Custom symbol for QwtPlotMarker

[pkj]

Thanks Uwe, works like a charm .
Anyone interested here's a trivial example:
Step 1 : subclass QwtSymbol

class Symbol:public QwtSymbol
{
public:
    Symbol(const QBrush &, const QPen &, const QSize & );
    virtual void drawSymbols( QPainter *, const QPointF *, int numPoints ) const;
    void drawSymbol( QPainter *, const QPointF & ) const;
};
 
Symbol::Symbol(const QBrush &br , const QPen &p, const QSize &sz)
    : QwtSymbol(QwtSymbol::NoSymbol, br, p, sz)
{
}
 
void Symbol::drawSymbol(QPainter *painter, const QPointF &pos) const
{
    drawSymbols( painter, &pos, 1 );
}
 
void Symbol::drawSymbols(QPainter *painter, const QPointF *points, int numPoints) const
{
    if ( numPoints <= 0 )
        return;
 
    painter->save();
    painter->setBrush( brush() );
    painter->setPen( pen() );
    const QSize sz = size();
    const int sw = sz.width();
    const int sh = sz.height();
    const int sw2 = sz.width() / 2;
    const int sh2 = sz.height() / 2;
    QPointF pos = points[0];
 
    QPainterPath path;
    path.moveTo(pos);
    path.lineTo(pos.x()-sw2,pos.y()); path.lineTo(pos.x(),pos.y()+sh2);  path.lineTo(pos);
    painter->drawPath(path);
    painter->restore();
}

class Symbol:public QwtSymbol
{
public:
    Symbol(const QBrush &, const QPen &, const QSize & );
    virtual void drawSymbols( QPainter *, const QPointF *, int numPoints ) const;
    void drawSymbol( QPainter *, const QPointF & ) const;
};

Symbol::Symbol(const QBrush &br , const QPen &p, const QSize &sz)
    : QwtSymbol(QwtSymbol::NoSymbol, br, p, sz)
{
}

void Symbol::drawSymbol(QPainter *painter, const QPointF &pos) const
{
    drawSymbols( painter, &pos, 1 );
}

void Symbol::drawSymbols(QPainter *painter, const QPointF *points, int numPoints) const
{
    if ( numPoints <= 0 )
        return;

    painter->save();
    painter->setBrush( brush() );
    painter->setPen( pen() );
    const QSize sz = size();
    const int sw = sz.width();
    const int sh = sz.height();
    const int sw2 = sz.width() / 2;
    const int sh2 = sz.height() / 2;
    QPointF pos = points[0];

    QPainterPath path;
    path.moveTo(pos);
    path.lineTo(pos.x()-sw2,pos.y()); path.lineTo(pos.x(),pos.y()+sh2);  path.lineTo(pos);
    painter->drawPath(path);
    painter->restore();
}

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Step 2: Subclass QwtMarker

class Marker:public QwtPlotMarker
{
public:
    Marker();
    void drawAt( QPainter *, const QRectF &, const QPointF & ) const;
    virtual void draw( QPainter *p, const QwtScaleMap &xMap, const QwtScaleMap &yMap,
        const QRectF & ) const;
};
 
Marker::Marker() :QwtPlotMarker()
{}
 
void Marker::drawAt(QPainter *painter, const QRectF &rect, const QPointF &pos) const
{
    symbol().drawSymbol(painter, pos);
    QwtPlotMarker::drawAt(painter, rect, pos);
}
void Marker::draw( QPainter *painter,
    const QwtScaleMap &xMap, const QwtScaleMap &yMap,
    const QRectF &canvasRect ) const
{
    const double x = xMap.transform( xValue() );
    const double y = yMap.transform( yValue() );
 
    drawAt( painter, canvasRect, QPointF( x, y ) );
}

class Marker:public QwtPlotMarker
{
public:
    Marker();
    void drawAt( QPainter *, const QRectF &, const QPointF & ) const;
    virtual void draw( QPainter *p, const QwtScaleMap &xMap, const QwtScaleMap &yMap,
        const QRectF & ) const;
};

Marker::Marker() :QwtPlotMarker()
{}

void Marker::drawAt(QPainter *painter, const QRectF &rect, const QPointF &pos) const
{
    symbol().drawSymbol(painter, pos);
    QwtPlotMarker::drawAt(painter, rect, pos);
}
void Marker::draw( QPainter *painter,
    const QwtScaleMap &xMap, const QwtScaleMap &yMap,
    const QRectF &canvasRect ) const
{
    const double x = xMap.transform( xValue() );
    const double y = yMap.transform( yValue() );

    drawAt( painter, canvasRect, QPointF( x, y ) );
}

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Step 3: Instantiate and use

...
...
 Marker *mrk = new Marker();
    mrk->setLinePen(QPen(Qt::black, 0, Qt::DashDotLine));
    mrk->setValue(10.0,10.0);
    mrk->setLineStyle(QwtPlotMarker::HLine);
    mrk->setSymbol(new Symbol(QColor(Qt::yellow), QColor(Qt::green), QSize(15,15)));    
    mrk->attach(qwt_plot_object);

...
...
 Marker *mrk = new Marker();
    mrk->setLinePen(QPen(Qt::black, 0, Qt::DashDotLine));
    mrk->setValue(10.0,10.0);
    mrk->setLineStyle(QwtPlotMarker::HLine);
    mrk->setSymbol(new Symbol(QColor(Qt::yellow), QColor(Qt::green), QSize(15,15)));    
    mrk->attach(qwt_plot_object);

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