Artifact
39d931a0ffd51263c27c81cdf5e0bb02d35ec464:
/*
* IdleHandler.java --
*
* This class is used to create handlers for idle events.
*
* Copyright (c) 1998 by Sun Microsystems, Inc.
*
* See the file "license.terms" for information on usage and redistribution
* of this file, and for a DISCLAIMER OF ALL WARRANTIES.
*
* RCS: @(#) $Id: IdleHandler.java,v 1.2 2002/12/19 03:34:36 mdejong Exp $
*/
package tcl.lang;
abstract public class IdleHandler {
// True if the cancel() method has been called.
boolean isCancelled;
// Global ref passed to Tcl, read/written from C
long clientData;
/*
*----------------------------------------------------------------------
*
* IdleHandler --
*
* Create a idle handler to be fired when the notifier is idle.
*
* Results:
* None.
*
* Side effects:
* The idle is registered in the list of idle handlers in the
* given notifier. When the notifier is idle, the
* processIdleEvent() method will be invoked exactly once inside
* the primary thread of the notifier.
*
*----------------------------------------------------------------------
*/
public
IdleHandler(
Notifier n) // The notifier to fire the event.
{
isCancelled = false;
clientData = doWhenIdle();
}
/*
*----------------------------------------------------------------------
*
* cancel --
*
* Mark this idle handler as cancelled so that it won't be invoked.
*
* Results:
* None.
*
* Side effects:
* The idle handler is marked as cancelled so that its
* processIdleEvent() method will not be called. If the idle
* event has already fired, then nothing this call has no effect.
*
*----------------------------------------------------------------------
*/
public synchronized void
cancel()
{
if (isCancelled) {
return;
}
isCancelled = true;
cancelIdleCall(clientData);
clientData = 0;
}
/*
*----------------------------------------------------------------------
*
* invoke --
*
* Execute the idle handler. This method is called by the
* native method JavaIdleProc only.
*
* Because the idle handler may be being cancelled by another
* thread, both this method and cancel() must be synchronized to
* ensure correctness.
*
* Results:
* None.
*
* Side effects:
* The idle handler may have arbitrary side effects.
*
*----------------------------------------------------------------------
*/
synchronized final void
invoke()
{
if (isCancelled) {
throw new TclRuntimeError("IdleHandler.invoke(): event was cancelled");
}
processIdleEvent();
clientData = 0;
}
/*
*----------------------------------------------------------------------
*
* processIdleEvent --
*
* This method is called when the idle is expired. Override
* This method to implement your own idle handlers.
*
* Results:
* None.
*
* Side effects:
* It can do anything.
*
*----------------------------------------------------------------------
*/
abstract public void
processIdleEvent();
/*
*----------------------------------------------------------------------
*
* doWhenIdle --
*
* Create a C level idle handler for this object.
*
* Results:
* Returns a pointer to store in clientData.
*
* Side effects:
* None.
*
*----------------------------------------------------------------------
*/
private final native long
doWhenIdle();
/*
*----------------------------------------------------------------------
*
* cancelIdleCall --
*
* Delete a C level idle handler.
*
* Results:
* None.
*
* Side effects:
* None.
*
*----------------------------------------------------------------------
*/
private final native void
cancelIdleCall(long clientData);
} // end IdleHandler