MainWindow的Worker线程的QT更新变量

我正在使用QT多线程概念显示OpenCV视频

我还希望更新按钮单击的私有"路径"变量。所以我添加了

connect(this, SIGNAL(send_to_worker(QString)),workers[view], SLOT(get_from_main(QString)));

但是，get_from_main(qString(函数永远不会被调用。

我可以知道从MainWindow更新Worker线程类变量的最安全方法是什么？

这是完整的代码..

class Worker : public QObject
{
    Q_OBJECT
public:
    Worker(QString path, int id);
    ~Worker();
public slots:
    void readVideo(QString path = "");
    void get_from_main(QString path);
signals:
    // frame and index of label which frame will be displayed
    void frameFinished(cv::Mat frame, int index);
    void finished(int index);
private:
    QString filepath;
    int index;
};
//worker.cpp
#include "worker.h"
#include <QDebug>
#include <QThread>
#include <QTime>
Worker::Worker(QString path, int id) : filepath(path), index(id)
{
}
Worker::~Worker()
{
}
void Worker::get_from_main(QString path)
{
      qDebug() << "updating";
}
void Worker::readVideo(QString path)
{
    if (path.length() > 0)
        filepath = path;
    cv::VideoCapture cap(filepath.toStdString());
    if (! cap.isOpened())
    {
        qDebug() << "Can't open video file " << filepath;
        emit finished(index);
        return;
    }
    cv::Mat frame;
    while (true)
    {
        cap >> frame;
        if (frame.empty())
        {
            frame = cv::Mat(cv::Size(720, 576), CV_8UC3, cv::Scalar(192, 0, 0));
            emit frameFinished(frame, index);
            break;
        }

        emit frameFinished(frame.clone(), index);
        QThread::msleep(30);
    }
    emit finished(index);
}
//mainwindow.h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
#include <opencv2/opencv.hpp>
#include "worker.h"
#define MAX_NUM_CAM 8
namespace Ui {
class MainWindow;
}
class QThread;
class QLabel;
class MainWindow : public QMainWindow
{
    Q_OBJECT
public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();
    void init();
private slots:
    void displayFrame(cv::Mat frame, int index);
    void file_open_clicked();
signals:
send_to_worker(QString path);

private:
    Ui::MainWindow *ui;
    int numCams;
    QLabel *labels[MAX_NUM_CAM];
    QThread* threads[MAX_NUM_CAM];
    Worker* workers[MAX_NUM_CAM];
};
#endif // MAINWINDOW_H

//mainwindow.cpp
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QDebug>
#include <QThread>
#include <QLabel>
#include <QGridLayout>
MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    qRegisterMetaType< cv::Mat >("cv::Mat");
    qDebug() << "Main thread " << QThread::currentThreadId();
    init();
}
MainWindow::~MainWindow()
{
    delete ui;
}
void MainWindow::init()
{
    QGridLayout *grid = new QGridLayout;
    int numCols = 2;
    numCams = 4;
    int row = 0, col = 0;
    for (int i = 0; i < numCams; i++)
    {
        labels[i] = new QLabel;
        row = i / numCols;
        col = i % numCols;
        grid->addWidget(labels[i], row, col);

        threads[i] = new QThread;
        workers[i] = new Worker(QString("/home/shang/Videos/%1.mp4").arg(i+1), i);
        workers[i]->moveToThread(threads[i]);
        connect(workers[i], SIGNAL(frameFinished(cv::Mat, int)), this, SLOT(displayFrame(cv::Mat,int)));
        connect(threads[i], SIGNAL(started()), workers[i], SLOT(readVideo()));
        connect(workers[i], SIGNAL(finished(int)), threads[i], SLOT(quit()));
        connect(workers[i], SIGNAL(finished(int)), workers[i], SLOT(deleteLater()));
        connect(threads[i], SIGNAL(finished()), threads[i], SLOT(deleteLater()));
        threads[i]->start();
    }
    this->centralWidget()->setLayout(grid);
}
void MainWindow::file_open_clicked(){
       QString Path = QFileDialog::getSaveFileName( this,tr("OpenVideo"),"","Video (*.avi)");
    if(Path.isEmpty())
        return;
     view =3; 
    connect(this, SIGNAL(send_to_worker(QString)),workers[view], SLOT(get_from_main(QString)));
    emit this->send_to_worker(recorder_Path);
}
void MainWindow::displayFrame(cv::Mat frame, int index)
{
    QPixmap p = QPixmap::fromImage(QImage(frame.data, frame.cols, frame.rows, frame.step, QImage::Format_RGB888).rgbSwapped());
    p = p.scaled(QSize(frame.cols/2, frame.rows/2));
    labels[index]->setPixmap(p);
}

QT OpenCV使用STD播放视频:: thread