'for listview column auto-resizing
Private Const LVM_FIRST As Long = &H1000
Private Const LVM_SETCOLUMNWIDTH As Long = (LVM_FIRST + 30)
Private Const LVSCW_AUTOSIZE As Long = -1
Private Const LVSCW_AUTOSIZE_USEHEADER As Long = -2

Private Declare Function SendMessage Lib "user32" _
   Alias "SendMessageA" _
  (ByVal hwnd As Long, _
   ByVal wMsg As Long, _
   ByVal wParam As Long, _
   lParam As Any) As Long

'EnumDisplayDevices Requirements
'  Windows NT/2000/XP: Included in Windows 2000 and later.
'  Windows 95/98/Me:   Included in Windows 98 and later.
Private Type DISPLAY_DEVICE
   cb As Long
   DeviceName(0 To 31) As Byte
   DeviceString(0 To 127) As Byte
   StateFlags As Long
   DeviceID(0 To 127) As Byte
   DeviceKey(0 To 127) As Byte
End Type

Private Const DD_ATTACHED_TO_DESKTOP As Long = &H1
Private Const DD_MULTI_DRIVER        As Long = &H2
Private Const DD_PRIMARY_DEVICE      As Long = &H4
Private Const DD_MIRRORING_DRIVER    As Long = &H8
Private Const DD_VGA_COMPATIBLE      As Long = &H10
Private Const DD_REMOVABLE           As Long = &H20
Private Const DD_DISCONNECT          As Long = &H2000000 'WINVER >= 5
Private Const DD_REMOTE              As Long = &H4000000 'WINVER >= 5
Private Const DD_MODESPRUNED         As Long = &H8000000 'WINVER >= 5

Private Declare Function EnumDisplayDevices Lib "user32" _
   Alias "EnumDisplayDevicesA" _
  (ByVal lpDevice As Any, _
   ByVal iDevNum As Long, _
   lpDisplayDevice As DISPLAY_DEVICE, _
   ByVal dwFlags As Long) As Long
   


Private Sub Form_Load()

   With ListView1
      .ListItems.Clear
      .View = lvwReport
      .Sorted = False
      .ColumnHeaders.Clear
      .ColumnHeaders.Add , , "DisplayDevice Member"
      
      .ListItems.Add , , "Device Name"
      .ListItems.Add , , "Device String"
      .ListItems.Add , , "Device StateFlags:"
      .ListItems.Add , , "  - part of desktop"
      .ListItems.Add , , "  - primary device"
      .ListItems.Add , , "  - pseudo device"
      .ListItems.Add , , "  - VGA compatible"
      .ListItems.Add , , "  - removable (cannot be primary)"
      .ListItems.Add , , "  - more modes than output device"
      .ListItems.Add , , "Assoc Monitor Name"
      .ListItems.Add , , "Assoc Monitor String"
      .ListItems.Add , , "Assoc Monitor StateFlags:"
      .ListItems.Add , , "  - multi-driver"
   
   End With

   Command1.Caption = "EnumDisplayDevices"

End Sub


Private Sub Command1_Click()

   Call EnumSystemDisplayDevices
   Call lvAutosizeControl(ListView1)
   
End Sub


Private Sub EnumSystemDisplayDevices()
        
   Dim iDevNum As Long
   Dim thiscol As Long
   Dim sDeviceName As String 'required in 3 places
   Dim dev As DISPLAY_DEVICE
   
  'Query all display devices in the system by
  'calling EnumDisplayDevices in a loop, starting
  'with iDevNum set to 0, and incrementing until
  'the function fails (call returns non-zero if
  'true or 0 if false).
  
   dev.cb = Len(dev)
   iDevNum = 0
   
   Do While EnumDisplayDevices(0&, iDevNum, dev, 0&)

     'for each display device returned,
     'add a new column to the listview
     'and populate its data
      With ListView1
      
         sDeviceName = TrimNull(StrConv(dev.DeviceName, vbUnicode))
          
         .ColumnHeaders.Add , , sDeviceName
         thiscol = (.ColumnHeaders.Count - 1)
                   
         .ListItems(1).SubItems(thiscol) = sDeviceName
         .ListItems(2).SubItems(thiscol) = TrimNull(StrConv(dev.DeviceString, vbUnicode))
         .ListItems(3).SubItems(thiscol) = dev.StateFlags
         
         If dev.StateFlags And DD_ATTACHED_TO_DESKTOP Then
            .ListItems(4).SubItems(thiscol) = "Yes"
         End If
            
         If dev.StateFlags And DD_PRIMARY_DEVICE Then
            .ListItems(5).SubItems(thiscol) = "Yes"
         End If
         
         If dev.StateFlags And DD_MIRRORING_DRIVER Then
            .ListItems(6).SubItems(thiscol) = "Yes"
         End If
         
         If dev.StateFlags And DD_VGA_COMPATIBLE Then
            .ListItems(7).SubItems(thiscol) = "Yes"
         End If
         
         If dev.StateFlags And DD_REMOVABLE Then
            .ListItems(8).SubItems(thiscol) = "Yes"
         End If
         
         If dev.StateFlags And DD_MODESPRUNED Then
            .ListItems(9).SubItems(thiscol) = "Yes"
         End If
      
        'When null was passed as lpDevice above,
        'information about the display device (adapter)
        'was returned. By calling the API once again,
        'this time specifying lpDevice=dev.devicename and
        'iDevNum=0, the same call returns information about
        'the monitor connected to the specified device.
         If EnumDisplayDevices(sDeviceName, 0, dev, 0&) <> 0 Then
         
            .ListItems(10).SubItems(thiscol) = TrimNull(StrConv(dev.DeviceName, vbUnicode))
            .ListItems(11).SubItems(thiscol) = TrimNull(StrConv(dev.DeviceString, vbUnicode))
            .ListItems(12).SubItems(thiscol) = dev.StateFlags
         
            If dev.StateFlags And DD_MULTI_DRIVER Then
               .ListItems(13).SubItems(thiscol) = "Yes"
            End If
         
         End If
   
      End With

      iDevNum = iDevNum + 1
   
   Loop

End Sub


Private Sub lvAutosizeControl(lv As ListView)

   Dim col2adjust As Long

  'Size each column based on the maximum of
  'either the ColumnHeader text width, or,
  'if the items below it are wider, the
  'widest list item in the column
  
   lv.Visible = False
   For col2adjust = 0 To lv.ColumnHeaders.Count - 1
   
      Call SendMessage(lv.hwnd, _
                       LVM_SETCOLUMNWIDTH, _
                       col2adjust, _
                       ByVal LVSCW_AUTOSIZE_USEHEADER)

   Next
   lv.Visible = True
   
End Sub


Private Function TrimNull(item As String)

    Dim pos As Integer
   
   'double check that there is a chr$(0) in the string
    pos = InStr(item, Chr$(0))
    If pos Then
       TrimNull = Left$(item, pos - 1)
    Else
       TrimNull = item
    End If
  
End Function