qwt_plot_barchart.cpp

/******************************************************************************
 * 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_barchart.h"
#include "qwt_scale_map.h"
#include "qwt_column_symbol.h"
#include "qwt_text.h"
#include "qwt_graphic.h"
#include "qwt_legend_data.h"

#include <qpainter.h>

class QwtPlotBarChart::PrivateData
{
  public:
    PrivateData()
        : symbol( NULL )
        , legendMode( QwtPlotBarChart::LegendChartTitle )
    {
    }

    ~PrivateData()
    {
        delete symbol;
    }

    QwtColumnSymbol* symbol;
    QwtPlotBarChart::LegendMode legendMode;
};

/*!
   Constructor
   \param title Title of the curve
 */
QwtPlotBarChart::QwtPlotBarChart( const QwtText& title )
    : QwtPlotAbstractBarChart( title )
{
    init();
}

/*!
   Constructor
   \param title Title of the curve
 */
QwtPlotBarChart::QwtPlotBarChart( const QString& title )
    : QwtPlotAbstractBarChart( QwtText( title ) )
{
    init();
}

//! Destructor
QwtPlotBarChart::~QwtPlotBarChart()
{
    delete m_data;
}

void QwtPlotBarChart::init()
{
    m_data = new PrivateData;
    setData( new QwtPointSeriesData() );
}

//! \return QwtPlotItem::Rtti_PlotBarChart
int QwtPlotBarChart::rtti() const
{
    return QwtPlotItem::Rtti_PlotBarChart;
}

/*!
   Initialize data with an array of points

   \param samples Vector of points
   \note QVector is implicitly shared
   \note QPolygonF is derived from QVector<QPointF>
 */
void QwtPlotBarChart::setSamples(
    const QVector< QPointF >& samples )
{
    setData( new QwtPointSeriesData( samples ) );
}

/*!
   Initialize data with an array of doubles

   The indices in the array are taken as x coordinate,
   while the doubles are interpreted as y values.

   \param samples Vector of y coordinates
   \note QVector is implicitly shared
 */
void QwtPlotBarChart::setSamples(
    const QVector< double >& samples )
{
    QVector< QPointF > points;
    points.reserve( samples.size() );

    for ( int i = 0; i < samples.size(); i++ )
        points += QPointF( i, samples[ i ] );

    setData( new QwtPointSeriesData( points ) );
}

/*!
   Assign a series of samples

   setSamples() is just a wrapper for setData() without any additional
   value - beside that it is easier to find for the developer.

   \param data Data
   \warning The item takes ownership of the data object, deleting
           it when its not used anymore.
 */
void QwtPlotBarChart::setSamples( QwtSeriesData< QPointF >* data )
{
    setData( data );
}

/*!
   \brief Assign a symbol

   The bar chart will take the ownership of the symbol, hence the previously
   set symbol will be delete by setting a new one. If \p symbol is
   \c NULL no symbol will be drawn.

   \param symbol Symbol
   \sa symbol()
 */
void QwtPlotBarChart::setSymbol( QwtColumnSymbol* symbol )
{
    if ( symbol != m_data->symbol )
    {
        delete m_data->symbol;
        m_data->symbol = symbol;

        legendChanged();
        itemChanged();
    }
}

/*!
   \return Current symbol or NULL, when no symbol has been assigned
   \sa setSymbol()
 */
const QwtColumnSymbol* QwtPlotBarChart::symbol() const
{
    return m_data->symbol;
}

/*!
   Set the mode that decides what to display on the legend

   In case of LegendBarTitles barTitle() needs to be overloaded
   to return individual titles for each bar.

   \param mode New mode
   \sa legendMode(), legendData(), barTitle(), QwtPlotItem::ItemAttribute
 */
void QwtPlotBarChart::setLegendMode( LegendMode mode )
{
    if ( mode != m_data->legendMode )
    {
        m_data->legendMode = mode;
        legendChanged();
    }
}

/*!
   \return Legend mode
   \sa setLegendMode()
 */
QwtPlotBarChart::LegendMode QwtPlotBarChart::legendMode() const
{
    return m_data->legendMode;
}

/*!
   \return Bounding rectangle of all samples.
   For an empty series the rectangle is invalid.
 */
QRectF QwtPlotBarChart::boundingRect() const
{
    const size_t numSamples = dataSize();
    if ( numSamples == 0 )
        return QwtPlotSeriesItem::boundingRect();

