plot.cpp

#include <qprinter.h>
#include <qprintdialog.h>
#include <qwt_color_map.h>
#include <qwt_plot_spectrogram.h>
#include <qwt_scale_widget.h>
#include <qwt_scale_draw.h>
#include <qwt_plot_zoomer.h>
#include <qwt_plot_panner.h>
#include <qwt_plot_layout.h>
#include <qwt_plot_renderer.h>
#include "plot.h"

class MyZoomer: public QwtPlotZoomer
{
public:
    MyZoomer( QwtPlotCanvas *canvas ):
        QwtPlotZoomer( canvas )
    {
        setTrackerMode( AlwaysOn );
    }

    virtual QwtText trackerTextF( const QPointF &pos ) const
    {
        QColor bg( Qt::white );
        bg.setAlpha( 200 );

        QwtText text = QwtPlotZoomer::trackerTextF( pos );
        text.setBackgroundBrush( QBrush( bg ) );
        return text;
    }
};

class SpectrogramData: public QwtRasterData
{
public:
    SpectrogramData()
    {
        setInterval( Qt::XAxis, QwtInterval( -1.5, 1.5 ) );
        setInterval( Qt::YAxis, QwtInterval( -1.5, 1.5 ) );
        setInterval( Qt::ZAxis, QwtInterval( 0.0, 10.0 ) );
    }

    virtual double value( double x, double y ) const
    {
        const double c = 0.842;

        const double v1 = x * x + ( y - c ) * ( y + c );
        const double v2 = x * ( y + c ) + x * ( y + c );

        return 1.0 / ( v1 * v1 + v2 * v2 );
    }
};

class ColorMap: public QwtLinearColorMap
{
public:
    ColorMap():
        QwtLinearColorMap( Qt::darkCyan, Qt::red )
    {
        addColorStop( 0.1, Qt::cyan );
        addColorStop( 0.6, Qt::green );
        addColorStop( 0.95, Qt::yellow );
    }
};

Plot::Plot( QWidget *parent ):
    QwtPlot( parent )
{
    d_spectrogram = new QwtPlotSpectrogram();
    d_spectrogram->setRenderThreadCount( 0 ); // use system specific thread count

    d_spectrogram->setColorMap( new ColorMap() );

    d_spectrogram->setData( new SpectrogramData() );
    d_spectrogram->attach( this );

    QList<double> contourLevels;
    for ( double level = 0.5; level < 10.0; level += 1.0 )
        contourLevels += level;
    d_spectrogram->setContourLevels( contourLevels );

    const QwtInterval zInterval = d_spectrogram->data()->interval( Qt::ZAxis );
    // A color bar on the right axis
    QwtScaleWidget *rightAxis = axisWidget( QwtPlot::yRight );
    rightAxis->setTitle( "Intensity" );
    rightAxis->setColorBarEnabled( true );
    rightAxis->setColorMap( zInterval, new ColorMap() );

    setAxisScale( QwtPlot::yRight, zInterval.minValue(), zInterval.maxValue() );
    enableAxis( QwtPlot::yRight );

    plotLayout()->setAlignCanvasToScales( true );
    replot();

    // LeftButton for the zooming
    // MidButton for the panning
    // RightButton: zoom out by 1
    // Ctrl+RighButton: zoom out to full size

    QwtPlotZoomer* zoomer = new MyZoomer( canvas() );
    zoomer->setMousePattern( QwtEventPattern::MouseSelect2,
        Qt::RightButton, Qt::ControlModifier );
    zoomer->setMousePattern( QwtEventPattern::MouseSelect3,
        Qt::RightButton );

    QwtPlotPanner *panner = new QwtPlotPanner( canvas() );
    panner->setAxisEnabled( QwtPlot::yRight, false );
    panner->setMouseButton( Qt::MidButton );

    // Avoid jumping when labels with more/less digits
    // appear/disappear when scrolling vertically

    const QFontMetrics fm( axisWidget( QwtPlot::yLeft )->font() );
    QwtScaleDraw *sd = axisScaleDraw( QwtPlot::yLeft );
    sd->setMinimumExtent( fm.width( "100.00" ) );

    const QColor c( Qt::darkBlue );
    zoomer->setRubberBandPen( c );
    zoomer->setTrackerPen( c );
}

void Plot::showContour( bool on )
{
    d_spectrogram->setDisplayMode( QwtPlotSpectrogram::ContourMode, on );
    replot();
}

void Plot::showSpectrogram( bool on )
{
    d_spectrogram->setDisplayMode( QwtPlotSpectrogram::ImageMode, on );
    d_spectrogram->setDefaultContourPen( on ? QPen() : QPen( Qt::NoPen ) );
    replot();
}

#ifndef QT_NO_PRINTER

void Plot::printPlot()
{
#if 1
    QPrinter printer;
#else
    QPrinter printer( QPrinter::HighResolution );
#endif
    printer.setOrientation( QPrinter::Landscape );
    printer.setOutputFileName( "spectrogram.pdf" );
    QPrintDialog dialog( &printer );
    if ( dialog.exec() )
    {
        QwtPlotRenderer renderer;

        renderer.setDiscardFlag( QwtPlotRenderer::DiscardBackground, false );
        renderer.setLayoutFlag( QwtPlotRenderer::KeepFrames, true );

        renderer.renderTo( this, printer );
    }
}

#endif