qwt_plot_curve.cpp

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/******************************************************************************
 * Qwt Widget Library
 * Copyright (C) 1997   Josef Wilgen
 * Copyright (C) 2002   Uwe Rathmann
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the Qwt License, Version 1.0
 *****************************************************************************/
 
#include "qwt_plot_curve.h"
#include "qwt_point_data.h"
#include "qwt_math.h"
#include "qwt_clipper.h"
#include "qwt_painter.h"
#include "qwt_scale_map.h"
#include "qwt_plot.h"
#include "qwt_spline_curve_fitter.h"
#include "qwt_symbol.h"
#include "qwt_point_mapper.h"
#include "qwt_text.h"
#include "qwt_graphic.h"
 
#include <qpainter.h>
#include <qpainterpath.h>
 
#include <climits>
 
static inline QRectF qwtIntersectedClipRect( const QRectF& rect, QPainter* painter )
{
    QRectF clipRect = rect;
    if ( painter->hasClipping() )
        clipRect &= painter->clipBoundingRect();
 
    return clipRect;
}
 
static void qwtUpdateLegendIconSize( QwtPlotCurve* curve )
{
    if ( curve->symbol() &&
        curve->testLegendAttribute( QwtPlotCurve::LegendShowSymbol ) )
    {
        QSize sz = curve->symbol()->boundingRect().size();
        sz += QSize( 2, 2 ); // margin
 
        if ( curve->testLegendAttribute( QwtPlotCurve::LegendShowLine ) )
        {
            // Avoid, that the line is completely covered by the symbol
 
            int w = qwtCeil( 1.5 * sz.width() );
            if ( w % 2 )
                w++;
 
            sz.setWidth( qMax( 8, w ) );
        }
 
        curve->setLegendIconSize( sz );
    }
}
 
static int qwtVerifyRange( int size, int& i1, int& i2 )
{
    if ( size < 1 )
        return 0;
 
    i1 = qBound( 0, i1, size - 1 );
    i2 = qBound( 0, i2, size - 1 );
 
    if ( i1 > i2 )
        qSwap( i1, i2 );
 
    return ( i2 - i1 + 1 );
}
 
class QwtPlotCurve::PrivateData
{
  public:
    PrivateData()
        : style( QwtPlotCurve::Lines )
        , baseline( 0.0 )
        , symbol( NULL )
        , pen( Qt::black )
        , paintAttributes( QwtPlotCurve::ClipPolygons | QwtPlotCurve::FilterPoints )
    {
        curveFitter = new QwtSplineCurveFitter;
    }
 
    ~PrivateData()
    {
        delete symbol;
        delete curveFitter;
    }
 
    QwtPlotCurve::CurveStyle style;
    double baseline;
 
    const QwtSymbol* symbol;
    QwtCurveFitter* curveFitter;
 
    QPen pen;
    QBrush brush;
 
    QwtPlotCurve::CurveAttributes attributes;
    QwtPlotCurve::PaintAttributes paintAttributes;
 
    QwtPlotCurve::LegendAttributes legendAttributes;
};
 
QwtPlotCurve::QwtPlotCurve( const QwtText& title )
    : QwtPlotSeriesItem( title )
{
    init();
}
 
QwtPlotCurve::QwtPlotCurve( const QString& title )
    : QwtPlotSeriesItem( QwtText( title ) )
{
    init();
}
 
QwtPlotCurve::~QwtPlotCurve()
{
    delete m_data;
}
 
void QwtPlotCurve::init()
{
    setItemAttribute( QwtPlotItem::Legend );
    setItemAttribute( QwtPlotItem::AutoScale );
 
    m_data = new PrivateData;
    setData( new QwtPointSeriesData() );
 
    setZ( 20.0 );
}
 
int QwtPlotCurve::rtti() const
{
    return QwtPlotItem::Rtti_PlotCurve;
}
 
void QwtPlotCurve::setPaintAttribute( PaintAttribute attribute, bool on )
{
    if ( on )
        m_data->paintAttributes |= attribute;
    else
        m_data->paintAttributes &= ~attribute;
}
 
bool QwtPlotCurve::testPaintAttribute( PaintAttribute attribute ) const
{
    return ( m_data->paintAttributes & attribute );
}
 
