QListWidget refresh issue

[summer_of_69]

Hi All,

I am using QListWidget to show output ( e.g:- similar to output window you see in VS2005 IDE) .The problem I am facing is it's not updating accordingly,can anyone help me with this.
I want it to add one item each second and show the updated result , but it just shows whole list after 5 second.

void POCSleep::on_pushButton_clicked()
{
	for(int i=0; i<5;i++)
	{
		ui.listWidget->update();
		mySleep(1); /* delay of one second*/
		displayMessage(QString("Number is: %1\n").arg( i+1));
	}
}
void POCSleep::displayMessage(QString qmsg)
{
	ui.listWidget->addItem(qmsg);
}

void POCSleep::on_pushButton_clicked()
{
	for(int i=0; i<5;i++)
	{
		ui.listWidget->update();
		mySleep(1); /* delay of one second*/
		displayMessage(QString("Number is: %1\n").arg( i+1));
	}
}
void POCSleep::displayMessage(QString qmsg)
{
	ui.listWidget->addItem(qmsg);
}

To copy to clipboard, switch view to plain text mode 

Thanks in advance.

[Lykurg]

Your sleep functions blocks the gui! Also that is not a good design. If you want it that way have a look at QCoreApplication::processEvents() and there is also an article on qt Quarterly about keepeing a gui app responsibly.

[summer_of_69]

Ok. May be I shall explain the whole scenerio.
I have one script (set of certain functions and commands) running at background ,It prints lot of information (till now I was using printf()) ,but now I want the same messages to be displayed in my DockWidget which contains QListWidget (for displaying messages).

What would be the appropriate way of doing this?

[shentian]

Is the script running in another process? If so, use QProcess to start it and read the messages from there. You can connect to QIODevice::readyRead to get notified when the process has written data to stdout.

[Lykurg]

What would be the appropriate way of doing this?

Use a worker thread for your "set of certain functions and commands" and use the signal slot mechanism to show the messages.

[summer_of_69]

void POCSleep::on_pushButton_clicked()
{
	for(int i=0; i<5;i++)
	{
		ui.listWidget->update();
		mySleep(1); /* delay of one second*/
		displayMessage(QString("Number is: %1\n").arg( i+1));
	}
}
void POCSleep::displayMessage(QString qmsg)
{
	ui.listWidget->addItem(qmsg);
}

void POCSleep::on_pushButton_clicked()
{
	for(int i=0; i<5;i++)
	{
		ui.listWidget->update();
		mySleep(1); /* delay of one second*/
		displayMessage(QString("Number is: %1\n").arg( i+1));
	}
}
void POCSleep::displayMessage(QString qmsg)
{
	ui.listWidget->addItem(qmsg);
}

To copy to clipboard, switch view to plain text mode 

Thanks for your valuable reply,this will definitely work.

One thing I am unable to understand why worker thread is required for this?
Can it be done in simpler way?? I have one class which take care of all script related functionalities I just need to call functions using my Dialog and display related error messages or any messages(which can be done in console using printf()) in my Qlistwidget.

[Lykurg]

If you don't want that your GUI thread is blocked (this is the case when u use sleep) then you have to use your own treads or call processEvents().

In Your case you also can use a QTimerLine or use QtConcurrent, depends on what you really want achieve. Your posted code seems to me like a "first testing". If you really only want to print 5 messages with a 1 second delay, then use QTimerLine.