Difference between invokeMethod and connect .

Marco Flad

my app contain a lot of labels in The mainWindow Thread which updated via connect(SIGNAL(),SLOT()) from a udp thread
(one way connection from udp to mainwindow ) , at first the app is crashing , i adedd timer in udp thread to emit update every 250ms and works ,but is slow and freezes for small time when the user make some interaction like touch on app .

so i found another method to update GUI From Thread QMetaObject::invokeMethod

QMetaObject::invokeMethod(label, SLOT(setText(const QString &)), Q_ARG(QString, "Hello"));

what the diffraance betwwen 2 ways ? 
is invoke Method not block main thread ? and completely done in the udp thread ?

thank you for help ,

SGaist

Hi,

How did you implement that that thread ?
How much data are you sending back to the GUI ?

Marco Flad

@SGaist said in Diffrance between invokeMethod and connect .:

How did you implement that that thread ?

Hi,

#include "udpthread.h"

UdpThread::UdpThread(QObject *parent) : QObject(parent)
{

    //constractor
    qDebug() << "UDP Construction  thread:" << QThread::currentThread();
    //intialize
    socket = new QUdpSocket(this);     //output data Socket Work as server
    qDebug() << "bind:" << socket->bind(28000, QUdpSocket::ShareAddress);   //to send on 28000
    qDebug() << "conn:" << connect(socket, SIGNAL(readyRead()), this, SLOT(readPendingDiagrams()));


    timer = new QTimer(this);
    connect(timer,SIGNAL(timeout()),this,SLOT(udpdateGui()));
    timer->start(250);
}

UdpThread::~UdpThread()
{
    qDebug() << "UDP DE-Construction thread:" << QThread::currentThread();

}


void UdpThread::readPendingDiagrams()
{

    qDebug() << "UDP RUN thread:" << QThread::currentThread();


    QByteArray Data;
    while (socket->hasPendingDatagrams()){
    Data.resize(socket->pendingDatagramSize());
    QHostAddress sender;
    quint16 senderPort;
    socket->readDatagram(Data.data(), Data.size(),&sender, &senderPort);

}

     parseFrame(Data , Data.length());
     Data.clear();

}


void UdpThread::udpdateGui()
{

    emit SendDataToGui(frame);

    qDebug() << "SIGNAL EMITTED FROM  THREAD" ;
}

frame : puiblic QBytArray of 144 ~byte
parseFrame : is a fuction contain heavy work

is There adiffrance betwwen Connect and invokeMethod ?
thanks for help.

SGaist

That class is not a thread.

invokeMethod is something that you call yourself. When you use connect you setup a relation between a signal emitter and a receiver.