ColourScale.cpp

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/* -*- 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 2006-2016 Chris Cannam and 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 "ColourScale.h"

#include "base/AudioLevel.h"
#include "base/LogRange.h"

#include <cmath>
#include <iostream>

using namespace std;

int ColourScale::m_maxPixel = 255;

ColourScale::ColourScale(Parameters parameters) :
    m_params(parameters),
    m_mapper(m_params.colourMap, m_params.inverted, 1.f, double(m_maxPixel))
{
    if (m_params.minValue >= m_params.maxValue) {
        SVCERR << "ERROR: ColourScale::ColourScale: minValue = "
             << m_params.minValue << ", maxValue = " << m_params.maxValue << endl;
        throw std::logic_error("maxValue must be greater than minValue");
    }

    m_mappedMin = m_params.minValue;
    m_mappedMax = m_params.maxValue;

    if (m_mappedMin < m_params.threshold) {
        m_mappedMin = m_params.threshold;
    }
    
    if (m_params.scaleType == ColourScaleType::Log) {

        // When used in e.g. spectrogram, we have a range with a min
        // value of zero. The LogRange converts that to a threshold
        // value of -10, so for a range of e.g. (0,1) we end up with
        // (-10,0) as the mapped range.
        // 
        // But in other contexts we could end up with a mapped range
        // much larger than that if we have a small non-zero minimum
        // value (less than 1e-10), or a particularly large
        // maximum. That's unlikely to give us good results, so let's
        // insist that the mapped log range has no more than 10
        // difference between min and max, to match the behaviour when
        // min == 0 at the input.
        //
        double threshold = -10.0;
        LogRange::mapRange(m_mappedMin, m_mappedMax, threshold);
        if (m_mappedMin < m_mappedMax + threshold) {
            m_mappedMin = m_mappedMax + threshold;
        }
        
    } else if (m_params.scaleType == ColourScaleType::PlusMinusOne) {
        
        m_mappedMin = -1.0;
        m_mappedMax =  1.0;

    } else if (m_params.scaleType == ColourScaleType::Absolute) {

        m_mappedMin = fabs(m_mappedMin);
        m_mappedMax = fabs(m_mappedMax);
        if (m_mappedMin >= m_mappedMax) {
            std::swap(m_mappedMin, m_mappedMax);
        }
    }

    if (m_mappedMin >= m_mappedMax) {
        SVCERR << "ERROR: ColourScale::ColourScale: minValue = " << m_params.minValue
             << ", maxValue = " << m_params.maxValue
             << ", threshold = " << m_params.threshold
             << ", scale = " << int(m_params.scaleType)
             << " resulting in mapped minValue = " << m_mappedMin
             << ", mapped maxValue = " << m_mappedMax << endl;
        throw std::logic_error("maxValue must be greater than minValue [after mapping]");
    }
}

ColourScale::~ColourScale()
{
}

ColourScaleType
ColourScale::getScale() const
{
    return m_params.scaleType;
}

int
ColourScale::getPixel(double value) const
{
    double maxPixF = m_maxPixel;

    if (m_params.scaleType == ColourScaleType::Phase) {
        double half = (maxPixF - 1.f) / 2.f;
        int pixel = 1 + int((value * half) / M_PI + half);
//        SVCERR << "phase = " << value << " pixel = " << pixel << endl;
        return pixel;
    }
    
    value *= m_params.gain;
    
    if (value < m_params.threshold) return 0;

    double mapped = value;

    if (m_params.scaleType == ColourScaleType::Log) {
        mapped = LogRange::map(value);
    } else if (m_params.scaleType == ColourScaleType::PlusMinusOne) {
        if (mapped < -1.f) mapped = -1.f;
        if (mapped > 1.f) mapped = 1.f;
    } else if (m_params.scaleType == ColourScaleType::Absolute) {
        if (mapped < 0.f) mapped = -mapped;
    }

    mapped *= m_params.multiple;
    
    if (mapped < m_mappedMin) {
        mapped = m_mappedMin;
    }
    if (mapped > m_mappedMax) {
        mapped = m_mappedMax;
    }

    double proportion = (mapped - m_mappedMin) / (m_mappedMax - m_mappedMin);

    int pixel = 0;

    if (m_params.scaleType == ColourScaleType::Meter) {
        pixel = AudioLevel::multiplier_to_preview(proportion, m_maxPixel-1) + 1;
    } else {
        pixel = int(proportion * maxPixF) + 1;
    }

    if (pixel < 0) {
        pixel = 0;
    }
    if (pixel > m_maxPixel) {
        pixel = m_maxPixel;
    }
    return pixel;
}

QColor
ColourScale::getColourForPixel(int pixel, int rotation) const
{
    if (pixel < 0) {
        pixel = 0;
    }
    if (pixel > m_maxPixel) {
        pixel = m_maxPixel;
    }
    if (pixel == 0) {
        if (m_mapper.hasLightBackground()) {
            return Qt::white;
        } else {
            return Qt::black;
        }
    } else {
        int target = int(pixel) + rotation;
        while (target < 1) target += m_maxPixel;
        while (target > m_maxPixel) target -= m_maxPixel;
        return m_mapper.map(double(target));
    }
}