qwt_symbol.cpp

/* -*- mode: C++ ; c-file-style: "stroustrup" -*- *****************************
 * 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_symbol.h"
#include "qwt_painter.h"
#include "qwt_graphic.h"
#include <qapplication.h>
#include <qpainter.h>
#include <qpainterpath.h>
#include <qpixmap.h>
#include <qpaintengine.h>
#include <qmath.h>
#ifndef QWT_NO_SVG
#include <qsvgrenderer.h>
#endif

namespace QwtTriangle
{
    enum Type
    {
        Left,
        Right,
        Up,
        Down
    };
}

static QwtGraphic qwtPathGraphic( const QPainterPath &path, 
    const QPen &pen, const QBrush& brush )
{
    QwtGraphic graphic;
    graphic.setRenderHint( QwtGraphic::RenderPensUnscaled );

    QPainter painter( &graphic );
    painter.setPen( pen );
    painter.setBrush( brush );
    painter.drawPath( path );
    painter.end();

    return graphic;
}

static inline QRectF qwtScaledBoundingRect( 
    const QwtGraphic &graphic, const QSizeF size )
{
    QSizeF scaledSize = size;
    if ( scaledSize.isEmpty() )
        scaledSize = graphic.defaultSize();
        
    const QSizeF sz = graphic.controlPointRect().size();

    double sx = 1.0;
    if ( sz.width() > 0.0 )
        sx = scaledSize.width() / sz.width();
    
    double sy = 1.0;
    if ( sz.height() > 0.0 )
        sy = scaledSize.height() / sz.height();

    return graphic.scaledBoundingRect( sx, sy );
}

static inline void qwtDrawPixmapSymbols( QPainter *painter,
    const QPointF *points, int numPoints, const QwtSymbol &symbol )
{
    QSize size = symbol.size();
    if ( size.isEmpty() )
        size = symbol.pixmap().size();

    const QTransform transform = painter->transform();
    if ( transform.isScaling() )
    {
        const QRect r( 0, 0, size.width(), size.height() );
        size = transform.mapRect( r ).size();
    }

    QPixmap pm = symbol.pixmap();
    if ( pm.size() != size )
        pm = pm.scaled( size );
    
    QPointF pinPoint( 0.5 * size.width(), 0.5 * size.height() );
    if ( symbol.isPinPointEnabled() )
        pinPoint = symbol.pinPoint();

    painter->resetTransform();

    for ( int i = 0; i < numPoints; i++ )
    {
        const QPointF pos = transform.map( points[i] ) - pinPoint;

        QwtPainter::drawPixmap( painter, 
            QRect( pos.toPoint(), pm.size() ), pm );
    }
}

#ifndef QWT_NO_SVG

static inline void qwtDrawSvgSymbols( QPainter *painter, 
    const QPointF *points, int numPoints, 
    QSvgRenderer *renderer, const QwtSymbol &symbol )
{
    if ( renderer == NULL || !renderer->isValid() )
        return;

    const QRectF viewBox = renderer->viewBoxF();
    if ( viewBox.isEmpty() )
        return;

    QSizeF sz = symbol.size();
    if ( !sz.isValid() )
        sz = viewBox.size();

    const double sx = sz.width() / viewBox.width();
    const double sy = sz.height() / viewBox.height();

    QPointF pinPoint = viewBox.center();
    if ( symbol.isPinPointEnabled() )
        pinPoint = symbol.pinPoint();

    const double dx = sx * ( pinPoint.x() - viewBox.left() );
    const double dy = sy * ( pinPoint.y() - viewBox.top() );

    for ( int i = 0; i < numPoints; i++ )
    {
        const double x = points[i].x() - dx;
        const double y = points[i].y() - dy;

        renderer->render( painter, 
            QRectF( x, y, sz.width(), sz.height() ) );
    }
}

