winform RichTextBox 控件

            Font newFont;
            var oldFont = this.richTextBox1.SelectionFont;

            if (oldFont.Bold)
            {
                newFont = new Font(oldFont, oldFont.Style & ~FontStyle.Bold);
            }
            else
            {
                newFont = new Font(oldFont, oldFont.Style | FontStyle.Bold);
            }
            this.richTextBox1.SelectionFont = newFont;
            this.richTextBox1.Focus();

            Font newFont;
            var oldFont = this.richTextBox1.SelectionFont;

            if (oldFont.Italic)
            {
                newFont = new Font(oldFont, oldFont.Style & ~FontStyle.Italic);
            }
            else
            {
                newFont = new Font(oldFont, oldFont.Style | FontStyle.Italic);
            }
            this.richTextBox1.SelectionFont = newFont;
            this.richTextBox1.Focus();

            Font newFont;
            var oldFont = this.richTextBox1.SelectionFont;

            if (oldFont.Underline)
            {
                newFont = new Font(oldFont, oldFont.Style & ~FontStyle.Underline);
            }
            else
            {
                newFont = new Font(oldFont, oldFont.Style | FontStyle.Underline);
            }
            this.richTextBox1.SelectionFont = newFont;
            this.richTextBox1.Focus();

            var fontFamily = this.richTextBox1.SelectionFont.FontFamily;
            var newFont = new Font(fontFamily, 20);
            this.richTextBox1.SelectionFont = newFont;
            this.richTextBox1.Focus();

            this.richTextBox1.SelectionAlignment = HorizontalAlignment.Center;

            this.richTextBox1.SaveFile("aa.rtf");
            this.richTextBox1.LoadFile("aa.rtf");