#include <QApplication>
#include <QBoxLayout>
#include <QPlainTextEdit>
#include <QPushButton>

int main(int argc, char *argv[])
{
    // comment out this line to be able to switch antialising
    QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
    QApplication a(argc, argv);

    auto layout = new QVBoxLayout;
    auto edit = new QPlainTextEdit;
    edit->setPlainText("this is a test\nfor turning on antialiasing\nof fonts\n");
    auto button = new QPushButton("switch AA");
    layout->addWidget(edit);
    layout->addWidget(button);
    QObject::connect(button, &QPushButton::pressed, [edit]() {
        QFont f = edit->font();
        f.setStyleStrategy(f.styleStrategy() & QFont::NoAntialias ? QFont::PreferAntialias
                                                                  : QFont::NoAntialias);
        edit->setFont(f);
    });

    QWidget w;
    w.setLayout(layout);
    w.show();
    return a.exec();
}