view data/fileio/MatrixFile.h @ 1196:c7b9c902642f 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 file copyright 2006-2009 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 MATRIX_FILE_H
#define MATRIX_FILE_H

#include "FileReadThread.h"

#include <sys/types.h>
#include <QString>
#include <QMutex>
#include <map>

class MatrixFile : public QObject
{
    Q_OBJECT

public:
    enum Mode { ReadOnly, WriteOnly };

    /**
     * Construct a MatrixFile object reading from and/or writing to
     * the matrix file with the given base name in the application's
     * temporary directory.
     *
     * If mode is ReadOnly, the file must exist and be readable.
     *
     * If mode is WriteOnly, the file must not exist.
     *
     * cellSize specifies the size in bytes of the object type stored
     * in the matrix.  For example, use cellSize = sizeof(float) for a
     * matrix of floats.  The MatrixFile object doesn't care about the
     * objects themselves, it just deals with raw data of a given size.
     *
     * width and height specify the dimensions of the file.  These
     * cannot be changed after construction.
     *
     * MatrixFiles are reference counted by name.  When the last
     * MatrixFile with a given name is destroyed, the file is removed.
     * These are temporary files; the normal usage is to have one
     * MatrixFile of WriteOnly type creating the file and then
     * persisting until all readers are complete.
     *
     * MatrixFile has no built-in cache and is not thread-safe.  Use a
     * separate MatrixFile in each thread.
     */
    MatrixFile(QString fileBase, Mode mode, int cellSize,
               int width, int height);
    virtual ~MatrixFile();

    Mode getMode() const { return m_mode; }

    int getWidth() const { return m_width; }
    int getHeight() const { return m_height; }
    int getCellSize() const { return m_cellSize; }

    /**
     * If this is set true on a write-mode MatrixFile, then the file
     * will close() itself when all columns have been written.
     */
    void setAutoClose(bool a) { m_autoClose = a; }

    void close(); // does not decrement ref count; that happens in dtor

    bool haveSetColumnAt(int x) const;
    void getColumnAt(int x, void *data); // may throw FileReadFailed
    void setColumnAt(int x, const void *data);

protected:
    int     m_fd;
    Mode    m_mode;
    int     m_flags;
    mode_t  m_fmode;
    int     m_cellSize;
    int     m_width;
    int     m_height;
    int     m_headerSize;
    QString m_fileName;

    std::vector<bool> m_setColumns; // only populated in writer
    bool m_autoClose;

    // In reader: if this is >= 0, we can read that column directly
    // without seeking (and we know that the column exists)
    mutable int m_readyToReadColumn;

    static std::map<QString, int> m_refcount;
    static QMutex m_createMutex;

    void initialise();
    bool seekTo(int col) const;
};

#endif