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Subject: Re: Delphi & filemngr drag drop
To use File Manager Drag & Drop, add a method to your form that
handles the WM_DROPFILES message. For example, the following
would be placed in the TForm1 declaration in the protected
section:
...
procedure WMDropFiles(var msg : TMessage); message WM_DROPFILES;
...
You would typically activate file drag & drop by calling
DragAcceptFiles() in the OnCreate event, and turn it off
with a subsequent call to DragAcceptFiles() in the OnClose
or OnDestroy events. The code follows:
procedure TForm1.WMDropFiles(var msg : TMessage);
var
i, n : word;
size : word;
fname : string;
hdrop : word;
begin
{1. Get the drop handle.}
hdrop := msg.WParam;
{2. Find out how many files were dropped by passing $ffff in arg #2.}
n := DragQueryFile(hdrop, $ffff, nil, 0);
{3. Loop through, reading in the filenames (w/full paths).}
for i := 0 to (n - 1) do begin
{4. Get the size of the filename string by passing 0 in arg #4.}
size := DragQueryFile(hdrop, i, nil, 0);
{5. Make sure it won't overflow our string (255 char. limit)}
if size < 255 then begin
fname[0] := Chr(size);
{6. Get the dropped filename.}
DragQueryFile(hdrop, i, @fname[1], size + 1);
{-- Do whatever you want to do with fname. --}
end;
end;
{7. Return zero.}
msg.Result := 0;
{8. Let the inherited message handler (if there is one) go at it.}
inherited;
end;
procedure TForm1.FormCreate(Sender: TObject);
begin
DragAcceptFiles(Handle, true);
end;
procedure TForm1.FormClose(Sender: TObject; var Action: TCloseAction);
begin
DragAcceptFiles(Handle, false);
end;
Keep in mind that you don't have to put all of this stuff
on a form. Any windowed control that has an HWnd handle
(descendants of TWinControl) should be able to accept
dropped files.
I hope this answers your question.
--Mark Johnson
______________________________________________________________________________
Mark R. Johnson _/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_
Atlanta, GA USA _/ http://www.mindspring.com/~cityzoo/cityzoo.html _/
keeper@mindspring.com _/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/
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From: jnhodges@nps.navy.mil (John N. Hodges)
Subject: Re: Delphi & filemngr drag drop
Date: 25 May 1995 15:28:05 GMT
As a follow up to Mark's response, if you want to make the minimized
program respond to dragged files, you have to do the exact same thing for
Application.Handle as well. In this case you would provide an OnMessage event
handler that checks for wm_dropfiles.
---
* LT Nick Hodges, USN Naval Postgraduate School *
* jnhodges@nps.navy.mil Information Technology Management *
* CIS: 71563,2250 AOL: NHodges Monterey, CA *
* The opinions expressed above are entirely my own and not the Navy's. *
* Visit my homepage: http://vislab-www.nps.navy.mil/~jnhodges *
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