app/analyzer/analyzerBase.cpp

/*
    SPDX-FileCopyrightText: 2003 Max Howell <max.howell@methylblue.com>
    SPDX-FileCopyrightText: 2009  Martin Sandsmark <sandsmark@samfundet.no>

    SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only OR LicenseRef-KDE-Accepted-GPL
*/

#include "analyzerBase.h"
#include <cmath>        //interpolate()

#include <QEvent>     //event()
#include <QPainter>

#include <phonon/audiodataoutput.h>


// INSTRUCTIONS Base2D
// 1. do anything that depends on height() in init(), Base2D will call it before you are shown
// 2. otherwise you can use the constructor to initialise things
// 3. reimplement analyze(), and paint to canvas(), Base2D will update the widget when you return control to it
// 4. if you want to manipulate the scope, reimplement transform()
// 5. for convenience <vector> <qpixmap.h> <qwdiget.h> are pre-included
// TODO make an INSTRUCTIONS file
//can't mod scope in analyze you have to use transform


Analyzer::Base::Base(QWidget *parent, uint scopeSize)
    : QWidget(parent)
    , m_fht(new FHT(scopeSize))
{}

void Analyzer::Base::transform(QVector<float> &scope ) //virtual
{
    //this is a standard transformation that should give
    //an FFT scope that has bands for pretty analyzers

    //NOTE resizing here is redundant as FHT routines only calculate FHT::size() values
    //scope.resize( m_fht->size() );

    float *front = static_cast<float*>( &scope.front() );

    float* f = new float[ m_fht->size() ];
    m_fht->copy( &f[0], front );
    m_fht->logSpectrum( front, &f[0] );
    m_fht->scale( front, 1.0 / 20 );

    scope.resize( m_fht->size() / 2 ); //second half of values are rubbish
    delete [] f;
}

void Analyzer::Base::drawFrame(const QMap<Phonon::AudioDataOutput::Channel, QVector<qint16> > &thescope)
{
    if (thescope.isEmpty())
        return;

    QVector<float> scope( 512 );
    int i = 0;

    for (uint x = 0; (int)x < m_fht->size(); ++x) {
        if (thescope.size() == 1) { // Mono
            const qint16 left = thescope[Phonon::AudioDataOutput::LeftChannel].value(x, 0);
            scope[x] = double(left);
        } else { // Anything > Mono is treated as Stereo
            // Use .value as Phonon(GStreamer) sometimes returns too small
            // samples, in that case we will simply assume the remainder would be
            // 0.
            // This in particualr happens when switching from mono files to
            // stereo and vice versa as the first sample sent after a switch
            // is of the previous channel allocation but with way to small
            // data size.
            const qint16 left = thescope[Phonon::AudioDataOutput::LeftChannel].value(x, 0);
            const qint16 right = thescope[Phonon::AudioDataOutput::RightChannel].value(x, 0);
            double value = double(left + right) / (2*(1<<15));
            scope[x] = value; // Average between the channels
        }
        i += 2;
    }

    transform(scope);
    analyze(scope);

    scope.resize( m_fht->size() );

    update();
}

int Analyzer::Base::resizeExponent( int exp )
{
    if ( exp < 3 )
        exp = 3;
    else if ( exp > 9 )
        exp = 9;

    if ( exp != m_fht->sizeExp() ) {
        delete m_fht;
        m_fht = new FHT( exp );
    }
    return exp;
}

int Analyzer::Base::resizeForBands(int bands)
{
    int exp;
    if ( bands <= 8 )
        exp = 4;
    else if ( bands <= 16 )
        exp = 5;
    else if ( bands <= 32 )
        exp = 6;
    else if ( bands <= 64 )
        exp = 7;
    else if ( bands <= 128 )
        exp = 8;
    else
        exp = 9;

    resizeExponent(exp);
    return m_fht->size() / 2;
}

void Analyzer::Base::paused() //virtual
{}

void Analyzer::Base::demo() //virtual
{
    static int t = 201; //FIXME make static to namespace perhaps
    //    qDebug() << Q_FUNC_INFO << t;

    if( t > 300 ) t = 1; //0 = wasted calculations
    if( t < 201 )
    {
        QVector<float> s( 512 );

        const double dt = double(t) / 200;
        for(int i = 0; i < s.size(); ++i)
            s[i] = dt * (sin( M_PI + (i * M_PI) / s.size() ) + 1.0);

        analyze(s);
    }
    else analyze(QVector<float>( 1, 0));

    ++t;
}


Analyzer::Base2D::Base2D(QWidget *parent, uint scopeSize)
    : Base(parent, scopeSize)
{
    QTimer::singleShot(0, this, &Base2D::init); // needs to know the size
    timer.setInterval(34);
    timer.setSingleShot(false);
    connect(&timer, &QTimer::timeout, this, &Base2D::demo);
    timer.start();
}

void Analyzer::Base2D::resizeEvent(QResizeEvent *e)
{
    QWidget::resizeEvent(e);

    m_canvas = QPixmap(size());
    m_canvas.fill(Qt::transparent);

    eraseCanvas(); //this is necessary, no idea why. but I trust mxcl.
}

void Analyzer::Base2D::paintEvent(QPaintEvent*)
{
    if(m_canvas.isNull())
        return;

    QPainter painter(this);
    painter.drawPixmap(rect(), m_canvas);
}

void Analyzer::interpolate( const QVector<float> &inVec, QVector<float> &outVec ) //static
{
    double pos = 0.0;
    const double step = (double)inVec.size() / outVec.size();

    for (int i = 0; i < outVec.size(); ++i, pos += step)
    {
        const double error = pos - std::floor( pos );
        const unsigned long offset = (unsigned long)pos;

        long indexLeft = offset + 0;

        if (indexLeft >= inVec.size())
            indexLeft = inVec.size() - 1;

        long indexRight = offset + 1;

        if (indexRight >= inVec.size())
            indexRight = inVec.size() - 1;

        outVec[i] = inVec[indexLeft ] * ( 1.0 - error ) +
                    inVec[indexRight] * error;
    }
}

void Analyzer::initSin( QVector<float> &v, const uint size ) //static
{
    double step = ( M_PI * 2 ) / size;
    double radian = 0;

    for ( uint i = 0; i < size; i++ )
    {
        v.push_back( sin( radian ) );
        radian += step;
    }
}