static const int SYMBOL_SIZE_MAX = 7;

Plot::Plot(QWidget* parent) :

    QwtPlot(parent),

    zoomer(this->canvas(), false),

    sZoomer(this, &zoomer)

{

    isAutoScaled = true;

    symbolSize = 0;

    numOfSamples = 1;

    QObject::connect(&zoomer, &Zoomer::unzoomed, this, &Plot::unzoomed);

    zoomer.setZoomBase();

    grid.attach(this);

    legend.attach(this);

    showGrid(false);

    darkBackground(false);

    snapshotOverlay = NULL;

    connect(&zoomer, &QwtPlotZoomer::zoomed,

            [this](const QRectF &rect)

            {

                onXScaleChanged();

            });

    connect(this, &QwtPlot::itemAttached,

            [this](QwtPlotItem *plotItem, bool on)

            {

                if (symbolSize) updateSymbols();

            });

    // init demo indicator

    QwtText demoText(" DEMO RUNNING ");  // looks better with spaces

    demoText.setColor(QColor("white"));

    demoText.setBackgroundBrush(Qt::darkRed);

    demoText.setBorderRadius(4);

    demoText.setRenderFlags(Qt::AlignLeft | Qt::AlignBottom);

    demoIndicator.setText(demoText);

    demoIndicator.hide();

    demoIndicator.attach(this);

}

Plot::~Plot()

{

    if (snapshotOverlay != NULL) delete snapshotOverlay;

}

void Plot::setYAxis(bool autoScaled, double yAxisMin, double yAxisMax)

{

    this->isAutoScaled = autoScaled;

    if (!autoScaled)

    {

        yMin = yAxisMin;

        yMax = yAxisMax;

    }

    zoomer.zoom(0);

    resetAxes();

}

void Plot::setXAxis(double xMin, double xMax)

{

    _xMin = xMin;

    _xMax = xMax;

    zoomer.zoom(0); // unzoom

    // set axis

    setAxisScale(QwtPlot::xBottom, xMin, xMax);

    replot(); // Note: if we don't replot here scale at startup isn't set correctly

    // reset zoom base

    auto base = zoomer.zoomBase();

    base.setLeft(xMin);

    base.setRight(xMax);

    zoomer.setZoomBase(base);

    onXScaleChanged();

}

void Plot::resetAxes()

{

    // reset y axis

    if (isAutoScaled)

    {

        setAxisAutoScale(QwtPlot::yLeft);

    }

    else

    {

        setAxisScale(QwtPlot::yLeft, yMin, yMax);

    }

    replot();

}

void Plot::unzoomed()

{

    resetAxes();

    onXScaleChanged();

}

void Plot::showGrid(bool show)

{

    grid.enableX(show);

    grid.enableY(show);

    replot();

}

void Plot::showMinorGrid(bool show)

{

    grid.enableXMin(show);

    grid.enableYMin(show);

    replot();

}

void Plot::showLegend(bool show)

{

    legend.setVisible(show);

    replot();

}

void Plot::showDemoIndicator(bool show)

{

    demoIndicator.setVisible(show);

    replot();

}

void Plot::unzoom()

{

    zoomer.zoom(0);

}

void Plot::darkBackground(bool enabled)

{

    QColor gridColor;

    if (enabled)

    {

        setCanvasBackground(QBrush(Qt::black));

        gridColor.setHsvF(0, 0, 0.25);

        grid.setPen(gridColor);

        zoomer.setRubberBandPen(QPen(Qt::white));

        zoomer.setTrackerPen(QPen(Qt::white));

        sZoomer.setPickerPen(QPen(Qt::white));

        legend.setTextPen(QPen(Qt::white));

    }

    else

    {

        setCanvasBackground(QBrush(Qt::white));

        gridColor.setHsvF(0, 0, 0.80);

        grid.setPen(gridColor);

        zoomer.setRubberBandPen(QPen(Qt::black));

        zoomer.setTrackerPen(QPen(Qt::black));

        sZoomer.setPickerPen(QPen(Qt::black));

        legend.setTextPen(QPen(Qt::black));

    }

    updateSymbols();

    replot();

}

/*

  Below crude drawing demostrates how color selection occurs for

  given channel index

  0°                     <--Hue Value-->                           360°

  |* . o . + . o . * . o . + . o . * . o . + . o . * . o . + . o . |

  * -> 0-3

  + -> 4-7

  o -> 8-15

  . -> 16-31

 */

QColor Plot::makeColor(unsigned int channelIndex)

{

    auto i = channelIndex;

    if (i < 4)

    {

        return QColor::fromHsv(360*i/4, 255, 230);

    }

    else

    {

        double p = floor(log2(i));

        double n = pow(2, p);

        i = i - n;

        return QColor::fromHsv(360*i/n + 360/pow(2,p+1), 255, 230);

    }

}