1. Start a new standard EXE project in Visual Basic. Form one is created by default
2. Add a normal module to the project, by clicking on the Project menu and choosing
insert module.
3. You will need to declare the following types, by typing the following in to the
beginning of the module
Type POINTAPI
x As Long
y As Long
End Type Type MSG
hWnd As Long
message As Long
wParam As Long
lParam As Long
time As Long
pt As POINTAPI
End Type
4. You now need to add the following Windows API calls to the module. Make sure that
each API is on one line
Declare Sub DragAcceptFiles Lib
"shell32.dll" (ByVal hWnd _
As Long, ByVal fAccept As Long) Declare
Sub DragFinish Lib "shell32.dll" (ByVal hDrop _
As Long)
Declare
Function DragQueryFile Lib "shell32.dll" Alias _
"DragQueryFileA" (ByVal hDrop As Long, ByVal UINT As _
Long, ByVal lpStr As String, ByVal ch As Long) As
Long
Declare Function
PeekMessage Lib "user32" Alias _
"PeekMessageA" (lpMsg As MSG, ByVal hWnd As Long, _
ByVal wMsgFilterMin As Long, ByVal wMsgFilterMax As _
Long, ByVal wRemoveMsg As Long) As Long
Public
Const PM_NOREMOVE = &H0
Public Const PM_NOYIELD = &H2
Public Const PM_REMOVE = &H1
Public Const WM_DROPFILES = &H233
5. You will now need to add the following procedures to the module.
'
This is the sub main procedure, that is called
' for any of the forms are loaded. Sub
Main()
' In order for this to function properly you should
' place of of your program execution code in
' the Sub Main(), Make sure you change the project
' startup to sub Main
Form1.Show
' This must be the last line! Nothing gets called
' after this
WatchForFiles
End Sub
Public Sub
WatchForFiles()
' This subroutine watchs for all of your WM_DROPFILES
' messages
' Dim Variables
Dim FileDropMessage As MSG ' Msg Type
Dim fileDropped As Boolean ' True if Files where dropped
Dim hDrop As Long ' Pointer to the dropped file structure
Dim filename As String * 128 ' the dropped filename
Dim numOfDroppedFiles As Long ' the amount of dropped files
Dim curFile As Long ' the current file number
' loop to keep checking for files
' NOTE : Do any code you want to execute before this
set
Do
' check for Dropped file messages
fileDropped = PeekMessage(FileDropMessage, 0, _
WM_DROPFILES, WM_DROPFILES, PM_REMOVE Or PM_NOYIELD)
If fileDropped Then
' Get the pointer to the dropped file structure
hDrop = FileDropMessage.wParam
' Get the toal number of files
numOfDroppedFiles = DragQueryFile(hDrop, True, _
filename, 127)
For curFile = 1 To numOfDroppedFiles
' Get the file name
ret% = DragQueryFile(hDrop, curFile - 1, filename, 127)
' at this pointer you can do what you want with the
' filename the filename will be a full qalified path
Form1.lblNumDropped = LTrim$(Str$(numOfDroppedFiles))
Form1.List1.AddItem filename
Next curFile
' We are now done with the structure, tell windows
' to discard it
DragFinish (hDrop)
End If
DoEvents
Loop
End Sub
6. Open up form one. Draw the following
7. Now open up the code window for form1 and type the following
Private
Sub Command1_Click()
' You can turn the form's / controls ability
' to accept the files by passing the hWnd as
' the first parameter and True/False as the
' Second If
Command1.Caption = "&Accept Files" Then
' allow the application to accept files
DragAcceptFiles Form1.hWnd, True
Command1.Caption = "&Do Not Accept"
Else
DragAcceptFiles Form1.hWnd, False
Command1.Caption = "&Accept Files"
End If
End Sub
Private
Sub Command2_Click()
' Clears the contents of the list box
List1.Clear
End Sub
Private Sub
Command3_Click()
' End the program
End
End Sub
Private Sub Form_Unload(Cancel As Integer)
End
End Sub
