/*
    Scan Tailor - Interactive post-processing tool for scanned pages.
    Copyright (C) 2007-2008  Joseph Artsimovich <joseph_a@mail.ru>

    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 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "ContentSpanFinder.h"
#include "imageproc/SlicedHistogram.h"

using namespace imageproc;

void
ContentSpanFinder::findImpl(
    SlicedHistogram const& histogram,
    VirtualFunction1<void, Span>& handler) const
{
    int const hist_size = histogram.size();

    int i = 0;
    int content_end = -m_minWhitespaceWidth;
    int content_begin = content_end;

    for (;;) {
        // Find the next content position.
        for (; i < hist_size; ++i) {
            if (histogram[i] != 0) {
                break;
            }
        }

        if (i - content_end >= m_minWhitespaceWidth) {
            // Whitespace is long enough to break the content block.

            // Note that content_end is initialized to
            // -m_minWhitespaceWidth to make this test
            // pass on the first content block, in order to avoid
            // growing a non existing content block.

            if (content_end - content_begin >= m_minContentWidth) {
                handler(Span(content_begin, content_end));
            }

            content_begin = i;
        }

        if (i == hist_size) {
            break;
        }

        // Find the next whitespace position.
        for (; i < hist_size; ++i) {
            if (histogram[i] == 0) {
                break;
            }
        }
        content_end = i;
    }

    if (content_end - content_begin >= m_minContentWidth) {
        handler(Span(content_begin, content_end));
    }
}
