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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>
int
PowerOfSqrtTwoZoomConstraint::getNearestBlockSize(int blockSize,
RoundingDirection dir) const
{
int type, power;
int rv = getNearestBlockSize(blockSize, type, power, dir);
return rv;
}
int
PowerOfSqrtTwoZoomConstraint::getNearestBlockSize(int blockSize,
int &type,
int &power,
RoundingDirection dir) const
{
// cerr << "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;
if (dir == RoundUp) rval = int(val + 0.01f);
else 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);
// SVDEBUG << "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));
}
// SVDEBUG << "Testing base " << base << endl;
if (base == blockSize) {
result = base;
break;
}
if (base > blockSize) {
if (dir == RoundNearest) {
if (base - blockSize < blockSize - prevBase) {
dir = RoundUp;
} else {
dir = RoundDown;
}
}
if (dir == RoundUp) {
result = base;
break;
} else {
type = prevType;
power = prevPower;
result = prevBase;
break;
}
}
prevType = type;
prevPower = power;
prevBase = base;
}
if (result > getMaxZoomLevel()) result = getMaxZoomLevel();
return result;
}
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