NAME

       XPAConvert - Converting the XPA API to 2.0

SYNOPSIS

       This document describes tips for converting from xpa 1.0 (Xt-based xpa) to xpa 2.0 (socket-based xpa).

DESCRIPTION

       The following are tips for converting from xpa 1.0 (Xt-based xpa) to xpa 2.0 (socket-based xpa). The
       changes are straight-forward and almost can be done automatically (we used editor macros for most of the
       conversion).

       •   The  existence  of the cpp XPA_VERSION directive to distinguish between 1.0 (where it is not defined)
           and 2.0 (where it is defined).

       •   Remove the first widget argument from all send and receive server callbacks.   Also  change  first  2
           arguments from XtPointer to void *. For example:

           #ifdef XPA_VERSION static void XPAReceiveFile(client_data, call_data, paramlist, buf, len)
                void *client_data;
                void *call_data;
                char *paramlist;
                char *buf;
                int len; #else static void XPAReceiveFile(w, client_data, call_data, paramlist, buf, len)
                Widget w;
                XtPointer client_data;
                XtPointer call_data;
                char *paramlist;
                char *buf;
                int len; #endif

       •   Server callbacks should be declared as returning int instead of void. They now should return 0 for no
           errors, -1 for error.

       •   The  mode  flags  have  changed  when defining XPA server callbacks.  The old S flag (save buffer) is
           replaced by freebuf=false.  The old E flag (empty buffer is OK) is no longer used (it was an artifact
           of the X implementation).

       •   Change NewXPACommand() to XPAcmdNew(), with the new calling sequence:

             xpa = NewXPACommand(toplevel, NULL, prefix, NULL);

           is changed to:

             xpa = XPACmdNew(xclass, name);

       •   Change the AddXPACommand() subroutine name to XPACmdAdd (with the same calling sequence):

             AddXPACommand(xpa, "file",
               "\tdisplay a new file\n\t\t  requires: filename",
               NULL, NULL, NULL, XPAReceiveFile, text, NULL);

           is changed to:

             XPACmdAdd(xpa, "file",
               "\tdisplay a new file\n\t\t  requires: filename",
               NULL, NULL, NULL, XPAReceiveFile, text, NULL);

       •   The XPAXtAppInput() routine should be called just before XtAppMainLoop() to add xpa  fds  to  the  Xt
           event loop:

             /* add the xpas to the Xt loop */
             XPAXtAddInput(app, NULL);

             /* process events */
             XtAppMainLoop(app);

       •   Change  NewXPA()  to  XPANew() and call XPAXtAddInput() if the XtAppMainLoop routine already has been
           entered:

             xpa = NewXPA(saotng->xim->toplevel, prefix, xparoot,
                          "FITS data or image filename\n\t\t  options: file type",
                          XPASendData, new, NULL,
                          XPAReceiveData, new, "SE");

           is changed to:

             sprintf(tbuf, "%s.%s", prefix, xparoot);
             xpa = XPANew("SAOTNG", tbuf,
                          "FITS data or image filename\n\t\t  options: file type",
                          XPASendData, new, NULL,
                          XPAReceiveData, new, "SE");
             XPAXtAddInput(XtWidgetToApplicationContext(saotng->xim->toplevel), xpa);

       •   Change XPAInternalReceiveCommand() to XPACmdInternalReceive() remove first argument  in  the  calling
           sequence):

             XPAInternalReceiveCommand(im->saotng->xim->toplevel,
                                       im->saotng, im->saotng->commands,
                                       "zoom reset", NULL, 0);

           is changed to:

             XPACmdInternalReceive(im->saotng, im->saotng->commands,
                                   "zoom reset", NULL, 0);

       •   Change DestroyXPA to XPAFree:

             DestroyXPA(im->dataxpa);

           is changed to:

             XPAFree(im->dataxpa);

SEE ALSO

       See xpa(n) for a list of XPA help pages

version 2.1.15                                    July 23, 2013                                    xpaconvert(7)