QProgressBar is a Qt class that provides a progress bar, which can be either horizontal or vertical.
The QProgressBar uses steps to show the progress. To use it, the minimum and maximum values should be specified. After that, when the progress bar receives a current step value, it will update itself to show the percentage of steps completed.
If both values are set to 0, the progress bar will turn into a "busy" indicator. An example of this is the following:
QProgressBar * b = new QProgressBar();
b->setMinimum(0);
b->setMaximum(0);
b->show();
Official documentation can be found here.
