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From: chuck@trantor.harris-atd.com (Chuck Musciano)
Newsgroups: comp.windows.open-look
Subject: Initiating drag and drop
Message-ID: <4861@trantor.harris-atd.com>
Date: 13 Nov 90 21:32:09 GMT
Sender: news@trantor.harris-atd.com
Reply-To: chuck@trantor.harris-atd.com (Chuck Musciano)
Organization: Advanced Technology Dept, Harris Corp, Melbourne, FL
Lines: 66


     I am trying to initiate a drag and drop operation from an XView tool.
I successfully create a cursor and get a fullscreen, and drag the cursor
to another window.  When I release the mouse button, my code sends a message
to the XV_POINTER_WINDOW under the mouse.

     Here's the problem.  If the receiver is filemgr, the message is received,
and the file is copied.  Any other tool, like textedit, ignores the message.
Even my tool, which can receive ACTION_DRAG_LOAD events, doesn't get the
message.  Why is it that messages from filemgr are received, but messages
from me are not?

     To further mystify matters, if I open a textedit window by double-clicking
a file in filemgr, and then drop something in that textedit window from my tool,
the message is received by filemgr!

     Could it be that receiving a DRAG event is an XView-level thing, while
sending a DRAG event is an X-level thing, and that tools need to be set to
receive both XView-level DRAG and X-level DRAG?  My tool receives XView-level
stuff as described in the XView Programmer's Guide.  How do I set it to
receive the equivalent X-level DRAG events?

     Here is my code, taken from a sample included with GUIDE.  Any
suggestions are appreciated.  Is this covered in any reference guide?
There is plenty on receiving a DRAG event, but nothing on starting one.

typedef	struct	{XID             xid;
		 int             x;
		 int             y;
		 Window          window;
		 Atom            property;
		} Drag_message;

Xv_window	dest_win;
Fullscreen	fullscreen;
int		xdrop, ydrop;
Window		source_xid, dest_xid;
Atom		drag_atom;
Drag_message	msg;

/* setting up fullscreen stuff removed for clarity */

source_xid = (Window) xv_get(source_window, XV_XID);
drag_atom = XInternAtom(display, "DRAG_DROP", FALSE);

XChangeProperty(display, source_xid, drag_atom, XA_STRING, 8,
		PropModeReplace, path, strlen(path) + 1);

msg.xid      = XV_POINTER_WINDOW;
msg.x        = xdrop;
msg.y        = ydrop;
msg.window   = source_xid;
msg.property = drag_atom;
 
xv_send_message(source_window, XV_POINTER_WINDOW, "XV_DO_DRAG_LOAD",
		32, &msg, sizeof(msg));

-- 

Chuck Musciano				ARPA  : chuck@trantor.harris-atd.com
Harris Corporation 			Usenet: ...!uunet!x102a!trantor!chuck
PO Box 37, MS 3A/1912			AT&T  : (407) 727-6131
Melbourne, FL 32902			FAX   : (407) 729-2537

A good newspaper is never good enough,
	but a lousy newspaper is a joy forever.		-- Garrison Keillor