Simulate Drop Files with SendMessage WM_DROPFILES

[nimedon]

Do anyone has any idea of how can I drop files to another app in the background?

 

I have found that it can be done with SendMessage WM_DROPFILEs, but I don't know how to structure the wParam.

 

I also found this on MSDN

http://msdn.microsoft.com/en-us/library/bb773269%28VS.85%29.aspx

 

But I still don't have any idea of how to do it,

I also found this code, but is for Delphi:

 

procedure DoDropFiles(Wnd: HWND; Files: TStringList);

var
 Size: Cardinal;
 DropFiles: PDropFiles;
 Run: PChar;
 MemHandle: THandle;
 I: Integer;

begin
 // first determine size of string buffer we have to allocate
 Size := 0;
 for I := 0 to Files.Count - 1 do
 begin
   // number of characters per string (as ANSI) plus one #0 terminator
   Inc(Size, Length(Files[i]) + 1);
 end;
 if Size > 0 then
 begin
   // entire string list is terminated by another #0, add drop files structure size too
   Inc(Size, 1 + SizeOf(TDropFiles));
   // allocate globally accessible memory
   MemHandle := GlobalAlloc(GHND or GMEM_SHARE, Size);
   DropFiles := GlobalLock(MemHandle);
   // fill the header
   with DropFiles^ do
   begin
     pFiles := SizeOf(TDropFiles); // offset of file list, it follows immediately the structure
     pt := Point(0, 0);            // drop point (client coords), not important here
     fNC := False;                 // is it on NonClient area }, not important here
     fWide := False;               // WIDE character switch, we pass ANSI string in this routine
   end;
   // and finally the file names
   Run := Pointer(DropFiles);
   Inc(Run, SizeOf(TDropFiles));
   for I := 0 to Files.Count - 1 do
   begin
     StrPCopy(Run, Files[i]);
     Inc(Run, Length(Files[i]));
   end;
   // put a final #0 character at the end
   Run^ := #0;
   // release the lock we have to the memory,...
   GlobalUnlock(MemHandle);
   // ...do the message...
   SendMessage(Wnd, WM_DROPFILES, MemHandle, 0);
   // ... and finally release the memory
   GlobalFree(MemHandle);
 end;
end;

procedure TMainForm.Button1Click(Sender: TObject);

var
 List: TStringList;

begin
 List := TStringList.Create;
 try
   List.Add('C:\Data\Test.txt');
   DoDropFiles(Handle, List);
 finally
   List.Free;
 end;
end;

Edited November 12, 2010 by nimedon

[snarfblam]

No simulation necessary. DotNET comes with drag-drop support built in; no need for mucking around with messages.

 

The Control.DoDragDrop method initiates a drag-drop operation. You'll want to look at the documentation:

The allowedEffects parameter determines which drag operations can occur. If the drag operation needs to interoperate with applications in another process' date=' data should either be a base managed class (String, Bitmap, or Metafile), or an object that implements ISerializable or [b']IDataObject[/b].

 

If you want to drag files to another application, you can populate a DataObject with a file list, then specify that as the data when you call DoDragDrop, with the appropriate DragDropEffects (probably move or copy).

 

someDataObject.SetFileDropList(someFileList);
DoDragDrop(someDataObject, DragDropEffects.Move);

[nimedon]

thanks for your answer snarfblam, I want to do it in the background, I mean I don't want the user to need to do or see anything, do you have any idea of how can I do it? thanks again!

[snarfblam]

Sorry, completely missed that. I guess you can disregard my post. Off the top of my head I don't know any more about doing a file drop via messages than you do.