Thread+send event

**gri** · 25th July 2007, 10:50

You could implement a slot for addItem() and call QMetaObject::invokeMethod() to call it from a thread.

**marcel** · 25th July 2007, 10:56

Emit a signal from the thread which can contain as parameters data for the item.
Connect this signal to a slot in the GUI thread which will create the item and update the widget.

This is how it must be done.

Another solution is to post a custom event, but is basically the same thing as emitting a signal, only more code to write.

The slot in the GUI will get called asynchronously.

Regards

**jpn** · 25th July 2007, 13:39

QCoreApplication::sendEvent() is not thread-safe but QCoreApplication::postEvent() is. Be sure to read notes in docs.

**Fastman** · 25th July 2007, 14:06

.....
....
thx

**marcel** · 25th July 2007, 14:09

Originally Posted by Fastman

.....
....
thx

What does that mean?
Aren't you satisfied with the explanations?
Then ask some more?
But first, really, you should search the forum. There have been numerously other similar posts.

Regards

**Fastman** · 25th July 2007, 14:58

No, many thanks, you have very much helped! I have just started to understand with QT, therefore at me it is a lot of questions

**Fastman** · 26th July 2007, 16:35

... can help me

my code:

Qt Code:

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class HSM : public QDialog
{
	Q_OBJECT
public:
	CProjectManager *m_pPrj;
	HSM(QWidget *parent = 0, Qt::WFlags flags = 0);
	~HSM();
private:
	Ui::HSMClass ui;
	Server server;
private slots:
	void on_pushButton_clicked();
	void SetLine(QString cMsg);
};

class HSM : public QDialog
{
	Q_OBJECT
public:
	CProjectManager *m_pPrj;
	HSM(QWidget *parent = 0, Qt::WFlags flags = 0);
	~HSM();
private:
	Ui::HSMClass ui;
	Server server;
private slots:
	void on_pushButton_clicked();
	void SetLine(QString cMsg);
};

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Qt Code:

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HSM::HSM(QWidget *parent, Qt::WFlags flags)
	: QDialog(parent, flags)
{
 
	ui.setupUi(this);
 
	QObject::connect(this, SIGNAL(SendMSG(QString)),
		this, SLOT(SetLine(QString cMsg)));// ???????
}
 
HSM::~HSM()
{
	//m_pPrj->FreeInst();
}
 
void HSM::on_pushButton_clicked()
{
	//some code
}
 
void HSM::SetLine(QString cMsg)
{
	ui.listWidget->addItem(cMsg);
}

HSM::HSM(QWidget *parent, Qt::WFlags flags)
	: QDialog(parent, flags)
{

	ui.setupUi(this);

	QObject::connect(this, SIGNAL(SendMSG(QString)),
		this, SLOT(SetLine(QString cMsg)));// ???????
}

HSM::~HSM()
{
	//m_pPrj->FreeInst();
}

void HSM::on_pushButton_clicked()
{
	//some code
}

void HSM::SetLine(QString cMsg)
{
	ui.listWidget->addItem(cMsg);
}

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Qt Code:

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class FortuneThread : public QThread
{
    Q_OBJECT
public:
    FortuneThread(int socketDescriptor,QObject *parent);
	~FortuneThread();
    void run();
signals:
    void error(QTcpSocket::SocketError socketError);
private:
    int socketDescriptor;	
};

class FortuneThread : public QThread
{
    Q_OBJECT
public:
    FortuneThread(int socketDescriptor,QObject *parent);
	~FortuneThread();
    void run();
signals:
    void error(QTcpSocket::SocketError socketError);
private:
    int socketDescriptor;	
};

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Qt Code:

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FortuneThread::FortuneThread(int socketDescriptor,QObject *parent)
    : QThread(parent), socketDescriptor(socketDescriptor)
{
 
}
 
FortuneThread::~FortuneThread()
{
 
}
void FortuneThread::run()
{
	Connection connection;
	if(!connection.setSocketDescriptor(socketDescriptor))
	{
		emit error(connection.error());
		return;
	}
	connect(&connection, SIGNAL(disconnected()), this, SLOT(quit()));
	exec();
}

FortuneThread::FortuneThread(int socketDescriptor,QObject *parent)
    : QThread(parent), socketDescriptor(socketDescriptor)
{
	
}

FortuneThread::~FortuneThread()
{

}
void FortuneThread::run()
{
	Connection connection;
	if(!connection.setSocketDescriptor(socketDescriptor))
	{
		emit error(connection.error());
		return;
	}
	connect(&connection, SIGNAL(disconnected()), this, SLOT(quit()));
	exec();
}

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Qt Code:

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class Connection : public QTcpSocket
{
    Q_OBJECT
public:
    Connection(QObject *parent = 0);
private slots:
    void processReadyRead();
signals:
	void SendMSG(QString cMsg);
 
