view data/model/PowerOfTwoZoomConstraint.cpp @ 492:23945cdd7161

* Update RDF query stuff again so as to set up a temporary datastore
  each time we want to query over an rdf file, instead of using rasqal
  against the file.  Seems the only way to avoid threading and storage
  management issues when trying to load from a single-source file and
  perform queries against our main datastore at the same time.  Maybe.

/* -*- 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.
*/

#include "PowerOfTwoZoomConstraint.h"

size_t
PowerOfTwoZoomConstraint::getNearestBlockSize(size_t req,
					      RoundingDirection dir) const
{
    size_t result = 0;

    for (size_t bs = 1; ; bs *= 2) {
	if (bs >= req) {
	    if (dir == RoundNearest) {
		if (bs - req < req - bs/2) {
		    result = bs;
		    break;
		} else {
		    result = bs/2;
		    break;
		}
	    } else if (dir == RoundDown) {
		result = bs/2;
		break;
	    } else {
		result = bs;
		break;
	    }
	}
    }

    if (result > getMaxZoomLevel()) result = getMaxZoomLevel();
    return result;
}