view data/fileio/DataFileReader.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 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 _DATA_FILE_READER_H_
#define _DATA_FILE_READER_H_

#include <QString>
#include <QObject>

class Model;

class DataFileReader : public QObject
{
public:
    /**
     * Return true if the file appears to be of the correct type.
     *
     * The DataFileReader will be constructed by passing a file path
     * to its constructor.  If the file can at that time be determined
     * to be not of a type that this reader can read, it should return
     * false in response to any subsequent call to isOK().
     *
     * If the file is apparently of the correct type, isOK() should
     * return true; if it turns out that the file cannot after all be
     * read (because it's corrupted or the detection misfired), then
     * the read() function may return NULL.
     */
    virtual bool isOK() const = 0;

    virtual QString getError() const { return ""; }

    /**
     * Read the file and return the corresponding data model.  This
     * function is not expected to be thread-safe or reentrant.  This
     * function may be interactive (i.e. it's permitted to pop up
     * dialogs and windows and ask the user to specify any details
     * that can't be automatically extracted from the file).
     *
     * Return NULL if the file cannot be parsed at all (although it's
     * preferable to return a partial model and warn the user).
     *
     * Caller owns the returned model and must delete it after use.
     */
    virtual Model *load() const = 0;
};

#endif