How can I have a Progressbar with movement

[roseicollis]

Hi,

I want to have a progressbar with some movement on it so the user can be able to know if the application is responding and wroking or not.

Something like this being a pbar: http://www.telex.com/binary/mapLoadBar.gif.pagespeed.ce.2tpbbkj2Zu.gif

Any idea about if Qt allows you to do it?

Thanks!

[anda_skoa]

Some platforms have an animation for progressbars even when there is no change to the actual value.

If you want a progressbar that shows progress for an unknown "total", set both minimum and maximum to 0 and just increment the value on each step.

Cheers,
_

[roseicollis]

Hi,

If I put

ui->pBar->setMinimum(0);
ui->pBar->setMaximum(0);
and then when I want I put: ui->pBar->setValue(value); incrementing the value everytime I call this line

then the pbar is static and does nothing, not movement and not increment.

[sulliwk06]

my first thought would be to make sure your event loop is running while you are incrementing the value

[anda_skoa]

Yes, this definitely works.



#include <QtWidgets>

int main(int argc, char ** argv)
{
QApplication app(argc, argv);

QProgressBar bar;
bar.setMinimum(0);
bar.setMaximum(0);
bar.resize(300, bar.sizeHint().height());
bar.show();

QTimer timer;
QObject::connect(&timer, &QTimer::timeout, [&bar]() { bar.setValue(bar.value() + 1); });
timer.start(500);

return app.exec();
}



TEMPLATE = app

QT += widgets
CONFIG += c++11

SOURCES = progressbartest.cpp

[nish]

Looks like your gui thread is busy doing stuff and cant update the progressbar. So either move your logic to another thread or call processEvents somewhere periodically.

[roseicollis]

Hi,

anda_skoa thanks for your time. About your answer.. that code gaves me so much problems.

Obviously I don't have this cpp... dunno for what is that line but I didnt wrote it:

SOURCES = progressbartest.cpp

But apart of that it says that:
void QTimer::timeout() is protected
and
no matching function for call to 'QObject::connect(QTimer*, void (QTimer::*)(),miain(int, char**)::<lambda()>)'

Im using this version of Qt over unix:

Qt Creator 2.8.0
Based on Qt 4.8.5

[wysota]

Im using this version of Qt over unix:

Qt Creator 2.8.0
Based on Qt 4.8.5

I suggest you update your forum user profile as it says you are using Qt5. The code anda_skoa provided will not work with Qt4 as it is using a lambda expression. I'm not sure why you'd run it though, if he says it works then you should focus on what is different in your own code.

[roseicollis]

Nish I already have 2 threads, one for GUI and another for the background job... but I must be doing something wront

wysota, totally agree with u, I have to apologize to anda_skoa.. I thought I was using Qt5 until I wanted to verify it and saw that -.-'' I've tried to use it just like
mybar.setMinimum(0);
mybar.setMaximum(0);

but then the thread stops because I have a gif on it (until I get that pbar with movement) and it stops moving....

[anda_skoa]

Obviously I don't have this cpp... dunno for what is that line but I didnt wrote it:

SOURCES = progressbartest.cpp

That is obviously the C++ code I've posted.



Based on Qt 4.8.5

Works the same way in Qt4 as far as the progressbar is concerned.



#include <QtGui>

class Advancer : public QObject
{
Q_OBJECT
public:
explicit Advancer(QProgressBar *bar) : QObject(bar), mBar(bar)
{
connect(&mTimer, SIGNAL(timeout()), this, SLOT(advance()));
}

void start(int interval)
{
mTimer.start(interval);
}

private:
QProgressBar *mBar;
QTimer mTimer;

private slots:
void advance()
{
mBar->setValue(mBar->value() + 1);
}
};

int main(int argc, char ** argv)
{
QApplication app(argc, argv);

QProgressBar bar;
bar.setMinimum(0);
bar.setMaximum(0);
bar.resize(300, bar.sizeHint().height());
bar.show();

Advancer *advancer = new Advancer(&bar);
advancer->start(500);

return app.exec();
}

#include "progressbartestqt4.moc"




TEMPLATE = app

SOURCES = progressbartestqt4.cpp


Cheers,
_