QFtp in a separate instances

[wysota]

Can we see some code related to ftp downloading?

[baray98]

my signal and slots connection

ftp = new QFtp(this);
        connect(ftp, SIGNAL(commandFinished(int, bool)),
                this, SLOT(ftpCommandFinished(int, bool)));
        connect(ftp, SIGNAL(listInfo(const QUrlInfo &)),
                this, SLOT(addToList(const QUrlInfo &)));
        connect(ftp, SIGNAL(dataTransferProgress(qint64, qint64)),
                this, SLOT(updateDataTransferProgress(qint64, qint64)));

ftp = new QFtp(this);
        connect(ftp, SIGNAL(commandFinished(int, bool)),
                this, SLOT(ftpCommandFinished(int, bool)));
        connect(ftp, SIGNAL(listInfo(const QUrlInfo &)),
                this, SLOT(addToList(const QUrlInfo &)));
        connect(ftp, SIGNAL(dataTransferProgress(qint64, qint64)),
                this, SLOT(updateDataTransferProgress(qint64, qint64)));

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void FtpDialog::downloadFile()
{
    m_dir = QFileDialog::getExistingDirectory(this, tr("Save To Directory"),
            m_dir,
            QFileDialog::ShowDirsOnly
            | QFileDialog::DontResolveSymlinks);
    if (m_dir.isEmpty())
    {
        return;
    }
    selectedFiles = fileList->selectedItems(); // fileList is a QTreeWidget
    disconnect(downloadButton, SIGNAL(clicked()), this, SLOT(downloadFile()));
    connect(downloadButton, SIGNAL(canceled()), this, SLOT(cancelDownload()));
    for (int i = 0; i < selectedFiles.count(); i++)
    {
        QTreeWidgetItem* item = selectedFiles.at(i);
        QIcon icon = item->icon(NameColumn);
        icon.addFile(":/ftpSelected.png");
        item->setIcon(NameColumn,icon);
    }
 
    for (int i = 0 ; i < selectedFiles.count(); i++)
    {
        currentFileItem = selectedFiles.at(i);
        fileList->setCurrentItem(currentFileItem);
        QString fileName = currentFileItem->text(NameColumn);
        done = false;
        if (QFile::exists(m_dir+"/"+fileName))
        {
            QMessageBox::critical(this, tr("FTP"),
                                  tr("There already exists a file called \"%1\" in "
                                     "the target directory. For safety reason,"
                                     "Delete the existing file manually in \"%2\" !")
                                  .arg(fileName)
                                  .arg(m_dir));
            continue;
        }
 
        file = new QFile(m_dir+"/"+fileName);
        if (!file->open(QIODevice::WriteOnly))
        {
            QMessageBox::information(this, tr("FTP"),
                                     tr("Unable to save the file %1: %2.")
                                     .arg(fileName).arg(file->errorString()));
            delete file;
            continue;
        }
        startTime = QTime::currentTime();
        ftp->get(currentFileItem->text(NameColumn), file); // getting file starts here 
        statusLabel->setText(tr("Downloading %1...to Directory %2").arg(fileName)
                             .arg(m_dir));
        downloadButton->setText("Cancel Download");
        while(ftp->hasPendingCommands() || ftp->currentCommand()!=QFtp::None)
        {
         qApp->processEvents();
        }
    }
    selectedFiles.clear();
    downloadButton->setText("Download");
    disconnect(downloadButton, SIGNAL(canceled()), this, SLOT(cancelDownload()));
    connect(downloadButton, SIGNAL(clicked()), this, SLOT(downloadFile()));
}
 
void FtpDialog::ftpCommandFinished(int, bool error)
{
    setCursor(Qt::ArrowCursor);
 
    if (ftp->currentCommand() == QFtp::ConnectToHost)
    {
        if (error)
        {
            QMessageBox::information(this, tr("FTP"),
                                     tr("Unable to connect to the FTP server "
                                        "at %1. Please check that the host "
                                        "name is correct.")
                                     .arg(ftpServerLineEdit->text()));
            connectOrDisconnect();
            return;
        }
 
        statusLabel->setText(tr("Logged onto %1.")
                             .arg(ftpServerLineEdit->text()));
        fileList->setFocus();
        downloadButton->setDefault(true);
        connectButton->setEnabled(true);
        return;
    }
    if (ftp->currentCommand() ==  QFtp::Close)
    {
        statusLabel->setText(tr("Disconnected from %1.")
                             .arg(ftpServerLineEdit->text()));
        return;
    }
 
 
    if (ftp->currentCommand() == QFtp::Login)
        ftp->list();
 
    if (ftp->currentCommand() == QFtp::Get)
    {
        if (error)
        {
            statusLabel->setText(tr("Canceled download of %1.")
                                 .arg(file->fileName()));
            file->close();
            file->remove();
 
            selectedFiles.clear();
            done = true;
        }
        else
        {
            statusLabel->setText(tr("Downloaded %1 ")
                                 .arg(file->fileName()));
            file->close();
            done = true;
            previousTime = QTime(0,0,0,0);
            previousReadBytes = 0;
            currentFileItem->setText(DownloadStatusColumn,QString("%1")
                                     .arg(100));
            currentFileItem->setIcon(NameColumn,QPixmap(":/ftpDownloaded.png"));
        }
        delete file;
        enableDownloadButton();
    }
    else if (ftp->currentCommand() == QFtp::List)
    {
        if (isDirectory.isEmpty())
        {
            fileList->addTopLevelItem(new QTreeWidgetItem(QStringList() << tr("<empty>")));
            fileList->setEnabled(false);
        }
    }
}

