qt5 仪表控件 码盘 电压表 油表 开源不装逼

首先声明，这是转载的，不过作者做的很漂亮，使得我无法拒绝给他转载。

效果：

原文：https://www.cnblogs.com/lifexy/p/9245918.html

原文比较啰嗦，我就简单摘录：

代码介绍

1.代码里通过 painter类来绘图,其中paintEvent()函数如下所示

void Dial::paintEvent(QPaintEvent *)
{
    QPainter painter(this);
    painter.setPen(Qt::NoPen);
    painter.setRenderHint(QPainter::Antialiasing,true);
    painter.setRenderHint(QPainter::SmoothPixmapTransform);
    painter.translate(width()/2,height()/2);
    radius = qMin(width(),height())/2;
    centerR=radius*0.4;       //设置中心圆大小
    drawObkColor(painter);           //外圆盘
    drawScalebkColor(painter);      //画刻度圆
    drawslideScaleColor(painter);   //画划过的颜色
    drawShade(painter);            //画阴影
    drawScaleColor(painter);
    drawbkColor(painter);          //画内圆
    drawScaleTextColor(painter);   //画刻度值
    drawPointColor(painter);
    drawCenterColor(painter);      //绘制中心圆
    drawIconValueColor(painter);
    drawlabelColor(painter);
}

2.然后进入drawObkColor()函数,来绘画外圆盘,函数如下所示

void Dial::drawObkColor(QPainter& paint)      //绘制外圆
{
        paint.save();
        QConicalGradient  Conical(0,0,90);
        Conical.setColorAt(0,oobkColor);
        Conical.setColorAt(0.5,oobkColor);
        Conical.setColorAt(0.12,oobkColor.darker(40));
        Conical.setColorAt(0.88,oobkColor.darker(40));
        Conical.setColorAt(0.4,oobkColor.darker(30));
        Conical.setColorAt(0.6,oobkColor.darker(30));
        Conical.setColorAt(0.25,oobkColor.darker(160));
        Conical.setColorAt(0.75,oobkColor.darker(160));
        Conical.setColorAt(1,oobkColor);
        paint.setBrush(Conical);
        paint.drawEllipse(QPointF(0,0), radius*0.96,radius*0.98);
        Conical.setAngle(270);
        Conical.setColorAt(0,obkColor.darker(40));
        Conical.setColorAt(0.5,obkColor.darker(40));
        Conical.setColorAt(0.25,obkColor.darker(160));
        Conical.setColorAt(0.75,obkColor.darker(160));
        paint.setBrush(Conical);
        paint.drawEllipse(QPointF(0,0), radius*0.93,radius*0.94);
        paint.restore();
}

外圆盘效果如下所示:

 

3.然后接下来开始画刻度圆,画了它后,才能开始画刻度和划过的颜色等

void Dial::drawScalebkColor(QPainter &paint)        //绘制刻度圆
{
    paint.save();
    paint.setBrush(bkColor);
    paint.drawEllipse(QPointF(0,0), radius*0.90,radius*0.90);

    paint.restore();
}

4.然后接下来开始画划过的颜色,就是上图指针划过后都会带有颜色的那种 (以单色颜色为例)

void Dial::drawslideScaleColor(QPainter &paint)    //画划过的颜色
{
    /*单一颜色*/  

    int Star_Angle= 210*16-(int)((value/(maxvalue-minvalue))*240*16);

    int spanAngle  =  210*16 - Star_Angle;

    if(spanAngle==0)
        return ;



    qreal SlideBottom =  ((qreal)radius*0.77)/((qreal)radius*0.90);    

    qreal SlideCenterTop = 1-(1-SlideBottom)/3;                        
    qreal SlideCenterBottom = SlideBottom+(1-SlideBottom)/3+0.01;      

    paint.save();

    QColor Tint_SlideColor = SingleSlideColor;


    QRadialGradient Radial(0,0,radius*0.90);


    Tint_SlideColor.setAlpha(40);
    Radial.setColorAt(1,Tint_SlideColor);
    Radial.setColorAt(SlideBottom-0.005,Tint_SlideColor);
    Radial.setColorAt(0,Qt::transparent);
    Radial.setColorAt(SlideBottom-0.006,Qt::transparent);


    Tint_SlideColor = SingleSlideColor;
    Tint_SlideColor.setAlpha(50);


    Radial.setColorAt(SlideCenterBottom-0.03,Tint_SlideColor);
    Radial.setColorAt(SlideCenterTop+0.03,Tint_SlideColor);

