Qt绘制雷达图（效果图）

心已赠人 2022-03-16 11:16 955阅读 2赞

*  效果图如下：

![在这里插入图片描述][20190227171837116.gif]

*  原理：

自定义控件，并使用QPainter等绘制。  
雷达图主要包括的元素有： 同心圆、十字架、文本标签、不同颜色、不同样式的圆圈、余晖等；可以设置目标显示的方位、距离等，经过我的测试，显示100个目标，界面不会卡顿，满足正常环境下的使用。

*  paintEvent（）的主要代码：

void SkyplotWidget::paintEvent(QPaintEvent *)
    {
        QSize          widgetSize(this->size());
        QPalette       p = palette();
        QPainter      *painter = new QPainter(this);
        float          topMargin ;
        float          leftMargin;
        float          size;
        float          satelliteSize;
        float          fontSize;
        float          availableWidth    = widgetSize.width ();
        float          availableHeight   = widgetSize.height();
    
        if( availableHeight > availableWidth )
        {
            size = widgetSize.width() * p_marginScale;
            topMargin   = ( widgetSize.width() - widgetSize.width() * p_marginScale + widgetSize.height() - widgetSize.width() ) / 2.0;
            leftMargin  = ( widgetSize.width() - widgetSize.width() * p_marginScale ) / 2.0;
        }
        else
        {
            size = widgetSize.height() * p_marginScale;
            leftMargin = ( widgetSize.height() - widgetSize.height() * p_marginScale + widgetSize.width() - widgetSize.height()) / 2.0;
            topMargin  = ( widgetSize.height() - widgetSize.height() * p_marginScale ) / 2.0;
        }
    
        satelliteSize = size * p_satScale;
        painter->setRenderHint(QPainter::Antialiasing, p_antialiased);
        painter->translate( leftMargin, topMargin );  //重新设置坐标原点
        fontSize = size * p_fontScale;
        painter->setFont(QFont( "Arial", static_cast< int >(fontSize)));
    
        //圆圈
        for(int i=0; i <= p_ellipses; i++)
        {
            float radius = size / 2.0 - i * ( size / ( 2.0  * p_ellipses ));
            painter->setPen( QPen( p_gridColor, p_gridWidth ) );
            painter->drawEllipse(QPoint( size/2.0, size/2.0 ), static_cast< int >( radius ), static_cast< int >(radius));
            if(p_withGridLabels)
            {
                painter->setPen( QPen( p_gridTextColor, p_gridWidth -2.5 ) );
                double tmp = ((p_ellipses - i) * (mMonitorScope / p_ellipses));
                QString distance = QString::number(((p_ellipses - i) * (mMonitorScope / p_ellipses)) ,10 , 2);
                painter->drawText(QPoint(size/2.0 + p_textMargin, size/2.0 - (radius + p_textMargin)), QString("%1 km").arg(distance)); //距离刻度
            }
        }
    
        //十字架
        for(int i=0; i < p_crosses; i++)
        {
            QLineF line1,line2;
            float angle = (static_cast<float>(i) * 90.0) / (static_cast<float>(p_crosses));
            line1.setP1( QPoint( size/2.0, size/2.0 ) );
            line1.setLength( size/2.0 );
    
            QRectF textRect(0, 0, 4.0 * fontSize, fontSize + 2.0);
    
            for(int c = 0; c < 4; c++)
            {
                line1.setAngle(angle + c*90.0 + 90.0);
                painter->setPen(QPen(p_gridColor, p_gridWidth));
                painter->drawLine(line1);
                if( p_withGridLabels )
                {
                    painter->setPen(QPen( p_gridTextColor, p_gridWidth));
                    line2 = QLineF(line1);
                    line2.setLength(size/2.0 + 2.0 * fontSize);
                    textRect.moveCenter(line2.p2());
                    if(i > 0)
                        painter->drawText( textRect, Qt::AlignCenter, QString("%1").arg((int)(360 - (c*90 ) - angle) , 3 , 10 , QChar('0')));
                    else
                    {
                        if(c == 0)
                        {
                            painter->drawText( textRect, Qt::AlignCenter,QString("000"));
                        }
                        else if(c == 1)
                        {
                            painter->drawText( textRect, Qt::AlignCenter, QString("270"));
                        }
                        else if(c == 2)
                        {
                            painter->drawText( textRect, Qt::AlignCenter, QString("180"));
                        }
                        else if(c == 3)
                        {
                            painter->drawText( textRect, Qt::AlignCenter, QString("090"));
                        }
                    }
                }
            }
        }
    
