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Q193943: HOWTO: Use GetDeviceCaps to Determine Margins on a Page

Article: Q193943
Product(s): Microsoft Visual Basic for Windows
Version(s): 4.0,5.0,6.0
Operating System(s): 
Keyword(s): kbprint kbAPI kbPrinting kbVBp kbVBp400 kbVBp500 kbVBp600 kbGrpDSVB
Last Modified: 03-JAN-2002

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The information in this article applies to:

- Microsoft Visual Basic Standard Edition, 32-bit, for Windows, version 4.0 
- Microsoft Visual Basic Professional Edition, 32-bit, for Windows, version 4.0 
- Microsoft Visual Basic Enterprise Edition, 32-bit, for Windows, version 4.0 
- Microsoft Visual Basic Learning Edition for Windows, versions 5.0, 6.0 
- Microsoft Visual Basic Professional Edition for Windows, versions 5.0, 6.0 
- Microsoft Visual Basic Enterprise Edition for Windows, versions 5.0, 6.0 
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SUMMARY
=======

The Visual Basic Printer object only exposes the physical size and printable
area of the paper you are printing on and does not give you access to the actual
margins or unprintable areas. You can retrieve this information, however, by
using the Win32 API function, GetDeviceCaps. This article demonstrates how to
retrieve and use this information.

MORE INFORMATION
================

GetDeviceCaps only takes two arguments. The first is a handle to the Device
Context, "DC", of the device you want to query. In the example below, this is
always the current printer. The second argument is a Long value that specifies
the item to return. The following example includes only the definitions for the
constants actually used in the demonstration code. In general, the units of the
return value vary, but for the items used here, the unit of measurement is
always pixels.

In the sample below, Command1 contains code that calls the GetDeviceCaps API
multiple times to retrieve various bits of printer information, which are then
displayed all at once at the end of the routine. The information retrieved
includes all of the default margins and describes the printable area of the
page.

The code for Command2 retrieves and uses the printer information to determine the
lowest printing position on the page, and uses this to print a centered page
footer that includes a page number. A page header, including the current date,
right-justified, is printer at the top of each page. In addition, a report
header prints at the top of the first page only. The sample further demonstrates
setting custom margins within the printable area using the technique of checking
the current X or Y position against a limit imposed in the code. You can easily
modify this to allow the user to choose these margins and even the text for the
footers or headers.

The printable area of the page always starts at position 0,0 (Printer.CurrentX =
0 and Printer.CurrentY = 0). By setting these values you can get to any point on
the page. The PrintHeader procedure prints some text in italics, and other text
normally, on the same line. It does this by changing the CurrentX and CurrentY
values to return to a new position on line that was previously printed.

NOTE: You can also mix font attributes by ending a print statement with a ";"
semicolon. This retains the last print position without starting a new line at
CurrentX = 0, which is the default behavior. In this way, you can print some
text, change font attributes (bold, italic, and so on), then print more text
starting right where you left off.

Step-by-Step Example
--------------------

1. Start a new project in Visual Basic. Form1 is created by default.

2. Add two CommandButtons to the Form and paste the following code into the
  Form's module:

        Option Explicit

        Private Declare Function GetDeviceCaps Lib "gdi32" _
         (ByVal hdc As Long, ByVal nIndex As Long) As Long

        ' Constants for nIndex argument of GetDeviceCaps
        Private Const HORZRES = 8
        Private Const VERTRES = 10
        Private Const LOGPIXELSX = 88
        Private Const LOGPIXELSY = 90
        Private Const PHYSICALWIDTH = 110
        Private Const PHYSICALHEIGHT = 111
        Private Const PHYSICALOFFSETX = 112
        Private Const PHYSICALOFFSETY = 113

        Private Sub PrintHeader(PrintTitle As Boolean, Margins As Long, _
         LMargin As Long)
         Dim BodyFontBold As Boolean, BodyFontSize As Integer
         Dim BodyFontItalic As Boolean, HeaderLine As String
         Dim PrtPositionX As Integer, PrtPositionY As Integer