void QwtPlotCurve::setLegendAttribute( LegendAttribute attribute, bool on )
{
    if ( on != testLegendAttribute( attribute ) )
    {
        if ( on )
            m_data->legendAttributes |= attribute;
        else
            m_data->legendAttributes &= ~attribute;
 
        qwtUpdateLegendIconSize( this );
        legendChanged();
    }
}
 
bool QwtPlotCurve::testLegendAttribute( LegendAttribute attribute ) const
{
    return ( m_data->legendAttributes & attribute );
}
 
void QwtPlotCurve::setLegendAttributes( LegendAttributes attributes )
{
    if ( attributes != m_data->legendAttributes )
    {
        m_data->legendAttributes = attributes;
 
        qwtUpdateLegendIconSize( this );
        legendChanged();
    }
}
 
QwtPlotCurve::LegendAttributes QwtPlotCurve::legendAttributes() const
{
    return m_data->legendAttributes;
}
 
void QwtPlotCurve::setStyle( CurveStyle style )
{
    if ( style != m_data->style )
    {
        m_data->style = style;
 
        legendChanged();
        itemChanged();
    }
}
 
QwtPlotCurve::CurveStyle QwtPlotCurve::style() const
{
    return m_data->style;
}
 
void QwtPlotCurve::setSymbol( QwtSymbol* symbol )
{
    if ( symbol != m_data->symbol )
    {
        delete m_data->symbol;
        m_data->symbol = symbol;
 
        qwtUpdateLegendIconSize( this );
 
        legendChanged();
        itemChanged();
    }
}
 
const QwtSymbol* QwtPlotCurve::symbol() const
{
    return m_data->symbol;
}
 
void QwtPlotCurve::setPen( const QColor& color, qreal width, Qt::PenStyle style )
{
    setPen( QPen( color, width, style ) );
}
 
void QwtPlotCurve::setPen( const QPen& pen )
{
    if ( pen != m_data->pen )
    {
        m_data->pen = pen;
 
        legendChanged();
        itemChanged();
    }
}
 
const QPen& QwtPlotCurve::pen() const
{
    return m_data->pen;
}
 
void QwtPlotCurve::setBrush( const QBrush& brush )
{
    if ( brush != m_data->brush )
    {
        m_data->brush = brush;
 
        legendChanged();
        itemChanged();
    }
}
 
const QBrush& QwtPlotCurve::brush() const
{
    return m_data->brush;
}
 
void QwtPlotCurve::drawSeries( QPainter* painter,
    const QwtScaleMap& xMap, const QwtScaleMap& yMap,
    const QRectF& canvasRect, int from, int to ) const
{
    const size_t numSamples = dataSize();
 
    if ( !painter || numSamples <= 0 )
        return;
 
    if ( to < 0 )
        to = numSamples - 1;
 
    if ( qwtVerifyRange( numSamples, from, to ) > 0 )
    {
        painter->save();
        painter->setPen( m_data->pen );
 
        /*
           Qt 4.0.0 is slow when drawing lines, but it's even
           slower when the painter has a brush. So we don't
           set the brush before we really need it.
         */
 
        drawCurve( painter, m_data->style, xMap, yMap, canvasRect, from, to );
        painter->restore();
 
        if ( m_data->symbol &&
            ( m_data->symbol->style() != QwtSymbol::NoSymbol ) )
        {
            painter->save();
            drawSymbols( painter, *m_data->symbol,
                xMap, yMap, canvasRect, from, to );
            painter->restore();
        }
    }
}
 
void QwtPlotCurve::drawCurve( QPainter* painter, int style,
    const QwtScaleMap& xMap, const QwtScaleMap& yMap,
    const QRectF& canvasRect, int from, int to ) const
{
    switch ( style )
    {
        case Lines:
            if ( testCurveAttribute( Fitted ) )
            {
                // we always need the complete
                // curve for fitting
                from = 0;
                to = dataSize() - 1;
            }
            drawLines( painter, xMap, yMap, canvasRect, from, to );
            break;
        case Sticks:
            drawSticks( painter, xMap, yMap, canvasRect, from, to );
            break;
        case Steps:
            drawSteps( painter, xMap, yMap, canvasRect, from, to );
            break;
        case Dots:
            drawDots( painter, xMap, yMap, canvasRect, from, to );
            break;
        case LinesAndDots: {
          if (testCurveAttribute(Fitted)) {
            from = 0;
            to = dataSize() - 1;
          }
          drawLines(painter, xMap, yMap, canvasRect, from, to);
 