    QRectF rect = QwtPlotSeriesItem::boundingRect();
    if ( rect.height() >= 0 )
    {
        const double baseLine = baseline();

        if ( rect.bottom() < baseLine )
            rect.setBottom( baseLine );

        if ( rect.top() > baseLine )
            rect.setTop( baseLine );
    }

    if ( orientation() == Qt::Horizontal )
        rect.setRect( rect.y(), rect.x(), rect.height(), rect.width() );

    return rect;
}

/*!
   Draw an interval of the bar chart

   \param painter Painter
   \param xMap Maps x-values into pixel coordinates.
   \param yMap Maps y-values into pixel coordinates.
   \param canvasRect Contents rect of the canvas
   \param from Index of the first point to be painted
   \param to Index of the last point to be painted. If to < 0 the
         curve will be painted to its last point.

   \sa drawSymbols()
 */
void QwtPlotBarChart::drawSeries( QPainter* painter,
    const QwtScaleMap& xMap, const QwtScaleMap& yMap,
    const QRectF& canvasRect, int from, int to ) const
{
    if ( to < 0 )
        to = dataSize() - 1;

    if ( from < 0 )
        from = 0;

    if ( from > to )
        return;


    const QRectF br = data()->boundingRect();
    const QwtInterval interval( br.left(), br.right() );

    painter->save();

    for ( int i = from; i <= to; i++ )
    {
        drawSample( painter, xMap, yMap,
            canvasRect, interval, i, sample( i ) );
    }

    painter->restore();
}

/*!
   Calculate the geometry of a bar in widget coordinates

   \param xMap x map
   \param yMap y map
   \param canvasRect Contents rect of the canvas
   \param boundingInterval Bounding interval of sample values
   \param sample Value of the sample

   \return Geometry of the column
 */
QwtColumnRect QwtPlotBarChart::columnRect(
    const QwtScaleMap& xMap, const QwtScaleMap& yMap,
    const QRectF& canvasRect, const QwtInterval& boundingInterval,
    const QPointF& sample ) const
{
    QwtColumnRect barRect;

    if ( orientation() == Qt::Horizontal )
    {
        const double barHeight = sampleWidth( yMap, canvasRect.height(),
            boundingInterval.width(), sample.y() );

        const double x1 = xMap.transform( baseline() );
        const double x2 = xMap.transform( sample.y() );

        const double y = yMap.transform( sample.x() );
        const double y1 = y - 0.5 * barHeight;
        const double y2 = y + 0.5 * barHeight;

        barRect.direction = ( x1 < x2 ) ?
            QwtColumnRect::LeftToRight : QwtColumnRect::RightToLeft;

        barRect.hInterval = QwtInterval( x1, x2 ).normalized();
        barRect.vInterval = QwtInterval( y1, y2 );
    }
    else
    {
        const double barWidth = sampleWidth( xMap, canvasRect.width(),
            boundingInterval.width(), sample.y() );

        const double x = xMap.transform( sample.x() );
        const double x1 = x - 0.5 * barWidth;
        const double x2 = x + 0.5 * barWidth;

        const double y1 = yMap.transform( baseline() );
        const double y2 = yMap.transform( sample.y() );

        barRect.direction = ( y1 < y2 ) ?
            QwtColumnRect::TopToBottom : QwtColumnRect::BottomToTop;

        barRect.hInterval = QwtInterval( x1, x2 );
        barRect.vInterval = QwtInterval( y1, y2 ).normalized();
    }

    return barRect;
}

/*!
   Draw a sample

   \param painter Painter
   \param xMap x map
   \param yMap y map
   \param canvasRect Contents rect of the canvas
   \param boundingInterval Bounding interval of sample values
   \param index Index of the sample
   \param sample Value of the sample

