APIs: Drag and Drop pour l'explorateur	Author(s) Dev Ashish

Drag and Drop (glissser-déplacer) pour l'explorateur.

Note: Pour tester le code de cet article, vous devez avoir également le code pour AddressOf.

    Nous pouvons utiliser AddressOf pour faire en sorte qu'on reconnaisse les fichiers qu'on dépose sur un formulaire depuis l'explorateur, par   drag and drop.

    Créer une formulaire Popup baptisé  "frmDragDrop" contenant un contrôle de liste "lstDrop". Enfin, placer le code derrière les procédures événementielles appropriées du formulaire.

'******** Code Start ********
Private Sub Form_Open(Cancel as Integer)
    Call sEnableDrop(Me)
    Call sHook(Me.Hwnd, "sDragDrop")
End Sub

Private Sub Form_Unload(Cancel As Integer)
    Call sUnhook(Me.Hwnd)
End Sub
'******** Code  End ********

Copier ce code dans un nouveau module.

'************* Code Start *************
Private Declare Function apiCallWindowProc Lib "user32" _
    Alias "CallWindowProcA" _
    (ByVal lpPrevWndFunc As Long, _
    ByVal Hwnd As Long, _
    ByVal Msg As Long, _
    ByVal wParam As Long, _
    ByVal lParam As Long) _
    As Long
   
Private Declare Function apiSetWindowLong Lib "user32" _
    Alias "SetWindowLongA" _
    (ByVal Hwnd As Long, _
    ByVal nIndex As Long, _
    ByVal wNewWord As Long) _
    As Long

Private Declare Function apiGetWindowLong Lib "user32" _
    Alias "GetWindowLongA" _
   (ByVal Hwnd As Long, _
   ByVal nIndex As Long) _
   As Long

Private Declare Sub sapiDragAcceptFiles Lib "shell32.dll" _
    Alias "DragAcceptFiles" _
    (ByVal Hwnd As Long, _
    ByVal fAccept As Long)
    
Private Declare Sub sapiDragFinish Lib "shell32.dll" _
    Alias "DragFinish" _
    (ByVal hDrop As Long)

Private Declare Function apiDragQueryFile Lib "shell32.dll" _
    Alias "DragQueryFileA" _
    (ByVal hDrop As Long, _
    ByVal iFile As Long, _
    ByVal lpszFile As String, _
    ByVal cch As Long) _
    As Long

Private lpPrevWndProc  As Long
Private Const GWL_WNDPROC  As Long = (-4)
Private Const GWL_EXSTYLE = (-20)
Private Const WM_DROPFILES = &H233
Private Const WS_EX_ACCEPTFILES = &H10&
Private hWnd_Frm As Long

Sub sDragDrop(ByVal Hwnd As Long, _
                            ByVal Msg As Long, _
                            ByVal wParam As Long, _
                            ByVal lParam As Long)

Dim lngRet As Long, strTmp As String, intLen As Integer
Dim lngCount As Long, i As Long, strOut As String
Const cMAX_SIZE = 50
    On Error Resume Next
    If Msg = WM_DROPFILES Then
        strTmp = String$(255, 0)
        lngCount = apiDragQueryFile(wParam, &HFFFFFFFF, strTmp, Len(strTmp))
        For i = 0 To lngCount - 1
            strTmp = String$(cMAX_SIZE, 0)
            intLen = apiDragQueryFile(wParam, i, strTmp, cMAX_SIZE)
            strOut = strOut & left$(strTmp, intLen) & ";"
        Next i
        strOut = left$(strOut, Len(strOut) - 1)
        Call sapiDragFinish(wParam)
        With Forms!frmDragDrop!lstDrop
            .RowSourceType = "Value List"
            .RowSource = strOut
            Forms!frmDragDrop.Caption = "DragDrop: " & _
                                                    .ListCount & _
                                                    " files dropped."
        End With
        
    Else
        lngRet = apiCallWindowProc( _
                            ByVal lpPrevWndProc, _
                            ByVal Hwnd, _
                            ByVal Msg, _
                            ByVal wParam, _
                            ByVal lParam)
    End If
End Sub

Sub sEnableDrop(frm As Form)
Dim lngStyle As Long, lngRet As Long
    lngStyle = apiGetWindowLong(frm.Hwnd, GWL_EXSTYLE)
    lngStyle = lngStyle Or WS_EX_ACCEPTFILES
    lngRet = apiSetWindowLong(frm.Hwnd, GWL_EXSTYLE, lngStyle)
    Call sapiDragAcceptFiles(frm.Hwnd, True)
    hWnd_Frm = frm.Hwnd
End Sub


Sub sHook(Hwnd As Long, _
                strFunction As String)
    lpPrevWndProc = apiSetWindowLong(Hwnd, _
                                            GWL_WNDPROC, _
                                            AddrOf(strFunction))
End Sub

Sub sUnhook(Hwnd As Long)
Dim lngTmp As Long
    lngTmp = apiSetWindowLong(Hwnd, _
                    GWL_WNDPROC, _
                    lpPrevWndProc)
    lpPrevWndProc = 0
End Sub
'**************** Code End ***************

Compiler l'ouvrage et sauvegarder. Ouvrir le formulaire et y déposer quelques fichiers depuis l'explorateur de Windows.