QTimer: Getting Started problems

[bodzio131]

I'm not sure you can omit brackets for slot state_update, probably should be:
@
connect( timer, SIGNAL( timeout() ), this, SLOT( state_update() ) );
@

Instead of QTimer you could also use QDialog::startTimer and virtual QDialog::timerEvent.

[SGaist]

Hi,

Remove the paintEvent, you are not painting anything.

@
void mita_screen::state_update()
{
ui->label->setText(QString("%1").arg(++mita_state));
}@

Is enough to update the label at on your timer's time out.

Why do you delete your ui variable in on_pushButton_clicked ? Also note, that it's already deleted in the destructor, so calling that function, then the destructor will cause a crash.

If you want to close the dialog, connect the pushButton clicked signal on the close slot of the dialog.

Hope it helps

[raven-worx]

change your connect-statement to:
@connect(timer, SIGNAL(timeout()), this, SLOT(state_update()));@

Edit: nvm ... too late :)

[tomma]

You just increment mita_state but never update it to screen.
Remove your "paintEvent":http://qt-project.org/doc/qt-4.8/qwidget.html#paintEvent implementation, which is all wrong, and update label text in state_update().

Also your connect call in line 14 should be @connect(timer, SIGNAL(timeout()), this, SLOT(state_update()));@

[sierdzio]

Slot connection is probably wrong

No need to reimplement the paint event

This should work:
@
mita_screen::mita_screen(QWidget *parent) :
QDialog(parent),
ui(new Ui::mita_screen)
{
mita_screen::setWindowFlags(Qt::SplashScreen);
ui->setupUi(this);

mita_state = 0;     // Initialise the state machine

QTimer *timer = new QTimer(this);
connect(timer, SIGNAL(timeout()), this, SLOT(state_update()));
timer->start(1000);

}

void mita_screen::state_update()
{
mita_state++;
ui->label->setText(QString::number(mita_state));

}
@

[sierdzio]

Wow, we really flooded the poor guy :)

[raven-worx]

[quote author="sierdzio" date="1366112776"]Wow, we really flooded the poor guy :)[/quote]

yep...within 3 mins ... lol

[SGaist]

[quote author="sierdzio" date="1366112776"]Wow, we really flooded the poor guy :)[/quote]

Like one other user said, we're parallelizing :D

[sierdzio]

Yeah, but it would be a tad better to spread across different threads (pun well intended :)).

[jastmc]

Hey, don't knock it!

Its much better to get too many responses that none at all.

Thanks for all your help!

James

[jastmc]

SGaist said:-

bq. Why do you delete your ui variable in on_pushButton_clicked ? Also note, that it’s already deleted in the destructor, so calling that function, then the destructor will cause a crash.
If you want to close the dialog, connect the pushButton clicked signal on the close slot of the dialog.

I changed my code to connect the on_pushButton_clicked() signal to the ~mita_screen() slot but the button has no effect when pressed. See below.

Can anyone please tell me whats wrong here?

@#include "mita_screen.h"
#include "ui_mita_screen.h"

mita_screen::mita_screen(QWidget *parent) :
QDialog(parent),
ui(new Ui::mita_screen)
{
mita_screen::setWindowFlags(Qt::SplashScreen);
ui->setupUi(this);

mita_state = 0;     // Initialise the state machine

QTimer *timer = new QTimer(this);
connect(timer, SIGNAL(timeout()), this, SLOT(state_update()));
timer->start(1000);

connect(ui->pushButton, SIGNAL(on_pushButton_clicked()), this, SLOT(~mita_screen()));

}

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

void mita_screen::state_update()
{
ui->label->setText(QString("%1").arg(++mita_state));

}

void mita_screen::on_pushButton_clicked()
{

}

void mita_screen::on_pushButton_pressed()
{

}
@

[SGaist]

You're connecting to the destructor:

1.It's not a slot
2.Never call a destructor, it's done for you when the object is destroyed.

As I said, connect to the "close slot":http://qt-project.org/doc/qt-4.8/qwidget.html#close

[raven-worx]

you can't connect to a destructor. Since your widget is a dialog connect it to the close() slot and additionaly to the deleteLater() slot or set the "widget attribute":http://qt-project.org/doc/qt-4.8/qwidget.html#setAttribute: to Qt::WA_DeleteOnClose to let Qt delete the dialog for you.

[jastmc]

Sorry, that was an older version, somehow. Thanks for your patience!
With this code, the button is ignored and has no effect.

What I meant to post was:-

@#include "mita_screen.h"
#include "ui_mita_screen.h"
#include <QtGui>
#include <QLabel>

mita_screen::mita_screen(QWidget *parent) :
QDialog(parent),
ui(new Ui::mita_screen)
{
mita_screen::setWindowFlags(Qt::SplashScreen);
ui->setupUi(this);

mita_state = 0;     // Initialise the state machine

QTimer *timer = new QTimer(this);
connect(timer, SIGNAL(timeout()), this, SLOT(state_update()));
timer->start(1000);

connect(ui->pushButton, SIGNAL(on_pushButton_clicked()), this, SLOT(mita_screen::close() ));
connect(ui->pushButton, SIGNAL(on_pushButton_clicked()), this, SLOT(mita_screen::deleteLater() ));

}

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

void mita_screen::state_update()
{
static int counter=0;

ui->label->setText(QString("%1").arg(++mita_state));

}

void mita_screen::on_pushButton_clicked()
{

}

void mita_screen::on_pushButton_pressed()
{

}
@

[sierdzio]

In your connect statement:

Not:
@
SLOT(mita_screen::close())
@

Instead:
@
SLOT(close())
@

[SGaist]

on_pushButton_clicked is a slot.

Try this:
@
connect(ui->pushButton, SIGNAL(clicked()), SLOT(close()));
@

Have a look at the "signal/slot":http://qt-project.org/doc/qt-4.8/signalsandslots.html and the "designer":http://qt-project.org/doc/qt-4.8/designer-manual.html documentation to have a better understanding of how it works