//=============================================================================
//  MusE Reader
//  Music Score Reader
//
//  Copyright (C) 2010 Werner Schweer
//
//  This program is free software; you can redistribute it and/or modify
//  it under the terms of the GNU General Public License version 2.
//
//  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, write to the Free Software
//  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
//=============================================================================

#include "pdf.h"

namespace Ms {
int Pdf::references;

//---------------------------------------------------------
//   numPages
//---------------------------------------------------------

int Pdf::numPages() const
{
    return _document->numPages();
}

//---------------------------------------------------------
//   Pdf
//---------------------------------------------------------

Pdf::Pdf()
{
    ++references;
}

//---------------------------------------------------------
//   open
//---------------------------------------------------------

bool Pdf::open(const QString& path)
{
    _document = Poppler::Document::load(path);
    if (!_document || _document->isLocked()) {
        delete _document;
        return false;
    }
    return true;
}

//---------------------------------------------------------
//   ~Pdf
//---------------------------------------------------------

Pdf::~Pdf()
{
    if (_document) {
        delete(_document);
    }
    --references;
}

//---------------------------------------------------------
//   binarization
//---------------------------------------------------------

QImage Pdf::binarization(QImage image)
{
    QImage bw = QImage(image.width(), image.height(), QImage::Format_MonoLSB);
    QVector<QRgb> ct(2);
    ct[0] = qRgb(255, 255, 255);
    ct[1] = qRgb(0, 0, 0);
    bw.setColorTable(ct);
    bw.fill(0);
    float thresh = 128;
    float new_thresh = 0;

    while (thresh != new_thresh) {
        float sum_black = 0;
        float sum_white = 0;
        int num_black = 0;
        int num_white = 0;
        new_thresh = thresh;
        for (int x = 0; x < image.width(); x++) {
            for (int y = 0; y < image.height(); y++) {
                QRgb c = image.pixel(x, y);
                float g = qGray(c);
                if (g < thresh) {
                    sum_black += g;
                    num_black++;
                } else {
                    sum_white += g;
                    num_white++;
                }
            }
        }
        thresh = (sum_black / num_black + sum_white / num_white) / 2.0;
    }

    int stride  = (bw.width() + 7) / 8;
    uchar* p    = bw.bits();

    for (int y = 0; y < bw.height(); ++y) {
        p = bw.scanLine(y);
        for (int x = 0; x < stride; ++x) {
            int temp = 0;
            for (int i = 0; i < 8; i++) {
                if (x * 8 + i >= bw.width()) {
                    continue;
                }
                QRgb c = image.pixel(x * 8 + i, y);
                float g = qGray(c);
                temp += ((g < thresh) ? 1 : 0) << i;
            }
            *p++ = temp;
        }
    }
    return bw;
}

//---------------------------------------------------------
//   page
//---------------------------------------------------------

QImage Pdf::page(int i)
{
    QImage image;
    // Paranoid safety check
    if (_document == 0) {
        return image;
    }

    Poppler::Page* pdfPage = _document->page(i);    // Document starts at page 0
    if (pdfPage == 0) {
        return image;
    }

    QSize size = pdfPage->pageSize();
    float scale = 2.0;
    // the size can be decided more intelligently
    image = pdfPage->renderToImage(scale * 72.0, scale * 72.0, 0, 0, scale * size.width(), scale * size.height());
    delete pdfPage;
    return binarization(image);
}
}