view base/ZoomConstraint.h @ 1833:21c792334c2e sensible-delimited-data-strings

Rewrite all the DelimitedDataString stuff so as to return vectors of individual cell strings rather than having the classes add the delimiters themselves. Rename accordingly to names based on StringExport. Take advantage of this in the CSV writer code so as to properly quote cells that contain delimiter characters.

/* -*- 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"

/**
 * ZoomConstraint is a simple interface that describes a limitation on
 * the available zoom sizes for a view, for example based on cache
 * strategy or a (processing) window-size limitation.
 *
 * The default ZoomConstraint imposes no actual constraint except for
 * a nominal maximum.
 */

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

    enum RoundingDirection {
        RoundDown,
        RoundUp,
        RoundNearest
    };

    /**
     * Given an "ideal" zoom level (frames per pixel or pixels per
     * frame) for a given zoom level, return the nearest viable block
     * size for this constraint.
     *
     * For example, if a block size of 1523 frames per pixel is
     * requested but the underlying model only supports value
     * summaries at powers-of-two block sizes, return 1024 or 2048
     * depending on the rounding direction supplied.
     */
    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;
    }

    /**
     * Return the minimum zoom level within range for this constraint.
     * Individual views will probably want to limit this, for example
     * in order to ensure that at least one or two samples fit in the
     * current window size, or in order to save on interpolation cost.
     */
    virtual ZoomLevel getMinZoomLevel() const {
        return { ZoomLevel::PixelsPerFrame, 512 };
    }
    
    /**
     * Return the maximum zoom level within range for this constraint.
     * This is quite large -- individual views will probably want to
     * limit how far a user might reasonably zoom out based on other
     * factors such as the duration of the file.
     */
    virtual ZoomLevel getMaxZoomLevel() const {
        return { ZoomLevel::FramesPerPixel, 4194304 }; // 2^22, arbitrarily
    }
};

#endif