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ACC2000: How to Convert Twips to Pixels

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


This article applies to a Microsoft Access database (.mdb) and to a Microsoft Access project (.adp).


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Summary

Because Microsoft Access stores dimension/location properties as twips, in certain cases you may have to convert twips to pixels, such as when you call a Windows API function. This article shows you how to do this.


Microsoft provides programming examples for illustration only, without warranty either expressed or implied. This includes, but is not limited to, the implied warranties of merchantability or fitness for a particular purpose. This article assumes that you are familiar with the programming language that is being demonstrated and with the tools that are used to create and to debug procedures. Microsoft support engineers can help explain the functionality of a particular procedure, but they will not modify these examples to provide added functionality or construct procedures to meet your specific requirements.

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More Information

You can use the following ConvertTwipsToPixels() function 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. Create a new module and type the following in the Declarations section:

    Option Explicit

    Declare Function GetDC Lib "user32" (ByVal hwnd As Long) As Long
    Declare Function ReleaseDC Lib "user32" (ByVal hwnd As Long, _
      ByVal hdc As Long) As Long
    Declare Function GetDeviceCaps Lib "gdi32" (ByVal hdc As Long, _
      ByVal nIndex As Long) As Long

    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.
  2. Type the following procedure:
    Function ConvertTwipsToPixels (lngTwips as Long, _
       lngDirection as long) As Long

       'Handle to device
       Dim lngDC as long                        
       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
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:

Function ShowConvert()
   Dim lngOldTwips As Long
   lngOldTwips = 2377
   ShowConvert = ConvertTwipsToPixels(lngOldTwips, 0)
End Function

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Keywords: 2000rtmpublic, acccon, kbinfo, kbprogramming, offcon, kb, kbarchive

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Article Info
Article ID : 210590
Revision : 3
Created on : 4/17/2018
Published on : 4/19/2018
Exists online : False
Views : 346