annotate base/XmlExportable.h @ 1752:6d09d68165a4 by-id

Further review of ById: make IDs only available when adding a model to the ById store, not by querying the item directly. This means any id encountered in the wild must have been added to the store at some point (even if later released), which simplifies reasoning about lifecycles

/* -*- 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 SV_XML_EXPORTABLE_H
#define SV_XML_EXPORTABLE_H

#include <QString>

#include "Debug.h"

class QTextStream;

class XmlExportable
{
public:
    enum {
        // The value NO_ID (-1) is never allocated as an export id
        NO_ID = -1
    };

    typedef int ExportId;
    
    XmlExportable() : m_exportId(NO_ID) { }
    virtual ~XmlExportable() { }

    /**
     * Return the numerical export identifier for this object.  It's
     * allocated the first time this is called, so objects on which
     * this is never called do not get allocated one.
     */
    ExportId getExportId() const;

    /**
     * Stream this exportable object out to XML on a text stream.
     */
    virtual void toXml(QTextStream &stream,
                       QString indent = "",
                       QString extraAttributes = "") const = 0;

    /**
     * Convert this exportable object to XML in a string.  The default
     * implementation calls toXml and returns the result as a string.
     * Do not override this unless you really know what you're doing.
     */
    virtual QString toXmlString(QString indent = "",
                                QString extraAttributes = "") const;

    static QString encodeEntities(QString);

    static QString encodeColour(int r, int g, int b); 

private:
    mutable int m_exportId;
};

#endif