Qt如何实现文本编辑器光标高亮技术

void Widget::oncursorPositionChanged()
{
    QTextCursor cursor = ui->textEdit->textCursor();
    //qDebug() << cursor.blockNumber() + 1 << ", "<< cursor.columnNumber() + 1;
    QString blockNum = QString::number(cursor.blockNumber() + 1);
    QString columnNumber = QString::number(cursor.columnNumber() + 1);
    const QString labelMes = "列:" + blockNum + ", 行:" + columnNumber;
    ui->labelPosition->setText(labelMes);
 
    //    设置当前行高亮
    QList<QTextEdit::ExtraSelection> extraSelections;
    QTextEdit::ExtraSelection ext;
 
    //    1，知道当前行
    ext.cursor = ui->textEdit->textCursor();
    QBrush qBrush(Qt::yellow);
 
    //    2，颜色
    ext.format.setBackground(qBrush);
    //   配置段属性：整行显示，没有这句话不行
    ext.format.setProperty(QTextFormat::FullWidthSelection, true);
 
    //    3，设置
    //把ext加到ext的容器中
    extraSelections.append(ext);
    ui->textEdit->setExtraSelections(extraSelections);
}
//解释这串代码，写上注释，并仔细阐述里面用到了什么技术？

void Widget::oncursorPositionChanged()

    // 获取 QTextEdit 中的当前光标对象
    QTextCursor cursor = ui->textEdit->textCursor();

    // 将行号和列号转为字符串
    QString blockNum = QString::number(cursor.blockNumber() + 1);
    QString columnNumber = QString::number(cursor.columnNumber() + 1);

    const QString labelMes = "列:" + blockNum + ", 行:" + columnNumber;
    ui->labelPosition->setText(labelMes);

    QList<QTextEdit::ExtraSelection> extraSelections;

QTextEdit::ExtraSelection ext;

ext.cursor = ui->textEdit->textCursor();

QBrush qBrush(Qt::yellow);

ext.format.setBackground(qBrush);

ext.format.setProperty(QTextFormat::FullWidthSelection, true);

extraSelections.append(ext);

ui->textEdit->setExtraSelections(extraSelections);

void Widget::updateCursorPositionInfo()
{
    QTextCursor cursor = ui->textEdit->textCursor();
 
    int line = cursor.blockNumber() + 1;
    int col = cursor.columnNumber() + 1;
 
    QString info = QString("行：%1，列：%2").arg(line).arg(col);
    ui->labelPosition->setText(info);
 
    QTextEdit::ExtraSelection selection;
    selection.format.setBackground(Qt::yellow);
    selection.format.setProperty(QTextFormat::FullWidthSelection, true);
    selection.cursor = cursor;
 
    QList<QTextEdit::ExtraSelection> selections;
    selections.append(selection);
 
    ui->textEdit->setExtraSelections(selections);
}

void Widget::oncursorPositionChanged()
{
    updateCursorPositionInfo();
}