   \sa drawSeries()
 */
void QwtPlotBarChart::drawSample( QPainter* painter,
    const QwtScaleMap& xMap, const QwtScaleMap& yMap,
    const QRectF& canvasRect, const QwtInterval& boundingInterval,
    int index, const QPointF& sample ) const
{
    const QwtColumnRect barRect = columnRect( xMap, yMap,
        canvasRect, boundingInterval, sample );

    drawBar( painter, index, sample, barRect );
}

/*!
   Draw a bar

   \param painter Painter
   \param sampleIndex Index of the sample represented by the bar
   \param sample Value of the sample
   \param rect Bounding rectangle of the bar
 */
void QwtPlotBarChart::drawBar( QPainter* painter,
    int sampleIndex, const QPointF& sample,
    const QwtColumnRect& rect ) const
{
    const QwtColumnSymbol* specialSym =
        specialSymbol( sampleIndex, sample );

    const QwtColumnSymbol* sym = specialSym;
    if ( sym == NULL )
        sym = m_data->symbol;

    if ( sym )
    {
        sym->draw( painter, rect );
    }
    else
    {
        // we build a temporary default symbol
        QwtColumnSymbol columnSymbol( QwtColumnSymbol::Box );
        columnSymbol.setLineWidth( 1 );
        columnSymbol.setFrameStyle( QwtColumnSymbol::Plain );
        columnSymbol.draw( painter, rect );
    }

    delete specialSym;
}

/*!
   Needs to be overloaded to return a
   non default symbol for a specific sample

   \param sampleIndex Index of the sample represented by the bar
   \param sample Value of the sample

   \return NULL, indicating to use the default symbol
 */
QwtColumnSymbol* QwtPlotBarChart::specialSymbol(
    int sampleIndex, const QPointF& sample ) const
{
    Q_UNUSED( sampleIndex );
    Q_UNUSED( sample );

    return NULL;
}

/*!
   \brief Return the title of a bar

   In LegendBarTitles mode the title is displayed on
   the legend entry corresponding to a bar.

   The default implementation is a dummy, that is intended
   to be overloaded.

   \param sampleIndex Index of the bar
   \return An empty text
   \sa LegendBarTitles
 */
QwtText QwtPlotBarChart::barTitle( int sampleIndex ) const
{
    Q_UNUSED( sampleIndex );
    return QwtText();
}

/*!
   \brief Return all information, that is needed to represent
          the item on the legend

   In case of LegendBarTitles an entry for each bar is returned,
   otherwise the chart is represented like any other plot item
   from its title() and the legendIcon().

   \return Information, that is needed to represent the item on the legend
   \sa title(), setLegendMode(), barTitle(), QwtLegend, QwtPlotLegendItem
 */
QList< QwtLegendData > QwtPlotBarChart::legendData() const
{
    QList< QwtLegendData > list;

    if ( m_data->legendMode == LegendBarTitles )
    {
        const size_t numSamples = dataSize();
        list.reserve( numSamples );

        for ( size_t i = 0; i < numSamples; i++ )
        {
            QwtLegendData data;

            data.setValue( QwtLegendData::TitleRole,
                QVariant::fromValue( barTitle( i ) ) );

            if ( !legendIconSize().isEmpty() )
            {
                data.setValue( QwtLegendData::IconRole,
                    QVariant::fromValue( legendIcon( i, legendIconSize() ) ) );
            }

            list += data;
        }
    }
    else
    {
        return QwtPlotAbstractBarChart::legendData();
    }

    return list;
}

/*!
   \return Icon representing a bar or the chart on the legend

   When the legendMode() is LegendBarTitles the icon shows
   the bar corresponding to index - otherwise the bar
   displays the default symbol.

   \param index Index of the legend entry
   \param size Icon size

   \sa setLegendMode(), drawBar(),
       QwtPlotItem::setLegendIconSize(), QwtPlotItem::legendData()
 */
QwtGraphic QwtPlotBarChart::legendIcon(
    int index, const QSizeF& size ) const
{
    QwtColumnRect column;
    column.hInterval = QwtInterval( 0.0, size.width() - 1.0 );
    column.vInterval = QwtInterval( 0.0, size.height() - 1.0 );

    QwtGraphic icon;
    icon.setDefaultSize( size );
    icon.setRenderHint( QwtGraphic::RenderPensUnscaled, true );

    QPainter painter( &icon );
    painter.setRenderHint( QPainter::Antialiasing,
        testRenderHint( QwtPlotItem::RenderAntialiased ) );

    int barIndex = -1;
    if ( m_data->legendMode == QwtPlotBarChart::LegendBarTitles )
        barIndex = index;

    drawBar( &painter, barIndex, QPointF(), column );

    return icon;
}