小编给大家分享一下如何使用Qt自定义控件实现多彩色仪表盘，相信大部分人都还不怎么了解，因此分享这篇文章给大家参考一下，希望大家阅读完这篇文章后大有收获，下面让我们一起去了解一下吧！
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具体内容如下
Qt自定义控件4：多彩色仪表盘
思路：外围三色的圆弧 红：蓝：绿 = 1：2：1，总共占270度。刻度线是根据所在圆弧的颜色而画，刻度线的角度也是根据坐标系的旋转而画。刻度值是根据刻度线的角度得到所要画的刻度的左上角的坐标，然后构成一个矩形，根据矩形画出刻度值。指针是根据四个点的坐标直接画的四边形，再旋转坐标系实现指针旋转的效果。下方的文字直接得到坐标横纵坐标位置得到矩形画出value的值
关键代码：CMPassrate3.cpp
void CMPassrate3::paintEvent(QPaintEvent *event){ 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); drawBG(&painter); drawE(&painter); drawLine(&painter); drawText(&painter); drawBootomText(&painter); drawPoint(&painter);}void CMPassrate3::drawE(QPainter* painter){ painter->setPen(Qt::NoPen); QRect rectOut(-outRadius,-outRadius,2*outRadius,2*outRadius); QRect rectInn(-innRadius,-innRadius,2*innRadius,2*innRadius); painter->save(); painter->setBrush(QColor("#04EEB2")); QPainterPath path; path.arcTo(rectOut,-45,270.0/4); QPainterPath subPath; subPath.addEllipse(rectInn); path -= subPath; painter->drawPath(path); painter->restore(); painter->save(); QPainterPath bluePath; QPainterPath blueSubPath; painter->setBrush(QColor("#2DC5F6")); bluePath.arcTo(rectOut,-45+(270.0/4),270.0/2); blueSubPath.addEllipse(rectInn); bluePath -= blueSubPath; painter->drawPath(bluePath); painter->restore(); painter->save(); QPainterPath redPath; QPainterPath redSubPath; painter->setBrush(QColor("#FA468C")); redPath.arcTo(rectOut,-45+270.0*3/4,270.0/4); redSubPath.addEllipse(rectInn); redPath -= redSubPath; painter->drawPath(redPath); painter->restore();}void CMPassrate3::drawLine(QPainter* painter){ painter->save(); painter->rotate(135); //270/8度一格 for(int i = 0;i<9;i++){ if(i<3){ painter->setPen(QColor("#FA468C")); }else if(i<6){ painter->setPen(QColor("#2DC5F6")); }else{ painter->setPen(QColor("#04EEB2")); } QLine line(QPoint(lineStart,0),QPoint(innRadius,0)); painter->drawLine(line); painter->rotate(270.0/8); } painter->restore();}void CMPassrate3::drawPoint(QPainter* painter){ const QPoint point[4]{ QPoint(0,0),QPoint(0,6),QPoint((lineStart-3)*qCos(135*3.14/180),(lineStart-3)*qSin(135*3.14/180)),QPoint(-6,0) }; float range = 270.0/100*value; painter->save(); painter->setBrush(QColor("#C2E481")); painter->rotate(range); painter->drawConvexPolygon(point,4); painter->restore();}void CMPassrate3::drawBG(QPainter* painter){//可以自行添加背景图片实现更加精美的效果// painter->save();// QImage image(":/image/images/bg1.jpg");// QRect rect(-this->width(),-this->height(),this->width()*2,this->height()*2);// painter->drawImage(rect,image);// painter->restore();}void CMPassrate3::drawText(QPainter *painter){ painter->save(); //初始为 painter->setPen(Qt::black); QFont font = painter->font(); font.setPixelSize(8); painter->setFont(font); float x,y; for(float i =0;i<=100;i+=12.5){ x = lineStart*qCos((135+(270.0/8)*((i+1)/12.5))*3.14/180); y = lineStart*qSin((135+(270.0/8)*((i+1)/12.5))*3.14/180); QRect rect; if(i<50){ rect.setX(x); rect.setY(y); }else if(i>50){ rect.setX(x-17); rect.setY(y-7); }else{ rect.setX(x); rect.setY(y); } rect.setWidth(17); rect.setHeight(10); painter->drawText(rect,Qt::AlignCenter,QString::number(i)); } painter->restore();}void CMPassrate3::drawBootomText(QPainter *painter){ painter->save(); painter->setPen(Qt::black); QFont font = painter->font(); font.setPixelSize(25); painter->setFont(font); painter->translate(0,outRadius-12); int length = 20; QRect rect(-length,-length,length*2,length*2); painter->drawText(rect,Qt::AlignCenter,QString::number(value)); painter->restore();}以上是“如何使用Qt自定义控件实现多彩色仪表盘”这篇文章的所有内容，感谢各位的阅读！相信大家都有了一定的了解，希望分享的内容对大家有所帮助，如果还想学习更多知识，欢迎关注创新互联行业资讯频道！
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