How to fill curve-sector area in QwtPolar?

[BulSV]

Hello everyone!
I know that in QwtPlotCurve exist method setBrush() but how it make in QwtPolarCurve?

[HappyCoder]

A QPen has a QBrush
QPen::QPen(const QBrush & brush, qreal width, Qt::PenStyle style = Qt::SolidLine, Qt::PenCapStyle cap = Qt::SquareCap, Qt::PenJoinStyle join = Qt::BevelJoin)
and
in docu of QwtPolarCurve you will find QwtPolarCurve::setPen (http://qwtpolar.sourceforge.net/)

[BulSV]

But it does not filled the sector created by the curve.

[Uwe]

I know that in QwtPlotCurve exist method setBrush() but how it make in QwtPolarCurve?

There is no feature like this provided out of the box.

To implement such a thing you would have to overload QwtPolarCurve::drawLines. You can start with copying the code you find in qwt_polar_curve.cpp to your derived class and remove the code dealing with curve fitting.
Then have a look at the last 2 lines ( the second line is nonsense and can be removed - there is no reason for drawing twice ):

QwtPainter::drawPolyline( painter, polyline );
 painter->drawPolyline( polyline );

QwtPainter::drawPolyline( painter, polyline );
 painter->drawPolyline( polyline );

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Instead of calling drawPolyline you would have to add some lines to polyline ( = the curve points translated in widget coordinates ), so that you have the area you want to fill. Then assign a brush and call QwtPainter::drawPolygon() instead.

HTH,
Uwe

[BulSV]

Sorry for the long delay in response - almost a month did not work on this project.

To implement such a thing you would have to overload QwtPolarCurve::drawLines. You can start with copying the code you find in qwt_polar_curve.cpp to your derived class and remove the code dealing with curve fitting.
Then have a look at the last 2 lines ( the second line is nonsense and can be removed - there is no reason for drawing twice ):

QwtPainter::drawPolyline( painter, polyline );
painter->drawPolyline( polyline );

QwtPainter::drawPolyline( painter, polyline );
painter->drawPolyline( polyline );

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Instead of calling drawPolyline you would have to add some lines to polyline ( = the curve points translated in widget coordinates ), so that you have the area you want to fill. Then assign a brush and call QwtPainter::drawPolygon() instead.

It didn't work - it is impossible not only to fill, but even change the color of the pen. Can I do something wrong? Here is my code:

QwtPolarCurveJamming.h

#include <qwt_polar_curve.h>
 
class QwtPolarCurveJamming : public QwtPolarCurve
{
protected:
    void drawLines( QPainter *,
                    const QwtScaleMap &azimuthMap, const QwtScaleMap &radialMap,
                    const QPointF &pole, int from, int to ) const;
};

#include <qwt_polar_curve.h>

class QwtPolarCurveJamming : public QwtPolarCurve
{
protected:
    void drawLines( QPainter *,
                    const QwtScaleMap &azimuthMap, const QwtScaleMap &radialMap,
                    const QPointF &pole, int from, int to ) const;
};

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QwtPolarCurveJamming.cpp

#include "qwt_polar_curve.h"
#include "qwt_polar.h"
#include <qwt_painter.h>
#include <qwt_scale_map.h>
#include <qwt_math.h>
#include <qwt_symbol.h>
#include <qwt_legend.h>
#include <qwt_curve_fitter.h>
#include <qwt_clipper.h>
#include <qpainter.h>
#include "QwtPolarCurveJamming.h"
 
static inline bool qwtInsidePole( const QwtScaleMap &map, double radius )
{
    return map.isInverting() ? ( radius > map.s1() ) : ( radius < map.s1() );
}
 
void QwtPolarCurveJamming::drawLines( QPainter *painter,
                                      const QwtScaleMap &azimuthMap, const QwtScaleMap &radialMap,
                                      const QPointF &pole, int from, int to ) const
{
    int size = to - from + 1;
    if ( size <= 0 )
        return;
 
