问QPlainTextEdit / QTextCursor -如何获取光标上方和下方的行，直到上方和下方为空行

EN

#include <QApplication>
#include <QPlainTextEdit>
#include <QTextBlock>

#include <QDebug>

static QString getLinesBetweenSpaces(const QTextBlock & block){
   QTextBlock before = block;
   QTextBlock after = block;

   if(block.text().trimmed().isEmpty())
       return "";

   QStringList lines{block.text()};

   do{
       before = before.previous();
       if(before.text().trimmed().isEmpty())
           break;
       lines.prepend(before.text());
   }
   while(before.isValid());

   do{
       after = after.next();
       if(after.text().trimmed().isEmpty())
           break;
        lines.append(after.text());
   }
   while(after.isValid());
   return lines.join("\n");
}

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

    const QStringList lines = {"AA", "BB", "CC", " ", "DD", "EE", "FF", " ", "GG", "HH", "II"};
    const QString text = lines.join("\n");
    QPlainTextEdit w;
    w.setPlainText(text);

    QObject::connect(&w, &QPlainTextEdit::cursorPositionChanged, [&w](){
       qDebug()<<  getLinesBetweenSpaces(w.textCursor().block());
    });
    w.show();

    return a.exec();
}