如何使用Qt自定义控件实现进度仪表盘

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具体内容如下

思路：外围的线共100根（自定义，可改变），总共占270度，然后按照 先画一条线然后旋转坐标系的思路画出完整的线。内部即是一个灰色的背景圆，一个圆弧和中间的value对应的文字。

关键代码：CMPassrate2.cpp

void CMPassrate2::paintEvent(QPaintEvent *event){//界面绘制事件 int width = this->width(); int height = this->height(); int side = qMin(width, height); QPainter painter(this); painter.setRenderHints(QPainter::Antialiasing | QPainter::TextAntialiasing); painter.translate(width / 2, height / 2); painter.scale(side / 200.0, side / 200.0); drawBGE(&painter); //画背景圆 drawTextE(&painter);//画文字所在圆弧 drawText(&painter);//画文字 drawLines(&painter);//画最外部的线}void CMPassrate2::updateValue(float value){//提供给外部的方法，用于更新value this->value = value; update();//每次更新value后，都重绘界面}void CMPassrate2::drawLines(QPainter* painter){ painter->save(); QPen pen; pen.setColor(QColor("#A7DD42")); pen.setWidth(2); painter->setPen(pen); float range = 270.0/lineCount; //自定义所有的线加起来占270度，100条线 painter->rotate(135);//旋转135度，开始画线，总共画270度。 QLine line(QPoint(outLineRadius,0),QPoint(innLineRadius,0)); for(int i = 1;i<=lineCount;i++){  if(i>value){   QPen pen;   pen.setColor(QColor("#D7D7D7"));   pen.setWidth(2);   painter->setPen(pen);  }  painter->drawLine(line);  painter->rotate(range); } painter->restore();}void CMPassrate2::drawBGE(QPainter* painter){ painter->save(); painter->setPen(Qt::NoPen); painter->setBrush(QColor("#EAEAEA")); QRect rect(-bgERadius,-bgERadius,bgERadius*2,bgERadius*2); painter->drawEllipse(rect); painter->restore();}void CMPassrate2::drawTextE(QPainter* painter){ painter->save(); painter->setPen(Qt::NoPen); painter->setBrush(QColor("#2DC877")); QPainterPath path; QRect rectOut(-textOutRadius,-textOutRadius,textOutRadius*2,textOutRadius*2); path.arcTo(rectOut,0,360); QPainterPath subPath; QRect rectInn(-textInnRadius,-textInnRadius,textInnRadius*2,textInnRadius*2); subPath.addEllipse(rectInn); path -= subPath; painter->drawPath(path); painter->restore();}void CMPassrate2::drawText(QPainter* painter){ painter->save(); painter->setPen(QColor("#62A0DB")); QRect rectInn(-textInnRadius,-textInnRadius,textInnRadius*2,textInnRadius*2); QFont font = painter->font(); font.setPixelSize(textSize); painter->setFont(font); painter->drawText(rectInn,Qt::AlignCenter,QString::number(value)); painter->restore();}