Remove QwtPlotPicker from a QwtPlot canvas

[KelvinSP]

Hello,

I'm using the class "curvetracker" from the Qwt playground with some minor modifications:

#include "curvetracker.h"
#include <qwt_picker_machine.h>
#include <qwt_series_data.h>
#include <qwt_plot.h>
#include <qwt_plot_curve.h>
 
struct compareX
{
    inline bool operator()( const double x, const QPointF &pos ) const
    {
        return ( x < pos.x() );
    }
};
 
CurveTracker::CurveTracker( QWidget *canvas ):
    QwtPlotPicker( canvas )
{
    setTrackerMode( QwtPlotPicker::ActiveOnly );
    setRubberBand( VLineRubberBand );
 
    setStateMachine( new QwtPickerDragPointMachine() );
}
 
QRect CurveTracker::trackerRect( const QFont &font ) const
{
    QRect r = QwtPlotPicker::trackerRect( font );
 
    // Align the rect to the first curve
    const QwtPlotItemList curves = plot()->itemList( QwtPlotItem::Rtti_PlotCurve );
    if ( curves.size() > 0 )
    {
        QPointF pos = invTransform( trackerPosition() );
 
        const QLineF line = curveLineAt(
            static_cast<const QwtPlotCurve *>( curves[0] ), pos.x() );
        if ( !line.isNull() )
        {
            const double curveY = line.pointAt(
                ( pos.x() - line.p1().x() ) / line.dx() ).y();
 
            pos.setY( curveY );
            pos = transform( pos );
 
            r.moveBottom( pos.y() );
        }
    }
 
    return r;
}
 
QwtText CurveTracker::trackerTextF( const QPointF &pos ) const
{
    QwtText trackerText;
 
    trackerText.setColor( Qt::white );
 
    // Background color of the rectangle
    //QColor c( "#5e5e5e" );
    QColor c( "#858585" );
    trackerText.setBorderPen( QPen( c, 2 ) );
    c.setAlpha( 200 );
    trackerText.setBackgroundBrush( c );
 
    QString info;
 
    const QwtPlotItemList curves =
        plot()->itemList( QwtPlotItem::Rtti_PlotCurve );
 
    for ( int i = 0; i < 1; i++ )
    {
        const QString curveInfo = curveInfoAt(
            static_cast<const QwtPlotCurve *>( curves[i] ), pos );
 
        if ( !curveInfo.isEmpty() )
        {
            if ( !info.isEmpty() )
                info += "<br>";
 
            info += curveInfo;
        }
    }
 
    trackerText.setText( info );
    return trackerText;
}
 
QString CurveTracker::curveInfoAt(
    const QwtPlotCurve *curve, const QPointF &pos ) const
{
    const QLineF line = curveLineAt( curve, pos.x() );
    if ( line.isNull() )
        return QString::null;
 
    int x = line.pointAt(
        ( pos.x() - line.p1().x() ) / line.dx() ).x();
    double y = line.pointAt(
        ( pos.x() - line.p1().x() ) / line.dx() ).y();
 
    // Info "window" args: color, x and y.
    QString info( "<font color=""%1"">x : %2<br>y : %3</font>" );
    return info.arg( "white" ).arg( x ).arg( QString::number(y, 'f', 3) ); // curve->pen().color().name()
}
 
QLineF CurveTracker::curveLineAt(
    const QwtPlotCurve *curve, double x ) const
{
    QLineF line;
 
    if ( curve->dataSize() >= 2 )
    {
        const QRectF br = curve->boundingRect();
        if ( br.isValid() && x >= br.left() && x <= br.right() )
        {
            int index = qwtUpperSampleIndex<QPointF>(
                *curve->data(), x, compareX() );
 
            if ( index == -1 &&
                x == curve->sample( curve->dataSize() - 1 ).x() )
            {
                // the last sample is excluded from qwtUpperSampleIndex
                index = curve->dataSize() - 1;
            }
 
            if ( index > 0 )
            {
                line.setP1( curve->sample( index - 1 ) );
                line.setP2( curve->sample( index ) );
            }
        }
    }
 
    return line;
}

#include "curvetracker.h"
#include <qwt_picker_machine.h>
#include <qwt_series_data.h>
#include <qwt_plot.h>
#include <qwt_plot_curve.h>

struct compareX
{
    inline bool operator()( const double x, const QPointF &pos ) const
    {
        return ( x < pos.x() );
    }
};

CurveTracker::CurveTracker( QWidget *canvas ):
    QwtPlotPicker( canvas )
{
    setTrackerMode( QwtPlotPicker::ActiveOnly );
    setRubberBand( VLineRubberBand );

    setStateMachine( new QwtPickerDragPointMachine() );
}

QRect CurveTracker::trackerRect( const QFont &font ) const
{
    QRect r = QwtPlotPicker::trackerRect( font );

