ACC: How to Convert Twips to Pixels

• Microsoft Access versions 1.0, 1.1, 2.0, 7.0, 97

SUMMARY

Advanced: Requires expert coding, interoperability, and multiuser skills.

Because Microsoft Access stores dimension/location properties as twips, it may be necessary to convert to pixels in certain cases, such as when calling a Windows API function. This article describes how to do this.

This article assumes that you are familiar with Visual Basic for Applications and with creating Microsoft Access applications using the programming tools provided with Microsoft Access. For more information about Visual Basic for Applications, please refer to your version of the "Building Applications with Microsoft Access" manual.

NOTE: Visual Basic for Applications is called Access Basic in Microsoft Access 2.0 and earlier. For more information about Access Basic, please refer to the "Introduction to Programming" manual in Microsoft Access version 1.x or the "Building Applications" manual in version 2.0.

MORE INFORMATION

You can use the ConvertTwipsToPixels() function below to convert twips to pixels. Note that pixels are not always square (the height and width are not the same); therefore, it is necessary to pass in the desired "direction" to use (horizontal or vertical).

1. To add this function to your application, type one of the following examples in a new module, depending on your version of Microsoft Access:

   In Microsoft Access 7.0 and 97:

       Option Explicit
       Declare Function GetDC% Lib "User32" (ByVal hw%)
       Declare Function ReleaseDC% Lib "User32" (ByVal hw%, ByVal hDC%)
       Declare Function GetDeviceCaps% Lib "Gdi32" (ByVal hDC%, _
          ByVal iCapability%)
   

       Const WU_LOGPIXELSX = 88
       Const WU_LOGPIXELSY = 90
   

   NOTE: You may have some Microsoft Windows API functions defined in an existing Microsoft Access library; therefore, your declarations may be duplicates. If you receive a duplicate procedure name error message, remove or comment out the declarations statement in your code.

       Function ConvertTwipsToPixels (lngTwips as Long, lngDirection _
       as long) As Long
       Dim lngDC as long                        'Handle to device
       Dim lngPixelsPerInch as Long
       Const nTwipsPerInch = 1440
       lngDC = GetDC(0)
       If (lngDirection = 0) Then       'Horizontal
           lngPixelsPerInch = GetDeviceCaps(lngDC, WU_LOGPIXELSX)
       Else                            'Vertical
           lngPixelsPerInch = GetDeviceCaps(lngDC, WU_LOGPIXELSY)
       End If
       lngDC = ReleaseDC(0, lngDC)
       ConvertTwipsToPixels = (lngTwips / nTwipsPerInch) * lngPixelsPerInch
       End Function
   
       Function ShowConvert()
          Dim lngOldTwips As Long
          lngOldTwips = 2377
          ShowConvert = ConvertTwipsToPixels(lngOldTwips, 0)
       End Function
   
      In Microsoft Access 1.x and 2.0:
   
      NOTE: In the following code samples, an underscore (_) at the end of a
      line is used as a line-continuation character. Remove the underscore
      from the end of the line when re-creating this code in Access Basic.
   
       Option Explicit
       Declare Function GetDC% Lib "User" (ByVal hw%)
       Declare Function ReleaseDC% Lib "User" (ByVal hw%, ByVal hDC%)
       Declare Function GetDeviceCaps% Lib "Gdi" (ByVal hDC%, _
           ByVal iCapability%)
   
       Const WU_LOGPIXELSX = 88
       Const WU_LOGPIXELSY = 90
   
      NOTE: You may have some Microsoft Windows API functions defined in an
      existing Microsoft Access library; therefore, your declarations may
      be duplicates. If you receive a duplicate procedure name error message,
      remove or comment out the declarations statement in your code.
   
       Function ConvertTwipsToPixels (nTwips%, nDirection%) As Integer
          Dim hDC%                        'Handle to device
          Dim nPixelsPerInch%
          Const nTwipsPerInch = 1440
          hDC% = GetDC(0)
          If (nDirection% = 0) Then       'Horizontal
             nPixelsPerInch% = GetDeviceCaps(hDC%, WU_LOGPIXELSX)
          Else                            'Vertical
             nPixelsPerInch% = GetDeviceCaps(hDC%, WU_LOGPIXELSY)
          End If
            hDC% = ReleaseDC(0, hDC%)
            ConvertTwipsToPixels = (nTwips% / nTwipsPerInch%) * nPixelsPerInch
       End Function
   
       Function ShowConvert()
          Dim intOldTwips As Integer
          intOldTwips = 2377
          ShowConvert = ConvertTwipsToPixels(intOldTwips, 0)
        End Function
   
   

2. To call this function, pass the number of twips you want to convert, and another parameter indicating the horizontal or vertical measurement (0 for horizontal, non-zero for vertical). The following is a sample call:

         OldTwips = 2377
         NewPixels = ConvertTwipsToPixels(OldTwips, 0)
   

REFERENCES

For more information about this topic, search for "declare statement," using the Microsoft Access Help Index.

Keywords          : kbprg PgmApi
Version           : 1.0 1.1 2.0 7.0 97
Platform          : WINDOWS
Hardware          : x86
Issue type        : kbhowto