加粗

void MainWindow::on_checkbox_Bold_stateChanged(int arg1)
{ui->textEdit->selectAll();QTextCharFormat fmt = ui->textEdit->currentCharFormat();if(arg1 == Qt::Checked){fmt.setFontWeight(QFont::Bold);}else{fmt.setFontWeight(QFont::Normal);}ui->textEdit->mergeCurrentCharFormat(fmt);//    QString str = ui->textEdit->toPlainText();
//    ui->textEdit->setText(str);ui->textEdit->append("追加文字");
}

下划线

void MainWindow::on_checkbox_Unline_stateChanged(int arg1)
{QTextCharFormat fmt = ui->textEdit->currentCharFormat();if(arg1 == Qt::Checked){fmt.setFontUnderline(true);}else{fmt.setFontUnderline(false);}ui->textEdit->mergeCurrentCharFormat(fmt);QString str = ui->textEdit->toPlainText();ui->textEdit->setText(str);ui->textEdit->append("追加文字");
}

斜体

void MainWindow::on_checkbox_Italic_stateChanged(int arg1)
{QTextCharFormat fmt = ui->textEdit->currentCharFormat();if(arg1 == Qt::Checked){fmt.setFontItalic(true);}else{fmt.setFontItalic(false);}ui->textEdit->mergeCurrentCharFormat(fmt);QString str = ui->textEdit->toPlainText();ui->textEdit->setText(str);ui->textEdit->append("追加文字");
}

字体大小

void MainWindow::on_spinSize_valueChanged(int arg1)
{QTextCharFormat fmt = ui->textEdit->currentCharFormat();fmt.setFontPointSize(arg1);ui->textEdit->mergeCurrentCharFormat(fmt);QString str = ui->textEdit->toPlainText();ui->textEdit->setText(str);ui->textEdit->append("追加文字");
}

字体设置

void MainWindow::on_fontComboBox_currentFontChanged(const QFont &f)
{QTextCharFormat fmt = ui->textEdit->currentCharFormat();fmt.setFont(f);ui->textEdit->mergeCurrentCharFormat(fmt);QString str = ui->textEdit->toPlainText();ui->textEdit->setText(str);ui->textEdit->append("追加文字");
}