ContentSpanFinder.cpp

/*
    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(const SlicedHistogram& histogram,
                                 const VirtualFunction<void, const Span&>& handler) const {
  const auto hist_size = static_cast<const int>(histogram.size());

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

  while (true) {
    // 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));
  }
}  // ContentSpanFinder::findImpl