qt - QObject::startTimer：定时器只能用于以 QThread 启动的线程

Question

我正在尝试在工作线程的事件循环中启动 Timer，但出现此错误： QObject::startTimer: Timers can only be used with threads started with QThread

这有什么问题？

#include <QObject>
#include <QThread>
#include <QTimer>

class A : public QObject
{
    Q_OBJECT
public:
    A();

private:
    QThread m_workerThread;
    QTimer m_myTimer;

};

A::A()
{
    this->moveToThread(&m_workerThread);
    m_myTimer.moveToThread(&m_workerThread);
    m_workerThread.start();
    m_myTimer.start(1000);
}

Answer 1

在任何地方初始化你的计时器，但在线程启动时立即启动它（将它附加到QThread::started信号）：

class A : public QObject
{
    Q_OBJECT
public:
    A();

private slots:
    void started();
    void timeout();

private:
    QThread m_workerThread;
    QTimer m_myTimer;
};

A::A()
{
    moveToThread(&m_workerThread);

    connect(&m_workerThread, SIGNAL(started()), this, SLOT(started()));
    connect(&m_myTimer, SIGNAL(timeout()), this, SLOT(timeout()));

    m_myTimer.setInterval(1000);
    m_myTimer.moveToThread(&m_workerThread);

    m_workerThread.start();
}

void A::started()
{
    timer.start();
}

void A::timeout()
{
    // timer handler
}

Answer 2

我想我想通了，我尝试从 GUI 线程启动计时器，在我将它移到工作线程之后，它似乎可以工作：

class A : public QObject
{
    Q_OBJECT
public:
    A();

private:
    QThread m_workerThread;
    QTimer m_myTimer;

public slots:
    void sl_startTimer();
};

A::A()
{
    this->moveToThread(&m_workerThread);
    m_myTimer.moveToThread(&m_workerThread);
    m_workerThread.start();
    QMetaObject::invokeMethod(this, "sl_startTimer", Qt::QueuedConnection);
}

void A::sl_startTimer()
{
    m_myTimer.start(1000);
}

Answer 3

这种方法对我来说似乎有点危险。通过将QObject移到 上QThread，您正在使线程负责对象的事件（信号、插槽、消息等）。但是，当对象被删除时，线程将在对象本身之前被删除，这可能会导致一些意外行为。

推荐的方法是分别实例化线程和对象。

Answer 4

希望这会有所帮助：

class ReadYoloResult : public QObject
{
    Q_OBJECT
public:
    ReadYoloResult(QObject *parent = 0);
    void startTimer();
    QThread workerThread;

private:
    QTimer *timer;

public slots:
    void timerSlot();
};

ReadYoloResult::ReadYoloResult(QObject * parent)
{
    this->moveToThread(&workerThread);
    timer = new QTimer();
    connect(timer,SIGNAL(timeout()),this,SLOT(timerSlot()));

    workerThread.start();

    //timer->start(1000);
}

void ReadYoloResult::startTimer(){
    timer->start(100);
}
void ReadYoloResult::timerSlot(){
    qDebug()<<"In timer slot";
}