        QBrush innerBrush = QBrush( Qt::SolidPattern );
        QBrush outerBrush = QBrush( );
        //卫星
        foreach( auto s, satellites )
        {
            //------w---设置每一个卫星的大小
            satelliteSize = size * s.rsize;
            // skip invisible satellites
            if(     s.state & SatelliteState::Invisible       ||  // the invisible flag is set
    
                    ( !( s.state & SatelliteState::Visible ) &         // neither visible nor half-visible
                      !( s.state & SatelliteState::HalfVisible ) ) ||
    
                    (  s.state & SatelliteState::Flashing && flash )    // flashing flag is set and flash is active
                    )
                continue;
    
            QRectF labelRect( 0, 0, s.label.length() * satelliteSize, satelliteSize+2 );
    
            double nmdX = 0,nmdY = 0;  //卫星的X轴坐标,卫星的Y轴坐标
            calculatePos(s.az , s.distance ,nmdX, nmdY);
            QPoint satPos(size/2.0 + size*(nmdX/mMonitorScope) * 0.5,size/2.0 +  size*(nmdY/mMonitorScope) * 0.5);
    
            // define the color's alpha value (0.3 or 1.0)
            QColor innerColor = s.innerColor;
            QColor outerColor = s.outerColor;
            QColor fontColor  = s.fontColor;
            if( s.state & SatelliteState::Visible )
            {
                innerColor.setAlphaF( 1.0 );
                outerColor.setAlphaF( 1.0 );
                fontColor.setAlphaF( 1.0 );
            }
            else
            {
                innerColor.setAlphaF( 0.3 );
                outerColor.setAlphaF( 0.3 );
                fontColor.setAlphaF( 0.3 );
            }
    
            // paint the inner circle
            innerBrush.setColor( innerColor );
            painter->setBrush( innerBrush );
            if( s.state & SatelliteState::Marked )
                painter->setPen( QPen( outerColor, satelliteSize/4 ) );
            else
                painter->setPen( QPen( p_gridColor, 0 ) );
            painter->drawEllipse( satPos, static_cast< int >( satelliteSize ), static_cast< int >( satelliteSize ) );
    
    
            // write the text
            painter->setPen( QPen( fontColor, 2 ) );
            painter->setFont( QFont( "Arial", static_cast< int >( satelliteSize ),  QFont::Bold ) );
            labelRect.moveCenter( satPos );
            painter->drawText( labelRect, Qt::AlignCenter, s.label );
    
        }
    
        foreach (auto l, indicatrix)
        {
            if(  l.lineState & SatelliteState::Invisible       ||  // the invisible flag is set
                 ( !( l.lineState & SatelliteState::Visible ) &         // neither visible nor half-visible
                   !( l.lineState & SatelliteState::HalfVisible ) ) ||
                 (  l.lineState & SatelliteState::Flashing && flash )    // flashing flag is set and flash is active
                 )
                continue;
    
            QPoint spoint ( l.point1.rx() * size / 100 + size/2, l.point1.ry() * size/100 + size/2);
            QPoint epoint ( l.point2.rx() * size / 100 + size/2, l.point2.ry() * size/100 + size/2);
    
            painter->setPen(QPen(l.lineColor,1.5,Qt::DashDotLine,Qt::RoundCap));
            painter->drawLine(spoint,epoint);
        }
    
        //余晖扫描
        //   int len = m_drawArea.width();
        qreal x = size/2.0 + (qreal)size/2 * cos(-m_pieRotate*3.14159/180);
        qreal y = size/2.0 + (qreal)size/2 * sin(-m_pieRotate*3.14159/180);
        painter->setPen(QPen(Qt::green));
        painter->drawLine(QPoint( size/2.0, size/2.0 ),QPointF(x,y));
    
        //扇形
        QConicalGradient gradient;
        gradient.setCenter(QPoint( size/2.0, size/2.0 ));
        gradient.setAngle(m_pieRotate + 180); //渐变与旋转方向恰好相反，以扇形相反的边作为渐变角度。
        gradient.setColorAt(0.4,QColor(169,253,51,100)); //从渐变角度开始0.5 - 0.75为扇形区域，由于Int类型计算不精确，将范围扩大到0.4-0.8
        gradient.setColorAt(0.8,QColor(169,253,51,0));
        painter->setBrush(QBrush(gradient));
        painter->setPen(Qt::NoPen);
        painter->drawPie(0,0,size,size,m_pieRotate*16,90*16);
        //--------------------------------------------------
        delete painter;
    }在这里插入代码片

*  下载地址：

代码下载地址稍后贴在下方评论区。

[20190227171837116.gif]: /images/20220316/11cac26df3e543e48338368ee7e199b4.png