HOWTO: Use GetDeviceCaps to Determine Margins on a Page

• Microsoft Visual Basic Standard, Professional, and Enterprise Editions, 32-bit only, for Windows, version 4.0
• Microsoft Visual Basic Learning, Professional, and Enterprise Editions for Windows, versions 5.0, 6.0

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 3
            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.

Additional query words:

Keywords : kbAPI kbPrinting kbVBp kbVBp400 kbVBp500 kbVBp600 kbGrpVB
Version : WINDOWS:4.0,5.0,6.0
Platform : WINDOWS
Issue type : kbhowto