annotate data/model/PowerOfSqrtTwoZoomConstraint.cpp @ 631:3a5ee4b6c9ad

* Complete the overhaul of CSV file import; now you can pick the purpose for
  each column in the file, and SV should do the rest.  The most significant
  practical improvement here is that we can now handle files in which time
  and duration do not necessarily appear in known columns.

/* -*- 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.f);
	}
	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;
}