if the TextEdit contains '[' or ']' character ,line height error

I get the dynamic height of fixed width through QFontmetrics

QFontMetrics metrics(qApp->font()); 
QRect rect = metrics.boundingRect(QRect(0,0,maxWidth,0),Qt::TextWrapAnywhere,text);
return rect.height();

Text and Label work properly, and TextEdit displays an error if it contains [height]