#include <QtWidgets>

#include <windows.h>

#define NUM_THREADS 1 
#define NUM_TIMERS  5 

class ThreadTest;

class MyThread : public QThread {
    Q_OBJECT
public:
    MyThread(ThreadTest* parent = 0);
    void run();

    ThreadTest* main;

signals:
    void myupdate();
};


class ThreadTest : public QWidget {
    Q_OBJECT
public:
    ThreadTest(QWidget* parent = 0);
    void paintEvent(QPaintEvent* event);

    int msgCnt;
    QTimer myTimer;
    MyThread* myThreads[NUM_THREADS];

    QTimer* moreTimers[NUM_TIMERS];

private slots:
    void myupdateSlot();
    void timeoutSlot();
    void moreTimersSlot();
};


MyThread::MyThread(ThreadTest* parent) : QThread(parent) {
    main = parent;
}

void MyThread::run() {
    QRandomGenerator64 gen;
    forever{
       quint64 r = gen.generate64();
       msleep(r % 1000);
       emit myupdate();  // Simulate message arriving from network 
    }
}



///////////////////////////////////////////////////////////////////////////////

ThreadTest::ThreadTest(QWidget* parent) : QWidget(parent) {
    msgCnt = 0;
    setWindowTitle(tr("ThreadTest"));
    resize(550, 400);

    qint32 x;
    for (x = 0; x < NUM_THREADS; x++) {
        myThreads[x] = new MyThread(this);
        connect(myThreads[x], SIGNAL(myupdate()), this, SLOT(myupdateSlot()));
        myThreads[x]->start();
    }
    for (x = 0; x < NUM_TIMERS; x++) {
        moreTimers[x] = new QTimer;
        connect(moreTimers[x], SIGNAL(timeout()), this, SLOT(moreTimersSlot()));
        moreTimers[x]->start(10);
    }

    connect(&myTimer, SIGNAL(timeout()), this, SLOT(timeoutSlot()));
    myTimer.setSingleShot(true);
    myTimer.start(100);
}


void ThreadTest::paintEvent(QPaintEvent*) {
    QPainter painter(this);
    painter.fillRect(rect(), Qt::black);
    QFont myfont = QFont("Verdana", 20);
    painter.setFont(myfont);
    painter.setPen(Qt::white);
    painter.drawText(rect(), Qt::AlignCenter, QString("Cnt=%1").arg(msgCnt));
    Sleep(30); // This version hangs the entire application
}


void ThreadTest::myupdateSlot() {
    msgCnt++;

    Sleep(30); // This version hangs the entire application

    myTimer.stop();
    myTimer.start(0);
}


void ThreadTest::timeoutSlot() {
    QRandomGenerator64 gen;
    quint64 r = gen.generate64();
    myTimer.start(r % 1000);
    update();
}


void ThreadTest::moreTimersSlot() { }


///////////////////////////////////////////////////////////////////////////////////////

int main(int argc, char* argv[])
{
    QApplication app(argc, argv);
    ThreadTest widget;
    widget.show();
    return app.exec();
}

#include <main.moc>