TkCreateGenericHandler(3) Tk Library Procedures TkCreateGenericHandler(3)

NAME
       TkCreateGenericHandler,  TkDeleteGenericHandler - associate procedure
       callback with all X events

SYNOPSIS
       ##iinncclluuddee <>

       TTkkCCrreeaatteeGGeenneerriiccHHaannddlleerr(proc, clientData)

       TTkkDDeelleetteeGGeenneerriiccHHaannddlleerr(proc, clientData)

AARRGGUUMMEENNTTSS
       TkGenericProc   *proc        (in)      Procedure  to  invoke  whenever
                                               any  X event occurs on any dis-
                                               play.

       ClientData       clientData   (in)      Arbitrary  one-word  value   to
                                               pass to proc.



DESCRIPTION
       TTkkCCrreeaatteeGGeenneerriiccHHaannddlleerr  arranges  for proc to be invoked in the future
       whenever any X event occurs.  This mechanism is not intended  for  dis-
       patching  X  events  on  windows  managed by Tk (you should use TTkkCCrree-
       aatteeEEvveennttHHaannddlleerr for this purpose).  TTkkCCrreeaatteeGGeenneerriiccHHaannddlleerr is intended
       for other purposes, such as tracing X events, monitoring events on win-
       dows not owned by Tk, accessing X-related libraries that were not orig-
       inally designed for use with Tk, and so on.

       The  callback  to  proc  will be made by TTkkHHaannddlleeEEvveenntt; this mechanism
       only works in programs that dispatch events through TTkkHHaannddlleeEEvveenntt  (or
       through   other   Tk  procedures  that  call  TTkkHHaannddlleeEEvveenntt,  such  as
       TTkkDDooOOnneeEEvveenntt or TTkkMMaaiinnLLoooopp).

       Proc should have arguments and result that  match  the  type  TTkkGGeenneerr-
       iiccPPrroocc:
              typedef int TkGenericProc(
                ClientData clientData,
                XEvent *eventPtr);
       The  clientData  parameter to proc is a copy of the clientData argument
       given to TTkkCCrreeaatteeGGeenneerriiccHHaannddlleerr when the callback was created.   Typi-
       cally,  clientData  points  to a data structure containing application-
       specific information about how to handle events.  EventPtr is a pointer
       to the X event.

       Whenever  an  X  event  is processed by TTkkHHaannddlleeEEvveenntt, proc is called.
       The return value from proc is normally  0.   A  non-zero  return  value
       indicates  that  the  event is not to be handled further; that is, proc
       has done all processing that is to be allowed for the event.

       If there are multiple generic event handlers, each one  is  called  for
       each event, in the order in which they were established.

       TTkkDDeelleetteeGGeenneerriiccHHaannddlleerr  may  be  called to delete a previously-created
       generic event handler:  it deletes each handler it finds  that  matches
       the  proc  and  clientData  arguments.  If no such handler exists, then
       TTkkDDeelleetteeGGeenneerriiccHHaannddlleerr returns without doing  anything.   Although  Tk
       supports  it,  it's  probably a bad idea to have more than one callback
       with the same proc and clientData arguments.

       Establishing a generic event handler does nothing to  ensure  that  the
       process  will  actually  receive the X events that the handler wants to
       process.  For example, it is the caller's responsibility to invoke XXSSee-
       lleeccttIInnppuutt to select the desired events, if that is necessary.

KKEEYYWWOORRDDSS
       bind, callback, event, handler



Tk                                                  TkCreateGenericHandler(3)