QSerialPort and QtQuick animation freezing on list and open serial ports

Anyone could help me, please.

I wrote a C++ method to find all serial ports, open, write and close and use to Q_INVOKABLE to call this method from a QML.

The problem is a freezing on push LoadingPage.qml if there are many serial ports connected, the animation start and then immediately freezes, when the function find finish, the animation start again. [SerialPort.qml]

How is it the better way to solve that?
Thanks

main.cpp

Code:

---

qmlRegisterType<Module::Physical>("MyType", 1, 0, "SerialPort");

---

Main.qml

Code:

---

ApplicationWindow {
    SerialPort {
        id: module
    }
}

---

SerialPort.qml

Code:

---

Button {
    text: qsTr("start")
    onClicked: {
        stackView.push(Qt.resolvedUrl("LoadingPage.qml"))
        module.find()
    }
}

---

serialport.h

Code:

---

Q_INVOKABLE QVector<QString> find();

---

serialport.cpp

Code:

---

QVector<QString> Physical::find()
{
    m_ports.clear();
 
    foreach (const QSerialPortInfo &info, QSerialPortInfo::availablePorts()) {
        bool hasError = false;
 
        QSerialPort port;
        port.setPort(info);
 
        if (port.open(QIODevice::ReadWrite)) {
            if (!hasError && !port.setBaudRate(serial::baudRate)) {
                emit error(tr("Can't set baud to %1, error %2")
                           .arg(port.portName())
                           .arg(port.error()));
                hasError |= true;
            }
            if (!hasError && !port.setDataBits(serial::dataBits)) {
                emit error(tr("Can't set data bits to %1, error %2")
                           .arg(port.portName())
                           .arg(port.error()));
                hasError |= true;
            }
 
            if (!hasError && !port.setParity(serial::parity)) {
                emit error(tr("Can't set parity to %1, error %2")
                           .arg(port.portName())
                           .arg(port.error()));
                hasError |= true;
            }
            if (!hasError && !port.setStopBits(serial::stopBits)) {
                emit error(tr("Can't set stop bits to %1, error %2")
                           .arg(port.portName())
                           .arg(port.error()));
                hasError |= true;
            }
            if (!hasError && !port.setFlowControl(serial::flowCtrl)) {
                emit error(tr("Can't set flow control to %1, error %2")
                           .arg(port.portName())
                           .arg(port.error()));
                hasError |= true;
            }
            if (!hasError) {
                m_ports.append(port.portName());
            }
 
            QByteArray data;
            data.resize(1);
            data[0] = ID_READ;
 
            port.write(data);
            port.close();
        }
    }
 
    return m_ports;
}

---

From StackOverflow, answered by Kuba Ober, source: http://stackoverflow.com/questions/2...n-serial-ports

Quote:

---

Your code runs in the GUI thread, and since it blocks the GUI thread, the user interaction is stopped as well.

You need to perform the scan in a separate thread. The Qt Concurrent framework is perfect for this, since you're performing a self-contained action that can be done in any thread. Your find() method must be turned into a stand-alone function or a static method (since that's what it really is).

You'd then run it as follows:

Code:

---

class Physical {
  QFuture<QStringList> m_future;
  QFutureWatcher<QStringList> m_futureWatcher;
  // A string list is a simpler type to type :)
  static QStringList doFindPorts() {
    ...
  }
  Q_SLOT void findPortsFinished() {
    QStringList ports(m_future);
    // use the list of ports
  }
 
public:
  Physical() {
    connect(&m_futureWatcher, SIGNAL(finished()), SLOT(findPortsFinished()));
    m_futureWatcher.set(m_future);
    ...
  }
  Q_SLOT void findPorts() {
    if (m_future.isRunning()) return;
    m_future = QtConcurrent::run(doFindPorts);
  }
};

---

---

That or processing the serial ports one at a time.

Cheers,
_

In general:

http://doc.qt.digia.com/qq/qq27-responsive-guis.html