How can I draw with brush on QLabel?

[suseway]

I have QLabel on the form. I use it to show an image like this:

QString fileName = "image.jpg";
    QImage image(fileName);
    ui->label->setPixmap(QPixmap::fromImage(image.scaled(349,228, Qt::KeepAspectRatio, Qt::FastTransformation)));
    ui->label->adjustSize();

QString fileName = "image.jpg";
    QImage image(fileName);
    ui->label->setPixmap(QPixmap::fromImage(image.scaled(349,228, Qt::KeepAspectRatio, Qt::FastTransformation)));
    ui->label->adjustSize();

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How can I paint with brush on my QLabel with mouse? For example, i press left mouse key, then dragging, it lefts brush'es line, then the results - on the QLabel.