🚀 go-pugleaf

In article <1992Aug17.104453.11070@monu6.cc.monash.edu.au>, ede978e@monu6.cc.monash.edu.au (Robert D. Nicholson) writes...
>I have to implement Drag and Drop behaviour in NS2.1, but I would also like
>to know wether NS3.0 can do it properly. (Look forward to reading the
>article on it simson)
> 
>OK, I would like to know wether drag and drop can be implemented such that
>the application can determine specifically which window is under the cursor.
> 
>ie. if there are overlapping windows, I must be able to tell which is at the
>top. ie. above all the rest
> 
>Anybody done this?

Yes! (Finally.)
The key is the little-known postscript operator "findwindow."

	<x> <y> <place> <otherwindow> findwindow <x'> <y'> <window> <bool>

(If you're planning on writing your own routine, note that <otherwindow>
 is a local window, while <window> is a global window! If it seems inconsistant
 to you, you are not alone!)

Here's how I implemented it.  "currentPoint" is in screen coords.  "dragWindow"
is the id of the window holding the image being dragged. (I want a window UNDER
what is being dragged.)  "acceptViewList" is a list of accepting views.
The id of the first accepting view under the point is returned.  If no
accepting view is found, nil is returned.

Many thanks to John Immordino at NeXTedge Developer Support who pointed out
findwindow to me when I really needed it!

26-line routine follows. 
=============================================================================
-Mike Kienenberger                       SXMLK@ALASKA           (BITNet)
 University of Alaska Computer Network   SXMLK@acad3.alaska.edu (Internet)
 University of Alaska-Fairbanks
=============================================================================

- checkForAcceptView:(NXPoint *)currentPoint under:dragWindow
{
    int count = 0;
    id currentView;
    unsigned int localWindowNumber;
    float dummy;
    int pwinFound;
    int pdidFind;

    PSfindwindow(currentPoint->x, currentPoint->y,
		 NX_BELOW, [dragWindow windowNum],
		 &dummy, &dummy, &pwinFound, &pdidFind);
    if (0 == pdidFind)  return nil;

    NXConvertGlobalToWinNum(pwinFound, &localWindowNumber);

    while (count < [acceptViewList count])
    {
        currentView = [acceptViewList objectAt:count];
        if ([[currentView window] windowNum] == localWindowNumber)
	    return currentView;
	++count;
    }
    return nil;
}