view layer/ImageRegionFinder.cpp @ 561:aced8ec09bc8

* 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 2007 QMUL.
    
    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 "ImageRegionFinder.h"

#include <QImage>
#include <cmath>
#include <stack>
#include <iostream>

ImageRegionFinder::ImageRegionFinder()
{
}

ImageRegionFinder::~ImageRegionFinder()
{
}

QRect
ImageRegionFinder::findRegionExtents(QImage *image, QPoint origin) const
{
    int w = image->width(), h = image->height();

    QImage visited(w, h, QImage::Format_Mono);
    visited.fill(0);

    std::stack<QPoint> s;
    s.push(origin);

    int xmin = origin.x();
    int xmax = xmin;
    int ymin = origin.y();
    int ymax = ymin;

    QRgb opix = image->pixel(origin);

    while (!s.empty()) {

        QPoint p = s.top();
        s.pop();

        visited.setPixel(p, 1);

        int x = p.x(), y = p.y();

        if (x < xmin) xmin = x;
        if (x > xmax) xmax = x;

        if (y < ymin) ymin = y;
        if (y > ymax) ymax = y;

        std::stack<QPoint> neighbours;

        int similarNeighbourCount = 0;

        for (int dx = -1; dx <= 1; ++dx) {
            for (int dy = -1; dy <= 1; ++dy) {

                if ((dx != 0 && dy != 0) ||
                    (dx == 0 && dy == 0)) 
                    continue;

                if (x + dx < 0 || x + dx >= w ||
                    y + dy < 0 || y + dy >= h)
                    continue;

                if (visited.pixelIndex(x + dx, y + dy) != 0)
                    continue;

                if (!similar(opix, image->pixel(x + dx, y + dy))) 
                    continue;

                neighbours.push(QPoint(x + dx, y + dy));
                ++similarNeighbourCount;
            }
        }

        if (similarNeighbourCount >= 2) {
            while (!neighbours.empty()) {
                s.push(neighbours.top());
                neighbours.pop();
            }
        }
    }

    return QRect(xmin, ymin, xmax - xmin, ymax - ymin);
}

bool
ImageRegionFinder::similar(QRgb a, QRgb b) const
{
    if (b == qRgb(0, 0, 0) || b == qRgb(255, 255, 255)) {
        // black and white are boundary cases, don't compare similar
        // to anything -- not even themselves
        return false;
    }

    float ar = float(qRed(a) / 255.f);
    float ag = float(qGreen(a) / 255.f);
    float ab = float(qBlue(a) / 255.f);
    float amag = sqrtf(ar * ar + ag * ag + ab * ab);
    float thresh = amag / 2;

    float dr = float(qRed(a) - qRed(b)) / 255.f;
    float dg = float(qGreen(a) - qGreen(b)) / 255.f;
    float db = float(qBlue(a) - qBlue(b)) / 255.f;
    float dist = sqrtf(dr * dr + dg * dg + db * db);

//    std::cerr << "thresh=" << thresh << ", dist=" << dist << std::endl;

    return (dist < thresh);
}