Conference bulova::decw_jan-89_to_nov-90

  Ok...First, I don't recall there being a problem with this call but the fact
that it returns NULL might indicate that there is a problem.

  You could try importing the C routine and try it out.

  BTW, what exactly are you trying to do?  Here is my guess; XtWindowToWidget
takes a window ID and a display structure and CREATES a widget instance.  If
you are expecting this call to return the widget ID that is ASSOCIATED with
the window ID then this won't work.  I've seen people try this... :^)

  I don't have any doc handy to check out the C routine.  It could be as
simple as an error in the passing mechanism...or just plain broke.  If you
import the C routine and it works as you expect then QAR the VAX binding call.

					-=> Jim <=-

  An observation ...

  Your imported procedure for XtAppCreateShell won't work.  If you are trying
to import the C routine it should look like :

  procedure xtappcreateshell (
    widget	    : out dwt.widget_type;
    name	    : in  string;
    class	    : in  string;
    widget_class    : in  dwt.widget_cls_type;
    display	    : in  dwt.display_type;
    arglist	    : in  dwt.arg_array_type;
    argcount	    : in  dwt.cardinal_type);

  pragma interface (external, xtappcreateshell);

  pragma import_valued_procedure (
    xtappcreateshell, "XtAppCreateShell",
    (dwt.widget_type, string, string, dwt.widget_cls_type,
     dwt.display_type, dwt.arg_array_type, dwt.cardinal_type),
    (value, reference, reference, value, value, reference, value));

  I'm at home...not on a workstation.  I made the above modification to your
program and did get NULL for the created widget.  As I stated in .-1 I don't
have any doc here so I can't try importing the C routine for XtWindowToWidget,
maybe someone else can.

					-=> Jim <=-

>  Your imported procedure for XtAppCreateShell won't work.

Hi Jim,

Sorry, you're right, but I forgot to include this important bit of 'C' code.


#include <decw$include/decwdwtapplprog.h>

Widget kjm_app_create_shell (display, arg_list, arg_count)
Display *display;
ArgList arg_list;
Cardinal arg_count;
{
return (XtAppCreateShell ( "shell",
                                "Shell",
                                applicationShellWidgetClass,
                                display,
                                arg_list,
                                arg_count));
}

I think I'll suggest to the customer to import the C routine, as you can
see from the above, he's done it before. I just wonder how many other
routines outside of the MIT C binding have this problem ?

Thanks for your efforts

Richard

RE .1:

>Here is my guess; XtWindowToWidget takes a window ID and a display
>structure and CREATES a widget instance.  If you are expecting this
>call to return the widget ID that is ASSOCIATED with the window ID
>then this won't work.

My doc says that it does just return the existing widget id that is 
the owner of the window.  Besides, I don't think it would make much 
sense to create a widget from a window -- no parent, arglist, etc.

RE probelm:

Perhaps your widget hasn't realized yet and therefore the window 
doesn't yet exist.  Try to get it from a callback after everything is 
visible.

    I don't know ADA, but someone who does should check that the
    parameter passing mechanism is correct.  Here is the code from .0:
    
                xt_window_to_widget (w_wid,
                                        x_evt.exev_display,
                                        x_evt.exev_window);
    
    Here is the implemenation of XT$WINDOW_TO_WIDGET:
    
Widget XT$WINDOW_TO_WIDGET(display, Pwindow)
    Display *display;
    Window *Pwindow;
{
   return( XtWindowToWidget(display, *Pwindow));
}

Leo
    

  Well first let me say that I was wrong in my first reply.  XtWindowToWidget
does return a widget ID that is associated with a window.  I have old doc and
there is just one sentence for the description and I read it wrong.  Bruce (.4)
pointed this out to me when I talked with him.

  Now for the second.  I'm still coming up to speed on C and based on what Leo
posted we need to look at the passing mechanisms in the Ada file.  I believe
that Steve Lionel could definitly be the one to help here.

  After looking at the Ada spec it has the mechanisms of WIDGET value,
DISPLAY reference, and WINDOW reference.  These seem ok...Steve, any suggestion?

					-=> Jim <=-

Importing the 'C' routine works, so I suspect that the ADA binding is
causing a problem, although I haven't tried this on VMS v5.3. Can anybody
confirm that it is still a problem under 5.3.

Richard

I no longer have the V5.1 Ada bindings, but looking at the V5.3 bindings
show that they SEEM to be correct.  The Display argument is a longword 
display ID by reference, the Window argument is a longword window ID
by reference.  I'm a bit baffled by the "Pwindow" type given by Leo - is
this something different than a window ID?

			Steve

> I'm a bit baffled by the "Pwindow" type given by Leo - is
> this something different than a window ID?

Pwindow is just the name given to the window ID parameter by the code.

Leo

    I've now logged an SPR on behalf of the customer, I've tried the
    same code out on V5.3 with the same result. I know a little bit
    of ADA but I'm not too hot on calling external functions.
    
    Richard