/****************************************************************************** $Id: qt/main.cpp   3.3.4   edited May 27 2003 $**** Copyright (C) 1992-2000 Trolltech AS.  All rights reserved.**** This file is part of an example program for Qt.  This example** program may be used, distributed and modified without limitation.*******************************************************************************/#include <qapplication.h>#include <qwidget.h>#include <qpushbutton.h>#include <qmultilineedit.h>#include <qthread.h>#include <qsemaphore.h>#include <qmutex.h>#include <qlayout.h>#include <qmessagebox.h>#include <qlabel.h>#if defined(QT_NO_THREAD)#  error Thread support not enabled.#endif// Use pointers to create semaphores after QApplication object!QSemaphore* yellowSem, *greenSem;class YellowThread : public QThread{public:    YellowThread(QWidget *o)	: receiver(o), stopped(FALSE)    { ; }    void run();    void stop();private:    QWidget *receiver;    QMutex mutex;    bool stopped;};void YellowThread::run(){    for (int i = 0; i < 20; i++) {	(*yellowSem)++;	QCustomEvent *event = new QCustomEvent(12345);     	event->setData(new QString("Yellow!"));	QApplication::postEvent(receiver, event);	msleep(200);	(*greenSem)--;	mutex.lock();	if (stopped) {	    stopped = FALSE;	    mutex.unlock();	    break;	}	mutex.unlock();    }    (*yellowSem)++;    QCustomEvent *event = new QCustomEvent(12346);    event->setData(new QString("Yellow!"));    QApplication::postEvent(receiver, event);    (*greenSem)--;}void YellowThread::stop(){    mutex.lock();    stopped = TRUE;    mutex.unlock();}class GreenThread: public QThread{public:   GreenThread(QWidget *o)	: receiver(o), stopped( FALSE )    { ; }    void run();    void stop();private:    QWidget *receiver;    QMutex mutex;    bool stopped;};void GreenThread::run(){    for (int i = 0; i < 20; i++) {	(*greenSem)++;	QCustomEvent *event = new QCustomEvent(12345);     	event->setData(new QString("Green!"));	QApplication::postEvent(receiver, event);	msleep(200);	(*yellowSem)--;	mutex.lock();	if (stopped) {	    stopped = FALSE;	    mutex.unlock();	    break;	}	mutex.unlock();    }    (*greenSem)++;    QCustomEvent *event = new QCustomEvent(12346);    event->setData(new QString("Green!"));    QApplication::postEvent(receiver, event);    msleep(10);    (*yellowSem)--;}void GreenThread::stop(){    mutex.lock();    stopped = TRUE;    mutex.unlock();}class SemaphoreExample : public QWidget{    Q_OBJECTpublic:    SemaphoreExample();    ~SemaphoreExample();    void customEvent(QCustomEvent *);public slots:    void startExample();protected:private:    QMultiLineEdit *mlineedit;    QPushButton *button;    QLabel *label;    YellowThread yellowThread;    GreenThread greenThread;};SemaphoreExample::SemaphoreExample()    : QWidget(), yellowThread(this), greenThread(this){    yellowSem = new QSemaphore(1);    greenSem = new QSemaphore(1);    button = new QPushButton("&Ignition!", this);    connect(button, SIGNAL(clicked()), SLOT(startExample()));    mlineedit = new QMultiLineEdit(this);    label = new QLabel(this);    QVBoxLayout *vbox = new QVBoxLayout(this, 5);    vbox->addWidget(button);    vbox->addWidget(mlineedit);    vbox->addWidget(label);}SemaphoreExample::~SemaphoreExample(){    bool stopYellow = yellowThread.running(),	  stopGreen = greenThread.running();    if (stopYellow)	yellowThread.stop();    if (greenThread.running())	greenThread.stop();    if (stopYellow)	yellowThread.wait();    if (stopGreen)	greenThread.wait();    delete yellowSem;    delete greenSem;}void SemaphoreExample::startExample(){    if (yellowThread.running() || greenThread.running()) {	QMessageBox::information(this, "Sorry",				 "The threads have not completed yet, and must finish before "				 "they can be started again.");	return;    }    mlineedit->clear();    while (yellowSem->available() < yellowSem->total()) (*yellowSem)--;    (*yellowSem)++;    yellowThread.start();    greenThread.start();}void SemaphoreExample::customEvent(QCustomEvent *event) {    switch (event->type()) {    case 12345:	{	    QString *s = (QString *) event->data();	    mlineedit->append(*s);	    if (*s == "Green!")		label->setBackgroundColor(green);	    else		label->setBackgroundColor(yellow);	    label->setText(*s);	    delete s;	    break;	}    case 12346:	{	    QString *s = (QString *) event->data();	    QMessageBox::information(this, (*s) + " - Finished",				     "The thread creating the \"" + *s +				     "\" events has finished.");	    delete s;	    break;	}    default:	{	    qWarning("Unknown custom event type: %d", event->type());	}    }}int main(int argc, char **argv){    QApplication app(argc, argv);    SemaphoreExample se;    app.setMainWidget(&se);    se.show();    return app.exec();}#include "main.moc"