annotate audioio/PlaySpeedRangeMapper.cpp @ 141:9a8c73ffdce0

* Make it possible to import an entire session from an RDF document.
  However, at the moment the timings of events appear to be constrained
  by how far the audio decoder has got through its audio file at the
  time the event is queried -- need to investigate.

/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */

/*
    Sonic Visualiser
    An audio file viewer and annotation editor.
    Centre for Digital Music, Queen Mary, University of London.
    This file copyright 2006 QMUL.
    
    This program is free software; you can redistribute it and/or
    modify it under the terms of the GNU General Public License as
    published by the Free Software Foundation; either version 2 of the
    License, or (at your option) any later version.  See the file
    COPYING included with this distribution for more information.
*/

#include "PlaySpeedRangeMapper.h"

#include <iostream>
#include <cmath>

PlaySpeedRangeMapper::PlaySpeedRangeMapper(int minpos, int maxpos) :
    m_minpos(minpos),
    m_maxpos(maxpos)
{
}

int
PlaySpeedRangeMapper::getPositionForValue(float value) const
{
    // value is percent
    float factor = getFactorForValue(value);
    int position = getPositionForFactor(factor);
    return position;
}

int
PlaySpeedRangeMapper::getPositionForFactor(float factor) const
{
    bool slow = (factor > 1.0);

    if (!slow) factor = 1.0 / factor;
    
    int half = (m_maxpos + m_minpos) / 2;

    factor = sqrtf((factor - 1.0) * 1000.f);
    int position = lrintf(((factor * (half - m_minpos)) / 100.0) + m_minpos);

    if (slow) {
        position = half - position;
    } else {
        position = position + half;
    }

//    std::cerr << "value = " << value << " slow = " << slow << " factor = " << factor << " position = " << position << std::endl;

    return position;
}

float
PlaySpeedRangeMapper::getValueForPosition(int position) const
{
    float factor = getFactorForPosition(position);
    float pc = getValueForFactor(factor);
    return pc;
}

float
PlaySpeedRangeMapper::getValueForFactor(float factor) const
{
    float pc;
    if (factor < 1.0) pc = ((1.0 / factor) - 1.0) * 100.0;
    else pc = (1.0 - factor) * 100.0;
//    std::cerr << "position = " << position << " percent = " << pc << std::endl;
    return pc;
}

float
PlaySpeedRangeMapper::getFactorForValue(float value) const
{
    // value is percent
    
    float factor;

    if (value <= 0) {
        factor = 1.0 - (value / 100.0);
    } else {
        factor = 1.0 / (1.0 + (value / 100.0));
    }

//    std::cerr << "value = " << value << " factor = " << factor << std::endl;
    return factor;
}

float
PlaySpeedRangeMapper::getFactorForPosition(int position) const
{
    bool slow = false;

    if (position < m_minpos) position = m_minpos;
    if (position > m_maxpos) position = m_maxpos;

    int half = (m_maxpos + m_minpos) / 2;

    if (position < half) {
        slow = true;
        position = half - position;
    } else {
        position = position - half;
    }

    // position is between min and half (inclusive)

    float factor;

    if (position == m_minpos) {
        factor = 1.0;
    } else {
        factor = ((position - m_minpos) * 100.0) / (half - m_minpos);
        factor = 1.0 + (factor * factor) / 1000.f;
    }

    if (!slow) factor = 1.0 / factor;

//    std::cerr << "position = " << position << " slow = " << slow << " factor = " << factor << std::endl;

    return factor;
}

QString
PlaySpeedRangeMapper::getUnit() const
{
    return "%";
}