soundeditor/qatsh/ColorMap.cpp

// ColorMap class implementation
//
//  A ubiquitous color map with contrast and brightness management.
//
// QATSH Copyright 2009 Jean-Philippe MEURET <jpmeuret@free.fr>

#include "ColorMap.h"

#include "ATSMath.h"
#include <iostream>


ColorMap::ColorMap()
: _eStyle(eStyleNumber), _dMinValue(0.0), _dMaxValue(0.0), _dContrast(0.0), _dBrightness(0.0)
{
}

ColorMap::ColorMap(ColorMap::EStyle eStyle, int nColors, 
		   double dMinValue, double dMaxValue, double dContrast, double dBrightness)
{
    reset(eStyle, nColors, dMinValue, dMaxValue, dContrast, dBrightness);
}

void ColorMap::reset(ColorMap::EStyle eStyle, int nColors, 
		     double dMinValue, double dMaxValue, double dContrast, double dBrightness)
{
    // Check requested temperature, nb of colors, value interval and contrast :
    // no reset if any issue.
    eStyle = (eStyle >= 0 && eStyle < eStyleNumber) ? eStyle : eStyleNumber;
    if (eStyle == eStyleNumber)
	return;

    nColors = (nColors > 1 && nColors <= 256) ? nColors : 0;
    if (nColors == 0)
	return;

    if (dMinValue >= dMaxValue)
	return;

    if (dContrast < 0 || dContrast > 1)
	return;

    if (dBrightness < 0 || dBrightness > 1)
	return;

    // Save scale properties.
    _eStyle = eStyle;
    _dMinValue = dMinValue;
    _dMaxValue = dMaxValue;
    _dContrast = dContrast;
    _dBrightness = dBrightness;

    // Clear color list.
    _qlColors.clear();

//     std::cout << "ColorMap::reset(contrast=" << _dContrast 
// 	      << ", brightness=" << _dBrightness<< std::endl;

    // Fill-in color list according to requested properties.
    switch(_eStyle)
    {
	// Medium : Use partial hue scale from 239=blue=cold to 0=red=hot)
        case eStyleStandard:
	{
	    double dT, dH, dV;
	    const double dContPower = pow(2.0, 10.0 * (_dContrast - 0.5));
	    const double dBrightPower = pow(2.0, -4.0);

	    for (int nColorInd = 0; nColorInd < nColors; nColorInd++)
	    {
		dT = pow(nColorInd  / (double)(nColors - 1), dContPower);
		dH = (1.0 - dT) * 240.0 / 360;
		dV = (0.5 + 0.5 * _dBrightness) * pow(dT, dBrightPower);
		_qlColors.append(QColor::fromHsvF(dH, 1.0, dV));
	    }
	}
	break;


	// Cold : from ??? = cold to ??? = hot
        case eStyleCold:
	{
	    double dT, dR, dG, dB;
	    const double dBright = 0.25 + 0.75 * _dBrightness;
	    const double dContPower = pow(2.0, 10.0 * (_dContrast - 0.5));

	    for (int nColorInd = 0; nColorInd < nColors; nColorInd++)
	    {
		dT = pow(nColorInd  / (double)(nColors - 1), dContPower);
		dR = dBright * dT;
		dG = dBright * (1.0 - dT);
		dB = dBright * 1.0;
 		_qlColors.append(QColor::fromRgbF(dR, dG, dB));
	    }
	}
	break;

	// Hot : from red = cold to yellowish white = hot
        case eStyleHot:
	{
	    double dR, dG, dB;
            const int nStop = (int)floor(3.0 * nColors / 8.0);
	    const double dBright = 0.25 + 0.75 * _dBrightness;
	    const double dContPower = pow(2.0, 10.0 * (_dContrast - 0.5));

	    for (int nColorInd = 0; nColorInd < nColors; nColorInd++)
	    {
		if (nColorInd < nStop)
		{
		    dR = dBright * pow(nColorInd / (double)nStop, dContPower);
		    dG = dBright * 0.0;
		    dB = dBright * 0.0;
		}
		else if (nColorInd >= 2*nStop)
		{
		    dR = dBright * 1.0;
		    dG = dBright * 1.0;
		    dB = dBright * pow((nColorInd - 2*nStop + 1) / (double)nStop, dContPower);
		}
		else
		{
		    dR = dBright * 1.0;
		    dG = dBright * pow((nColorInd - nStop + 1) / (double)nStop, dContPower);
		    dB = dBright * 0.0;
		}
 		_qlColors.append(QColor::fromRgbF(dR, dG, dB));
	    }
	}
	break;

        default: // Should never get there
	    break;
    }
}

int ColorMap::nbColors() const
{
    return _qlColors.size();
}

void ColorMap::setNbColors(int nColors)
{
    reset(_eStyle, nColors, _dMinValue, _dMaxValue, _dContrast, _dBrightness);
}

ColorMap::EStyle ColorMap::style() const
{
    return _eStyle;
}

void ColorMap::setStyle(EStyle eStyle)
{
    reset(eStyle, _qlColors.size(), _dMinValue, _dMaxValue, _dContrast, _dBrightness);
}

double ColorMap::minValue() const
{
    return _dMinValue;
}

void ColorMap::setMinValue(double dValue)
{
    reset(_eStyle, _qlColors.size(), dValue, _dMaxValue, _dContrast, _dBrightness);
}

double ColorMap::maxValue() const
{
    return _dMaxValue;
}

void ColorMap::setMaxValue(double dValue)
{
    reset(_eStyle, _qlColors.size(), _dMinValue, dValue, _dContrast, _dBrightness);
}

double ColorMap::contrast() const
{
    return _dContrast;
}

void ColorMap::setContrast(double dValue)
{
    reset(_eStyle, _qlColors.size(), _dMinValue, _dMaxValue, dValue, _dBrightness);
}

double ColorMap::brightness() const
{
    return _dBrightness;
}

void ColorMap::setBrightness(double dValue)
{
    reset(_eStyle, _qlColors.size(), _dMinValue, _dMaxValue, _dContrast, dValue);
}

// TODO: Contrast feature, through a contrast function to apply to input values
//       before querying for the color.
//       Normal contrast => linear function                    : y = a + b.x^1
//       High contrast   => exponential / square function      : y = a + b.x^n
//       Low contrast    => logarythmic / square root function : y = a + b.x^1/n

QColor ColorMap::color(double dValue) const
{
    //if (_eStyle == eStyleNumber || _dMinValue >= _dMaxValue)
    //return QColor(Qt::black);

    if (dValue < _dMinValue)
	return _qlColors[0];
    else if (dValue >= _dMaxValue)
	return _qlColors[_qlColors.size() - 1];
    else
	return _qlColors[(int)floor(_qlColors.size() * (dValue - _dMinValue) 
			                            / (_dMaxValue - _dMinValue))];
}

const QColor& ColorMap::color(int nIndex) const
{
    return _qlColors[nIndex];
}