Re: WM_DROPFILES

From:

"David Webber" <dave@musical-dot-demon-dot-co.uk>

Newsgroups:

microsoft.public.vc.mfc

Date:

Sat, 17 Nov 2007 18:45:52 -0000

Message-ID:

<uJ56goUKIHA.5360@TK2MSFTNGP03.phx.gbl>

"Tom Serface" <tom.nospam@camaswood.com> wrote in message
news:1447A1A1-DFD3-4B4D-BE31-021D07F4CEB5@microsoft.com...

Hello Tom, it's very god ogf you to go into this detail!

Hmmm. That is curious. D&D works for me for both release and debug
builds. I wonder if we're just doing it different ways. I drag and drop
into a dialog. I have a handler for the message:

ON_WM_DROPFILES()

and I've called:

DragAcceptFiles();

In OnInitDialog()

My handler looks like this:

void CMyDialog::OnDropFiles(HDROP hDropInfo)
{
    CDialog::OnDropFiles(hDropInfo);

    // Find how many files we are working with
    UINT nFiles = ::DragQueryFile(hDropInfo, (UINT) -1, NULL, 0);
    for(UINT nThisFile = 0; nThisFile < nFiles; ++nThisFile) {
         TCHAR szFile[_MAX_PATH];
         ::DragQueryFile(hDropInfo, nThisFile, szFile, _countof(szFile));
           // Do something with file
   }
   ::DragFinish(hDropInfo);
}

Are you doing it the same way?

Yes very like that with one or two minor differences - don't they all say
that :-)

First it is not in a dialogue, but in a class derived from CListBox and
another one derived from CListCtrl. In each case the derived control class
has an "initialise" member, called from OnInitDialog which previously filled
the list, and now also calls DragAcceptFiles(TRUE);

[This looks ok as the mouse cursor changes appropriately when I'm dragging
and it goes over the list.]

Then in the message map of the control class (not the dialogue) I have
ON_WM_DROPFILES() and the derived dialogue class has a function which looks
very like yours. My call to the base class
CListBox::OnDropFiles(hDropInfo); was at the end, but I have put it at the
start and it makes no difference - I suspect it does nothing anyway. [It
actually appears to be CWnd::OnDropFiles() in fact.]

When I launch explorer with "run as administrator, I have to confirm I want
to do it of course, but thereafter, as I drill down to the folder I'm
looking for, I see no hint that it is any different from a normal instance.
Should I?

Anyway it is ok running with normal privileges, but I had hoped to find an
easy way of debugging drag and drop, and am puzzled why this isn't working
for me.

[BTW also adding WM_ON_DROPFILES() and a handler to the CDialog- derived
class, means that it too gets called, but after the Control's version. I
found that out when I was experimenting with the app running with normal
privileges.]

Dave
--
David Webber
Author of 'Mozart the Music Processor'
http://www.mozart.co.uk
For discussion/support see
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