svcore
1.9
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00001 /* -*- c-basic-offset: 4 indent-tabs-mode: nil -*- vi:set ts=8 sts=4 sw=4: */ 00002 00003 /* 00004 Sonic Visualiser 00005 An audio file viewer and annotation editor. 00006 Centre for Digital Music, Queen Mary, University of London. 00007 This file copyright 2006 Chris Cannam. 00008 00009 This program is free software; you can redistribute it and/or 00010 modify it under the terms of the GNU General Public License as 00011 published by the Free Software Foundation; either version 2 of the 00012 License, or (at your option) any later version. See the file 00013 COPYING included with this distribution for more information. 00014 */ 00015 00016 #include "PowerOfSqrtTwoZoomConstraint.h" 00017 00018 #include <iostream> 00019 #include <cmath> 00020 00021 00022 int 00023 PowerOfSqrtTwoZoomConstraint::getNearestBlockSize(int blockSize, 00024 RoundingDirection dir) const 00025 { 00026 int type, power; 00027 int rv = getNearestBlockSize(blockSize, type, power, dir); 00028 return rv; 00029 } 00030 00031 int 00032 PowerOfSqrtTwoZoomConstraint::getNearestBlockSize(int blockSize, 00033 int &type, 00034 int &power, 00035 RoundingDirection dir) const 00036 { 00037 // cerr << "given " << blockSize << endl; 00038 00039 int minCachePower = getMinCachePower(); 00040 00041 if (blockSize < (1 << minCachePower)) { 00042 type = -1; 00043 power = 0; 00044 float val = 1.0, prevVal = 1.0; 00045 while (val + 0.01 < blockSize) { 00046 prevVal = val; 00047 val *= sqrt(2.f); 00048 } 00049 int rval; 00050 if (dir == RoundUp) rval = int(val + 0.01); 00051 else if (dir == RoundDown) rval = int(prevVal + 0.01); 00052 else if (val - blockSize < blockSize - prevVal) rval = int(val + 0.01); 00053 else rval = int(prevVal + 0.01); 00054 // SVDEBUG << "returning " << rval << endl; 00055 return rval; 00056 } 00057 00058 int prevBase = (1 << minCachePower); 00059 int prevPower = minCachePower; 00060 int prevType = 0; 00061 00062 int result = 0; 00063 00064 for (unsigned int i = 0; ; ++i) { 00065 00066 power = minCachePower + i/2; 00067 type = i % 2; 00068 00069 int base; 00070 if (type == 0) { 00071 base = (1 << power); 00072 } else { 00073 base = (((unsigned int)((1 << minCachePower) * sqrt(2.) + 0.01)) 00074 << (power - minCachePower)); 00075 } 00076 00077 // SVDEBUG << "Testing base " << base << endl; 00078 00079 if (base == blockSize) { 00080 result = base; 00081 break; 00082 } 00083 00084 if (base > blockSize) { 00085 if (dir == RoundNearest) { 00086 if (base - blockSize < blockSize - prevBase) { 00087 dir = RoundUp; 00088 } else { 00089 dir = RoundDown; 00090 } 00091 } 00092 if (dir == RoundUp) { 00093 result = base; 00094 break; 00095 } else { 00096 type = prevType; 00097 power = prevPower; 00098 result = prevBase; 00099 break; 00100 } 00101 } 00102 00103 prevType = type; 00104 prevPower = power; 00105 prevBase = base; 00106 } 00107 00108 if (result > getMaxZoomLevel()) result = getMaxZoomLevel(); 00109 return result; 00110 }