annotate data/model/PowerOfSqrtTwoZoomConstraint.cpp @ 1520:954d0cf29ca7 import-audio-data

Switch the normalisation option in WritableWaveFileModel from normalising on read to normalising on write, so that the saved file is already normalised and therefore can be read again without having to remember to normalise it

/* -*- 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;
}