- Tcl_IdleProc *proc (in)
Procedure to invoke.
- ClientData clientData (in)
Arbitrary one-word value to pass to proc.
Tcl_DoWhenIdle() arranges for proc to be
when the application becomes idle. The application is
considered to be idle when Tcl_DoOneEvent() has been
called, couldn't find any events to handle, and is about
to go to sleep waiting for an event to occur. At this
point all pending Tcl_DoWhenIdle() handlers are
invoked. For each call to Tcl_DoWhenIdle() there will
be a single call to proc; after proc is
invoked the handler is automatically removed.
Tcl_DoWhenIdle() is only usable in programs that
use Tcl_DoOneEvent() to dispatch events.
Proc should have arguments and result that match the
typedef void Tcl_IdleProc(ClientData clientData);
The clientData parameter to proc is a copy of
argument given to Tcl_DoWhenIdle(). Typically,
points to a data structure containing application-specific information about
what proc should do.
may be used to cancel one or more previous
calls to Tcl_DoWhenIdle(): if there is a
handler registered for proc and clientData, then
is removed without invoking it. If there is more than one
handler on the idle list that refers to proc and
all of the handlers are removed. If no existing handlers match
proc and clientData then nothing happens.
Tcl_DoWhenIdle() is most useful in situations where
(a) a piece of work will have to be done but (b) it's
possible that something will happen in the near future
that will change what has to be done or require something
different to be done. Tcl_DoWhenIdle() allows the
actual work to be deferred until all pending events have
been processed. At this point the exact work to be done
will presumably be known and it can be done exactly once.
For example, Tcl_DoWhenIdle() might be used by an editor
to defer display updates until all pending commands have
been processed. Without this feature, redundant redisplays
might occur in some situations, such as the processing of
a command file.
At present it is not safe for an idle callback to reschedule itself
continuously. This will interact badly with certain features of Tk
that attempt to wait for all idle callbacks to complete. If you would
like for an idle callback to reschedule itself continuously, it is
better to use a timer handler with a zero timeout period.
Windows 8.1. Windows Server 2012 R2. Windows 10. Windows Server 2016. Windows Server 2019. Windows 11. Windows Server 2022.
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