How to set up the RichTextBox control for WYSIWYG printing


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.

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The Visual Basic 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. 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 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, 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. 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.


  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:
    Private Const AnInch As Long = 1440   '1440 twips per inch
    Private Const QuarterInch As Long = 360

    Private Sub Form_Load()
    Dim PrintableWidth As Long
    Dim PrintableHeight As Long
    Dim x As Single

    ' 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

    'initialize the printer object
    x = Printer.TwipsPerPixelX
    Printer.Orientation = vbPRORPortrait 'vbPRORLandscape

    ' Tell the RTF to base it's display off of the printer
    Call WYSIWYG_RTF(RichTextBox1, QuarterInch, QuarterInch, QuarterInch, QuarterInch, PrintableWidth, PrintableHeight) '1440 Twips=1 Inch

    ' Set the form width to match the line width
    Me.Width = PrintableWidth + 200
    Me.Height = PrintableHeight + 800
    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, AnInch, AnInch, AnInch, AnInch
    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 Sub WYSIWYG_RTF(RTF As RichTextBox, LeftMarginWidth As Long, RightMarginWidth As Long, TopMarginWidth As Long, BottomMarginWidth As Long, PrintableWidth As Long, PrintableHeight As Long)
    Dim LeftOffset As Long
    Dim LeftMargin As Long
    Dim RightMargin As Long
    Dim TopOffset As Long
    Dim TopMargin As Long
    Dim BottomMargin As Long
    Dim PrinterhDC As Long
    Dim r As Long

    Printer.ScaleMode = vbTwips

    ' Get the left offset to the printable area on the page in twips
    LeftOffset = GetDeviceCaps(Printer.hdc, PHYSICALOFFSETX)
    LeftOffset = Printer.ScaleX(LeftOffset, vbPixels, vbTwips)

    ' Calculate the Left, and Right margins
    LeftMargin = LeftMarginWidth - LeftOffset
    RightMargin = (Printer.Width - RightMarginWidth) - LeftOffset

    ' Calculate the line width
    PrintableWidth = RightMargin - LeftMargin

    ' Get the top offset to the printable area on the page in twips
    TopOffset = GetDeviceCaps(Printer.hdc, PHYSICALOFFSETY)
    TopOffset = Printer.ScaleX(TopOffset, vbPixels, vbTwips)

    ' Calculate the Left, and Right margins
    TopMargin = TopMarginWidth - TopOffset
    BottomMargin = (Printer.Height - BottomMarginWidth) - TopOffset

    ' Calculate the line width
    PrintableHeight = BottomMargin - TopMargin

    ' 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 PrintableWidth)
    End Sub

    ' 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
    ' 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

    ' Commit the print job

    ' 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.

ID članka: 146022 – Zadnji pregled: 5. apr. 2005 – Revizija: 1

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