dvips: Virtual fonts
6.1.3 Virtual fonts
-------------------
A "virtual font" is constructed by extracting characters from one or
more existing fonts and rearranging them, or synthesizing new characters
in various ways. The explanation in this manual is intended to suffice
for understanding enough about virtual fonts to use them with Dvips. It
isn't a reference manual on virtual fonts. For more information: The
primary document on virtual fonts is Donald E. Knuth, 'TUGboat' 11(1),
Apr. 1990, pp. 13-23, "Virtual Fonts: More Fun for Grand Wizards"
(<mirror.ctan.org/info/virtual-fonts.knuth>). (Don't be intimidated by
the subtitle.)
A virtual font ('.vf') file specifies, for each character in the
virtual font, a recipe for typesetting that character. A VF file, like
a TFM file, is in a compressed binary format. The 'vftovp' and 'vptovf'
programs convert a VF file to a human-readable VPL (virtual property
list) format and back again. ⇒(web2c)vftovp invocation, and
⇒(web2c)vptovf invocation.
In the case of a PostScript font F being used in a straightforward
way, the recipe says: character I in the VF font is character J in font
F. The font F is called a "base font". For example, the VF file could
remap the characters of the PostScript font to the positions where TeX
expects to find them. ⇒Encodings.
Since TeX reads only TFM files, not VF's, each VF must have a
corresponding TFM for use with TeX. This corresponding TFM is created
when you run 'vptovf'.
You can "expand" virtual fonts into their base fonts with DVIcopy
(⇒(web2c)dvicopy invocation). This is useful if you are using a
DVI translator that doesn't itself understand vf's.
If a virtual font has no entry at a given codepoint and the first
'MAPFONT' designates an (u)pTeX JFM, we designate the glyph of the same
codepoint in the TFM(JFM) with the smallest font ID. This feature helps
to reduce the size of Japanese virtual fonts. For more information
about the extensive support of Japanese in TeX, see
<https://github.com/texjporg>.
Info Catalog
dvips: Glyph files
dvips: Font concepts
dvips: Encodings