          QPen prev_pen = painter->pen();
          QPen new_pen = prev_pen;
          new_pen.setWidth(prev_pen.width() * 3);
 
          painter->setPen(new_pen);
          drawDots(painter, xMap, yMap, canvasRect, from, to);
          painter->setPen(prev_pen);
        } break;
 
        case NoCurve:
        default:
            break;
    }
}
 
void QwtPlotCurve::drawLines( QPainter* painter,
    const QwtScaleMap& xMap, const QwtScaleMap& yMap,
    const QRectF& canvasRect, int from, int to ) const
{
    if ( from > to )
        return;
 
    const bool doFit = ( m_data->attributes & Fitted ) && m_data->curveFitter;
    const bool doAlign = !doFit && QwtPainter::roundingAlignment( painter );
    const bool doFill = ( m_data->brush.style() != Qt::NoBrush )
        && ( m_data->brush.color().alpha() > 0 );
 
    QRectF clipRect;
    if ( m_data->paintAttributes & ClipPolygons )
    {
        clipRect = qwtIntersectedClipRect( canvasRect, painter );
 
        const qreal pw = QwtPainter::effectivePenWidth( painter->pen() );
        clipRect = clipRect.adjusted(-pw, -pw, pw, pw);
    }
 
    QwtPointMapper mapper;
 
    if ( doAlign )
    {
        mapper.setFlag( QwtPointMapper::RoundPoints, true );
        mapper.setFlag( QwtPointMapper::WeedOutIntermediatePoints,
            testPaintAttribute( FilterPointsAggressive ) );
    }
 
    mapper.setFlag( QwtPointMapper::WeedOutPoints,
        testPaintAttribute( FilterPoints ) ||
        testPaintAttribute( FilterPointsAggressive ) );
 
    mapper.setBoundingRect( canvasRect );
 
    QPolygonF polyline = mapper.toPolygonF( xMap, yMap, data(), from, to );
 
    if ( doFill )
    {
        if ( doFit )
        {
            // it might be better to extend and draw the curvePath, but for
            // the moment we keep an implementation, where we translate the
            // path back to a polyline.
 
            polyline = m_data->curveFitter->fitCurve( polyline );
        }
 
        if ( painter->pen().style() != Qt::NoPen )
        {
            // here we are wasting memory for the filled copy,
            // do polygon clipping twice etc .. TODO
 
            QPolygonF filled = polyline;
            fillCurve( painter, xMap, yMap, canvasRect, filled );
            filled.clear();
 
            if ( m_data->paintAttributes & ClipPolygons )
                QwtClipper::clipPolygonF( clipRect, polyline, false );
 
            QwtPainter::drawPolyline( painter, polyline );
        }
        else
        {
            fillCurve( painter, xMap, yMap, canvasRect, polyline );
        }
    }
    else
    {
        if ( testPaintAttribute( ClipPolygons ) )
        {
            QwtClipper::clipPolygonF( clipRect, polyline, false );
        }
 
        if ( doFit )
        {
            if ( m_data->curveFitter->mode() == QwtCurveFitter::Path )
            {
                const QPainterPath curvePath =
                    m_data->curveFitter->fitCurvePath( polyline );
 
                painter->drawPath( curvePath );
            }
            else
            {
                polyline = m_data->curveFitter->fitCurve( polyline );
                QwtPainter::drawPolyline( painter, polyline );
            }
        }
        else
        {
            QwtPainter::drawPolyline( painter, polyline );
        }
    }
}
 
void QwtPlotCurve::drawSticks( QPainter* painter,
    const QwtScaleMap& xMap, const QwtScaleMap& yMap,
    const QRectF& canvasRect, int from, int to ) const
{
    Q_UNUSED( canvasRect )
 
    painter->save();
    painter->setRenderHint( QPainter::Antialiasing, false );
 
    const bool doAlign = QwtPainter::roundingAlignment( painter );
 
    double x0 = xMap.transform( m_data->baseline );
    double y0 = yMap.transform( m_data->baseline );
    if ( doAlign )
    {
        x0 = qRound( x0 );
        y0 = qRound( y0 );
    }
 
    const Qt::Orientation o = orientation();
 
