c++ - 如果从QRunnable或其他线程调用Qt信号和插槽，则它们不起作用

Question

我正在尝试学习如何在Qt中使用多线程并将其在QtWidget应用程序中使用。因此，我已经设置了这个简单的测试用例。

主窗口
该表单有一些按钮，每个按钮将执行另一种表单(与此相关的对话框)。

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    connect(ui->btnShowCalibrationDialog, &QPushButton::clicked,
            this, [&](){

        CalibrationDialog dlg;
        dlg.exec();
    });
}

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

CalibrationDialog 此对话框具有QPushButton和QTextEdit。单击该按钮后，我将运行QRunnable类(下一个!)

Calibrationdialog.h(我已为您省去了包含物和保护装置!)

    class CalibrationDialog : public QDialog
    {
        Q_OBJECT

    public:
        explicit CalibrationDialog(QWidget *parent = nullptr);
        ~CalibrationDialog();

    public slots:
        void onBeginWorkRequested();
        void onReceiveData(int data);

    private:
        Ui::CalibrationDialog *ui;
    };

标定对话框

#include "worker.h"

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

    connect(ui->btnBegin, &QPushButton::clicked,
            this, &CalibrationDialog::onBeginWorkRequested);
}

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

void CalibrationDialog::onBeginWorkRequested()
{
    qDebug() << "CalibrationDialog::onBeginWorkRequested()" << "on" << QThread::currentThreadId();
    Worker* worker = new Worker();
    QThreadPool* pool = QThreadPool::globalInstance();
    connect(worker, &Worker::reportProgress,
            this, &CalibrationDialog::onReceiveData);
    pool->start(worker);
    pool->waitForDone();
}

void CalibrationDialog::onReceiveData(int data)
{
    ui->teResults->append(QString::number(data));
    ui->teResults->ensureCursorVisible();
}

Worker 这是一些可运行的...我想报告进度，以便以响应方式显示在对话框的textedit中!

worker

class Worker : public QObject, public QRunnable
{
    Q_OBJECT

public:
    explicit Worker(QObject *parent = nullptr);
    void run() override;

private:
    int mProgress = 0;

signals:
    void reportProgress(int progress);

};

worker.cpp

Worker::Worker(QObject *parent) : QObject(parent)
{

}

void Worker::run()
{
    qDebug() << "Worker is running #" << QThread::currentThreadId();
    while(true) {
        mProgress += 100;
        emit reportProgress(mProgress);
        QThread::msleep(500);
    }
}

我在调试器中看到控件进入了while循环...但是对话框未处理信号!我的意思是textedit保持为空!

我试图阅读文档并在线搜索...我得出的结论是，我的问题出在线程亲和力的荒原上....但我不知道是否是这种情况，以及如何解决。请协助!

Answer 1

删除pool->waitForDone();，切勿在GUI中使用waitForX方法，因为它们阻止了信号的执行。