         If PrintTitle Then ' Only Print Title on first Page
            PrtPositionX = Printer.Width / 2  ' center of page
            ' Save any attributes you change for the header...
            BodyFontBold = Printer.Font.Bold
            BodyFontSize = Printer.Font.Size
            ' Change the font for the header...
            Printer.Font.Size = 16
            Printer.Font.Bold = True
            ' Print header lines...
            HeaderLine = "Title of This Test Report"
            ' Center Report title
            Printer.CurrentX = PrtPositionX - (LMargin + _
              Printer.TextWidth(HeaderLine) / 2)
            Printer.Print HeaderLine
            ' Reset the font...
            Printer.Font.Size = BodyFontSize
            Printer.Font.Bold = BodyFontBold
         Else
            Printer.NewPage   ' Otherwise we are at the bottom of a page
         End If
         PrtPositionY = Printer.CurrentY  ' remember this line
         BodyFontItalic = Printer.Font.Italic
         Printer.Font.Italic = True
         Printer.Print "My very nice, Visual Basic report"
         Printer.Font.Italic = BodyFontItalic
         HeaderLine = Format(Date, "Long Date")
         ' Right justify today's date
         Printer.CurrentX = Printer.Width - (Margins + _
            Printer.TextWidth(HeaderLine))
         Printer.CurrentY = PrtPositionY  ' return to previous line
         Printer.Print HeaderLine
        End Sub

        Private Sub PrintFooter(LastLine As Integer, _
           LineHeight As Integer, LMargin As Long)
         Dim PrtPositionX As Integer, PrintText As String
         Static PageNum As Integer

         PageNum = PageNum + 1
         PrtPositionX = Printer.Width / 2   ' center of page
         ' Move to the end of the page to print the Page Footer:
         ' LastLine is where there is only room for one more line.
         ' Set CurrentY to LastLine minus LineHeight times the number of
         ' additional lines in the Footer.
         Printer.CurrentY = LastLine - LineHeight  ' for 2 footer lines
         PrintText = "Sample Page Footer"
         ' Print the Footer text centered
         Printer.CurrentX = PrtPositionX - (LMargin + _
            Printer.TextWidth(PrintText) / 2)
         Printer.Print PrintText
         PrintText = "This is Page " & CStr(PageNum) & " of Test Report"
         Printer.CurrentX = PrtPositionX - (LMargin + _
            Printer.TextWidth(PrintText) / 2)
         Printer.Print PrintText
        End Sub

        Private Function GetLargeString() As String
         Dim BaseString As String, I As Integer

         BaseString = "This is just a fairly long string to demonstrate how "
         BaseString = BaseString & "to wrap text to impose your own right "
         BaseString = BaseString & "margin.  "
         For I = 1 To 2   ' See Q298825 to use a larger String
           BaseString = BaseString & BaseString
         Next I
         GetLargeString = BaseString
        End Function

        Private Sub Command1_Click()
        Dim dpiX As Long, dpiY As Long
        Dim MarginLeft As Long, MarginRight As Long
        Dim MarginTop As Long, MarginBottom As Long
        Dim PrintAreaHorz As Long, PrintAreaVert As Long
        Dim PhysHeight As Long, PhysWidth As Long
        Dim Info As String

        dpiX = GetDeviceCaps(Printer.hdc, LOGPIXELSX)
        Info = "Pixels X: " & dpiX & " dpi"

        dpiY = GetDeviceCaps(Printer.hdc, LOGPIXELSY)
        Info = Info & vbCrLf & "Pixels Y: " & dpiY & " dpi"

        MarginLeft = GetDeviceCaps(Printer.hdc, PHYSICALOFFSETX)
        Info = Info & vbCrLf & "Unprintable space on left: " & _
        MarginLeft & " pixels = " & MarginLeft / dpiX & " inches"

        MarginTop = GetDeviceCaps(Printer.hdc, PHYSICALOFFSETY)
        Info = Info & vbCrLf & "Unprintable space on top: " & _
        MarginTop & " pixels = " & MarginTop / dpiY & " inches"

        PrintAreaHorz = GetDeviceCaps(Printer.hdc, HORZRES)
        Info = Info & vbCrLf & "Printable space (Horizontal): " & _
        PrintAreaHorz & " pixels = " & PrintAreaHorz / dpiX & " inches"

