c – Qt无法将目标移动到线程

我在Qt 5.7(在 Windows 10上)应用程序中遇到了一个奇怪的错误,并且无法找到这种行为的常见罪魁祸首：

>被移动的对象具有父对象 – 大多数情况并非如此
>尝试将对象拉到线程而不是推送它 – 这是错误的原因但是我不知道它来自哪里

完整的错误消息是

QObject::moveToThread: Current thread (0x2afcca68) is not the object’s
thread (0x34f4acc8). Cannot move to target thread (0x34f4adc8)

QObject::setParent: Cannot set parent,new parent is in a different
thread

这里也是我的代码：

main.cpp中

#include <QApplication>
#include <QQuickItem>
#include "CustomQuickWidget.h"

int main(int argc,char *argv[])
{
    QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
    QApplication app(argc,argv);

    const QUrl source = QUrl(QLatin1String("qrc:/main"));
    CustomQuickWidget widget(source);

    return app.exec();
}

main(main.qml的别名)：

// You can put any random QML content in this case really as long as it doesn't create a window since the CustomQuickWidget does that.
Rectangle {
    id: window
    visible: true
    width: 600
    height: 480
}

CustomQuickWidget.cpp

#include "CustomQuickWidget.h"
#include <QQuickItem>

CustomQuickWidget::CustomQuickWidget(const QUrl &source,QWidget *parent) : QQuickWidget(source,parent) {
    // Setup the recognizer
    this->airWheelRecognizer = new QAirWheelGestureRecognizer();
    this->airWheelType = QGestureRecognizer::registerRecognizer(airWheelRecognizer);
    // and turn on grabbing for all the supported gestures
    grabGesture(airWheelType);
    grabGesture(Qt::SwipeGesture);
    grabGesture(Qt::TapGesture);

    // Create thread and device worker
    this->deviceThread = new QThread(this);
    this->deviceWorker = new DeviceMapper(this,Q_NULLPTR); // NOTE: this here is NOT for parent. The constructor's signature for this class is: DeviceMapper(QObject* receiver,QList<Qt::GestureType>* gestureIDs,QObject* parent = Q_NULLPTR)
    this->deviceWorker->init();

    // Create timer that will trigger the data retrieval slot upon timeout
    this->timer = new QTimer();
    this->timer->setTimerType(Qt::PreciseTimer);
    this->timer->setInterval(5);

    // Move timer and device mapper to other thread
    this->timer->moveToThread(this->deviceThread);
    this->deviceWorker->moveToThread(this->deviceThread); // FIXME For unknown reason: QObject::moveToThread: Current thread (...) is not the object's thread. Cannot move to target thread

    // Connect widget,timer and device mapper
    createConnections();

    // Run thread
    this->deviceThread->start();

    // Connect device and start data retrieval
    QTimer::singleShot(0,this->deviceWorker,&(this->deviceWorker->slotToggleConnection));
    QTimer::singleShot(0,&(this->deviceWorker->slotToggleRun));

    this->show();
}

CustomQuickWidget::~CustomQuickWidget()
{
    if (this->deviceThread) {
        this->deviceThread->quit();
        this->deviceThread->wait();
    }
}

void CustomQuickWidget::createConnections()
{
    connect(this->timer,SIGNAL(timeout()),SLOT(slotRetrieveData()));

    connect(this->deviceThread,SIGNAL(started()),this->timer,SLOT(start()));
    connect(this->deviceThread,SIGNAL(finished()),SLOT(deleteLater()));
    connect(this->deviceThread,this->deviceThread,SLOT(deleteLater()));
}

bool CustomQuickWidget::event(QEvent* event) {
    if (event->type() == QEvent::Gesture) { 
        bool res = gestureEvent(static_cast<QGestureEvent*>(event)); // Not important so not included as code here
        return res;
    }

    return QWidget::event(event);
}

正如你所看到的,我在这里有一个典型的工人线程.我确保我的工作人员(这里是DeviceMapper)没有父母.它也在我的小部件中实例化(QThread也在其中创建),但随着计时器一起移动到线程.

现在除了标题中的明显问题之外,我还要提到以下内容：

>当这个> timer-> moveToThread(this-> deviceThread)时没有这样的错误;叫做
>这个相同的代码在另一个项目中没有任何问题,这是一个子项目 – 一个子项目创建共享库(我也在这个项目中使用),另一个 – 使用该库的应用程序.

我的其他应用程序和这个应用程序之间的唯一区别是使用QQuickWidget(而不是QWidget)和QML.我是QML的新手,这也是我的第一个QQuickWidget,所以我可能会错过一些需要“激活”的明显设置.

我还补充道

cout << this->deviceWorker->thread()->currentThreadId() << endl;
cout << this->thread()->currentThreadId() << endl;

就在此之前 – > deviceWorker-> moveToThread(this-> deviceThread);我得到了

0x18b0
0x18b0

这意味着在moveToThread(…)之前,我的对象属于QThread实例化的同一个线程.在moveToThread(…)之后打印线程ID会返回相同的结果,但由于无法将对象正确地移动到另一个线程,因此这是预期的.

更新：

仅在构建处于发布模式时出现错误消息,但无论构建类型如何,我仍然存在该错误.