c# - 一些 Alt 键改变了我的 RichTextBox 字体

Question

标签： c#.netwinformsfontsrichtextbox

Answer 1

This is the default behavior.
RichTextBox automatically finds a fallback font to represent those characters that the currently specified Font can't handle.
If not otherwise instructed, it changes the Font selection with the fallback Font.

Read this rant about the same default behavior of the RichTextBox ancestor (the RichEdit control, from which the WinForms control derives): Don't change the font, dammit!

There are means to change this behavior. At least in the way the RichTextBox control reports the current Font and Font selection. The C++ code in the previous blog post is one.

A StackOverflow Question/Answer on the subject:
How to force a Win32 RichEdit fallback to SimSun with East Asian text.

But you don't need to fallback to C++ for this.
See the RichTextBox.LanguageOption and the RichTextBoxLanguageOptions flags.

You can insert this line of code right after the InitializeComponent() proc in your Form constructor:

richTextBox1.LanguageOption = RichTextBoxLanguageOptions.DualFont;

or

richTextBox1.LanguageOption = RichTextBoxLanguageOptions.DualFont | 
                              RichTextBoxLanguageOptions.UIFonts;

There's a slight difference. See the reference Docs and test this behaviour in your specific context.
If you insert an Unicode symbol that is not handled by the current Font, a fallback is always possible, but the RichTextBox UI will not change the Font, not even the SelectionFont.
And Clipboard.SetText(), Clipboard.GetText() will work as usual.