用大写字母和粗体格式化 RichTextBox 的第一行

Question

如果我有一个 RichTextBox 并希望输出第一行是带有大写字母和粗体的字体，而下一行则相反，我该怎么办？

输出如下：

我的名字是
戴安娜
我的地址是
中国

Answer 1

嘿，试试这个，它有效，但如果用户输入速度非常快，例如按住“Enter”等，您可能会看到文本闪烁一秒钟。

    private void Form_Load(object sender, EventArgs e)
    {
        // append the function to the RichTextBox's TextChanged event
        MyRichTextBox.TextChanged += Capitalize_Bold_FirstLine;
    }

    private void Capitalize_Bold_FirstLine(object sender, EventArgs e)
    {
        RichTextBox box = sender as RichTextBox;
        if (box != null && box.Text != "")
        {
            // get the current selection text of the textbox
            int ss = box.SelectionStart;
            int sl = box.SelectionLength;
            // get the position where the first line ends
            int firstLineEnd = box.Text.IndexOf('\n');
            if (firstLineEnd < 0)
                firstLineEnd = box.Text.Length;

            // split the lines
            string[] lines = box.Text.Split('\n');
            // capitalize the first line
            lines[0] = lines[0].ToUpper();
            // join them back and set the new text
            box.Text = String.Join("\n", lines);
            // select the first line and make it bold
            box.SelectionStart = 0;
            box.SelectionLength = firstLineEnd;
            box.SelectionFont = new Font(box.Font, FontStyle.Bold);
            // select the rest and make it regular
            box.SelectionStart = firstLineEnd;
            box.SelectionLength = box.Text.Length - firstLineEnd;
            box.SelectionFont = new Font(box.Font, FontStyle.Regular);
            // go back to what the user had selected
            box.SelectionStart = ss;
            box.SelectionLength = sl;
        }
    }