#endif

static inline void qwtDrawGraphicSymbols( QPainter *painter, 
    const QPointF *points, int numPoints, const QwtGraphic &graphic,
    const QwtSymbol &symbol )
{
    const QRectF pointRect = graphic.controlPointRect();
    if ( pointRect.isEmpty() )
        return;

    double sx = 1.0;
    double sy = 1.0;

    const QSize sz = symbol.size();
    if ( sz.isValid() )
    {
        sx = sz.width() / pointRect.width();
        sy = sz.height() / pointRect.height();
    }

    QPointF pinPoint = pointRect.center();
    if ( symbol.isPinPointEnabled() )
        pinPoint = symbol.pinPoint();

    const QTransform transform = painter->transform();

    for ( int i = 0; i < numPoints; i++ )
    {
        QTransform tr = transform;
        tr.translate( points[i].x(), points[i].y() );
        tr.scale( sx, sy );
        tr.translate( -pinPoint.x(), -pinPoint.y() );

        painter->setTransform( tr );

        graphic.render( painter );
    }

    painter->setTransform( transform );
}

static inline void qwtDrawEllipseSymbols( QPainter *painter,
    const QPointF *points, int numPoints, const QwtSymbol &symbol )
{
    painter->setBrush( symbol.brush() );
    painter->setPen( symbol.pen() );

    const QSize size = symbol.size();

    if ( QwtPainter::roundingAlignment( painter ) )
    {
        const int sw = size.width();
        const int sh = size.height();
        const int sw2 = size.width() / 2;
        const int sh2 = size.height() / 2;

        for ( int i = 0; i < numPoints; i++ )
        {
            const int x = qRound( points[i].x() );
            const int y = qRound( points[i].y() );

            const QRectF r( x - sw2, y - sh2, sw, sh );
            QwtPainter::drawEllipse( painter, r );
        }
    }
    else
    {
        const double sw = size.width();
        const double sh = size.height();
        const double sw2 = 0.5 * size.width();
        const double sh2 = 0.5 * size.height();

        for ( int i = 0; i < numPoints; i++ )
        {
            const double x = points[i].x();
            const double y = points[i].y();

            const QRectF r( x - sw2, y - sh2, sw, sh );
            QwtPainter::drawEllipse( painter, r );
        }
    }
}

static inline void qwtDrawRectSymbols( QPainter *painter,
    const QPointF *points, int numPoints, const QwtSymbol &symbol )
{
    const QSize size = symbol.size();

    QPen pen = symbol.pen();
    pen.setJoinStyle( Qt::MiterJoin );
    painter->setPen( pen );
    painter->setBrush( symbol.brush() );
    painter->setRenderHint( QPainter::Antialiasing, false );

    if ( QwtPainter::roundingAlignment( painter ) )
    {
        const int sw = size.width();
        const int sh = size.height();
        const int sw2 = size.width() / 2;
        const int sh2 = size.height() / 2;

        for ( int i = 0; i < numPoints; i++ )
        {
            const int x = qRound( points[i].x() );
            const int y = qRound( points[i].y() );

            const QRect r( x - sw2, y - sh2, sw, sh );
            QwtPainter::drawRect( painter, r );
        }
    }
    else
    {
        const double sw = size.width();
        const double sh = size.height();
        const double sw2 = 0.5 * size.width();
        const double sh2 = 0.5 * size.height();

        for ( int i = 0; i < numPoints; i++ )
        {
            const double x = points[i].x();
            const double y = points[i].y();

            const QRectF r( x - sw2, y - sh2, sw, sh );
            QwtPainter::drawRect( painter, r );
        }
    }
}

static inline void qwtDrawDiamondSymbols( QPainter *painter,
    const QPointF *points, int numPoints, const QwtSymbol &symbol )
{
    const QSize size = symbol.size();

