view layer/ScrollableMagRangeCache.h @ 1127:9fb8dfd7ce4c spectrogram-minor-refactor

Fix threshold in spectrogram -- it wasn't working in the last release.
There is a new protocol for this. Formerly the threshold parameter had a
range from -50dB to 0 with the default at -50, and -50 treated internally
as "no threshold". However, there was a hardcoded, hidden internal threshold
for spectrogram colour mapping at -80dB with anything below this being rounded
to zero. Now the threshold parameter has range -81 to -1 with the default
at -80, -81 is treated internally as "no threshold", and there is no hidden
internal threshold. So the default behaviour is the same as before, an
effective -80dB threshold, but it is now possible to change this in both
directions. Sessions reloaded from prior versions may look slightly different
because, if the session says there should be no threshold, there will now
actually be no threshold instead of having the hidden internal one.

Still need to do something in the UI to make it apparent that the -81dB
setting removes the threshold entirely. This is at least no worse than the
previous, also obscured, magic -50dB setting.

/* -*- 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 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 SCROLLABLE_MAG_RANGE_CACHE_H
#define SCROLLABLE_MAG_RANGE_CACHE_H

#include "base/BaseTypes.h"
#include "base/MagnitudeRange.h"

#include "LayerGeometryProvider.h"

/**
 * A cached set of magnitude range records for a view that scrolls
 * horizontally, such as a spectrogram. The cache object holds a
 * magnitude range per column of the view, can report width (likely
 * the same as the underlying view, but it's the caller's
 * responsibility to set the size appropriately), can scroll the set
 * of ranges, and can report and update which columns have had a range
 * specified.
 *
 * The only way to *update* the valid area in a cache is to update the
 * magnitude range for a column using the sampleColumn call.
 */
class ScrollableMagRangeCache
{
public:
    ScrollableMagRangeCache() :
	m_startFrame(0),
	m_zoomLevel(0)
    {}

    void invalidate() {
	m_ranges = std::vector<MagnitudeRange>(m_ranges.size());
    }
    
    int getWidth() const {
	return int(m_ranges.size());
    }

    /**
     * Set the width of the cache in columns. If the new size differs
     * from the current size, the cache is invalidated.
     */
    void resize(int newWidth) {
        if (getWidth() != newWidth) {
	    m_ranges = std::vector<MagnitudeRange>(newWidth);
        }
    }
	
    int getZoomLevel() const {
	return m_zoomLevel;
    }

    /**
     * Set the zoom level. If the new zoom level differs from the
     * current one, the cache is invalidated. (Determining whether to
     * invalidate the cache here is the only thing the zoom level is
     * used for.)
     */
    void setZoomLevel(int zoom) {
        if (m_zoomLevel != zoom) {
            m_zoomLevel = zoom;
            invalidate();
        }
    }

    sv_frame_t getStartFrame() const {
	return m_startFrame;
    }

    /**
     * Set the start frame. If the new start frame differs from the
     * current one, the cache is invalidated. To scroll, i.e. to set
     * the start frame while retaining cache validity where possible,
     * use scrollTo() instead.
     */
    void setStartFrame(sv_frame_t frame) {
        if (m_startFrame != frame) {
            m_startFrame = frame;
            invalidate();
        }
    }

    bool isColumnSet(int column) const {
	return in_range_for(m_ranges, column) && m_ranges.at(column).isSet();
    }

    bool areColumnsSet(int x, int count) const {
	for (int i = 0; i < count; ++i) {
	    if (!isColumnSet(x + i)) return false;
	}
	return true;
    }
    
    /**
     * Get the magnitude range for a single column.
     */
    MagnitudeRange getRange(int column) const {
	return m_ranges.at(column);
    }

    /**
     * Get the magnitude range for a range of columns.
     */
    MagnitudeRange getRange(int x, int count) const;
    
    /**
     * Set the new start frame for the cache, according to the
     * geometry of the supplied LayerGeometryProvider, if possible
     * also moving along any existing valid data within the cache so
     * that it continues to be valid for the new start frame.
     */
    void scrollTo(const LayerGeometryProvider *v, sv_frame_t newStartFrame);
    
    /**
     * Update a column in the cache, by column index. (Column zero is
     * the first column in the cache, it has nothing to do with any
     * underlying model that the cache may be used with.)
     */
    void sampleColumn(int column, const MagnitudeRange &r);
    
    /**
     * Update a column in the cache, by frame.
     */
    void sampleColumn(const LayerGeometryProvider *v, sv_frame_t frame,
		      const MagnitudeRange &r);
    
private:
    std::vector<MagnitudeRange> m_ranges;
    sv_frame_t m_startFrame;
    int m_zoomLevel;
};

#endif