Combo Box Text Width

[Guest]

I am changing the drop down width of a combo box to fully display the
longest string in the list with %CB_SETDROPPEDWIDTH. How can I determine
the width in pixels of the longest string in the list so I know the required
dropdown width (pixels) to use? Currently I use an arbitrary value (yuk!).
(Control Send hDlg, %ID_UserID, %CB_SETDROPPEDWIDTH, 200&, 0&)

Thanks,

Ron

[Semen Matusovski]

Ron --
I like to use in similar situations GetTextExtentPoint32.
Don't exactly know, how combo box uses DROPPEDWIDTH, but looks logical to set DROPPEDWIDTH as maximum value of lpsize.cx for all elements + GetSystemMetrics(%SM_CXHSCROLL) + something for internal borders (2 * GetSystemMetrics(%SM_CXDLGFRAME) ?)

[This message has been edited by Semen Matusovski (edited June 04, 2000).]

[Guest]

Thanks for the reply, Semen. I rummaged through some books and code
and pieced together something which appears to work pretty good.

This function calculates the average width of a character then based
upon the longest string in the combo box, it sets the dropdown width.

Function GetDlgUnits(hWnd As Long) As Long
 
  Local strTemp   As Asciiz * 64
  Local szl       As SIZEL
  Local hFont     As Long
  Local hOldFont  As Long
  Local avgWidth  As Long
  Local hDc       As Long
  
  hDc = GetDC(hWnd)
  
  hFont     = GetStockObject(%ANSI_VAR_FONT)
  hOldFont  = SelectObject(hDc, hFont)
  
  strTemp = "1234567890ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
  GetTextExtentPoint32 hDc, strTemp, 62, szl
  ' 62 = "strTemp" string length
  avgWidth = szl.cx \ 62
  
  SelectObject hDc, hOldFont
  DeleteObject hFont
  ReleaseDC hWnd, hDc
  
  Function = avgWidth
 
End Function
 
Usage:
 
  '1 - Determine the maximum length string in the combo box (your own code)
 
  Local lngLongestCBItem As Long
  lngLongestCBItem = 35  ' use actual calculated length
 
  avgWidth = GetDlgUnits(hWnd)
 
  'Add a slight border on the right.  
  'Some strings might require this to be tweaked.  
  'It's all based on average character width  
  NewWidth = ((lngLongestCBItem) * avgWidth) + 1&
  
  Control Send hwnd, iD, %CB_SETDROPPEDWIDTH, NewWidth,  0&

[Semen Matusovski]

Ron --
I told about somethink like this

   #Compile Exe
   #Register None
   #Dim All
   #Include "win32api.INC"
   
   CallBack Function DlgProc
      Static hFont As Long
      Local El As Asciiz * 256, lpSize As SizeL, cxx As Long, i As Long, _
          hWndCmb As Long, hdc As Long
      Select Case CbMsg
         Case %WM_INITDIALOG
            Control Add ComboBox, CbHndl, 100, , 5, 5, 50, 150, _
               %CBS_AUTOHSCROLL Or %CBS_DROPDOWNLIST Or %WS_TABSTOP Or %WS_VSCROLL
            hWndCmb = GetDlgItem(CbHndl, 100)
            hDC = GetDC(hWndCmb)
            hFont = CreateFont(-15, 0, 0, 0, %FW_NORMAL, 0, 0, 0, _
               %ANSI_CHARSET, %OUT_TT_PRECIS, %CLIP_DEFAULT_PRECIS, _
               %DEFAULT_QUALITY, %FF_DONTCARE, "Arial")
            SelectObject hDC, hFont
            SendMessage hWndCmb, %WM_SETFONT, hFont, 0
            cxx = 0
            For i = 20 To 1 Step -1
                
               El = "# " + Str$(i) + " " + String$(i, "a") + " |"
               GetTextExtentPoint32 hdc, El, Len(El), lpSize
               cxx = Max(cxx, lpSize.cx)
               ComboBox Add CbHndl, 100, El
            Next
            SendMessage hWndCmb, %CB_SETDROPPEDWIDTH, _
               cxx + GetSystemMetrics(%SM_CXVSCROLL)+ 2 * GetSystemMetrics(%SM_CXDLGFRAME), 0
            ReleaseDC hWndCmb, hDC
         Case %WM_DESTROY
            DeleteObject hFont
      End Select
   End Function
   Function PbMain
      Local hDlg    As Long
      Dialog New 0, "", ,, 300, 200, %WS_CAPTION Or %WS_SYSMENU To hDlg
      Dialog Show Modal hDlg Call DlgProc
   End Function

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