    const QwtSeriesData< QPointF >* series = data();
 
    for ( int i = from; i <= to; i++ )
    {
        const QPointF sample = series->sample( i );
        double xi = xMap.transform( sample.x() );
        double yi = yMap.transform( sample.y() );
        if ( doAlign )
        {
            xi = qRound( xi );
            yi = qRound( yi );
        }
 
        if ( o == Qt::Horizontal )
            QwtPainter::drawLine( painter, x0, yi, xi, yi );
        else
            QwtPainter::drawLine( painter, xi, y0, xi, yi );
    }
 
    painter->restore();
}
 
void QwtPlotCurve::drawDots( QPainter* painter,
    const QwtScaleMap& xMap, const QwtScaleMap& yMap,
    const QRectF& canvasRect, int from, int to ) const
{
    const QColor color = painter->pen().color();
 
    if ( painter->pen().style() == Qt::NoPen || color.alpha() == 0 )
    {
        return;
    }
 
    const bool doFill = ( m_data->brush.style() != Qt::NoBrush )
        && ( m_data->brush.color().alpha() > 0 );
    const bool doAlign = QwtPainter::roundingAlignment( painter );
 
    QwtPointMapper mapper;
    mapper.setBoundingRect( canvasRect );
    mapper.setFlag( QwtPointMapper::RoundPoints, doAlign );
 
    if ( m_data->paintAttributes & FilterPoints )
    {
        if ( ( color.alpha() == 255 )
            && !( painter->renderHints() & QPainter::Antialiasing ) )
        {
            mapper.setFlag( QwtPointMapper::WeedOutPoints, true );
        }
    }
 
    if ( doFill )
    {
        mapper.setFlag( QwtPointMapper::WeedOutPoints, false );
 
        QPolygonF points = mapper.toPolygonF(
            xMap, yMap, data(), from, to );
 
        QwtPainter::drawPoints( painter, points );
        fillCurve( painter, xMap, yMap, canvasRect, points );
    }
    else if ( m_data->paintAttributes & ImageBuffer )
    {
        const QImage image = mapper.toImage( xMap, yMap,
            data(), from, to, m_data->pen,
            painter->testRenderHint( QPainter::Antialiasing ),
            renderThreadCount() );
 
        painter->drawImage( canvasRect.toAlignedRect(), image );
    }
    else if ( m_data->paintAttributes & MinimizeMemory )
    {
        const QwtSeriesData< QPointF >* series = data();
 
        for ( int i = from; i <= to; i++ )
        {
            const QPointF sample = series->sample( i );
 
            double xi = xMap.transform( sample.x() );
            double yi = yMap.transform( sample.y() );
 
            if ( doAlign )
            {
                xi = qRound( xi );
                yi = qRound( yi );
            }
 
            QwtPainter::drawPoint( painter, QPointF( xi, yi ) );
        }
    }
    else
    {
        if ( doAlign )
        {
            const QPolygon points = mapper.toPoints(
                xMap, yMap, data(), from, to );
 
            QwtPainter::drawPoints( painter, points );
        }
        else
        {
            const QPolygonF points = mapper.toPointsF(
                xMap, yMap, data(), from, to );
 
            QwtPainter::drawPoints( painter, points );
        }
    }
}
 
void QwtPlotCurve::drawSteps( QPainter* painter,
    const QwtScaleMap& xMap, const QwtScaleMap& yMap,
    const QRectF& canvasRect, int from, int to ) const
{
    const bool doAlign = QwtPainter::roundingAlignment( painter );
 
    QPolygonF polygon( 2 * ( to - from ) + 1 );
    QPointF* points = polygon.data();
 
    bool inverted = orientation() == Qt::Vertical;
    if ( m_data->attributes & Inverted )
        inverted = !inverted;
 
    const QwtSeriesData< QPointF >* series = data();
 
    int i, ip;
    for ( i = from, ip = 0; i <= to; i++, ip += 2 )
    {
        const QPointF sample = series->sample( i );
        double xi = xMap.transform( sample.x() );
        double yi = yMap.transform( sample.y() );
        if ( doAlign )
        {
            xi = qRound( xi );
            yi = qRound( yi );
        }
 
        if ( ip > 0 )
        {
            const QPointF& p0 = points[ip - 2];
            QPointF& p = points[ip - 1];
 
