annotate data/model/PowerOfTwoZoomConstraint.cpp @ 1881:b504df98c3be

Ensure completion on output model is started at zero, so if it's checked before the input model has become ready and the transform has begun, it is not accidentally reported as complete (affected re-aligning models in Sonic Lineup when replacing the session)

/* -*- 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 "PowerOfTwoZoomConstraint.h"

ZoomLevel
PowerOfTwoZoomConstraint::getNearestZoomLevel(ZoomLevel requested,
                                              RoundingDirection dir) const
{
    int blockSize;

    if (requested.zone == ZoomLevel::FramesPerPixel) {
        blockSize = getNearestBlockSize(requested.level, dir);
        if (blockSize > getMaxZoomLevel().level) {
            blockSize = getMaxZoomLevel().level;
        }
        return { requested.zone, blockSize };
    } else {
        RoundingDirection opposite = dir;
        if (dir == RoundUp) opposite = RoundDown;
        else if (dir == RoundDown) opposite = RoundUp;
        blockSize = getNearestBlockSize(requested.level, opposite);
        if (blockSize > getMinZoomLevel().level) {
            blockSize = getMinZoomLevel().level;
        }
        if (blockSize == 1) {
            return { ZoomLevel::FramesPerPixel, 1 };
        } else {
            return { requested.zone, blockSize };
        }
    }
}

int
PowerOfTwoZoomConstraint::getNearestBlockSize(int req,
                                              RoundingDirection dir) const
{
    int max = getMaxZoomLevel().level;

    if (req > max) {
        return max;
    }

    for (int bs = 1; bs <= max; bs *= 2) {
        if (bs < req) {
            continue;
        } else if (bs == req) {
            return bs;
        } else { // bs > req
            if (dir == RoundNearest) {
                if (bs - req < req - bs/2) {
                    return bs;
                } else {
                    return bs/2;
                }
            } else if (dir == RoundDown) {
                return bs/2;
            } else {
                return bs;
            }
        }
    }

    return max;
}