ZoomConstraint.h

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/* -*- 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_ZOOM_CONSTRAINT_H
#define SV_ZOOM_CONSTRAINT_H

#include <stdlib.h>

#include "ZoomLevel.h"

class ZoomConstraint
{
public:
    virtual ~ZoomConstraint() { }

    enum RoundingDirection {
        RoundDown,
        RoundUp,
        RoundNearest
    };

    virtual ZoomLevel getNearestZoomLevel(ZoomLevel requestedZoomLevel,
                                          RoundingDirection = RoundNearest)
        const
    {
        // canonicalise
        if (requestedZoomLevel.level == 1) {
            requestedZoomLevel.zone = ZoomLevel::FramesPerPixel;
        }
        if (getMaxZoomLevel() < requestedZoomLevel) return getMaxZoomLevel();
        else return requestedZoomLevel;
    }

    virtual ZoomLevel getMinZoomLevel() const {
        return { ZoomLevel::PixelsPerFrame, 512 };
    }
    
    virtual ZoomLevel getMaxZoomLevel() const {
        return { ZoomLevel::FramesPerPixel, 4194304 }; // 2^22, arbitrarily
    }
};

#endif