            if ( inverted )
            {
                p.rx() = p0.x();
                p.ry() = yi;
            }
            else
            {
                p.rx() = xi;
                p.ry() = p0.y();
            }
        }
 
        points[ip].rx() = xi;
        points[ip].ry() = yi;
    }
 
    if ( m_data->paintAttributes & ClipPolygons )
    {
        QRectF clipRect = qwtIntersectedClipRect( canvasRect, painter );
 
        const qreal pw = QwtPainter::effectivePenWidth( painter->pen() );
        clipRect = clipRect.adjusted(-pw, -pw, pw, pw);
 
        const QPolygonF clipped = QwtClipper::clippedPolygonF(
            clipRect, polygon, false );
 
        QwtPainter::drawPolyline( painter, clipped );
    }
    else
    {
        QwtPainter::drawPolyline( painter, polygon );
    }
 
    if ( m_data->brush.style() != Qt::NoBrush )
        fillCurve( painter, xMap, yMap, canvasRect, polygon );
}
 
 
void QwtPlotCurve::setCurveAttribute( CurveAttribute attribute, bool on )
{
    if ( bool( m_data->attributes & attribute ) == on )
        return;
 
    if ( on )
        m_data->attributes |= attribute;
    else
        m_data->attributes &= ~attribute;
 
    itemChanged();
}
 
bool QwtPlotCurve::testCurveAttribute( CurveAttribute attribute ) const
{
    return m_data->attributes & attribute;
}
 
void QwtPlotCurve::setCurveFitter( QwtCurveFitter* curveFitter )
{
    delete m_data->curveFitter;
    m_data->curveFitter = curveFitter;
 
    itemChanged();
}
 
QwtCurveFitter* QwtPlotCurve::curveFitter() const
{
    return m_data->curveFitter;
}
 
void QwtPlotCurve::fillCurve( QPainter* painter,
    const QwtScaleMap& xMap, const QwtScaleMap& yMap,
    const QRectF& canvasRect, QPolygonF& polygon ) const
{
    if ( m_data->brush.style() == Qt::NoBrush )
        return;
 
    closePolyline( painter, xMap, yMap, polygon );
    if ( polygon.count() <= 2 ) // a line can't be filled
        return;
 
    QBrush brush = m_data->brush;
    if ( !brush.color().isValid() )
        brush.setColor( m_data->pen.color() );
 
    if ( m_data->paintAttributes & ClipPolygons )
    {
        const QRectF clipRect = qwtIntersectedClipRect( canvasRect, painter );
        QwtClipper::clipPolygonF( clipRect, polygon, true );
    }
 
    painter->save();
 
    painter->setPen( Qt::NoPen );
    painter->setBrush( brush );
 
    QwtPainter::drawPolygon( painter, polygon );
 
    painter->restore();
}
 
void QwtPlotCurve::closePolyline( QPainter* painter,
    const QwtScaleMap& xMap, const QwtScaleMap& yMap,
    QPolygonF& polygon ) const
{
    if ( polygon.size() < 2 )
        return;
 
    const bool doAlign = QwtPainter::roundingAlignment( painter );
 
    double baseline = m_data->baseline;
 
    if ( orientation() == Qt::Vertical )
    {
        if ( yMap.transformation() )
            baseline = yMap.transformation()->bounded( baseline );
 
        double refY = yMap.transform( baseline );
        if ( doAlign && qAbs( refY ) < std::numeric_limits< int >::max() )
            refY = qRound( refY );
 
        polygon += QPointF( polygon.last().x(), refY );
        polygon += QPointF( polygon.first().x(), refY );
    }
    else
    {
        if ( xMap.transformation() )
            baseline = xMap.transformation()->bounded( baseline );
 
        double refX = xMap.transform( baseline );
        if ( doAlign && qAbs( refX ) < std::numeric_limits< int >::max() )
            refX = qRound( refX );
 
        polygon += QPointF( refX, polygon.last().y() );
        polygon += QPointF( refX, polygon.first().y() );
    }
}
 
