view data/model/PowerOfSqrtTwoZoomConstraint.cpp @ 490:c3fb8258e34d

* Make it possible to import an entire session from an RDF document.
  However, at the moment the timings of events appear to be constrained
  by how far the audio decoder has got through its audio file at the
  time the event is queried -- need to investigate.

/* -*- 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;
}