    QPen pen = symbol.pen();
    pen.setJoinStyle( Qt::MiterJoin );
    painter->setPen( pen );
    painter->setBrush( symbol.brush() );

    if ( QwtPainter::roundingAlignment( painter ) )
    {
        for ( int i = 0; i < numPoints; i++ )
        {
            const int x = qRound( points[i].x() );
            const int y = qRound( points[i].y() );

            const int x1 = x - size.width() / 2;
            const int y1 = y - size.height() / 2;
            const int x2 = x1 + size.width();
            const int y2 = y1 + size.height();

            QPolygonF polygon;
            polygon += QPointF( x, y1 );
            polygon += QPointF( x1, y );
            polygon += QPointF( x, y2 );
            polygon += QPointF( x2, y );

            QwtPainter::drawPolygon( painter, polygon );
        }
    }
    else
    {
        for ( int i = 0; i < numPoints; i++ )
        {
            const QPointF &pos = points[i];

            const double x1 = pos.x() - 0.5 * size.width();
            const double y1 = pos.y() - 0.5 * size.height();
            const double x2 = x1 + size.width();
            const double y2 = y1 + size.height();

            QPolygonF polygon;
            polygon += QPointF( pos.x(), y1 );
            polygon += QPointF( x2, pos.y() );
            polygon += QPointF( pos.x(), y2 );
            polygon += QPointF( x1, pos.y() );

            QwtPainter::drawPolygon( painter, polygon );
        }
    }
}

static inline void qwtDrawTriangleSymbols(
    QPainter *painter, QwtTriangle::Type type,
    const QPointF *points, int numPoints,
    const QwtSymbol &symbol )
{
    const QSize size = symbol.size();

    QPen pen = symbol.pen();
    pen.setJoinStyle( Qt::MiterJoin );
    painter->setPen( pen );

    painter->setBrush( symbol.brush() );

    const bool doAlign = QwtPainter::roundingAlignment( painter );

    double sw2 = 0.5 * size.width();
    double sh2 = 0.5 * size.height();

    if ( doAlign )
    {
        sw2 = qFloor( sw2 );
        sh2 = qFloor( sh2 );
    }

    QPolygonF triangle( 3 );
    QPointF *trianglePoints = triangle.data();

    for ( int i = 0; i < numPoints; i++ )
    {
        const QPointF &pos = points[i];

        double x = pos.x();
        double y = pos.y();

        if ( doAlign )
        {
            x = qRound( x );
            y = qRound( y );
        }

        const double x1 = x - sw2;
        const double x2 = x1 + size.width();
        const double y1 = y - sh2;
        const double y2 = y1 + size.height();

        switch ( type )
        {
            case QwtTriangle::Left:
            {
                trianglePoints[0].rx() = x2;
                trianglePoints[0].ry() = y1;

                trianglePoints[1].rx() = x1;
                trianglePoints[1].ry() = y;

                trianglePoints[2].rx() = x2;
                trianglePoints[2].ry() = y2;

                break;
            }
            case QwtTriangle::Right:
            {
                trianglePoints[0].rx() = x1;
                trianglePoints[0].ry() = y1;

                trianglePoints[1].rx() = x2;
                trianglePoints[1].ry() = y;

                trianglePoints[2].rx() = x1;
                trianglePoints[2].ry() = y2;

                break;
            }
            case QwtTriangle::Up:
            {
                trianglePoints[0].rx() = x1;
                trianglePoints[0].ry() = y2;

                trianglePoints[1].rx() = x;
                trianglePoints[1].ry() = y1;

                trianglePoints[2].rx() = x2;
                trianglePoints[2].ry() = y2;

                break;
            }
            case QwtTriangle::Down:
            {
                trianglePoints[0].rx() = x1;
                trianglePoints[0].ry() = y1;

                trianglePoints[1].rx() = x;
                trianglePoints[1].ry() = y2;

                trianglePoints[2].rx() = x2;
                trianglePoints[2].ry() = y1;

                break;
            }
        }
        QwtPainter::drawPolygon( painter, triangle );
    }
}

static inline void qwtDrawLineSymbols(
    QPainter *painter, int orientations,
    const QPointF *points, int numPoints, const QwtSymbol &symbol )
{
    const QSize size = symbol.size();

    int off = 0;

