Mercurial > hg > svcore
view data/model/PowerOfSqrtTwoZoomConstraint.cpp @ 517:77b4ce536d8f
* print Done when done
author | Chris Cannam |
---|---|
date | Thu, 11 Dec 2008 11:30:15 +0000 |
parents | 166c22eff678 |
children | d7f3dfe6f9a4 |
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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> size_t PowerOfSqrtTwoZoomConstraint::getNearestBlockSize(size_t blockSize, RoundingDirection dir) const { int type, power; size_t rv = getNearestBlockSize(blockSize, type, power, dir); return rv; } size_t PowerOfSqrtTwoZoomConstraint::getNearestBlockSize(size_t blockSize, int &type, int &power, RoundingDirection dir) const { // std::cerr << "given " << blockSize << std::endl; size_t minCachePower = getMinCachePower(); if (blockSize < (1U << minCachePower)) { type = -1; power = 0; float val = 1.0, prevVal = 1.0; while (val + 0.01 < blockSize) { prevVal = val; val *= sqrt(2); } size_t rval; if (dir == RoundUp) rval = size_t(val + 0.01); else if (dir == RoundDown) rval = size_t(prevVal + 0.01); else if (val - blockSize < blockSize - prevVal) rval = size_t(val + 0.01); else rval = size_t(prevVal + 0.01); // std::cerr << "returning " << rval << std::endl; return rval; } unsigned int prevBase = (1 << minCachePower); unsigned int prevPower = minCachePower; unsigned int prevType = 0; size_t result = 0; for (unsigned int i = 0; ; ++i) { power = minCachePower + i/2; type = i % 2; unsigned int base; if (type == 0) { base = (1 << power); } else { base = (((unsigned int)((1 << minCachePower) * sqrt(2) + 0.01)) << (power - minCachePower)); } // std::cerr << "Testing base " << base << std::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; }