view layer/ColourScale.h @ 1551:e79731086b0f

Fixes to NoteLayer, particularly to calculation of vertical scale when model unit is not Hz. To avoid inconsistency we now behave as if the unit is always Hz from the point of view of the external API and display, converting at the point where we obtain values from the events themselves. Also various fixes to editing.

/* -*- 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.
*/

#ifndef COLOUR_SCALE_H
#define COLOUR_SCALE_H

#include "ColourMapper.h"

enum class ColourScaleType {
    Linear,
    Meter,
    Log,
    Phase,
    PlusMinusOne,
    Absolute
};

/**
 * Map values within a range onto a set of colours, with a given
 * distribution (linear, log etc) and optional colourmap rotation.
 */
class ColourScale
{
public:
    struct Parameters {
        Parameters() : colourMap(0), scaleType(ColourScaleType::Linear),
                       minValue(0.0), maxValue(1.0), inverted(false),
                       threshold(0.0), gain(1.0), multiple(1.0) { }

        /** A colour map index as used by ColourMapper */
        int colourMap;
        
        /** Distribution for the scale */
        ColourScaleType scaleType;
        
        /** Minimum value in source range */
        double minValue;
        
        /** Maximum value in source range. Must be > minValue */
        double maxValue;

        /** Whether the colour scale should be mapped inverted */
        bool inverted;

        /** Threshold below which every value is mapped to background
            pixel 0 */
        double threshold;

        /** Gain to apply before thresholding, mapping, and clamping */
        double gain;

        /** Multiple to apply after thresholding and mapping. In most
         *  cases the gain parameter is the one you want instead of
         *  this, but this can be used for example with Log scale to
         *  produce the log of some power of the original value,
         *  e.g. multiple = 2 gives log(x^2). */
        double multiple;
    };
    
    /**
     * Create a ColourScale with the given parameters.
     *
     * Note that some parameters may be ignored for some scale
     * distribution settings. For example, min and max are ignored for
     * PlusMinusOneScale and PhaseColourScale and threshold and gain
     * are ignored for PhaseColourScale.
     */
    ColourScale(Parameters parameters);
    ~ColourScale();

    ColourScale(const ColourScale &) = default;
    ColourScale &operator=(const ColourScale &) = default;

    /**
     * Return the general type of scale this is.
     */
    ColourScaleType getScale() const;
    
    /**
     * Return a pixel number (in the range 0-255 inclusive)
     * corresponding to the given value.  The pixel 0 is used only for
     * values below the threshold supplied in the constructor. All
     * other values are mapped onto the range 1-255.
     */
    int getPixel(double value) const;

    /**
     * Return the colour for the given pixel number (which must be in
     * the range 0-255). The pixel 0 is always the background
     * colour. Other pixels are mapped taking into account the given
     * colourmap rotation (which is also a value in the range 0-255).
     */
    QColor getColourForPixel(int pixel, int rotation) const;
    
    /**
     * Return the colour corresponding to the given value. This is
     * equivalent to getColourForPixel(getPixel(value), rotation).
     */
    QColor getColour(double value, int rotation) const {
        return getColourForPixel(getPixel(value), rotation);
    }

private:
    Parameters m_params;
    ColourMapper m_mapper;
    double m_mappedMin;
    double m_mappedMax;
    static int m_maxPixel;
};

#endif