FENÊTRES TRANSPARENTES W2K+

'Fonctionne uniquement sur Windows 2000 et plus

'Utilisation :
'Dans l'événement Form_Load mettre :
'WndSetOpacity hWnd, , 125 (rend la fenêtre translucide à 50%
'WndSetOpacity hWnd, vbBlack, ,False (rend la couleur noir transparente)


Private Const GWL_EXSTYLE = (-20)
Private Const LWA_COLORKEY = &H1
Private Const LWA_ALPHA = &H2
Private Const WS_EX_LAYERED = &H80000
Private Declare Function GetWindowLong Lib "user32" Alias "GetWindowLongA" (ByVal hWnd As Long, ByVal nIndex As Long) As Long
Private Declare Function SetLayeredWindowAttributes Lib "user32.dll" (ByVal hWnd As Long, ByVal crKey As Long, ByVal bAlpha As Byte, ByVal dwFlags As Long) As Long
Private Declare Function SetWindowLong Lib "user32" Alias "SetWindowLongA" (ByVal hWnd As Long, ByVal nIndex As Long, ByVal dwNewLong As Long) As Long

Public Function WndSetOpacity(ByVal hWnd As Long, Optional ByVal crKey As Long = vbBlack, Optional ByVal Alpha As Byte = 255, Optional ByVal ByAlpha As Boolean = True) As Boolean
'Return : True si il n'y a pas eu d'erreur.
'hWnd  : hWnd de la fenêtre à rendre transparente
'crKey : Couleur à rendre transparente si ByAlpha=False (utiliser soit les constantes vb:vbWhite ou en hexa:&HFFFFFF)
'Alpha : 0-255 0=transparent 255=Opaque si ByAlpha=true (défaut)
  Dim ExStyle As Long
  ExStyle = GetWindowLong(hWnd, GWL_EXSTYLE)
  If ExStyle <> (ExStyle Or WS_EX_LAYERED) Then
    ExStyle = (ExStyle Or WS_EX_LAYERED)
    Call SetWindowLong(hWnd, GWL_EXSTYLE, ExStyle)
  End If
  WndSetOpacity = (SetLayeredWindowAttributes(hWnd, crKey, Alpha, IIf(ByAlpha, LWA_ALPHA, LWA_COLORKEY)) <> 0)
End Function