Fixed text inside or adjacent to QProgressBar with scaling font size in Qt

Question

I am new with Qt (using Qt Creator) and the QProgressBar. I am interested in learning how to have a fixed text value (not the value of the progress bar) inside or adjacent to the left of a QProgressBar and have its font size scale according with the size of the progress bar.

For example:

or

I have considered using a QLabel but failed and I could not find any examples online.

Any code sample illustrating the solution for me to understand and learn from will be much appreciated.

Answer 1

If label inside the progressbar will do, then here is an example. This might not be exactly what you want, but it should send you in the right direction. I adjust the font size in the resize event. In this example the font size is calculated based on the size of the label, which is the same size as the progress bar.

#include <QApplication>
#include <QProgressBar>
#include <QWidget>
#include <QLabel>
#include <QLayout>
#include <QTimer>

class Widget : public QWidget
{
    Q_OBJECT
    QProgressBar progressBar;
    QLabel *label;
public:
    Widget(QWidget *parent = nullptr) : QWidget(parent)
    {
        progressBar.setRange(0, 100);
        progressBar.setValue(20);
        progressBar.setTextVisible(false);
        progressBar.setSizePolicy(QSizePolicy::Preferred, QSizePolicy::Minimum);
        label = new QLabel(&progressBar);
        label->setText("Hello World!");

        setLayout(new QHBoxLayout);
        layout()->addWidget(&progressBar);
    }

protected:
    void resizeEvent(QResizeEvent *)
    {
        label->resize(progressBar.size());
        QFontMetrics fm(label->font());
        float multiplier_horizontal = (float)label->width() / fm.width(label->text());
        float multiplier_vertical = (float)label->height() / fm.height();
        QFont font = label->font();
        font.setPointSize(font.pointSize() * qMin(multiplier_horizontal, multiplier_vertical));
        label->setFont(font);
    }
};

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    Widget w;
    w.show();

    return a.exec();
}

#include "main.moc"