Chris@224: /* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
Chris@224: 
Chris@224: /*
Chris@224:     Sonic Visualiser
Chris@224:     An audio file viewer and annotation editor.
Chris@224:     Centre for Digital Music, Queen Mary, University of London.
Chris@224:     This file copyright 2006 Chris Cannam.
Chris@224:     
Chris@224:     This program is free software; you can redistribute it and/or
Chris@224:     modify it under the terms of the GNU General Public License as
Chris@224:     published by the Free Software Foundation; either version 2 of the
Chris@224:     License, or (at your option) any later version.  See the file
Chris@224:     COPYING included with this distribution for more information.
Chris@224: */
Chris@224: 
Chris@224: #include "LogRange.h"
Chris@224: 
Chris@224: #include <algorithm>
Chris@464: #include <iostream>
Chris@224: #include <cmath>
Chris@224: 
Chris@224: void
Chris@224: LogRange::mapRange(float &min, float &max, float logthresh)
Chris@224: {
Chris@224:     if (min > max) std::swap(min, max);
Chris@224:     if (max == min) max = min + 1;
Chris@224: 
Chris@464: //    std::cerr << "LogRange::mapRange: min = " << min << ", max = " << max << std::endl;
Chris@464: 
Chris@224:     if (min >= 0.f) {
Chris@224: 
Chris@224:         max = log10f(max); // we know max != 0
Chris@224: 
Chris@224:         if (min == 0.f) min = std::min(logthresh, max);
Chris@224:         else min = log10f(min);
Chris@224: 
Chris@464: //        std::cerr << "LogRange::mapRange: positive: min = " << min << ", max = " << max << std::endl;
Chris@464: 
Chris@224:     } else if (max <= 0.f) {
Chris@224:         
Chris@224:         min = log10f(-min); // we know min != 0
Chris@224:         
Chris@224:         if (max == 0.f) max = std::min(logthresh, min);
Chris@224:         else max = log10f(-max);
Chris@224:         
Chris@224:         std::swap(min, max);
Chris@224:         
Chris@464: //        std::cerr << "LogRange::mapRange: negative: min = " << min << ", max = " << max << std::endl;
Chris@464: 
Chris@224:     } else {
Chris@224:         
Chris@224:         // min < 0 and max > 0
Chris@224:         
Chris@224:         max = log10f(std::max(max, -min));
Chris@224:         min = std::min(logthresh, max);
Chris@464: 
Chris@464: //        std::cerr << "LogRange::mapRange: spanning: min = " << min << ", max = " << max << std::endl;
Chris@224:     }
Chris@224: 
Chris@224:     if (min == max) min = max - 1;
Chris@224: }        
Chris@224: 
Chris@224: float
Chris@224: LogRange::map(float value, float thresh)
Chris@224: {
Chris@224:     if (value == 0.f) return thresh;
Chris@224:     return log10f(fabsf(value));
Chris@224: }
Chris@224: 
Chris@266: float
Chris@266: LogRange::unmap(float value)
Chris@266: {
Chris@266:     return powf(10.0, value);
Chris@266: }