/**
* Until {@link #condition()} becomes <code>true</code> or the timeout elapses, call {@link
* Display#sleep()} and run the event loop.
*
* <p>If <code>timeout < 0</code>, the event loop is never driven and only the condition is
* checked. If <code>timeout == 0</code>, the event loop is driven at most once, but <code>
* Display.sleep()</code> is never invoked.
*
* @param display the display to run the event loop of
* @param timeout the timeout in milliseconds
* @return <code>true</code> if the condition became <code>true</code>, <code>false</code> if the
* timeout elapsed
*/
public final boolean waitForCondition(Display display, long timeout) {
// if the condition already holds, succeed
if (condition()) return true;
if (timeout < 0) return false;
// if driving the event loop once makes the condition hold, succeed
// without spawning a thread.
driveEventQueue(display);
if (condition()) return true;
// if the timeout is negative or zero, fail
if (timeout == 0) return false;
// repeatedly sleep until condition becomes true or timeout elapses
DisplayWaiter waiter = new DisplayWaiter(display);
DisplayWaiter.Timeout timeoutState = waiter.start(timeout);
boolean condition;
try {
do {
if (display.sleep()) driveEventQueue(display);
condition = condition();
} while (!condition && !timeoutState.hasTimedOut());
} finally {
waiter.stop();
}
return condition;
}
/**
* Call {@link Display#sleep()} and run the event loop once if <code>sleep</code> returns before
* the timeout elapses. Returns <code>true</code> if any events were processed, <code>false</code>
* if not.
*
* <p>If <code>timeout < 0</code>, nothing happens and false is returned. If <code>timeout == 0
* </code>, the event loop is driven exactly once, but <code>Display.sleep()</code> is never
* invoked.
*
* @param display the display to run the event loop of
* @param timeout the timeout in milliseconds
* @return <code>true</code> if any event was taken off the event queue, <code>false</code> if not
*/
public static boolean runEventLoop(Display display, long timeout) {
if (timeout < 0) return false;
if (timeout == 0) return driveEventQueue(display);
// repeatedly sleep until condition becomes true or timeout elapses
DisplayWaiter waiter = new DisplayWaiter(display);
DisplayWaiter.Timeout timeoutState = waiter.start(timeout);
boolean events = false;
if (display.sleep() && !timeoutState.hasTimedOut()) {
driveEventQueue(display);
events = true;
}
waiter.stop();
return events;
}
