Signal/Slot doesn't work after moveToThread



  • I have implemented this approach to decouple the GUI from the Businesslayer:

    main.c
    @
    #include "Core.h"

    int main(int argc, char *argv[])
    {
    QApplication a(argc, argv);
    Dialog w;
    Core *core = new Core(&w);
    w.show();

    return a.exec();
    }
    @

    IGui
    @
    class IGui
    {
    //--- slots
    public:
    virtual void onWorkFinished() = 0;

    //--- signals
    signals:
    void doWork();
    };
    @

    Core
    @
    #include "IGui.h"

    class Core : public QObject
    {
    Q_OBJECT

    public:
    explicit Core(IGui *gui, QObject *parent = 0);

    signals:
    void workFinished();

    private slots:
    void onDoWork();

    private:
    QThread m_workerThread;

    };

    Core::Core(IGui *gui, QObject *parent) :
    QObject(parent)
    {
    connect(dynamic_cast<QObject *>(gui), SIGNAL(doWork()),
    this, SLOT(onDoWork()));
    connect(this, SIGNAL(workFinished()),
    dynamic_cast<QObject *>(gui), SLOT(onWorkFinished()));

    //this->moveToThread(&m_workerThread);
    }

    void Core::onDoWork()
    {
    qDebug() << Q_FUNC_INFO;
    QThread::msleep(1000);
    emit workFinished();
    }
    @

    Dialog
    @
    #include "IGui.h"

    namespace Ui {
    class Dialog;
    }

    class Dialog : public QDialog, public IGui
    {
    Q_OBJECT

    public:
    explicit Dialog(QWidget *parent = 0);
    ~Dialog();

    public slots:
    void onWorkFinished();

    private slots:
    void on_pushButton_clicked();

    private:
    Ui::Dialog *ui;

    signals:
    void doWork();
    };

    Dialog::Dialog(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::Dialog)
    {
    ui->setupUi(this);
    }

    Dialog::~Dialog()
    {
    delete ui;
    }

    void Dialog::onWorkFinished()
    {
    qDebug() << Q_FUNC_INFO;
    }

    void Dialog::on_pushButton_clicked()
    {
    emit doWork();
    }
    @

    This works fine so far.

    I want the onDoWork to be executed in a new thread so that the GUI is not blocked.

    I thought I can do this by doing a moveToThread and then connect object.

    But if I uncomment the moveToThread line the two signal/slot connections above doesn't work anymore.

    So my first question is:
    Why does they not work anymore?

    Second question is:
    Is this the right way to achieve that the onDoWork runs in a new thread?



  • I don't see you calling "start":http://qt-project.org/doc/qt-4.8/qthread.html#start on the m_workerThread object. So this would mean the thread is never started. So no running eventloop.

    Another option to run the onDoWork() function in another thread would be to use "QtConcurrent":http://qt-project.org/doc/qt-4.8/qtconcurrentrun.html .


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