QTextDocument is faster do show big html file as Chrome Browser

patrik08

I am excited by the new qt5, I remember that 9 years ago QTextDocument had other behaviors ..
Maybe the pictures I do not know

A pdf of 1MB (libre office use) converted into html to a readable quality reaches 60MB as html in the attached code ...
QTextDocument draws all 20 pages in 35sec.
Chrome Browser after 2 minutes says it does not respond ...

If I show images from QPdfium, the time are much longer ... can anyone explain it?
here waht i run ...




/// same game to odt format image if load faster
static inline QByteArray html_image(QImage x, const QSize area) {
  if (x.isNull()) {
    return QByteArray();
  }
  QByteArray ba;
  QBuffer bu(&ba);
  //bu.open(QBuffer::ReadWrite);
  bu.open(QIODevice::WriteOnly);
  x.save(&bu,"JPG",5);
  bu.close();
  QString head0 =  QString("<img style='max-width:90vw' src='data:image/png;base64,");
  QString head1 = QString("\'  width=\'");
  head1 += QString::number(area.width());
  head1 += QString("\' height=\'");
  head1 += QString::number(area.height());
  head1 += QString("' />");
  head0.replace(QChar(39), QChar(34));
  head1.replace(QChar(39), QChar(34));
  QByteArray endchunk = ba.toBase64(); ///  tra_chunk.toBase64();
  x.~QImage();
  //// qDebug() << __FUNCTION__ << "- size-> " << endchunk.size();
  endchunk.prepend(head0.toLatin1());
  endchunk.append(head1.toLatin1());
   //// qDebug() << __FUNCTION__ << "- " << endchunk;
  return endchunk;
}

/* MM_TO_POINT  A4  210 mm × 297 mm some work to QTextDocument */
static inline QByteArray html_pdf_file(const QString file) {  //// pdf file ...
  const qreal pixelscreenscale = 2;
   QSize _A4( MM_TO_POINT(210) / pixelscreenscale , MM_TO_POINT(297) / pixelscreenscale  ); /// screen .. to print get full...
   QByteArray body,tmp,line;
   body += QByteArray("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.0//EN\" \"http://www.w3.org/TR/REC-html40/strict.dtd\"> ");
   body += QByteArray("<html><head><meta name=\"qrichtext\" content=\"1\" /><meta http-equiv=\"Content-Type\" content=\"text/html; charset=utf-8\" />" );
   body += QByteArray("</head><body>" );

#ifdef LOADPDFIUMYES
  qreal scale = MM_TO_POINT(210) / _A4.width(); /// must give pixelscreenscale!!!
  QPdfium *m_pdf = new QPdfium();
  m_pdf->loadFile(file);
  if (!m_pdf->isValid()) {
      return QByteArray();
  }
  const int pagex = m_pdf->pageCount();
  if (pagex > 0) {
      int dd=-1;
      do {
         dd++;
         //// qDebug() << __FUNCTION__ << " - " << scale << "- page  " << dd;
         QPdfiumPage page = m_pdf->page(dd);
         QImage image = page.image(scale);
         if (image.isNull()) {
           return QByteArray();
         }
         QByteArray img64 = html_image(image,_A4);  /// .toLatin1();
         image.~QImage();
         line += QByteArray("<p align=\"center\" style=\" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;\">  ");
         line += img64;
         line += QByteArray("</p>");
         body.append(line);
      } while( dd < (pagex -1) );
  }
#endif
  QByteArray footer = QByteArray("</body></html>");
  body.append(footer);
  return body;
}