        PrintAreaVert = GetDeviceCaps(Printer.hdc, VERTRES)
        Info = Info & vbCrLf & "Printable space (Vertical): " & _
        PrintAreaVert & " pixels = " & PrintAreaVert / dpiY & " inches"

        PhysWidth = GetDeviceCaps(Printer.hdc, PHYSICALWIDTH)
        Info = Info & vbCrLf & "Total space (Horizontal): " & _
        PhysWidth & " pixels = " & PhysWidth / dpiX & " inches"

        MarginRight = PhysWidth - PrintAreaHorz - MarginLeft
        Info = Info & vbCrLf & "Unprintable space on right: " & _
        MarginRight & " pixels = " & MarginRight / dpiX & " inches"

        PhysHeight = GetDeviceCaps(Printer.hdc, PHYSICALHEIGHT)
        Info = Info & vbCrLf & "Total space (Vertical): " & _
        PhysHeight & " pixels = " & PhysHeight / dpiY & " inches"

        MarginBottom = PhysHeight - PrintAreaVert - MarginTop
        Info = Info & vbCrLf & "Unprintable space on bottom: " & _
        MarginBottom & " pixels = " & MarginBottom / dpiY & " inches"

        MsgBox Info, , "GetDeviceCaps Returned the Following:"
        End Sub

        Private Sub Command2_Click()
        Dim FooterLines As Integer, TextLine As String
        Dim LineHeight As Integer, LastLine As Integer
        Dim TotWidth As Long, TotHeight As Long
        Dim MarginTop As Long, MarginBottom As Long
        Dim TotalPrtAreaVert As Long, TotalPrtAreaHorz As Long
        Dim MarginLeft As Long, MarginRight As Long
        Dim LeftMargin As Long, HorzMargins As Long
        Dim Line As Integer, RptHeaderPrint As Boolean
        Dim BreakPoint As Integer, PrintLength As Integer
        Dim TempString As String, CharLength As Integer
        Dim WrapPoint As Integer, EstWrapPoint As Integer

        Printer.Font.Name = "Arial"
        Printer.Font.Size = 12

        ' The next 8 values are in Pixels.
        ' TotalPrtAreaVert is eqivalent to Printer.ScaleHeight
        TotalPrtAreaVert = GetDeviceCaps(Printer.hdc, VERTRES)
        TotHeight = GetDeviceCaps(Printer.hdc, PHYSICALHEIGHT)
        MarginTop = GetDeviceCaps(Printer.hdc, PHYSICALOFFSETY)
        MarginBottom = TotHeight - TotalPrtAreaVert - MarginTop
        ' TotalPrtAreaHorz is eqivalent to Printer.ScaleWidth
        TotalPrtAreaHorz = GetDeviceCaps(Printer.hdc, HORZRES)
        TotWidth = GetDeviceCaps(Printer.hdc, PHYSICALWIDTH)
        MarginLeft = GetDeviceCaps(Printer.hdc, PHYSICALOFFSETX)
        MarginRight = TotWidth - TotalPrtAreaHorz - MarginLeft

        HorzMargins = (MarginRight + MarginLeft) * Printer.TwipsPerPixelX
        LeftMargin = MarginLeft * Printer.TwipsPerPixelX
        ' Covert to twips for ease of use
        TotalPrtAreaHorz = TotalPrtAreaHorz * Printer.TwipsPerPixelX
        LineHeight = Printer.TextHeight("Test")
        FooterLines = 2   ' number of lines in footer
        LastLine = TotalPrtAreaVert * Printer.TwipsPerPixelY - LineHeight
        ' Set the break point a line high so we can check it after printing
        BreakPoint = LastLine - LineHeight * FooterLines
        ' reduce the right margin by 1 inch, which is 1440 twips
        PrintLength = TotalPrtAreaHorz - 1440

