Change font of QTabWidget

[krzysieklfc]

I read that QTabWidget uses OS specific styling and it may be tricky to change the look. I experimented a lot but still can't figure it out.
I subclassed both QTabWidget and QTabBar and set the custom TabBar.

void TabBar::tabBarPaintEvent(QPaintEvent* event)
{
	QStylePainter painter(this);
	QStyleOptionTab opt;

	for (int i = 0; i != count(); i++)
	{
		initStyleOption(&opt, i);
		painter.setFont(QFont("Roboto", 15));
		painter.drawControl(QStyle::CE_TabBarTabShape, opt);
		painter.drawControl(QStyle::CE_TabBarTabLabel, opt);
	}
}

[KillerSmath]

Hi @krzysieklfc and welcome to Qt Forum.

The QTabBar uses a default style to paint itself.
You can change the font family, font size, background color and several properties using a QProxyStyle to change how the QTabBar is painted.

#include <QProxyStyle>
#include <QPainter>

class TabBarProxyStyle : public QProxyStyle {
public:
    TabBarProxyStyle(QStyle *style = nullptr) : QProxyStyle(style) { }

    void drawControl(ControlElement element, const QStyleOption* option, QPainter* painter, const QWidget* widget) const override
    {
        if (element == CE_TabBarTab) {
            painter->save(); // save the painter to restore later
            painter->setFont(QFont("Roboto", 15)); // change the defaul font of painter
            QProxyStyle::drawControl(element, option, painter, widget); // paint the TabBarTab using the default drawControl
            painter->restore(); // restore to default painter
        }
        else{
            QProxyStyle::drawControl(element, option, painter, widget); // use default drawControl to paint all other components without changes.
        }
    }
};

So, you just need to change the default style to the custom ProxyStyle

tabWidget->tabBar()->setStyle(new TabBarProxyStyle);