    QPolygonF polyline;
    polyline.resize( size );
    QPointF *polylineData = polyline.data();
 
    for ( int i = from; i <= to; i++ )
    {
        QwtPointPolar point = sample( i );
        if ( !qwtInsidePole( radialMap, point.radius() ) )
        {
            double r = radialMap.transform( point.radius() );
            const double a = azimuthMap.transform( point.azimuth() );
            polylineData[i - from] = qwtPolar2Pos( pole, r, a );
        }
        else
        {
            polylineData[i - from] = pole;
        }
    }
 
    /*QRectF clipRect;
    if ( painter->hasClipping() )
        clipRect = painter->clipRegion().boundingRect();
    else
    {
        clipRect = painter->window();
        if ( !clipRect.isEmpty() )
            clipRect = painter->transform().inverted().mapRect( clipRect );
    }
 
    if ( !clipRect.isEmpty() )
    {
        double off = qCeil( qMax( qreal( 1.0 ), painter->pen().widthF() ) );
        clipRect = clipRect.toRect().adjusted( -off, -off, off, off );
        polyline = QwtClipper::clipPolygonF( clipRect, polyline );
    }*/
 
    painter->setBrush(QBrush(Qt::red));
    painter->setPen(Qt::red);
//    painter->drawPolygon(polyline);
//    QwtPainter::fillRect(painter, polyline.boundingRect(), QBrush(Qt::red));
    QwtPainter::drawPolygon(painter, polyline);
//     QwtPainter::drawPolyline( painter, polyline );
//     painter->drawPolyline( polyline );
}

#include "qwt_polar_curve.h"
#include "qwt_polar.h"
#include <qwt_painter.h>
#include <qwt_scale_map.h>
#include <qwt_math.h>
#include <qwt_symbol.h>
#include <qwt_legend.h>
#include <qwt_curve_fitter.h>
#include <qwt_clipper.h>
#include <qpainter.h>
#include "QwtPolarCurveJamming.h"

static inline bool qwtInsidePole( const QwtScaleMap &map, double radius )
{
    return map.isInverting() ? ( radius > map.s1() ) : ( radius < map.s1() );
}

void QwtPolarCurveJamming::drawLines( QPainter *painter,
                                      const QwtScaleMap &azimuthMap, const QwtScaleMap &radialMap,
                                      const QPointF &pole, int from, int to ) const
{
    int size = to - from + 1;
    if ( size <= 0 )
        return;

    QPolygonF polyline;
    polyline.resize( size );
    QPointF *polylineData = polyline.data();

    for ( int i = from; i <= to; i++ )
    {
        QwtPointPolar point = sample( i );
        if ( !qwtInsidePole( radialMap, point.radius() ) )
        {
            double r = radialMap.transform( point.radius() );
            const double a = azimuthMap.transform( point.azimuth() );
            polylineData[i - from] = qwtPolar2Pos( pole, r, a );
        }
        else
        {
            polylineData[i - from] = pole;
        }
    }

    /*QRectF clipRect;
    if ( painter->hasClipping() )
        clipRect = painter->clipRegion().boundingRect();
    else
    {
        clipRect = painter->window();
        if ( !clipRect.isEmpty() )
            clipRect = painter->transform().inverted().mapRect( clipRect );
    }

    if ( !clipRect.isEmpty() )
    {
        double off = qCeil( qMax( qreal( 1.0 ), painter->pen().widthF() ) );
        clipRect = clipRect.toRect().adjusted( -off, -off, off, off );
        polyline = QwtClipper::clipPolygonF( clipRect, polyline );
    }*/

    painter->setBrush(QBrush(Qt::red));
    painter->setPen(Qt::red);
//    painter->drawPolygon(polyline);
//    QwtPainter::fillRect(painter, polyline.boundingRect(), QBrush(Qt::red));
    QwtPainter::drawPolygon(painter, polyline);
//     QwtPainter::drawPolyline( painter, polyline );
//     painter->drawPolyline( polyline );
}

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[BulSV]

Finally it works!
I changed method drawLines() in the file "qwt_polar_curve.h" from "void drawLines()" to "virtual void drawLines()" and recompiled qwtpolar library.