comparison base/LogRange.cpp @ 224:8ff1ad4e7a9c

* Work on harmonising colour and scale ranges between types of layer
* Add normalize options to colour 3d plot layer

+/* -*- 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 Chris Cannam.
+    
+    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 "LogRange.h"
+
+#include <algorithm>
+#include <cmath>
+
+void
+LogRange::mapRange(float &min, float &max, float logthresh)
+{
+    if (min > max) std::swap(min, max);
+    if (max == min) max = min + 1;
+
+    if (min >= 0.f) {
+
+        max = log10f(max); // we know max != 0
+
+        if (min == 0.f) min = std::min(logthresh, max);
+        else min = log10f(min);
+
+    } else if (max <= 0.f) {
+        
+        min = log10f(-min); // we know min != 0
+        
+        if (max == 0.f) max = std::min(logthresh, min);
+        else max = log10f(-max);
+        
+        std::swap(min, max);
+        
+    } else {
+        
+        // min < 0 and max > 0
+        
+        max = log10f(std::max(max, -min));
+        min = std::min(logthresh, max);
+    }
+
+    if (min == max) min = max - 1;
+}        
+
+float
+LogRange::map(float value, float thresh)
+{
+    if (value == 0.f) return thresh;
+    return log10f(fabsf(value));
+}
+