    Tint_SlideColor = SingleSlideColor;
    Tint_SlideColor.setAlpha(50);
    Radial.setColorAt(SlideCenterBottom-0.01,SingleSlideColor.darker(200));
    Radial.setColorAt(SlideCenterTop+0.01,SingleSlideColor.darker(200));

    Radial.setColorAt(SlideCenterBottom,SingleSlideColor);
    Radial.setColorAt(SlideCenterTop,SingleSlideColor);

    paint.setPen(Qt::NoPen);
    paint.setBrush(Radial);

    paint.drawPie(QRectF((qreal)-radius*0.90,(qreal)-radius*0.90,(qreal)radius*1.80,(qreal)radius*1.80),Star_Angle,spanAngle);

    paint.restore();
 


  //... ...  
   
}

效果:

5.然后接下来便开始画刻度和刻度值,其中比较重要的就是绘制刻度值

drawScaleTextColor()画刻度值函数如下所示:

void Dial::drawScaleTextColor(QPainter &paint)    //绘制刻度值
{
    /*绘制文字刻度*/
    paint.save();

    paint.setPen(ScaleColor);

    QString text("%1");

    int size;           //动态计算文字大小

    if(radius<=120)
       size = 10;
    else if((radius>120)&&(radius<500))
       size = 13+(radius-120)/30;
    else if(radius>=500)
       size = 13+(radius-120)/40;

    paint.setFont(QFont("Euphemia",size,QFont::DemiBold));

    QPoint TextPoint(0,radius*0.77-size*0.9);        //设置90°的文字
    TextPoint = CustomRotate(TextPoint,90,240);   //获取点=210°的文字位置
    qreal TextRotate=210;

     for(int i=0;i<7;i++)              //设置7个刻度值
    {
    
          //... ...

          qreal Current_Value =(qreal)i*((maxvalue-minvalue)/6);

          if((Current_Value>value&&(paint.pen().color()!=ScaleColor)))
          {
              paint.setPen(ScaleColor);

          }
          else if((Current_Value<=value&&(paint.pen().color()!=slideScaleColor)))
          {
              paint.setPen(slideScaleColor);
          }

       paint.drawText(QRect(TextPoint.x()-size*1.5+offest[i].x(),TextPoint.y()-size*1.2+offest[i].y(),size*3,size*2.4),alingns[i],text.arg((maxvalue-minvalue)*i/6));
       TextPoint = CustomRotate(TextPoint,TextRotate,40);   //获取点=210°的文字位置
       TextRotate-=40;
    }

    paint.restore();
}

效果如下所示:

6.然后接下来开始画指针

void Dial::drawPointColor(QPainter &paint)          //绘制指针
{

    qreal PointTop;                //动态计算指针头
    qreal PointBottom;             //动态计算指针底部
    if(radius<=120)
    {
        PointTop = 2;
        PointBottom = 6;
    }
    else if((radius>120)&&(radius<500))
    {
        PointTop = 2 + (radius-120)/100;
        PointBottom = PointTop*3;
    }
    else if(radius>=500)
    {
        PointTop = 2 + (radius-120)/140;
        PointBottom = PointTop*3;
    }

    //指针
    const QPointF  Pointer[4] = {
        QPointF(- PointTop / 2, radius*0.80),
        QPointF(PointTop / 2, radius*0.80),
        QPointF(PointBottom / 2, centerR*0.9),
        QPointF(-PointBottom / 2, centerR*0.9)
    };

    paint.save();


    paint.setBrush(PointerColor);
    paint.setPen(PointerColor.darker(300));


    qreal Current_Angle =60+(int)((value/(maxvalue-minvalue))*240);

    paint.rotate(Current_Angle);

    paint.drawConvexPolygon(Pointer, 4);

    paint.restore();

}

7.然后继续画中心圆

void Dial::drawCenterColor(QPainter &paint)      //绘制中心圆
{
    paint.save();

    QRadialGradient Radial(0,0,centerR,0,0);

    Radial.setColorAt(1,centercolor.lighter(170));
    Radial.setColorAt(0.98,centercolor.lighter(150));
    Radial.setColorAt(0.95,centercolor.lighter(130));
    Radial.setColorAt(0.70,centercolor);

    paint.setBrush(Radial);
    paint.drawEllipse(QPointF(0,0), centerR,centerR);

    paint.restore();

}

剩下的代码就是画标签和值还有图标啦,由于渐变代码多一些,所以具体参考可以去下载源代码.下载地址:

https://download.youkuaiyun.com/download/qq_37997682/11214644

原文章pdf下载：http://labisart.com/blog/index.php/Home/Index/article/aid/202