Qt绘制雷达图（效果图）
- 效果图如下：
- 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(i) * 90.0) / (static_cast(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
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