comparison layer/ColourScale.cpp @ 1068:521f7e8b0559 spectrogram-minor-refactor

Introduce ColourScale to handle colour mapping for both spectrogram and colour 3d plot layers

+/* -*- 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>
+
+int ColourScale::m_maxPixel = 255;
+
+ColourScale::ColourScale(int colourMap,
+			 Scale scale,
+			 double minValue,
+			 double maxValue,
+			 double threshold,
+			 double gain) :
+    m_mapper(colourMap, 1.f, double(m_maxPixel)),
+    m_scale(scale),
+    m_min(minValue),
+    m_max(maxValue),
+    m_threshold(threshold),
+    m_gain(gain)
+{
+    if (minValue >= maxValue) {
+	throw std::logic_error("maxValue must be greater than minValue");
+    }
+
+    m_mappedMin = m_min;
+    m_mappedMax = m_max;
+
+    if (m_scale == LogColourScale) {
+
+	LogRange::mapRange(m_mappedMin, m_mappedMax);
+	
+    } else if (m_scale == PlusMinusOneScale) {
+	
+	m_mappedMin = -1.0;
+	m_mappedMax =  1.0;
+
+    } else if (m_scale == AbsoluteScale) {
+
+	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) {
+	throw std::logic_error("maxValue must be greater than minValue [after mapping]");
+    }
+}
+
+int
+ColourScale::getPixel(double value)
+{
+    double maxPixF = m_maxPixel;
+
+    if (m_scale == PhaseColourScale) {
+	double half = (maxPixF - 1.f) / 2.f;
+	return 1 + int((value * half) / M_PI + half);
+    }
+    
+    value *= m_gain;
+
+    if (value < m_threshold) return 0;
+
+    double mapped = value;
+
+    if (m_scale == LogColourScale) {
+	mapped = LogRange::map(value);
+    } else if (m_scale == PlusMinusOneScale) {
+	if (mapped < -1.f) mapped = -1.f;
+	if (mapped > 1.f) mapped = 1.f;
+    } else if (m_scale == AbsoluteScale) {
+	if (mapped < 0.f) mapped = -mapped;
+    }
+	
+    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_scale == MeterColourScale) {
+	pixel = AudioLevel::multiplier_to_preview(proportion, m_maxPixel-1) + 1;
+    } else {
+	pixel = int(proportion * maxPixF) + 1;
+    }
+
+    if (pixel > m_maxPixel) pixel = m_maxPixel;
+    if (pixel < 0) pixel = 0;
+    return pixel;
+}
+
+QColor
+ColourScale::getColourForPixel(int pixel, int rotation)
+{
+    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));
+    }
+}