Problem with QThread

[Stefanoxjx]

Hello guys, I have a problem with QThread.
I have a class that copies some files, and during this operation, I would like to update a progress bar in a QDialog.
I tried running the copy method on a thread, but the QDialog only appears at the end of the file copy.
Where am I going wrong?
Thanks.

Ciao.

backup.h

class CopyData : public QObject
{
    Q_OBJECT

public:
    CopyData();
     ~CopyData() {};

public slots:
    void sltExecuteCopy(QString sourceDir, QString destDir);

signals:
    void sigProgress(QString fileName, uint32_t fileCount);
    void sigCopyEnded(void);
};


class Backup : public QObject
{
    Q_OBJECT

public:
    Backup();
    ~Backup() {delete this;}

private:
    //Variabili
    QString       BackupDestDir, SavedName;

    //QMessageBox   *WaitDbBackup, *WaitCertsBackup;
    QDialog       *dlgBackup;
    QLabel        *lblBackup;
    QProgressBar  *pbBackupCerts;
    QTextEdit     *teBackupCerts;
    CopyData      *cd;
    QThread       *cdThread;

//protected:
//    void showEvent(QShowEvent *event) override;

private slots:
    void    sltBackupFinished(void);
    void    sltUpdateProgress(QString fileName, uint32_t fileCount);
    void    sltBackupCertsEnded(void);

signals:
    void sigStartCertsBackup(void);
    void sigDialogShowed(QString srcDir, QString destDir);
};

backup.cpp

Backup::Backup(void)
{
    dlgDbBackup = new QDialog(this);
    QVBoxLayout *vlMain = new QVBoxLayout(dlgDbBackup);

    dlgDbBackup->setLayout(vlMain);
    QLabel *lblBackup = new QLabel("Some pre operations...");
    vlMain->addWidget(lblBackup);

    QPushButton btnGo = new QPushButton("Go", this);
    connect(btnGo, &QPushButton::clicked, this, &Backup::sltBackupEnded);
    vlMain->addWidget(btnStop);

    dlgDbBackup->exec();
}

/* Grrrrr!!! Doesn't work!!!
void DbBackup::showEvent(QShowEvent *event)
{
    DbBackup::showEvent(event);
    cdThread->start();
    QMetaObject::invokeMethod(cd, "sltExecuteCopy", Qt::DirectConnection,
                              Q_ARG(QString, "pippo"),
                              Q_ARG(QString, "pluto"));

}*/

void Backup::sltBackupEnded(void)
{
    delete dlgDbBackup;

    int exitCode = 0; //for debug only
    
    if(exitCode != 0)
    {
        QMessageBox::critical(this, "Backup", "Backu problem");
        return;
    }
    else
    {
//        CopyMade = true;
        QMessageBox MsgBox;
        MsgBox.setWindowTitle("Backup");
        MsgBox.setText("Pre operations ok, do you want to proceed?");
        MsgBox.setIcon(QMessageBox::Question);
        MsgBox.setStandardButtons(QMessageBox::Yes | QMessageBox::No);
        QAbstractButton *BtnYes = MsgBox.button(QMessageBox::Yes);
        BtnYes->setText("Si");
        QAbstractButton *BtnNo = MsgBox.button(QMessageBox::No);
        BtnNo->setText("No");
        MsgBox.exec();

        if(MsgBox.clickedButton() == BtnNo) return;
    }

    QString srcDir = //source path
    QString destDir = //Destination path
    srcDir.replace(R"(\\)", "/").replace(R"(\)", "/");
    destDir.replace(R"(\\)", "/").replace(R"(\)", "/");;

    Dir.mkdir(destDir);

    QDialog *dlgBackupCerts = new QDialog(this);
    QVBoxLayout *vlMain = new QVBoxLayout(dlgBackupCerts);
    dlgBackupCerts->setLayout(vlMain);

    pbBackupCerts = new QProgressBar(this);
    pbBackupCerts->setRange(0, totFiles);
    vlMain->addWidget(pbBackupCerts);

    teBackupCerts = new QTextEdit(this);
    vlMain->addWidget(teBackupCerts);

    cd = new CopyData;
    cdThread = new QThread(this);

    connect(cd, &CopyData::sigProgress, this, &DbBackup::sltUpdateProgress);// DialogoAggiornabile::aggiornaEtichetta);
    connect(cd, &CopyData::sigCopyEnded, this, &DbBackup::sltBackupCertsEnded);

    cd->moveToThread(cdThread);


//        cdThread->start();
//        QMetaObject::invokeMethod(cd, "sltExecuteCopy", Qt::DirectConnection,
//                                  Q_ARG(QString, srcDir),
//                                  Q_ARG(QString, destDir));


    dlgBackupCerts->show();

    cdThread->start();
    QMetaObject::invokeMethod(cd, "sltExecuteCopy", Qt::DirectConnection,
                                  Q_ARG(QString, srcDir),
                                  Q_ARG(QString, destDir));

}

void Backup::sltUpdateProgress(QString fileName, uint32_t fileCount)
{
    pbBackupCerts->setValue(fileCount);
    teBackupCerts->append(fileName);
}

void Backup::sltBackupCertsEnded(void)
{
    cdThread->quit();
    cdThread->wait();
}


CopyData::CopyData() //QString srcDir, QString destDir)
{
    qDebug() << "Constructor";
}


void CopyData::sltExecuteCopy(QString srcDir, QString destDir)
{
    QDir sourceDirectory(srcDir);
    QDir destinationDirectory(destDir);

    uint32_t i = 0;
    foreach(QString directoryName, sourceDirectory.entryList(QDir::Dirs | QDir::NoDotAndDotDot))
    {
        destinationDirectory.mkpath(destDir+"/"+directoryName);
        QString destinationPath = destDir+"/"+directoryName;
        destinationDirectory.mkpath(destinationPath);

        QDir currentSrcDir(srcDir + "/" + directoryName);
        qDebug() << currentSrcDir;

        foreach(QString fileName, currentSrcDir.entryList(QDir::Files))
        {
            qDebug() << i << srcDir+"/"+directoryName+"/"+fileName << "--->" << destDir+"/"+directoryName+"/"+fileName;
            QFile::copy(srcDir+"/"+directoryName+"/"+fileName, destDir+"/"+directoryName+"/"+fileName);
            emit sigProgress(fileName, ++i);
        }
    }

//    QDir finalDestination(destDir); //cantiere: gestire errori
//    finalDestination.refresh();

    emit sigCopyEnded();
}

[Christian Ehrlicher]

@Stefanoxjx said in Problem with QThread:

QMetaObject::invokeMethod(cd, "sltExecuteCopy", Qt::DirectConnection,
                              Q_ARG(QString, srcDir),
                              Q_ARG(QString, destDir));

What do you expect when you execute the function directly in the main thread?
Where do you have this from? Please follow the official documentation and start the worker function with an appropriate signal (in the example it's a separate signal but QThread::started can be used here too).