    QPen pen = symbol.pen();
    if ( pen.width() > 1 )
    {
        pen.setCapStyle( Qt::FlatCap );
        off = 1;
    }

    painter->setPen( pen );
    painter->setRenderHint( QPainter::Antialiasing, false );

    if ( QwtPainter::roundingAlignment( painter ) )
    {
        const int sw = qFloor( size.width() );
        const int sh = qFloor( size.height() );
        const int sw2 = size.width() / 2;
        const int sh2 = size.height() / 2;

        for ( int i = 0; i < numPoints; i++ )
        {
            if ( orientations & Qt::Horizontal )
            {
                const int x = qRound( points[i].x() ) - sw2;
                const int y = qRound( points[i].y() );

                QwtPainter::drawLine( painter, x, y, x + sw + off, y );
            }
            if ( orientations & Qt::Vertical )
            {
                const int x = qRound( points[i].x() );
                const int y = qRound( points[i].y() ) - sh2;

                QwtPainter::drawLine( painter, x, y, x, y + sh + off );
            }
        }
    }
    else
    {
        const double sw = size.width();
        const double sh = size.height();
        const double sw2 = 0.5 * size.width();
        const double sh2 = 0.5 * size.height();

        for ( int i = 0; i < numPoints; i++ )
        {
            if ( orientations & Qt::Horizontal )
            {
                const double x = points[i].x() - sw2;
                const double y = points[i].y();

                QwtPainter::drawLine( painter, x, y, x + sw, y );
            }
            if ( orientations & Qt::Vertical )
            {
                const double y = points[i].y() - sh2;
                const double x = points[i].x();

                QwtPainter::drawLine( painter, x, y, x, y + sh );
            }
        }
    }
}

static inline void qwtDrawXCrossSymbols( QPainter *painter,
    const QPointF *points, int numPoints, const QwtSymbol &symbol )
{
    const QSize size = symbol.size();
    int off = 0;

    QPen pen = symbol.pen();
    if ( pen.width() > 1 )
    {
        pen.setCapStyle( Qt::FlatCap );
        off = 1;
    }
    painter->setPen( pen );


    if ( QwtPainter::roundingAlignment( painter ) )
    {
        const int sw = size.width();
        const int sh = size.height();
        const int sw2 = size.width() / 2;
        const int sh2 = size.height() / 2;

        for ( int i = 0; i < numPoints; i++ )
        {
            const QPointF &pos = points[i];

            const int x = qRound( pos.x() );
            const int y = qRound( pos.y() );

            const int x1 = x - sw2;
            const int x2 = x1 + sw + off;
            const int y1 = y - sh2;
            const int y2 = y1 + sh + off;

            QwtPainter::drawLine( painter, x1, y1, x2, y2 );
            QwtPainter::drawLine( painter, x2, y1, x1, y2 );
        }
    }
    else
    {
        const double sw = size.width();
        const double sh = size.height();
        const double sw2 = 0.5 * size.width();
        const double sh2 = 0.5 * size.height();

        for ( int i = 0; i < numPoints; i++ )
        {
            const QPointF &pos = points[i];

            const double x1 = pos.x() - sw2;
            const double x2 = x1 + sw;
            const double y1 = pos.y() - sh2;
            const double y2 = y1 + sh;

            QwtPainter::drawLine( painter, x1, y1, x2, y2 );
            QwtPainter::drawLine( painter, x1, y2, x2, y1 );
        }
    }
}

static inline void qwtDrawStar1Symbols( QPainter *painter,
    const QPointF *points, int numPoints, const QwtSymbol &symbol )
{
    const QSize size = symbol.size();
    painter->setPen( symbol.pen() );

    if ( QwtPainter::roundingAlignment( painter ) )
    {
        QRect r( 0, 0, size.width(), size.height() );

        for ( int i = 0; i < numPoints; i++ )
        {
            r.moveCenter( points[i].toPoint() );

            const double sqrt1_2 = 0.70710678118654752440; /* 1/sqrt(2) */

            const double d1 = r.width() / 2.0 * ( 1.0 - sqrt1_2 );

