如何从 Qt 中的工作线程 class 启动计时器？

Question

控制器的声明部分class:

class ProtocolPacket: public QQuickItem
{
private:

    Q_OBJECT

    ...
    QThread objWorkerThread;

public:
    ProtocolPacket();
    ~ProtocolPacket();
...

controller的构造函数class:

ProtocolPacket::ProtocolPacket()
{
    ReadWriteSerialPort *objReadWriteSerialPort = new ReadWriteSerialPort;
    objReadWriteSerialPort->moveToThread(&objWorkerThread);

    connect(&objWorkerThread, &QThread::finished,
            objReadWriteSerialPort, &QObject::deleteLater);

    /// Following signals of ProtocolPacket class are connected to the corresponding
    /// slots of thread class ReadWriteSerialPort.
    connect(this, &ProtocolPacket::cameraValueChanged,
            objReadWriteSerialPort, &ReadWriteSerialPort::receiveAndSendUpdatedCameraValue);
    ...
    ...
    objWorkerThread.start();
}

工作线程的构造函数class:

ReadWriteSerialPort::ReadWriteSerialPort()
{
    ...
    serialPort.setPortName ("/dev/ttyUSB0");
    serialPort.setBaudRate (QSerialPort::Baud19200);

    if(serialPort.open (QIODevice::ReadWrite))
    {
        serialPort.setDataBits(QSerialPort::Data8);
        serialPort.setParity(QSerialPort::NoParity);
        serialPort.setStopBits(QSerialPort::OneStop);
    }

    objWriter = new SerialPortWriter(&serialPort);
    objReader = new SerialPortReader(&serialPort);

    timerSendVelocityPackets = new QTimer(this);
    connect (timerSendVelocityPackets, SIGNAL (timeout()),
             this, SLOT (sendVelocityPacket()));

    timerSendHealthFeedbackPackets = new QTimer(this);
    connect (timerSendHealthFeedbackPackets, SIGNAL (timeout()),
             this, SLOT (formAndSendHealthFeedbackPackets()));

    timerReceivePackets = new QTimer (this);
    connect (timerReceivePackets, SIGNAL (timeout()),
             this, SLOT (receiveAndUnpackPacket()));
    timerReceivePackets->start (300);
}

我收到错误消息：

QObject::startTimer: Timers cannot be started from another thread

我做错了什么？

我希望从 worker class 启动计时器：ReadWriteSerialPort

Answer 1

在移动到另一个线程的对象中构造的每个对象都必须设置其父对象：

class ReadWriteSerialPort : public QObject {
  QSerialPort serialPort { this }; // important
  QTimer timerSendVelocityPackets { this }; // etc.
  ...
};

您还必须确保 没有从其他线程直接调用 ReadWriteSerialPort 的线程不安全方法。

此外，除非您正在轮询数据，否则定时器驱动的数据包接收是不正确的。你应该对串口发出的readyRead信号进行操作。

我也质疑单独的 reader 和作者：通常这些任务都需要知道目标设备的预期状态，所以将它们分开可能没有帮助。没有看到更多代码就很难说。

如何从 Qt 中的工作线程 class 启动计时器？

How to start timers from the worker thread class in Qt?

qt

multithreading

timer

qthread