void QwtPlotCurve::drawSymbols( QPainter* painter, const QwtSymbol& symbol,
    const QwtScaleMap& xMap, const QwtScaleMap& yMap,
    const QRectF& canvasRect, int from, int to ) const
{
    QwtPointMapper mapper;
    mapper.setFlag( QwtPointMapper::RoundPoints,
        QwtPainter::roundingAlignment( painter ) );
    mapper.setFlag( QwtPointMapper::WeedOutPoints,
        testPaintAttribute( QwtPlotCurve::FilterPoints ) );
 
    const QRectF clipRect = qwtIntersectedClipRect( canvasRect, painter );
    mapper.setBoundingRect( clipRect );
 
    const int chunkSize = 500;
 
    for ( int i = from; i <= to; i += chunkSize )
    {
        const int n = qMin( chunkSize, to - i + 1 );
 
        const QPolygonF points = mapper.toPointsF( xMap, yMap,
            data(), i, i + n - 1 );
 
        if ( points.size() > 0 )
            symbol.drawSymbols( painter, points );
    }
}
 
void QwtPlotCurve::setBaseline( double value )
{
    if ( m_data->baseline != value )
    {
        m_data->baseline = value;
        itemChanged();
    }
}
 
double QwtPlotCurve::baseline() const
{
    return m_data->baseline;
}
 
int QwtPlotCurve::closestPoint( const QPointF& pos, double* dist ) const
{
    const QwtPlot* plot = this->plot();
 
    if ( ( plot == NULL ) || !plot->isAxisValid( xAxis() ) || !plot->isAxisValid( yAxis() ) )
        return -1;
 
    const size_t numSamples = dataSize();
    if ( numSamples <= 0 )
        return -1;
 
    const QwtSeriesData< QPointF >* series = data();
 
    const QwtScaleMap xMap = plot->canvasMap( xAxis() );
    const QwtScaleMap yMap = plot->canvasMap( yAxis() );
 
    int index = -1;
    double dmin = 1.0e10;
 
    for ( uint i = 0; i < numSamples; i++ )
    {
        const QPointF sample = series->sample( i );
 
        const double cx = xMap.transform( sample.x() ) - pos.x();
        const double cy = yMap.transform( sample.y() ) - pos.y();
 
        const double f = qwtSqr( cx ) + qwtSqr( cy );
        if ( f < dmin )
        {
            index = i;
            dmin = f;
        }
    }
    if ( dist )
        *dist = std::sqrt( dmin );
 
    return index;
}
 
int QwtPlotCurve::adjacentPoint( Qt::Orientation orientation, qreal value ) const
{
    const QwtSeriesData< QPointF >* data = this->data();
    if ( data == nullptr )
        return -1;
 
    if ( orientation == Qt::Horizontal )
    {
        struct compareX
        {
            inline bool operator()( const double x, const QPointF& pos ) const
            {
                return ( x < pos.x() );
            }
        };
 
        return qwtUpperSampleIndex< QPointF >( *data, value, compareX() );
    }
    else
    {
        struct compareY
        {
            inline bool operator()( const double y, const QPointF& pos ) const
            {
                return ( y < pos.y() );
            }
        };
 
        return qwtUpperSampleIndex< QPointF >( *data, value, compareY() );
    }
 
    return -1;
}
 
qreal QwtPlotCurve::interpolatedValueAt( Qt::Orientation orientation, double value ) const
{
    const QRectF br = boundingRect();
    if ( br.width() <= 0.0 )
        return qQNaN();
 
    double v;
 
    if ( orientation == Qt::Horizontal )
    {
        if ( value < br.left() || value > br.right() )
            return qQNaN();
 
        const int index = adjacentPoint( orientation, value );
 
        if ( index == -1 )
        {
            const QPointF last = sample( dataSize() - 1 );
 
            if ( value != last.x() )
                return qQNaN();
 
            v = last.y();
        }
        else
        {
            const QLineF line( sample( index - 1 ), sample( index ) );
            v = line.pointAt( ( value - line.p1().x() ) / line.dx() ).y();
        }
    }
    else
    {
        if ( value < br.top() || value > br.bottom() )
            return qQNaN();
 
        const int index = adjacentPoint( orientation, value );
 
        if ( index == -1 )
        {
            const QPointF last = sample( dataSize() - 1 );
 
            if ( value != last.y() )
                return qQNaN();
 
            v = last.x();
        }
        else
        {
            const QLineF line( sample( index - 1 ), sample( index ) );
            v = line.pointAt( ( value - line.p1().y() ) / line.dy() ).x();
        }
    }
 
    return v;
}
 
QwtGraphic QwtPlotCurve::legendIcon( int index, const QSizeF& size ) const
{
    Q_UNUSED( index );
 
    if ( size.isEmpty() )
        return QwtGraphic();
 