            QwtPainter::drawLine( painter,
                qRound( r.left() + d1 ), qRound( r.top() + d1 ),
                qRound( r.right() - d1 ), qRound( r.bottom() - d1 ) );
            QwtPainter::drawLine( painter,
                qRound( r.left() + d1 ), qRound( r.bottom() - d1 ),
                qRound( r .right() - d1), qRound( r.top() + d1 ) );

            const QPoint c = r.center();

            QwtPainter::drawLine( painter,
                c.x(), r.top(), c.x(), r.bottom() );
            QwtPainter::drawLine( painter,
                r.left(), c.y(), r.right(), c.y() );
        }
    }
    else
    {
        QRectF r( 0, 0, size.width(), size.height() );

        for ( int i = 0; i < numPoints; i++ )
        {
            r.moveCenter( points[i] );

            const double sqrt1_2 = 0.70710678118654752440; /* 1/sqrt(2) */

            const QPointF c = r.center();
            const double d1  = r.width() / 2.0 * ( 1.0 - sqrt1_2 );

            QwtPainter::drawLine( painter,
                r.left() + d1, r.top() + d1,
                r.right() - d1, r.bottom() - d1 );
            QwtPainter::drawLine( painter,
                r.left() + d1, r.bottom() - d1,
                r.right() - d1, r.top() + d1 );
            QwtPainter::drawLine( painter,
                c.x(), r.top(),
                c.x(), r.bottom() );
            QwtPainter::drawLine( painter,
                r.left(), c.y(),
                r.right(), c.y() );
        }
    }
}

static inline void qwtDrawStar2Symbols( QPainter *painter,
    const QPointF *points, int numPoints, const QwtSymbol &symbol )
{
    QPen pen = symbol.pen();
    if ( pen.width() > 1 )
        pen.setCapStyle( Qt::FlatCap );
    pen.setJoinStyle( Qt::MiterJoin );
    painter->setPen( pen );

    painter->setBrush( symbol.brush() );

    const double cos30 = 0.866025; // cos(30°)

    const double dy = 0.25 * symbol.size().height();
    const double dx = 0.5 * symbol.size().width() * cos30 / 3.0;

    QPolygonF star( 12 );
    QPointF *starPoints = star.data();

    const bool doAlign = QwtPainter::roundingAlignment( painter );

    for ( int i = 0; i < numPoints; i++ )
    {
        double x = points[i].x();
        double y = points[i].y();
        if ( doAlign )
        {
            x = qRound( x );
            y = qRound( y );
        }

        double x1 = x - 3 * dx;
        double y1 = y - 2 * dy;
        if ( doAlign )
        {
            x1 = qRound( x - 3 * dx );
            y1 = qRound( y - 2 * dy );
        }

        const double x2 = x1 + 1 * dx;
        const double x3 = x1 + 2 * dx;
        const double x4 = x1 + 3 * dx;
        const double x5 = x1 + 4 * dx;
        const double x6 = x1 + 5 * dx;
        const double x7 = x1 + 6 * dx;

        const double y2 = y1 + 1 * dy;
        const double y3 = y1 + 2 * dy;
        const double y4 = y1 + 3 * dy;
        const double y5 = y1 + 4 * dy;

        starPoints[0].rx() = x4;
        starPoints[0].ry() = y1;

        starPoints[1].rx() = x5;
        starPoints[1].ry() = y2;

        starPoints[2].rx() = x7;
        starPoints[2].ry() = y2;

        starPoints[3].rx() = x6;
        starPoints[3].ry() = y3;

        starPoints[4].rx() = x7;
        starPoints[4].ry() = y4;

        starPoints[5].rx() = x5;
        starPoints[5].ry() = y4;

        starPoints[6].rx() = x4;
        starPoints[6].ry() = y5;

        starPoints[7].rx() = x3;
        starPoints[7].ry() = y4;

        starPoints[8].rx() = x1;
        starPoints[8].ry() = y4;

        starPoints[9].rx() = x2;
        starPoints[9].ry() = y3;

        starPoints[10].rx() = x1;
        starPoints[10].ry() = y2;

        starPoints[11].rx() = x3;
        starPoints[11].ry() = y2;