    // Align the rect to the first curve
    const QwtPlotItemList curves = plot()->itemList( QwtPlotItem::Rtti_PlotCurve );
    if ( curves.size() > 0 )
    {
        QPointF pos = invTransform( trackerPosition() );

        const QLineF line = curveLineAt(
            static_cast<const QwtPlotCurve *>( curves[0] ), pos.x() );
        if ( !line.isNull() )
        {
            const double curveY = line.pointAt(
                ( pos.x() - line.p1().x() ) / line.dx() ).y();

            pos.setY( curveY );
            pos = transform( pos );

            r.moveBottom( pos.y() );
        }
    }

    return r;
}

QwtText CurveTracker::trackerTextF( const QPointF &pos ) const
{
    QwtText trackerText;

    trackerText.setColor( Qt::white );

    // Background color of the rectangle
    //QColor c( "#5e5e5e" );
    QColor c( "#858585" );
    trackerText.setBorderPen( QPen( c, 2 ) );
    c.setAlpha( 200 );
    trackerText.setBackgroundBrush( c );

    QString info;

    const QwtPlotItemList curves =
        plot()->itemList( QwtPlotItem::Rtti_PlotCurve );

    for ( int i = 0; i < 1; i++ )
    {
        const QString curveInfo = curveInfoAt(
            static_cast<const QwtPlotCurve *>( curves[i] ), pos );

        if ( !curveInfo.isEmpty() )
        {
            if ( !info.isEmpty() )
                info += "<br>";

            info += curveInfo;
        }
    }

    trackerText.setText( info );
    return trackerText;
}

QString CurveTracker::curveInfoAt(
    const QwtPlotCurve *curve, const QPointF &pos ) const
{
    const QLineF line = curveLineAt( curve, pos.x() );
    if ( line.isNull() )
        return QString::null;

    int x = line.pointAt(
        ( pos.x() - line.p1().x() ) / line.dx() ).x();
    double y = line.pointAt(
        ( pos.x() - line.p1().x() ) / line.dx() ).y();

    // Info "window" args: color, x and y.
    QString info( "<font color=""%1"">x : %2<br>y : %3</font>" );
    return info.arg( "white" ).arg( x ).arg( QString::number(y, 'f', 3) ); // curve->pen().color().name()
}

QLineF CurveTracker::curveLineAt(
    const QwtPlotCurve *curve, double x ) const
{
    QLineF line;

    if ( curve->dataSize() >= 2 )
    {
        const QRectF br = curve->boundingRect();
        if ( br.isValid() && x >= br.left() && x <= br.right() )
        {
            int index = qwtUpperSampleIndex<QPointF>(
                *curve->data(), x, compareX() );

            if ( index == -1 &&
                x == curve->sample( curve->dataSize() - 1 ).x() )
            {
                // the last sample is excluded from qwtUpperSampleIndex
                index = curve->dataSize() - 1;
            }

            if ( index > 0 )
            {
                line.setP1( curve->sample( index - 1 ) );
                line.setP2( curve->sample( index ) );
            }
        }
    }

    return line;
}

To copy to clipboard, switch view to plain text mode 

In my plot class, I am using it like this:

// dataPlot_ = QwtPlot
CurveTracker* tracker = new CurveTracker( dataPlot_->canvas() );
tracker->setStateMachine( new QwtPickerTrackerMachine() );
tracker->setRubberBandPen( QPen(Qt::black, 1) );

// dataPlot_ = QwtPlot
CurveTracker* tracker = new CurveTracker( dataPlot_->canvas() );
tracker->setStateMachine( new QwtPickerTrackerMachine() );
tracker->setRubberBandPen( QPen(Qt::black, 1) );

To copy to clipboard, switch view to plain text mode 

Ok, it is working, but now I need to clean/reset my entire QwtPlot object.

I'm using the following command to do so:

dataPlot_->detachItems(QwtPlotItem::Rtti_PlotItem, true);

dataPlot_->detachItems(QwtPlotItem::Rtti_PlotItem, true);

To copy to clipboard, switch view to plain text mode 

but when I move the mouse over my QwtPlot my application break. Investigating the problem I discovered that it is crashing because of the CurveTracker.

How can I remove/delete the CurveTracker (QwtPlotPicker) from my dataPlot_ (QwtPlot) canvas?

Thanks

---

Added after 1 22 minutes:

I solved the problem by disabling my QwtPlotPicker:

tracker->setEnabled(false);

tracker->setEnabled(false);

To copy to clipboard, switch view to plain text mode 

I don't know if it is the best/right solution, but it worked.

Anyway, if anyone knows a better way to do so please let me know.

[Uwe]

If you don't need it anymore:

delete tracker;

delete tracker;

To copy to clipboard, switch view to plain text mode 

Uwe

[KelvinSP]

If you don't need it anymore:

delete tracker;

delete tracker;

To copy to clipboard, switch view to plain text mode 

Uwe

Thanks a lot Uwe, it worked.