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Visual Basic File Routines DragAcceptFiles: File Drag/Drop in VB |
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Posted: | Thursday December 26, 1996 | |
Updated: | Monday December 26, 2011 | |
Applies to: | VB4-32, VB5, VB6 | |
Developed with: | VB4-32, Windows 95 | |
OS restrictions: | None | |
Author: | Joseph J Guadagno | |
Prerequisites |
None. Note that this page pre-dated the availability of VB's easier OLE drag/drop methods. |
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Code
taken from the web, authored by Joseph J Guadagno, Bethpage, NY. Note that beginning with VB5 the OLEDragDrop and related routines provide increased functionality and simpler code than this VB4-32 method. |
BAS Module Code |
Place the following code into the general declarations area of a bas module: |
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Option Explicit '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' ' Copyright ©1996-2011 VBnet/Randy Birch, All Rights Reserved. ' Some pages may also contain other copyrights by the author. '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' ' Distribution: You can freely use this code in your own ' applications, but you may not reproduce ' or publish this code on any web site, ' online service, or distribute as source ' on any media without express permission. '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' Public Type POINTAPI x As Long y As Long End Type Public Type MSG hWnd As Long message As Long wParam As Long lParam As Long time As Long pt As POINTAPI End Type Public Declare Sub DragAcceptFiles Lib "shell32" _ (ByVal hWnd As Long, _ ByVal fAccept As Long) Public Declare Sub DragFinish Lib "shell32" _ (ByVal hDrop As Long) Public Declare Function DragQueryFile Lib "shell32" _ Alias "DragQueryFileA" _ (ByVal hDrop As Long, _ ByVal UINT As Long, _ ByVal lpStr As String, _ ByVal ch As Long) As Long Public 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 Public 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 watches for all WM_DROPFILES messages 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 number 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 total number of files numOfDroppedFiles = DragQueryFile(hDrop, True, filename, 127) For curFile = 1 To numOfDroppedFiles 'get the file name Call DragQueryFile(hDrop, curFile - 1, filename, 127) 'at this pointer you can do what you want with the filename 'the filename will be a full qualified 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 'be nice DoEvents Loop End Sub |
Form Code |
On a form, add three command buttons, a listbox and a label. Add the following code to the form: |
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Option Explicit Private Sub Command1_Click() 'You can turn the form's / controls ability 'to accept the files by passing DragAcceptFiles 'the hWnd as the first parameter and True/False 'as the second parameter 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 Unload Me End Sub |
Comments |
Run the project. Open Explorer, and press the Accept Files
button (Command1). Drag any number of files from explorer onto the form's listbox and release. The full path and filename of each file
dropped will be displayed. Pressing Do Not Accept turns off the drag drop sensing. |
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Copyright ©1996-2011 VBnet and Randy Birch. All Rights Reserved. |