What font is used if a Unicode-character is not found in the selected font (Tahoma)?

Question

I have written a WPF user control that uses Tahoma as a font to display unicode strings, which works fine. However, I have noticed that some eastern asian characters are actually missing in Tahoma, i.e. this font does not support all common Unicode characters.

However, when I display a string that contains some east asian letters, that I suppose are missing in Tahoma.ttf, the character is displayed correctly anyway, instead of a black rectangle that I expected to get for the missing unicode character.

So out of curiosity: is there any fallback mechanism, i.e. does Windows 7 or C# WPF replace the missing characters from a fallback font? Can anybody please explain how exactly this is working, and which font is actually used as a allback?

Answer 1

See the Font Fallback section of the FontFamily reference.

Answer 2

Thanks alot H.B., with your keyword, I was able to find this really helpful ressource from Microsoft, that explains how Font Fallback and Font Linking work:

http://msdn.microsoft.com/en-us/goglobal/bb688134

Here is a good quote:

A user running Windows XP selects the Tahoma font to enter some text first in English, next in Hebrew, and then in Telugu. Since Tahoma is an OpenType font, it provides support for Latin and Hebrew scripts, but does not contain any Telugu glyphs. Uniscribe detects this lack of font support and automatically renders the Telugu script by using its fallback font, which is Gautami.