How to preserve current font/style while making changes to RTF text in C# Windows Forms?

Question

Using Visual Studio to create a Windows Forms application, using C#. I have a RichTextBox. This box supports formatting like colours, bold, and underline.

I've added buttons such that people can format their text right in the box. For example, the Bold button does this:

if (!message.SelectionFont.Bold)
    message.SelectionFont = new Font(message.Font, FontStyle.Bold);
else
    message.SelectionFont = new Font(message.Font, FontStyle.Regular);

This works fine for bolding and unbolding regular text. The issue is when it is combined with other formatting. The creation of a new Font wipes away the original formatting, and leaves me with pure bold or pure regular text.

How can I preserve original formatting, while changing text to bold?

It shouldn't be hard-coded. I shouldn't be checking if(bold), if(italics), if(underline) for every option, as ideally I'll be adding more options later (colour, font, font size, etc).

Answer 1

Doesn't seem to be an easy way to do this.

This link might be of interest: How do I maintain RichText formatting (bold/italic/etc) when changing any one element?

Answer 2

You can add or remove properties to the enumeration FontStyle as was answered here.

Changing font in C#?