Detect and Handle System Idling

KIdleTime is a helper framework to get reporting information on idle time of the system. It is useful not only for finding out about the current idle time of the system, but also for getting notified upon idle time events, such as custom timeouts or user activity. It features:

  • current idling time
  • timeout notifications, to be emitted if the system idled for a specified time
  • activity notifications, if the user resumes acting after an idling period

Using It

For understanding how to use KIdleTime, we create a small testing application, called KIdleTest. This application initially waits for the first user action and afterwards registers some timeout intervals, and acts whenever the system idles for such a time. The KIdleTime framework provides a singleton KIdleTime, which provides us with all necessary signals and information about the idling status of the system. For our example, we start with connecting to the signals for user resuming from idling and for reaching timeouts that we will set ourselves:

    // connect to idle events
    connect(KIdleTime::instance(), &KIdleTime::resumingFromIdle, this, &KIdleTest::resumeEvent);
    connect(KIdleTime::instance(), qOverload<int, int>(&KIdleTime::timeoutReached), this, &KIdleTest::timeoutReached);

    // register to get informed for the very next user event

    printf("Your idle time is %d\n", KIdleTime::instance()->idleTime());
    printf("Welcome!! Move your mouse or do something to start...\n");

We also tell KIdleTime to notify us the very next time when the user acts. Note that this is actually only for the next time. If we were interested in further events, we had to invoke catchNextResumeEvent() again. Next, in our event listener for the user resume event, we add register a couple of idle intervals:

void KIdleTest::resumeEvent()

    printf("Great! Now stay idle for 5 seconds to get a nice message. From 10 seconds on, you can move your mouse to get back here.\n");
    printf("If you will stay idle for too long, I will simulate your activity after 25 seconds, and make everything start back\n");


If any of these idle intervals is reached, our initially registered timeoutReached(...) slot is invoked and we print out an appropriate message.

void KIdleTest::timeoutReached(int id, int timeout)

    if (timeout == 5000) {
        printf("5 seconds passed, stay still some more...\n");
    } else if (timeout == 10000) {
        printf("Cool. You can move your mouse to start over\n");
    } else if (timeout == 25000) {
        printf("Uff, you're annoying me. Let's start again. I'm simulating your activity now\n");
    } else {
        qDebug() << "OUCH";

From there on, depending on the reached idle interval, we go back to one of the former steps.