view audioio/PlaySpeedRangeMapper.cpp @ 140:9ccaa8fd9b9f

* Add code to identify (usually) the type of an XML file that contains
  either SV session or layer data, and use it to permit loading files
  with plain .xml extension that contain complete uncompression sessions

/* -*- 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 "%";
}