#include <QDomDocument>
#include <QDomElement>

#include <QString>
#include <QByteArray>

#include <QLabel>

#include <QApplication>


static QByteArray Text(const QDomElement &elem)
{ QByteArray text{ elem.tagName().toUtf8() + "\n" };
  for(QDomNode cur{elem.firstChild()}; !cur.isNull(); cur=cur.nextSibling())
    { switch(cur.nodeType())
      { case QDomNode::TextNode     :
          text += cur.toText().data().toUtf8().toHex() + "\n";
          break;

        case QDomNode::ElementNode  :
          text += Text(cur.toElement()) + "\n";
          break;
      }
    }
  return text;
}


int main(int argc, char *argv[])
{
  QApplication app(argc,argv);

  // document without "only spacing" elements
  QDomDocument docu;
  QDomElement root{ docu.createElement(QStringLiteral("root")) };

  QDomElement elema{ docu.createElement(QStringLiteral("A")) };
  elema.appendChild( docu.createTextNode(QStringLiteral("1")) ); // in hex: 0x31
  root.appendChild(elema);

  QDomElement elemb{ docu.createElement(QStringLiteral("B")) };
  elemb.appendChild( docu.createTextNode(QStringLiteral("    ")) ); // just spaces, 0x20
  root.appendChild(elemb);

  docu.appendChild(root);

  // read document into another document
  QDomDocument read;
  const QByteArray data{ docu.toByteArray(2) }; // notice the two spaces in as textNode data

  // comment out either line below to test
  const QDomDocument::ParseOption parseoption =
//    QDomDocument::ParseOption::Default;  // filters out the all-spaces node, and does not add phantom nodes
    QDomDocument::ParseOption::PreserveSpacingOnlyNodes; // preserves spacing only node, but adds phantom nodes
  read.setContent(data,parseoption);

  // content of text nodes as text
  const QByteArray text{ Text(read.documentElement()) };

  // show text
  QLabel label{ text };
  label.show();

  return QApplication::exec();
}