        QwtPainter::drawPolygon( painter, star );
    }
}

static inline void qwtDrawHexagonSymbols( QPainter *painter,
    const QPointF *points, int numPoints, const QwtSymbol &symbol )
{
    painter->setBrush( symbol.brush() );
    painter->setPen( symbol.pen() );

    const double cos30 = 0.866025; // cos(30°)
    const double dx = 0.5 * ( symbol.size().width() - cos30 );

    const double dy = 0.25 * symbol.size().height();

    QPolygonF hexaPolygon( 6 );
    QPointF *hexaPoints = hexaPolygon.data();

    const bool doAlign = QwtPainter::roundingAlignment( painter );

    for ( int i = 0; i < numPoints; i++ )
    {
        double x = points[i].x();
        double y = points[i].y();
        if ( doAlign )
        {
            x = qRound( x );
            y = qRound( y );
        }

        double x1 = x - dx;
        double y1 = y - 2 * dy;
        if ( doAlign )
        {
            x1 = qCeil( x1 );
            y1 = qCeil( y1 );
        }

        const double x2 = x1 + 1 * dx;
        const double x3 = x1 + 2 * dx;

        const double y2 = y1 + 1 * dy;
        const double y3 = y1 + 3 * dy;
        const double y4 = y1 + 4 * dy;

        hexaPoints[0].rx() = x2;
        hexaPoints[0].ry() = y1;

        hexaPoints[1].rx() = x3;
        hexaPoints[1].ry() = y2;

        hexaPoints[2].rx() = x3;
        hexaPoints[2].ry() = y3;

        hexaPoints[3].rx() = x2;
        hexaPoints[3].ry() = y4;

        hexaPoints[4].rx() = x1;
        hexaPoints[4].ry() = y3;

        hexaPoints[5].rx() = x1;
        hexaPoints[5].ry() = y2;

        QwtPainter::drawPolygon( painter, hexaPolygon );
    }
}

class QwtSymbol::PrivateData
{
public:
    PrivateData( QwtSymbol::Style st, const QBrush &br,
            const QPen &pn, const QSize &sz ):
        style( st ),
        size( sz ),
        brush( br ),
        pen( pn ),
        isPinPointEnabled( false )
    {
        cache.policy = QwtSymbol::AutoCache;
#ifndef QWT_NO_SVG
        svg.renderer = NULL;
#endif
    }

    ~PrivateData()
    {
#ifndef QWT_NO_SVG
        delete svg.renderer;
#endif
    }

    Style style;
    QSize size;
    QBrush brush;
    QPen pen;

    bool isPinPointEnabled;
    QPointF pinPoint;

    struct Path
    {
        QPainterPath path;
        QwtGraphic graphic;

    } path;

    struct Pixmap
    {
        QPixmap pixmap;

    } pixmap;

    struct Graphic
    {
        QwtGraphic graphic;

    } graphic;

#ifndef QWT_NO_SVG
    struct SVG
    {
        QSvgRenderer *renderer;
    } svg;
#endif

    struct PaintCache
    {
        QwtSymbol::CachePolicy policy;
        QPixmap pixmap;

    } cache;
};

/*!
  Default Constructor
  \param style Symbol Style

  The symbol is constructed with gray interior,
  black outline with zero width, no size and style 'NoSymbol'.
*/
QwtSymbol::QwtSymbol( Style style )
{
    d_data = new PrivateData( style, QBrush( Qt::gray ),
        QPen( Qt::black, 0 ), QSize() );
}

