QPainter painter(this);
    painter.save(); //保存原来坐标系统
    painter.translate(200, 300);
    painter.rotate(210); //坐标旋转degrees 度
    painter.drawRect (60,30,50,40);
    painter.drawEllipse (0,0,50,80);
    painter.drawEllipse (0,0,5,6);
    painter.restore(); //回复原来的坐标系统