void FtpDialog::downloadFile()
{
    m_dir = QFileDialog::getExistingDirectory(this, tr("Save To Directory"),
            m_dir,
            QFileDialog::ShowDirsOnly
            | QFileDialog::DontResolveSymlinks);
    if (m_dir.isEmpty())
    {
        return;
    }
    selectedFiles = fileList->selectedItems(); // fileList is a QTreeWidget
    disconnect(downloadButton, SIGNAL(clicked()), this, SLOT(downloadFile()));
    connect(downloadButton, SIGNAL(canceled()), this, SLOT(cancelDownload()));
    for (int i = 0; i < selectedFiles.count(); i++)
    {
        QTreeWidgetItem* item = selectedFiles.at(i);
        QIcon icon = item->icon(NameColumn);
        icon.addFile(":/ftpSelected.png");
        item->setIcon(NameColumn,icon);
    }

    for (int i = 0 ; i < selectedFiles.count(); i++)
    {
        currentFileItem = selectedFiles.at(i);
        fileList->setCurrentItem(currentFileItem);
        QString fileName = currentFileItem->text(NameColumn);
        done = false;
        if (QFile::exists(m_dir+"/"+fileName))
        {
            QMessageBox::critical(this, tr("FTP"),
                                  tr("There already exists a file called \"%1\" in "
                                     "the target directory. For safety reason,"
                                     "Delete the existing file manually in \"%2\" !")
                                  .arg(fileName)
                                  .arg(m_dir));
            continue;
        }

        file = new QFile(m_dir+"/"+fileName);
        if (!file->open(QIODevice::WriteOnly))
        {
            QMessageBox::information(this, tr("FTP"),
                                     tr("Unable to save the file %1: %2.")
                                     .arg(fileName).arg(file->errorString()));
            delete file;
            continue;
        }
        startTime = QTime::currentTime();
        ftp->get(currentFileItem->text(NameColumn), file); // getting file starts here 
        statusLabel->setText(tr("Downloading %1...to Directory %2").arg(fileName)
                             .arg(m_dir));
        downloadButton->setText("Cancel Download");
        while(ftp->hasPendingCommands() || ftp->currentCommand()!=QFtp::None)
        {
         qApp->processEvents();
        }
    }
    selectedFiles.clear();
    downloadButton->setText("Download");
    disconnect(downloadButton, SIGNAL(canceled()), this, SLOT(cancelDownload()));
    connect(downloadButton, SIGNAL(clicked()), this, SLOT(downloadFile()));
}

void FtpDialog::ftpCommandFinished(int, bool error)
{
    setCursor(Qt::ArrowCursor);

    if (ftp->currentCommand() == QFtp::ConnectToHost)
    {
        if (error)
        {
            QMessageBox::information(this, tr("FTP"),
                                     tr("Unable to connect to the FTP server "
                                        "at %1. Please check that the host "
                                        "name is correct.")
                                     .arg(ftpServerLineEdit->text()));
            connectOrDisconnect();
            return;
        }

        statusLabel->setText(tr("Logged onto %1.")
                             .arg(ftpServerLineEdit->text()));
        fileList->setFocus();
        downloadButton->setDefault(true);
        connectButton->setEnabled(true);
        return;
    }
    if (ftp->currentCommand() ==  QFtp::Close)
    {
        statusLabel->setText(tr("Disconnected from %1.")
                             .arg(ftpServerLineEdit->text()));
        return;
    }


    if (ftp->currentCommand() == QFtp::Login)
        ftp->list();

    if (ftp->currentCommand() == QFtp::Get)
    {
        if (error)
        {
            statusLabel->setText(tr("Canceled download of %1.")
                                 .arg(file->fileName()));
            file->close();
            file->remove();

            selectedFiles.clear();
            done = true;
        }
        else
        {
            statusLabel->setText(tr("Downloaded %1 ")
                                 .arg(file->fileName()));
            file->close();
            done = true;
            previousTime = QTime(0,0,0,0);
            previousReadBytes = 0;
            currentFileItem->setText(DownloadStatusColumn,QString("%1")
                                     .arg(100));
            currentFileItem->setIcon(NameColumn,QPixmap(":/ftpDownloaded.png"));
        }
        delete file;
        enableDownloadButton();
    }
    else if (ftp->currentCommand() == QFtp::List)
    {
        if (isDirectory.isEmpty())
        {
            fileList->addTopLevelItem(new QTreeWidgetItem(QStringList() << tr("<empty>")));
            fileList->setEnabled(false);
        }
    }
}

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[wysota]

Why are you using processEvents()? Why not rely on QFtp's signals?

[baray98]

like what for example... it thought there was nothing wrong in that but can you elaborate on the logic of not using processEvents().

baray98

[wysota]

You are practically spinning a local event loop effectively stopping the flow and probably preventing your other window from executing its code. You should really use an event controlled approach.

You should connect to its signals, queue requests and return from the function. When QFtp is done doing its job, it will call your slot so can do everything you want to do.