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).


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.


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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
Svojstva

ID članka: 210590 - posljednja izmjena: 23. lip 2005. - verzija: 1

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