pd.hDC
      fr.chrg.cpMin = 0
      fr.chrg.cpMax = -1

      fr.rc.nTop = TM * 1440
      fr.rcPage.nTop = fr.rc.nTop

      fr.rc.nLeft = LM * 1440
      fr.rcPage.nLeft = fr.rc.nLeft

      '- Get page dimensions in Twips
      iWidthTwips& = int((GetDeviceCaps(pd.hDC, %HORZRES) / GetDeviceCaps(pd.hDC, %LOGPIXELSX)) * 1440)
      iHeightTwips& = int((GetDeviceCaps(pd.hDC, %VERTRES) / GetDeviceCaps(pd.hDC, %LOGPIXELSY)) * 1440)

      fr.rc.nRight = iWidthTwips& - RM * 1440
      fr.rcPage.nRight = fr.rc.nRight

      fr.rc.nBottom = iHeightTwips& - BM * 1440
      fr.rcPage.nBottom = fr.rc.nBottom

      '- Fill rDocInfo structure
      rDocInfo.cbSize = len(rDocInfo)
      zString = "RTF Printer"
      rDocInfo.lpszDocName = VARPTR(zString)
      rDocInfo.lpszOutput = %NULL

      '- Here we go
      StartDoc pd.hDC, rDocInfo
      StartPage pd.hDC

      '- This does the printing. We send messages
      '  to the edit box telling it to format it's
      '  text to fit the Printer's DC.
      '
      iTextOut = 0
      iTextAmt = SendMessage(rtfEdit, %WM_GETTEXTLENGTH, 0, 0)

      do while iTextOut < iTextAmt

         iTextOut = SendMessage(rtfEdit, %EM_FORMATRANGE, _
                     1, VARPTR(fr))

         if iTextOut < iTextAmt then
            EndPage pd.hDC
            StartPage pd.hDC
            fr.chrg.cpMin = iTextOut
            fr.chrg.cpMax = -1
         end if

      loop

      SendMessage rtfEdit, %EM_FORMATRANGE, 1, %NULL

      '- Finish the printing.
      EndPage pd.hDC
      EndDoc pd.hDC

      DeleteDC pd.hDC
      SetCursor LoadCursor( %NULL, BYVAL %IDC_ARROW )

   else
      ' MsgBox "Canceled !"
   end if


END SUB

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I have used the below extended control to achieve my RTF printing.

    using System;
    using System.Windows.Forms;
    using System.Drawing;
    using System.Runtime.InteropServices;
    using System.Drawing.Printing;

    namespace RichTextBoxPrintCtrl
    {
        public class RichTextBoxPrintCtrl : RichTextBox
        {
            //Convert the unit used by the .NET framework (1/100 inch) 
            //and the unit used by Win32 API calls (twips 1/1440 inch)
            private const double anInch = 14.4;

            [StructLayout(LayoutKind.Sequential)]
            private struct RECT
            {
                public int Left;
                public int Top;
                public int Right;
                public int Bottom;
            }

            [StructLayout(LayoutKind.Sequential)]
            private struct CHARRANGE
            {
                public int cpMin;         //First character of range (0 for start of doc)
                public int cpMax;           //Last character of range (-1 for end of doc)
            }

            [StructLayout(LayoutKind.Sequential)]
            private struct FORMATRANGE
            {
                public IntPtr hdc;             //Actual DC to draw on
                public IntPtr hdcTarget;       //Target DC for determining text formatting
                public RECT rc;                //Region of the DC to draw to (in twips)
                public RECT rcPage;            //Region of the whole DC (page size) (in twips)
                public CHARRANGE chrg;         //Range of text to draw (see earlier declaration)
            }

            private const int WM_USER = 0x0400;
            private const int EM_FORMATRANGE = WM_USER + 57;

            [DllImport("USER32.dll")]
            private static extern IntPtr SendMessage(IntPtr hWnd, int msg, IntPtr wp, IntPtr lp);

            // Render the contents of the RichTextBox for printing
            //  Return the last character printed + 1 (printing start from this point for next page)
            public int Print(int charFrom, int charTo, PrintPageEventArgs e)
            {
                //Calculate the area to render and print
                RECT rectToPrint;
                rectToPrint.Top = (int)(e.MarginBounds.Top * anInch);
                rectToPrint.Bottom = (int)(e.MarginBounds.Bottom * anInch);
                rectToPrint.Left = (int)(e.MarginBounds.Left * anInch);
                rectToPrint.Right = (int)(e.MarginBounds.Right * anInch);

                //Calculate the size of the page
                RECT rectPage;
                rectPage.Top = (int)(e.PageBounds.Top * anInch);
                rectPage.Bottom = (int)(e.PageBounds.Bottom * anInch);
                rectPage.Left = (int)(e.PageBounds.Left * anInch);
                rectPage.Right = (int)(e.PageBounds.Right * anInch);

                IntPtr hdc = e.Graphics.GetHdc();

                FORMATRANGE fmtRange;
                fmtRange.chrg.cpMax = charTo;               //Indicate character from to character to 
                fmtRange.chrg.cpMin = charFrom;
                fmtRange.hdc = hdc;                    //Use the same DC for measuring and rendering
                fmtRange.hdcTarget = hdc;              //Point at printer hDC
                fmtRange.rc = rectToPrint;             //Indicate the area on page to print
                fmtRange.rcPage = rectPage;            //Indicate size of page

                IntPtr res = IntPtr.Zero;

                IntPtr wparam = IntPtr.Zero;
                wparam = new IntPtr(1);

                //Get the pointer to the FORMATRANGE structure in memory
                IntPtr lparam = IntPtr.Zero;
                lparam = Marshal.AllocCoTaskMem(Marshal.SizeOf(fmtRange));
                Marshal.StructureToPtr(fmtRange, lparam, false);

                //Send the rendered data for printing 
                res = SendMessage(Handle, EM_FORMATRANGE, wparam, lparam);

                //Free the block of memory allocated
                Marshal.FreeCoTaskMem(lparam);

                //Release the device context handle obtained by a previous call
                e.Graphics.ReleaseHdc(hdc);

                //Return last + 1 character printer
                return res.ToInt32();
            }

        }
    }