HOWTO: Set Up the RichTextBox Control for WYSIWYG Printing

• Professional and Enterprise Editions of Microsoft Visual Basic, 32-bit only, for Windows, version 4.0

SUMMARY

The SelPrint method of the RichTextBox control does not allow a programmer to set the position of the output on the printer. In addition, the RichTextBox control does not provide a method for displaying its contents as they would show up on the printer. This article explains how to set up a RichTextBox with a WYSIWYG (What You See Is What You Get) display and then how to print it.

MORE INFORMATION

The Visual Basic 4.0 RichTextBox control is a sub-classed control based on the RichTextBox provided by the Win32 operating system. The operating system control supports many messages that are not exposed in Visual Basic 4.0. One of these messages is EM_SETTARGETDEVICE. The EM_SETTARGETDEVICE message is used to tell a RichTextBox to base its display on a target device such as a printer. Another message that is not fully exposed by Visual Basic 4.0 is EM_FORMATRANGE. The EM_FORMATRANGE message sends a page at a time to an output device using the specified coordinates. Using these messages in Visual Basic 4.0, it is possible to make a RichTextBox support WYSIWYG display and output.

The following example illustrates how to take advantage of the EM_SETTARGETDEVICE and EM_FORMATRANGE messages from Visual Basic 4.0. The example provides two re-usable procedures to send these messages. The first procedure WYSIWYG_RTF() sets a RichTextBox to provide a WYSIWYG display based on the default printer and specified margins. The second procedure PrintRtf() prints the contents of the RichTextBox with the specified margins.

EXAMPLE

1. Start a new project in the Visual Basic 32-bit edition. Form1 is created by default.

2. Put a CommandButton and a RichTextBox control on Form1.

3. Add the following code to Form1:

   Option Explicit

      Private Sub Form_Load()
         Dim LineWidth As Long
   
         ' Initialize Form and Command button
         Me.Caption = "Rich Text Box WYSIWYG Printing Example"
         Command1.Move 10, 10, 600, 380
         Command1.Caption = "&Print"
   
         ' Set the font of the RTF to a TrueType font for best results
         RichTextBox1.SelFontName = "Arial"
         RichTextBox1.SelFontSize = 10
   
         ' Tell the RTF to base it's display off of the printer
         LineWidth = WYSIWYG_RTF(RichTextBox1, 1440, 1440) '1440 Twips=1 Inch
   
         ' Set the form width to match the line width
         Me.Width = LineWidth + 200
      End Sub
   
      Private Sub Form_Resize()
         ' Position the RTF on form
         RichTextBox1.Move 100, 500, Me.ScaleWidth - 200, Me.ScaleHeight - 600
      End Sub
   
      Private Sub Command1_Click()
         ' Print the contents of the RichTextBox with a one inch margin
         PrintRTF RichTextBox1, 1440, 1440, 1440, 1440 ' 1440 Twips = 1 Inch
      End Sub
   
   

4. Insert a new standard module into the project, Module1.bas is created by default.

5. Add the following code to Module1:

   Option Explicit

   Private Type Rect

         Left As Long
         Top As Long
         Right As Long
         Bottom As Long
   

   End Type

   Private Type CharRange

        cpMin As Long     ' First character of range (0 for start of doc)
        cpMax As Long     ' Last character of range (-1 for end of doc)
      End Type
   
      Private Type FormatRange
        hdc As Long       ' Actual DC to draw on
        hdcTarget As Long ' Target DC for determining text formatting
        rc As Rect        ' Region of the DC to draw to (in twips)
        rcPage As Rect    ' Region of the entire DC (page size) (in twips)
        chrg As CharRange ' Range of text to draw (see above declaration)
      End Type
   
      Private Const WM_USER As Long = &H400
      Private Const EM_FORMATRANGE As Long = WM_USER + 57
      Private Const EM_SETTARGETDEVICE As Long = WM_USER + 72
      Private Const PHYSICALOFFSETX As Long = 112
      Private Const PHYSICALOFFSETY As Long = 113
   
      Private Declare Function GetDeviceCaps Lib "gdi32" ( _
         ByVal hdc As Long, ByVal nIndex As Long) As Long
      Private Declare Function SendMessage Lib "USER32" Alias "SendMessageA" _
         (ByVal hWnd As Long, ByVal msg As Long, ByVal wp As Long, _
         lp As Any) As Long
      Private Declare Function CreateDC Lib "gdi32" Alias "CreateDCA" _
         (ByVal lpDriverName As String, ByVal lpDeviceName As String, _
         ByVal lpOutput As Long, ByVal lpInitData As Long) As Long
   
      ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
      '
      ' WYSIWYG_RTF - Sets an RTF control to display itself the same as it
      '               would print on the default printer
      '
      ' RTF - A RichTextBox control to set for WYSIWYG display.
      '
      ' LeftMarginWidth - Width of desired left margin in twips
      '
      ' RightMarginWidth - Width of desired right margin in twips
      '
      ' Returns - The length of a line on the printer in twips
      '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
      Public Function WYSIWYG_RTF(RTF As RichTextBox, LeftMarginWidth As Long,
      _
         RightMarginWidth As Long) As Long
         Dim LeftOffset As Long, LeftMargin As Long, RightMargin As Long
         Dim LineWidth As Long
         Dim PrinterhDC As Long
         Dim r As Long
   
         ' Start a print job to initialize printer object
         Printer.Print Space(1)
         Printer.ScaleMode = vbTwips
   