        PrintHeader True, HorzMargins, LeftMargin  ' Report Header
        RptHeaderPrint = False
        ' Print the Footer when the current Y position >=
        ' LastLine - LineHeight * <Number Of Lines In Footer>
        For Line = 1 To 120
           If RptHeaderPrint Then
              PrintHeader False, HorzMargins, LeftMargin  ' Page Header
              RptHeaderPrint = False
           End If
           TextLine = "This is line " & Line
           ' To indent or set a new left margin, reset CurrentX before each
           ' new line.
           ' To use a new right margin, wrap lines at appropriate points.
           If Line >= 10 And Line <= 14 Then
              TextLine = TextLine & " indented."
              Printer.CurrentX = 2 * 1440  ' indent 2 additional inches
           ElseIf Line >= 48 And Line <= 52 Then
              TextLine = GetLargeString()  ' Need String long for demo
           End If
           ' Use TotalPrtAreaHorz to use the default right margin
           ' or use your own value for PrintLength for a custom right margin
           ' in this example we bring in the right margin by 1 inch
           If Printer.TextWidth(TextLine) > PrintLength Then  ' Wrap text
              ' This estimating technique is used for simplicity
              ' First, approximate character length
              CharLength = Printer.TextWidth("aeiou.") / 6
              ' Where to start looking for a line break (wrap)
              EstWrapPoint = PrintLength / CharLength
              WrapPoint = EstWrapPoint
              Line = Line - 1  ' Since current line has already been counted

              Do While Len(TextLine) > EstWrapPoint
                 TextLine = Trim(TextLine)   ' remove spaces from either end
                 ' break on a space near the estimated break point
                 Do While InStr(WrapPoint, TextLine, " ") <> WrapPoint
                    WrapPoint = WrapPoint - 1
                 Loop
                 TempString = Mid(TextLine, 1, WrapPoint)  ' what will fit
                 Printer.Print Trim(TempString)  ' print what will fit
                 TextLine = Mid(TextLine, WrapPoint + 1) ' get remaining text
                 WrapPoint = EstWrapPoint  ' Reset the estimated wrap point
                 Line = Line + 1  ' Increment line counter
                 If Printer.CurrentY >= BreakPoint Then  ' another line?
                    PrintFooter LastLine, LineHeight, LeftMargin
                    If Len(TextLine) > 0 Then  ' Print header if text remains
                       PrintHeader False, HorzMargins, LeftMargin
                    End If
                 End If
              Loop
              If Len(TextLine) > 0 Then  ' leftover text?
                 Printer.Print TextLine
                 Line = Line + 1  ' Increment line counter
                 If Printer.CurrentY >= BreakPoint Then  ' another line?
                    PrintFooter LastLine, LineHeight, LeftMargin
                    RptHeaderPrint = True  ' Print Header if more lines
                 End If
              End If
           Else
              Printer.Print TextLine
              If Printer.CurrentY >= BreakPoint Then
                 PrintFooter LastLine, LineHeight, LeftMargin
                 RptHeaderPrint = True  ' Print Header if more lines
              End If
           End If
        Next Line
        If Printer.CurrentY > 0 Then
           PrintFooter LastLine, LineHeight, LeftMargin  ' For last page
        End If
        Printer.EndDoc   ' Finish
        MsgBox "Check Printer for results.", , "Done!"
        End Sub

3. Run the project.

4. Click Command1. You will see a message box listing the margins and printable
  area of the page.

5. Click Command2. Several pages are printed. The printing includes:

  Report Header - Only printed at the top of page 1.

  Page Header - Consists of some text printed in italics and the current date
  right-justified on the page. Printed on all pages.

  Page Footer - Consists of some text and a page number printed on multiple
  lines. Printed on all pages.

  Additionally, lines numbered 10 through 14 are indented an additional 2 inches
  and lines numbered 48 through 56 demonstrate enforcing a custom right margin.

For additional information about using the TextWidth method with large strings,
click the article number below to view the article in the Microsoft Knowledge
Base:

  Q298825 PRB: Run-time Error '6' When You Use the TextWidth Method

(c) Microsoft Corporation 1998, All Rights Reserved. Contributions by Chris E.
Jolley, Microsoft Corporation.


Additional query words:

======================================================================
Keywords          : kbprint kbAPI kbPrinting kbVBp kbVBp400 kbVBp500 kbVBp600 kbGrpDSVB 
Technology        : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2 kbVB500Search kbVB600Search kbVB500 kbVB600 kbVB400Search kbVB400
Version           : :4.0,5.0,6.0
Issue type        : kbhowto

=============================================================================

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