thread question

[gt.beta2]

Hi
I was reading one example about threads(wish i know almost nothing about) and got carried away by the imagination

I have one dialog:

ubmsr.h

#ifndef UBMSR_H
#define UBMSR_H
 
#include <QtGui/QDialog>
 
#include "senderThread.h"
 
namespace Ui
{
    class UbmsrClass;
}
 
class Ubmsr : public QDialog
{
    Q_OBJECT
 
public:
    Ubmsr(QWidget *parent = 0);
    ~Ubmsr();
private slots:
    void startOrStopSenderThread();
private:
    Ui::UbmsrClass *ui;
    senderThread *sender;
};
 
#endif // UBMSR_H

#ifndef UBMSR_H
#define UBMSR_H

#include <QtGui/QDialog>

#include "senderThread.h"

namespace Ui
{
    class UbmsrClass;
}

class Ubmsr : public QDialog
{
    Q_OBJECT

public:
    Ubmsr(QWidget *parent = 0);
    ~Ubmsr();
private slots:
    void startOrStopSenderThread();
private:
    Ui::UbmsrClass *ui;
    senderThread *sender;
};

#endif // UBMSR_H

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ubmsr.cpp

#include "ubmsr.h"
#include "ui_ubmsr.h"
 
Ubmsr::Ubmsr(QWidget *parent)
    : QDialog(parent), ui(new Ui::UbmsrClass)
{
    ui->setupUi(this);
    sender = new senderThread;
    sender->setMessage("Hello!");
    connect(ui->senderButton, SIGNAL(clicked()), this, SLOT(startOrStopSenderThread()));
}
 
Ubmsr::~Ubmsr()
{
    delete ui;
}
 
void Ubmsr::startOrStopSenderThread(){
    ui->senderButton->setText("asdasd");
    if (sender->isRunning()) {
        sender->stop();
        ui->senderButton->setText(tr("Start Sender"));
        ui->senderMsg->setEnabled(true);
        ui->senderPort->setEnabled(true);
    }else{
        sender->start();
        ui->senderButton->setText(tr("Stop Sender"));
        ui->senderMsg->setEnabled(false);
        ui->senderPort->setEnabled(false);
    }
}

#include "ubmsr.h"
#include "ui_ubmsr.h"

Ubmsr::Ubmsr(QWidget *parent)
    : QDialog(parent), ui(new Ui::UbmsrClass)
{
    ui->setupUi(this);
    sender = new senderThread;
    sender->setMessage("Hello!");
    connect(ui->senderButton, SIGNAL(clicked()), this, SLOT(startOrStopSenderThread()));
}

Ubmsr::~Ubmsr()
{
    delete ui;
}

void Ubmsr::startOrStopSenderThread(){
    ui->senderButton->setText("asdasd");
    if (sender->isRunning()) {
        sender->stop();
        ui->senderButton->setText(tr("Start Sender"));
        ui->senderMsg->setEnabled(true);
        ui->senderPort->setEnabled(true);
    }else{
        sender->start();
        ui->senderButton->setText(tr("Stop Sender"));
        ui->senderMsg->setEnabled(false);
        ui->senderPort->setEnabled(false);
    }
}

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senderThread.h

#ifndef SENDERTHREAD_H
#define SENDERTHREAD_H
 
#include <QThread>
 
class senderThread : public QThread
{
    Q_OBJECT
 
public:
    senderThread();
    void setMessage(const QString &message);
    void stop();
 
protected:
    void run();
 
private:
    volatile bool senderStopped;
    QString messageStr;
 
};
 
#endif

#ifndef SENDERTHREAD_H
#define SENDERTHREAD_H

#include <QThread>

class senderThread : public QThread
{
    Q_OBJECT

public:
    senderThread();
    void setMessage(const QString &message);
    void stop();

protected:
    void run();

private:
    volatile bool senderStopped;
    QString messageStr;

};

#endif

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senderThread.cpp

#include <QtCore>
#include <iostream>
 
#include "senderThread.h"
 
using namespace std;
 
senderThread::senderThread()
{
    senderStopped = false;
}
 
void senderThread::setMessage(const QString &message)
{
    messageStr = message;
}
 
void senderThread::run()
{
    while (!senderStopped)
        cerr << qPrintable(messageStr);
    senderStopped = false;
    cerr << endl;}
 
void senderThread::stop()
{
    senderStopped = true;
}

#include <QtCore>
#include <iostream>

#include "senderThread.h"

using namespace std;

senderThread::senderThread()
{
    senderStopped = false;
}

void senderThread::setMessage(const QString &message)
{
    messageStr = message;
}

void senderThread::run()
{
    while (!senderStopped)
        cerr << qPrintable(messageStr);
    senderStopped = false;
    cerr << endl;}

void senderThread::stop()
{
    senderStopped = true;
}

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I can start and stop the thread and change the button label.

Is it possible to access the objects in the ui from a member function in the thread class?!

The final idea is to have 2 diferent threads sending and reading from a local network and showin all in the dialog i created.

I already managed the network issue ... the problem is putting this all togheter

How can i do it?

Thanks

[wysota]

No, you can't access GUI objects from non-gui thread. You should do "worker" stuff in the "worker" thread and then send a signal or event to the main thread that it needs to render the data on screen.

[Lykurg]

Is it possible to access the objects in the ui from a member function in the thread class?!

Hi, this is not a very mature answer due to I am also not familiar with threads, but accessing a member is only possible by setting a pointer in the thread to the "main" class. But that's a bad idea, so leave it! But you can even use the signal and slot mechanism through the thread border. That should probably be the solution to your problem.

Lykurg

Edit: too late...

[gt.beta2]

I'm having trouble with the translation.
What does thread-safe or reentrant mean?
In short words if possible
Thanks

opss ... found it http://doc.trolltech.com/4.5/threads...eading-classes

[gt.beta2]

Still about this subject... i've been reading about QtConcurrentRun.
Would it be possible for me to launch 2 member functions of the initial Ubmsr class in 2 different thread using this?
Imagine that f1() is broadcasting every 1 second and f2() is listening in other port!? This way i would have access to the GUI objects.

Does this make sense or showld i forget it?

[wysota]

In theory you could do that. But my personal opinion is that it's not worth the trouble. If you want to have multiple threads, then use a classical threaded approach and use signals and slots to communicate with the main thread that will manipulate the GUI. The real question is if you should use threads at all.