QTextEdit：仅当滚动条位于底部时自动向下滚动

在添加文本之前查询滚动条

QScrollBar *scrollbar &＃61; ui->text_accept->verticalScrollBar();bool scrollbarAtBottom &＃61; (scrollbar->value() >&＃61; (scrollbar->maximum() - 50));int scrollbarPrevValue &＃61; scrollbar->value();QTextCursor cursor &＃61; ui->text_accept->textCursor();//将光标移动到文本末尾cursor.movePosition(QTextCursor::End);ui->text_accept->setTextCursor(cursor);ui->text_accept->setFontPointSize(10);ui->text_accept->insertPlainText(str.toUpper());if (scrollbarAtBottom)ui->text_accept->ensureCursorVisible();elseui->text_accept->verticalScrollBar()->setValue(scrollbarPrevValue);