Re: Problem with drag&drop into a control

From:
"David Ching" <dc@remove-this.dcsoft.com>
Newsgroups:
microsoft.public.vc.mfc
Date:
Fri, 28 Nov 2008 16:27:53 -0800
Message-ID:
<DB990FAB-E73D-4CA2-8DCF-57546B05EBB9@microsoft.com>
"James Duy Trinh (VietDoor)" <vietdoor@gmail.com> wrote in message
news:%23UxXYzQUJHA.1172@TK2MSFTNGP03.phx.gbl...

i use an Old inherit from COleDataSource, and register format
UINT g_uCustomClipbrdFormat = RegisterClipboardFormat(CFSTR_FILECONTENTS);

// --------------------------------------------------
// my code starts here
//COleDataSource datasrc;
//for dragging image
COleDataSourceEx datasrc;

HGLOBAL hgDrop;
DROPFILES* pDrop;
CStringList lsDraggedFiles;
POSITION pos;
int nSelItem;
CString sFile;
UINT uBuffSize = 0;
TCHAR* pszBuff;
FORMATETC etc = { CF_HDROP, NULL, DVASPECT_CONTENT, -1, TYMED_HGLOBAL };
//FORMATETC etc = { g_uCustomClipbrdFormat, NULL, DVASPECT_CONTENT, -1,
TYMED_HGLOBAL };

*pResult = 0; // return value ignored

// For every selected item in the list, put the filename into
lsDraggedFiles.
pos = this->GetFirstSelectedItemPosition();

...


What function was this in?

My point is you should set breakpoints in all the methods that Windows would
call during the Drag and Drop and make sure you are performing correct
actions and returning appropriate values. IOW, assume it's all broken and
simplify all the code to do the bare bones (like supply a string "Hello
World") and see if that works. Then re-add all of this code until it
breaks, and you can see what the problem is. Since your code works when
dropping onto some targets but not others, it's something subtle.

-- David

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