};

class Connection : public QTcpSocket
{
    Q_OBJECT
public:
    Connection(QObject *parent = 0);
private slots:
    void processReadyRead();
signals:
	void SendMSG(QString cMsg);

};

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Qt Code:

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Connection::Connection(QObject *parent)
    : QTcpSocket(parent)
{
	QObject::connect(this, SIGNAL(readyRead()), this, SLOT(processReadyRead()));
}
 
void Connection::processReadyRead()
{
 
//some code
//
//
	emit SendMSG("new_line");	
}

Connection::Connection(QObject *parent)
    : QTcpSocket(parent)
{
	QObject::connect(this, SIGNAL(readyRead()), this, SLOT(processReadyRead()));
}

void Connection::processReadyRead()
{

//some code
//
//
	emit SendMSG("new_line");	
}

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Qt Code:

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class Server : public QTcpServer
{
    Q_OBJECT
public:
    Server(QObject *parent = 0);
signals:
    void newConnection(Connection *connection);
protected:
    void incomingConnection(int socketDescriptor);
};

class Server : public QTcpServer
{
    Q_OBJECT
public:
    Server(QObject *parent = 0);
signals:
    void newConnection(Connection *connection);
protected:
    void incomingConnection(int socketDescriptor);
};

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Qt Code:

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Server::Server(QObject *parent):QTcpServer(parent)
{
	if (!listen(QHostAddress::Any,1718)) {
		return;
	}
}
 
void Server::incomingConnection(int socketDescriptor)
{
 
	FortuneThread *thread = new FortuneThread(socketDescriptor,this);
	connect(thread, SIGNAL(finished()), thread, SLOT(deleteLater()));
	thread->start();
 
}

Server::Server(QObject *parent):QTcpServer(parent)
{
	if (!listen(QHostAddress::Any,1718)) {
		return;
	}
}

void Server::incomingConnection(int socketDescriptor)
{

	FortuneThread *thread = new FortuneThread(socketDescriptor,this);
	connect(thread, SIGNAL(finished()), thread, SLOT(deleteLater()));
	thread->start();
	
}

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But at connection of the client record all the same does not appear Where I was mistaken?

**marcel** · 26th July 2007, 16:53

In the constructor of HSM.
There is no signal HSM::SendMSG(). The signal is in Connection. If you look at the debug output you will see a warning.

You could chain the signals. Connect SendMsg to a a signal in the FortuneThread. This signal should be connected in the GUI, to the slot SetLine.

This is because the GUI thread does not have access to Connection.

Where do you instantiate and start the thread?

Regards

**Fastman** · 26th July 2007, 18:05

Originally Posted by marcel

Where do you instantiate and start the thread?

Qt Code:

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void Server::incomingConnection(int socketDescriptor)
{
    FortuneThread *thread = new FortuneThread(socketDescriptor,this);
    connect(thread, SIGNAL(finished()), thread, SLOT(deleteLater()));
    thread->start();
}

void Server::incomingConnection(int socketDescriptor)
{
    FortuneThread *thread = new FortuneThread(socketDescriptor,this);
    connect(thread, SIGNAL(finished()), thread, SLOT(deleteLater()));
    thread->start();
}

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**marcel** · 26th July 2007, 18:23

Yes, but this line:

Qt Code:

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QObject::connect(this, SIGNAL(SendMSG(QString)),
this, SLOT(SetLine(QString cMsg)));// ???????

QObject::connect(this, SIGNAL(SendMSG(QString)),
this, SLOT(SetLine(QString cMsg)));// ???????

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is incorrect.

In incommingConnection, add:

Qt Code:

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connect(thread, SIGNAL(SendMSG(QString)), this, SLOT(SetLine(QString)));

connect(thread, SIGNAL(SendMSG(QString)), this, SLOT(SetLine(QString)));

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Add a signal in the FortuneThread class:

Qt Code:

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void SendMSG(QString);

void SendMSG(QString);

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and in FortuneThread::run(), add:

Qt Code:

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connect(&connection, SIGNAL(SendMSG(QString)), this, [B]SIGNAL[/B](SendMSG(QString)));

connect(&connection, SIGNAL(SendMSG(QString)), this, [B]SIGNAL[/B](SendMSG(QString)));

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Regards

**Fastman** · 26th July 2007, 19:11

Thanks for your answers, I shall try tomorrow. I shall necessarily write that has turned out

**marcel** · 26th July 2007, 21:01

OK. If you do things correctly, it will work.

Regards

**Fastman** · 27th July 2007, 09:09

Originally Posted by marcel

OK. If you do things correctly, it will work.

Regards

OOOO !!!! Realy Work !!!!!!
Marcel = Guru

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