- Update - see this large collection of open source and free Thai fonts, including Fah Kwang and Charmonman listed below
One challenge for using Thai script on a computer is that Thai characters are more vertical than roman alphabet characters. If one is mixing roman and Thai characters in a document, the Thai characters tend to be much smaller (and therefore illegible if the roman characters are optimized for space and legibility).
A good (bad) example is the very legible source code editing font Hack which does not have Thai character support. This means the operating system substitutes the Thai system font, which makes reading difficult. The best that can be done is increasing the font size and decreasing the line height and the line length. This makes the latin characters
At this point I have found two fonts with excellent mixed-character set support. Another has reasonable support in a stylized font.
Linux Libertine, which continues to amaze as a one of the most successful open source truetype font projects has excellent Thai character support. Libertine is a Serif font. Actually, Linux Libertine has zero Thai character support, but the default Thai font substitution works exceedingly well with Linux Libertine.
Free Thailand Government Fonts
- For a Sans Serif font (with full roman character support), the Fah kwang font pdf sample is an excellent option.
- For a stylized font (without roman character support), Charmonman pdf sample is a nice option.