Tk_RestrictEvents(3Tk)Tk_RestrictEvents(3Tk)NAMETk_RestrictEvents - filter and selectively delay X events
SYNOPSIS
#include <tk.h>
Tk_RestrictProc *
Tk_RestrictEvents(proc, arg, prevArgPtr)
ARGUMENTS
Tk_RestrictProc *proc (in) Predicate procedure to call to
filter incoming X events.
NULL means do not restrict
events at all.
char *arg (in) Arbitrary argument to pass to
proc.
char **prevArgPtr (in/out) Pointer to place to save
argument to previous restrict
procedure.
DESCRIPTION
This procedure is useful in certain situations where applications are
only prepared to receive certain X events. After Tk_RestrictEvents is
called, Tk_DoOneEvent (and hence Tk_MainLoop) will filter X input events
through proc. Proc indicates whether a given event is to be processed
immediately or deferred until some later time (e.g. when the event
restriction is lifted). Proc is a standard X predicate procedure, of the
sort passed to XCheckIfEvent. It must have arguments and result that
match the type Tk_RestrictProc:
typedef Bool Tk_RestrictProc(
Display *display,
XEvent *eventPtr,
char *arg);
The display argument to proc is the display from which eventPtr was
received, and eventPtr points to an event under consideration. The arg
argument is a copy of the arg passed to Tk_RestrictEvents; it may be
used to provide proc with information it needs to filter events. Proc
must return True or False. True means the event should be processed
immediately and False means the event should not be processed now, but
should be saved for some later time.
Tk_RestrictEvents uses its return value and prevArgPtr to return
information about the current event restriction procedure (a NULL return
value means there are currently no restrictions). These values may be
used to restore the previous restriction state when there is no longer
any need for the current restriction.
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Tk_RestrictEvents(3Tk)Tk_RestrictEvents(3Tk)
There are very few places where Tk_RestrictEvents is needed. Please use
it only where it is absolutely necessary. If only a local restriction is
needed, it can probably be achieved more cleanly by changing event-to-Tcl
bindings or by calling Tk_DeleteEventHandler.
KEYWORDS
delay, event, filter, restriction
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