comparison base/LogRange.h @ 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.
+*/
+
+#ifndef _LOG_RANGE_H_
+#define _LOG_RANGE_H_
+
+class LogRange
+{
+public:
+    /**
+     * Map a linear range onto a logarithmic range.  min and max are
+     * passed as the extents of the linear range and returned as the
+     * extents of the logarithmic range.  thresh is the minimum value
+     * for the log range, to be used if the linear range spans zero.
+     */
+    static void mapRange(float &min, float &max, float thresh = -10);
+
+    /**
+     * Map a value onto a logarithmic range.  This just means taking
+     * the base-10 log of the absolute value, or using the threshold
+     * value if the absolute value is zero.
+     */
+    static float map(float value, float thresh = -10);
+};
+
+#endif