CHAPTER 4 - REPAINT, EVENT-HANDLING, ON-OFF & TIDY-UP ROUTINE CALLS

4.1 INTRODUCTION

1. Event Handling Routines

   These are called by the xdl_get_events routine when an event from a view-object window is processed. The events are considered in two classes with Expose and Configure Notify events causing the window's repaint routine to be called and with other events causing the window's general event handling routine to be called.

2. On-off Routine

   The on-off routine for a view-object is called by the xdl_get_events routine when the view-object is one of those in the list of view-objects from which the application is prepared to receive input. It is called once with the 'on' option at the start of the xdl_get_events routine and a second time with the 'off' option set just before the routine xdl_get_events makes a return to the calling program.

3. Tidy-up Routine

   This routine is called by the xdl_delete_view_object routine when a view-object is deleted. It enables the user to free any workspace or other resources allocated to the view-object just prior to its removal. Tidy-up routines will also be called for any library routines associated with the view-object.

List of sections:

Repaint/Event-Handling Routine Calls
On-Off Routine Calls
Tidy-Up Routine Calls

4.2 REPAINT/EVENT-HANDLING ROUTINE CALLS

The repaint and general event handling routines are called as follows:

   (*repaint/ehp) (wid, event, iv, global, callback)

   Window wid;          The (X) window id of the window in generating the
                        event.

   XEvent *event;       A pointer to the XEvent structure for the X
                        event.

   int iv;              The offset in the XDL_view_objects array for the
                        view-object to which the window belongs.

   char *global;        A pointer to the global data area associated
                        with the window. This will normally be the
                        global data area associated with the view-object
                        to which the window belongs except in the case
                        of a library routine window in which case it will
                        be a private data area for the routine.

   void (*callback)()   This will normally be a NULL except for events
                        associated with windows created by library
                        routines such as the panel item routines.

4.3 ON-OFF ROUTINE CALLS

The on-off routine is called as follows:

   (*on_off) (iv, iflag)

   int iv;        The offset in the XDL_view_objects array for the
                  view-object to which the window belongs.

   int iflag;     Flag = 1, set view-object to program input 'on' mode.
                       = 0, set view-object to program input 'off' mode.

4.4 TIDY-UP ROUTINE CALLS

The tidy-up routine is called as follows:

   (*tidy_up) (global)

   char *global;        A pointer to the global data area associated
                        with the window. This will normally be the
                        global data area associated with the view-object
                        to which the window belongs except in the case
                        of a library routine window in which case it will
                        be a private data area for the routine.