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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.
*/
#include "PowerOfTwoZoomConstraint.h"
namespace sv {
ZoomLevel
PowerOfTwoZoomConstraint::getNearestZoomLevel(ZoomLevel requested,
RoundingDirection dir) const
{
int blockSize;
if (requested.zone == ZoomLevel::FramesPerPixel) {
blockSize = getNearestBlockSize(requested.level, dir);
if (blockSize > getMaxZoomLevel().level) {
blockSize = getMaxZoomLevel().level;
}
return { requested.zone, blockSize };
} else {
RoundingDirection opposite = dir;
if (dir == RoundUp) opposite = RoundDown;
else if (dir == RoundDown) opposite = RoundUp;
blockSize = getNearestBlockSize(requested.level, opposite);
if (blockSize > getMinZoomLevel().level) {
blockSize = getMinZoomLevel().level;
}
if (blockSize == 1) {
return { ZoomLevel::FramesPerPixel, 1 };
} else {
return { requested.zone, blockSize };
}
}
}
int
PowerOfTwoZoomConstraint::getNearestBlockSize(int req,
RoundingDirection dir) const
{
int max = getMaxZoomLevel().level;
if (req > max) {
return max;
}
for (int bs = 1; bs <= max; bs *= 2) {
if (bs < req) {
continue;
} else if (bs == req) {
return bs;
} else { // bs > req
if (dir == RoundNearest) {
if (bs - req < req - bs/2) {
return bs;
} else {
return bs/2;
}
} else if (dir == RoundDown) {
return bs/2;
} else {
return bs;
}
}
}
return max;
}
} // end namespace sv
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