void MainWindow::Painter() { QPainter painter; QImage image(500,500,QImage::Format_ARGB32); painter.begin(&image); painter.drawLine(QPoint(0,0),QPoint(100,100)); QPen pen(Qt::green,5,Qt::DotLine,Qt::RoundCap,Qt::RoundJoin); painter.setPen(pen); QRect rectangle(70.0,40.0,80.0,60.0); int startAngle=30*16; int spanAngle=120*16; painter.drawArc(rectangle,startAngle,spanAngle); painter.end(); ui->label->setPixmap(QPixmap::fromImage(image)); }