view data/model/PowerOfSqrtTwoZoomConstraint.cpp @ 1455:ec9e65fcf749

The use of the begin/end pairs here just seems to cause too many rows to be deleted (from the visual representation, not the underlying model). Things apparently work better if we just modify the underlying model and let the change signals percolate back up again. To that end, update the change handlers so as to cover their proper ranges with dataChanged signals.

/* -*- 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;
}