...how will I know...?

[Sebastiani]

I need to recieve data dragged from another application into my program in the form of Clipboard data. Question: how will I know when the user has dropped the data "in" (my app will already be running)? I will use a thread, presumably, but I just don't know when to initiate the transfer. I thougt maybe windows sends my app a message, but of the possible ones, none seemed conspicuous. Nonetheless, I'll try those first, but if anyone here knows, I'd appreciate the tip!

[Sebastiani]

Aargh! One more thing. Windows won't let me drag anything onto my app anyway! How do I tell it to do so?

[Sebastiani]

Ok, here's a little class that will take care of the implementation.
Just be sure to place the Allow() function under your WM_DROPFILES handler, and pass it your WPARAM.
Enjoy.

class DragDrop {
 public:

 int file_count;
 String * files;

 void Allow(HWND hwnd) {
   DragAcceptFiles(hwnd, TRUE);
  }

 bool Accept(WPARAM wp) {
   if( files ){
    delete [] files;
   }
   iter = 0;
   data = (HDROP)wp;
   file_count =  DragQueryFile(data, 0xFFFFFFFF, NULL, 0);
   files = new String[ file_count ];
     if( files == NULL ){
      return false;
      }
   while(iter < file_count) {
    DragQueryFile(data, iter, buffer, 256);
    files[iter++] = buffer;
   }
  DragFinish(data);
  return true;
 }

 DragDrop()
 :files(NULL) {
  /* */
 }

 ~DragDrop() {
   if( files ){
    delete [] files;
   }
 }
 private:

  HDROP data;
  int iter;
  char buffer[256];

};

[-KEN-]

I've had this in my favorites for a while, I hope it's of use to you: http://cprogramming.com/cboard/showt...&threadid=7829

[Ken Fitlike]

...or can register your wnd as a drop target by giving it the WS_EX_ACCEPTFILES extended style. Presumably that's what DragAcceptFiles does: calls SetWindowLong with the GWL_EXSTYLE flag to set the extended style bit.