view data/model/RelativelyFineZoomConstraint.cpp @ 1752:6d09d68165a4 by-id

Further review of ById: make IDs only available when adding a model to the ById store, not by querying the item directly. This means any id encountered in the wild must have been added to the store at some point (even if later released), which simplifies reasoning about lifecycles

/* -*- 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 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 "RelativelyFineZoomConstraint.h"

#include <vector>
#include <algorithm>
#include <iostream>

using namespace std;

ZoomLevel
RelativelyFineZoomConstraint::getNearestZoomLevel(ZoomLevel requested,
                                                  RoundingDirection dir) const
{
    static vector<int> levels;

    int maxLevel = getMaxZoomLevel().level;

    if (levels.empty()) {
        int level = 1;
        while (level <= maxLevel) {
//            cerr << level << " ";
            levels.push_back(level);
            int step = level / 10;
            int pwr = 0;
            while (step > 0) {
                ++pwr;
                step /= 2;
            }
            step = (1 << pwr);
            level += step;
        }
//        cerr << endl;
    }

    RoundingDirection effective = dir;
    if (requested.zone == ZoomLevel::PixelsPerFrame) {
        if (dir == RoundUp) effective = RoundDown;
        else if (dir == RoundDown) effective = RoundUp;
    }

    // iterator pointing to first level that is >= requested
    auto i = lower_bound(levels.begin(), levels.end(), requested.level);

    ZoomLevel newLevel(requested);

    if (i == levels.end()) {
        newLevel.level = maxLevel;

    } else if (*i == requested.level) {
        newLevel.level = requested.level;

    } else if (effective == RoundUp) {
        newLevel.level = *i;

    } else if (effective == RoundDown) {
        if (i != levels.begin()) {
            --i;
        }
        newLevel.level = *i;

    } else { // RoundNearest
        if (i != levels.begin()) {
            auto j = i;
            --j;
            if (requested.level - *j < *i - requested.level) {
                newLevel.level = *j;
            } else {
                newLevel.level = *i;
            }
        }
    }

    // canonicalise
    if (newLevel.level == 1) {
        newLevel.zone = ZoomLevel::FramesPerPixel;
    }

    using namespace std::rel_ops;
    if (newLevel > getMaxZoomLevel()) {
        newLevel = getMaxZoomLevel();
    } else if (newLevel < getMinZoomLevel()) {
        newLevel = getMinZoomLevel();
    }
    
    return newLevel;
}