         ' Get the offset to the printable area on the page in twips
         LeftOffset = Printer.ScaleX(GetDeviceCaps(Printer.hdc, _
            PHYSICALOFFSETX), vbPixels, vbTwips)
   
         ' Calculate the Left, and Right margins
         LeftMargin = LeftMarginWidth - LeftOffset
         RightMargin = (Printer.Width - RightMarginWidth) - LeftOffset
   
         ' Calculate the line width
         LineWidth = RightMargin - LeftMargin
   
         ' Create an hDC on the Printer pointed to by the Printer object
         ' This DC needs to remain for the RTF to keep up the WYSIWYG display
         PrinterhDC = CreateDC(Printer.DriverName, Printer.DeviceName, 0, 0)
   
         ' Tell the RTF to base it's display off of the printer
         '    at the desired line width
         r = SendMessage(RTF.hWnd, EM_SETTARGETDEVICE, PrinterhDC, _
            ByVal LineWidth)
   
         ' Abort the temporary print job used to get printer info
         Printer.KillDoc
   
         WYSIWYG_RTF = LineWidth
      End Function
   
      ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
      '
      ' PrintRTF - Prints the contents of a RichTextBox control using the
      '            provided margins
      '
      ' RTF - A RichTextBox control to print
      '
      ' LeftMarginWidth - Width of desired left margin in twips
      '
      ' TopMarginHeight - Height of desired top margin in twips
      '
      ' RightMarginWidth - Width of desired right margin in twips
      '
      ' BottomMarginHeight - Height of desired bottom margin in twips
      '
      ' Notes - If you are also using WYSIWYG_RTF() on the provided RTF
      '         parameter you should specify the same LeftMarginWidth and
      '         RightMarginWidth that you used to call WYSIWYG_RTF()
      ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
      Public Sub PrintRTF(RTF As RichTextBox, LeftMarginWidth As Long, _
         TopMarginHeight, RightMarginWidth, BottomMarginHeight)
         Dim LeftOffset As Long, TopOffset As Long
         Dim LeftMargin As Long, TopMargin As Long
         Dim RightMargin As Long, BottomMargin As Long
         Dim fr As FormatRange
         Dim rcDrawTo As Rect
         Dim rcPage As Rect
         Dim TextLength As Long
         Dim NextCharPosition As Long
         Dim r As Long
   
         ' Start a print job to get a valid Printer.hDC
         Printer.Print Space(1)
         Printer.ScaleMode = vbTwips
   
         ' Get the offsett to the printable area on the page in twips
         LeftOffset = Printer.ScaleX(GetDeviceCaps(Printer.hdc, _
            PHYSICALOFFSETX), vbPixels, vbTwips)
         TopOffset = Printer.ScaleY(GetDeviceCaps(Printer.hdc, _
            PHYSICALOFFSETY), vbPixels, vbTwips)
   
         ' Calculate the Left, Top, Right, and Bottom margins
         LeftMargin = LeftMarginWidth - LeftOffset
         TopMargin = TopMarginHeight - TopOffset
         RightMargin = (Printer.Width - RightMarginWidth) - LeftOffset
         BottomMargin = (Printer.Height - BottomMarginHeight) - TopOffset
   
         ' Set printable area rect
         rcPage.Left = 0
         rcPage.Top = 0
         rcPage.Right = Printer.ScaleWidth
         rcPage.Bottom = Printer.ScaleHeight
   
         ' Set rect in which to print (relative to printable area)
         rcDrawTo.Left = LeftMargin
         rcDrawTo.Top = TopMargin
         rcDrawTo.Right = RightMargin
         rcDrawTo.Bottom = BottomMargin
   
         ' Set up the print instructions
         fr.hdc = Printer.hdc   ' Use the same DC for measuring and rendering
         fr.hdcTarget = Printer.hdc  ' Point at printer hDC
         fr.rc = rcDrawTo            ' Indicate the area on page to draw to
         fr.rcPage = rcPage          ' Indicate entire size of page
         fr.chrg.cpMin = 0           ' Indicate start of text through
         fr.chrg.cpMax = -1          ' end of the text
   
         ' Get length of text in RTF
         TextLength = Len(RTF.Text)
   
         ' Loop printing each page until done
         Do
            ' Print the page by sending EM_FORMATRANGE message
            NextCharPosition = SendMessage(RTF.hWnd, EM_FORMATRANGE, True, fr)
            If NextCharPosition >= TextLength Then Exit Do  'If done then exit
            fr.chrg.cpMin = NextCharPosition ' Starting position for next page
            Printer.NewPage                  ' Move on to next page
            Printer.Print Space(1) ' Re-initialize hDC
            fr.hDC = Printer.hDC
            fr.hDCTarget = Printer.hDC
         Loop
   
         ' Commit the print job
         Printer.EndDoc
   
         ' Allow the RTF to free up memory
         r = SendMessage(RTF.hWnd, EM_FORMATRANGE, False, ByVal CLng(0))
      End Sub
   
   

6. Save the project.

7. Run the project.

8. Enter or paste some text into the RichTextBox.

9. Press the Print command button. Note that the printed output should word-wrap at the same locations as displayed on the screen. Also, the output should be printed with the specified one-inch margin all around.

Keywords          : APrgPrint vb432 VB4WIN vbwin kbprg kbprint
Technology        : kbvba
Version           : WINDOWS:4.0
Platform          : NT WINDOWS
Issue type        : kbhowto