qt之QPainter绘制三种圆形的方式

void MainWindow::paintEvent(QPaintEvent *event){QMainWindow::paintEvent(event);QPainter painter(this);QPen pen(Qt::blue,8);pen.setCapStyle(Qt::RoundCap);pen.setJoinStyle(Qt::RoundJoin);painter.setPen(pen);painter.setBrush(Qt::NoBrush);// 关键：无填充painter.drawEllipse(10,10,100,100);painter.drawArc(120,10,100,100,0,360*16);//后面两个参数表示起始角度和终点角度QPainterPath path;path.moveTo(230+100, 60);//移动到起始位置path.arcTo(230, 10, 100, 100, 0, 360);path.closeSubpath();  // 闭合路径painter.drawPath(path);}