/*!
  \brief Constructor
  \param style Symbol Style
  \param brush brush to fill the interior
  \param pen outline pen
  \param size size

  \sa setStyle(), setBrush(), setPen(), setSize()
*/
QwtSymbol::QwtSymbol( QwtSymbol::Style style, const QBrush &brush,
    const QPen &pen, const QSize &size )
{
    d_data = new PrivateData( style, brush, pen, size );
}

/*!
  \brief Constructor

  The symbol gets initialized by a painter path. The style is
  set to QwtSymbol::Path, the size is set to empty ( the path
  is displayed unscaled ).

  \param path painter path
  \param brush brush to fill the interior
  \param pen outline pen

  \sa setPath(), setBrush(), setPen(), setSize()
*/

QwtSymbol::QwtSymbol( const QPainterPath &path, 
    const QBrush &brush, const QPen &pen )
{
    d_data = new PrivateData( QwtSymbol::Path, brush, pen, QSize() );
    setPath( path );
}

//! Destructor
QwtSymbol::~QwtSymbol()
{
    delete d_data;
}

/*!
  Change the cache policy

  The default policy is AutoCache

  \param policy Cache policy
  \sa CachePolicy, cachePolicy()
*/
void QwtSymbol::setCachePolicy(
    QwtSymbol::CachePolicy policy )
{
    if ( d_data->cache.policy != policy )
    {
        d_data->cache.policy = policy;
        invalidateCache();
    }
}

/*!
  \return Cache policy
  \sa CachePolicy, setCachePolicy()
*/
QwtSymbol::CachePolicy QwtSymbol::cachePolicy() const
{
    return d_data->cache.policy;
}

/*!
  \brief Set a painter path as symbol

  The symbol is represented by a painter path, where the 
  origin ( 0, 0 ) of the path coordinate system is mapped to
  the position of the symbol.

  When the symbol has valid size the painter path gets scaled
  to fit into the size. Otherwise the symbol size depends on
  the bounding rectangle of the path.

  The following code defines a symbol drawing an arrow:

  \verbatim
#include <qwt_symbol.h>

QwtSymbol *symbol = new QwtSymbol();

QPen pen( Qt::black, 2 );
pen.setJoinStyle( Qt::MiterJoin );

symbol->setPen( pen );
symbol->setBrush( Qt::red );

QPainterPath path;
path.moveTo( 0, 8 );
path.lineTo( 0, 5 );
path.lineTo( -3, 5 );
path.lineTo( 0, 0 );
path.lineTo( 3, 5 );
path.lineTo( 0, 5 );

QTransform transform;
transform.rotate( -30.0 );
path = transform.map( path );

symbol->setPath( path );
symbol->setPinPoint( QPointF( 0.0, 0.0 ) );

setSize( 10, 14 );
\endverbatim

  \param path Painter path

  \note The style is implicitely set to QwtSymbol::Path.
  \sa path(), setSize()
 */
void QwtSymbol::setPath( const QPainterPath &path )
{
    d_data->style = QwtSymbol::Path;
    d_data->path.path = path;
    d_data->path.graphic.reset();
}

/*!
   \return Painter path for displaying the symbol
   \sa setPath()
*/
const QPainterPath &QwtSymbol::path() const
{
    return d_data->path.path;
}

/*!
  Set a pixmap as symbol

  \param pixmap Pixmap

  \sa pixmap(), setGraphic()

  \note the style() is set to QwtSymbol::Pixmap
  \note brush() and pen() have no effect
 */
void QwtSymbol::setPixmap( const QPixmap &pixmap )
{
    d_data->style = QwtSymbol::Pixmap;
    d_data->pixmap.pixmap = pixmap;
}

/*!
  \return Assigned pixmap
  \sa setPixmap()
 */