QT自带的进度条，设置qss样式border-radius: 15px;，会有一个问题，进度条刚开始进度为1%时，由于进度条的宽度小于radius的大小，刚开始的进度条并不是圆角的，而是方角的，为了解决这个问题，自定义类QProgressBar，对paintEvent(QPaintEvent*e)进行重载，重新绘制进度条。 实现效果：
void ProgressBar::paintEvent(QPaintEvent *e) { //height-40px; QPainter painter(this); QPainterPath draw_path; int radius=20; double percent=static_cast<double>(value())/static_cast<double>(maximum()); percent=percent/15; painter.setRenderHint(QPainter::Antialiasing); while (radius*2>height()) { radius--; } draw_path.clear(); draw_path.moveTo(radius,0); draw_path.arcTo(QRect(0,0,radius*2,radius*2),90,90); draw_path.lineTo(0,height()-radius); draw_path.arcTo(QRect(0,0,radius*2,radius*2),180,90); draw_path.lineTo(width()-radius,height()); draw_path.arcTo(QRect(width()-radius*2,0,radius*2,radius*2),270,90); draw_path.lineTo(width(),radius); draw_path.arcTo(QRect(width()-radius*2,0,radius*2,radius*2),0,90); draw_path.lineTo(radius,0); if(value()>0){ painter.fillPath(draw_path,QColor("#D8D8D8")); }else{ painter.fillPath(draw_path,Qt::transparent); //若进度位0%，进度条自动隐身 } draw_path.clear(); double x_move=(percent*width()); double theta=acos(abs(x_move-radius)/radius); double y_move=(sin(theta)*radius); if(percent*width()<=radius){ draw_path.moveTo(x_move,radius-y_move); draw_path.arcTo(QRect(0,0,radius*2,radius*2),static_cast<int>(180-theta/M_PI*180),static_cast<int>(theta/M_PI*180)); draw_path.arcTo(QRect(0,0,radius*2,radius*2),180,static_cast<int>(theta/M_PI*180)); draw_path.lineTo(static_cast<int>(x_move),static_cast<int>(radius-y_move)); // painter.setPen(QColor(0, 0, 0)); // painter.drawArc(QRect(0,0,radius*2,radius*2),static_cast<int>(180-theta/M_PI*180)*16,static_cast<int>(theta/M_PI*180)*16); // painter.drawArc(QRect(0,0,radius*2,radius*2),180*16,static_cast<int>(theta/M_PI*180)*16); // painter.drawLine(QPointF(x_move,radius+y_move),QPointF(x_move,radius-y_move)); } else if(percent*width()<radius*2){ draw_path.moveTo(radius,0); draw_path.arcTo(QRect(0,0,radius*2,radius*2),90,90); draw_path.arcTo(QRect(0,0,radius*2,radius*2),180,90); draw_path.arcTo(QRect(0,0,radius*2,radius*2),270,static_cast<int>(90-theta/M_PI*180)); draw_path.lineTo(static_cast<int>(x_move),static_cast<int>(radius-y_move)); draw_path.arcTo(QRect(0,0,radius*2,radius*2),90-static_cast<int>(90-theta/M_PI*180),static_cast<int>(90-theta/M_PI*180)); // painter.setPen(QColor(0, 0, 0)); // painter.drawArc(QRect(0,0,radius*2,radius*2),90*16,90*16); // painter.drawArc(QRect(0,0,radius*2,radius*2),180*16,90*16); // painter.drawArc(QRect(0,0,radius*2,radius*2),270*16,static_cast<int>(90-theta/M_PI*180)*16); // painter.drawLine(QPointF(x_move,radius+y_move),QPointF(x_move,radius-y_move)); // painter.drawArc(QRect(0,0,radius*2,radius*2),(90-static_cast<int>(90-theta/M_PI*180))*16,static_cast<int>(90-theta/M_PI*180)*16); }else{ qDebug()<<"3"<<percent; draw_path.moveTo(radius,0); draw_path.arcTo(QRect(0,0,radius*2,radius*2),90,90); draw_path.lineTo(0,height()-radius*2); draw_path.arcTo(QRect(0,0,radius*2,radius*2),180,90); draw_path.lineTo(percent*width()-radius*2,height()); draw_path.arcTo(QRect(static_cast<int>(percent*width())-radius*2,0,radius*2,radius*2),270,90); draw_path.lineTo(percent*width(),radius*2); draw_path.arcTo(QRect(static_cast<int>(percent*width()-radius*2),0,radius*2,radius*2),0,90); draw_path.lineTo(radius*2,0); } painter.fillPath(draw_path,QColor("#67B5B7")); }