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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 "PowerOfSqrtTwoZoomConstraint.h"
#include <iostream>
#include <cmath>
#include "base/Debug.h"
namespace sv {
ZoomLevel
PowerOfSqrtTwoZoomConstraint::getNearestZoomLevel(ZoomLevel requested,
RoundingDirection dir) const
{
int type, power;
int blockSize;
if (requested.zone == ZoomLevel::FramesPerPixel) {
blockSize = getNearestBlockSize(requested.level, type, power, dir);
return { requested.zone, blockSize };
} else {
RoundingDirection opposite = dir;
if (dir == RoundUp) opposite = RoundDown;
else if (dir == RoundDown) opposite = RoundUp;
blockSize = getNearestBlockSize(requested.level, type, power, opposite);
if (blockSize > getMinZoomLevel().level) {
blockSize = getMinZoomLevel().level;
}
if (blockSize == 1) {
return { ZoomLevel::FramesPerPixel, 1 };
} else {
return { requested.zone, blockSize };
}
}
}
int
PowerOfSqrtTwoZoomConstraint::getNearestBlockSize(int blockSize,
int &type,
int &power,
RoundingDirection dir) const
{
// SVCERR << "given " << blockSize << endl;
int minCachePower = getMinCachePower();
if (blockSize < (1 << minCachePower)) {
type = -1;
power = 0;
float val = 1.0, prevVal = 1.0;
while (val + 0.01 < blockSize) {
prevVal = val;
val *= sqrtf(2.f);
}
int rval = int(val + 0.01f);
// SVCERR << "got val = " << val << ", rval = " << rval << ", prevVal = " << prevVal << endl;
if (rval != blockSize && dir != RoundUp) {
if (dir == RoundDown) {
rval = int(prevVal + 0.01f);
} else if (val - float(blockSize) < float(blockSize) - prevVal) {
rval = int(val + 0.01f);
} else {
rval = int(prevVal + 0.01);
}
}
// SVCERR << "returning " << rval << endl;
return rval;
}
int prevBase = (1 << minCachePower);
int prevPower = minCachePower;
int prevType = 0;
int result = 0;
for (unsigned int i = 0; ; ++i) {
power = minCachePower + i/2;
type = i % 2;
int base;
if (type == 0) {
base = (1 << power);
} else {
base = (((unsigned int)((1 << minCachePower) * sqrt(2.) + 0.01))
<< (power - minCachePower));
}
// SVCERR << "Testing base " << base << " (i = " << i << ", power = " << power << ", type = " << type << ")" << endl;
if (base == blockSize) {
result = base;
// SVCERR << "Equal, accepting" << endl;
break;
}
if (base > blockSize) {
if (dir == RoundNearest) {
if (base - blockSize < blockSize - prevBase) {
dir = RoundUp;
// SVCERR << "Closer to " << base << " than " << prevBase
// << ", rounding up" << endl;
} else {
dir = RoundDown;
// SVCERR << "Closer to " << prevBase << " than " << base
// << ", rounding down" << endl;
}
}
if (dir == RoundUp) {
result = base;
break;
} else {
type = prevType;
power = prevPower;
result = prevBase;
break;
}
}
prevType = type;
prevPower = power;
prevBase = base;
}
if (result > getMaxZoomLevel().level) {
result = getMaxZoomLevel().level;
}
// SVCERR << "Returning result " << result << endl;
return result;
}
} // end namespace sv
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