    QwtGraphic graphic;
    graphic.setDefaultSize( size );
    graphic.setRenderHint( QwtGraphic::RenderPensUnscaled, true );
 
    QPainter painter( &graphic );
    painter.setRenderHint( QPainter::Antialiasing,
        testRenderHint( QwtPlotItem::RenderAntialiased ) );
 
    if ( m_data->legendAttributes == 0 ||
        m_data->legendAttributes & QwtPlotCurve::LegendShowBrush )
    {
        QBrush brush = m_data->brush;
 
        if ( brush.style() == Qt::NoBrush &&
            m_data->legendAttributes == 0 )
        {
            if ( style() != QwtPlotCurve::NoCurve )
            {
                brush = QBrush( pen().color() );
            }
            else if ( m_data->symbol &&
                ( m_data->symbol->style() != QwtSymbol::NoSymbol ) )
            {
                brush = QBrush( m_data->symbol->pen().color() );
            }
        }
 
        if ( brush.style() != Qt::NoBrush )
        {
            QRectF r( 0, 0, size.width(), size.height() );
            painter.fillRect( r, brush );
        }
    }
 
    if ( m_data->legendAttributes & QwtPlotCurve::LegendShowLine )
    {
        if ( pen() != Qt::NoPen )
        {
            QPen pn = pen();
            pn.setCapStyle( Qt::FlatCap );
 
            painter.setPen( pn );
 
            const double y = 0.5 * size.height();
            QwtPainter::drawLine( &painter, 0.0, y, size.width(), y );
        }
    }
 
    if ( m_data->legendAttributes & QwtPlotCurve::LegendShowSymbol )
    {
        if ( m_data->symbol )
        {
            QRectF r( 0, 0, size.width(), size.height() );
            m_data->symbol->drawSymbol( &painter, r );
        }
    }
 
    return graphic;
}
 
void QwtPlotCurve::setSamples( QwtSeriesData< QPointF >* data )
{
    setData( data );
}
 
void QwtPlotCurve::setSamples( const QVector< QPointF >& samples )
{
    setData( new QwtPointSeriesData( samples ) );
}
 
void QwtPlotCurve::setRawSamples(
    const double* xData, const double* yData, int size )
{
    setData( new QwtCPointerData< double >( xData, yData, size ) );
}
 
void QwtPlotCurve::setRawSamples(
    const float* xData, const float* yData, int size )
{
    setData( new QwtCPointerData< float >( xData, yData, size ) );
}
 
void QwtPlotCurve::setRawSamples( const double* yData, int size )
{
    setData( new QwtCPointerValueData< double >( yData, size ) );
}
 
void QwtPlotCurve::setRawSamples( const float* yData, int size )
{
    setData( new QwtCPointerValueData< float >( yData, size ) );
}
 
void QwtPlotCurve::setSamples(
    const double* xData, const double* yData, int size )
{
    setData( new QwtPointArrayData< double >( xData, yData, size ) );
}
 
void QwtPlotCurve::setSamples(
    const float* xData, const float* yData, int size )
{
    setData( new QwtPointArrayData< float >( xData, yData, size ) );
}
 
void QwtPlotCurve::setSamples( const QVector< double >& xData,
    const QVector< double >& yData )
{
    setData( new QwtPointArrayData< double >( xData, yData ) );
}
 
void QwtPlotCurve::setSamples( const QVector< float >& xData,
    const QVector< float >& yData )
{
    setData( new QwtPointArrayData< float >( xData, yData ) );
}
 
void QwtPlotCurve::setSamples( const double* yData, int size )
{
    setData( new QwtValuePointData< double >( yData, size ) );
}
 
void QwtPlotCurve::setSamples( const float* yData, int size )
{
    setData( new QwtValuePointData< float >( yData, size ) );
}
 
void QwtPlotCurve::setSamples( const QVector< double >& yData )
{
    setData( new QwtValuePointData< double >( yData ) );
}
 
void QwtPlotCurve::setSamples( const QVector< float >& yData )
{
    setData( new QwtValuePointData< float >( yData ) );
}