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NAME | DESCRIPTION | LIMITATIONS | FILES | SEE ALSO | COPYING | COLOPHON |
LJ4_FONT(5) File Formats Manual LJ4_FONT(5)
lj4_font - groff fonts for use with devlj4
Nominally, all Hewlett-Packard LaserJet 4–series and newer printers
have the same internal fonts: 45 scalable fonts and one bitmapped
Lineprinter font. The scalable fonts are available in sizes between
0.25 point and 999.75 points, in 0.25-point increments; the
Lineprinter font is available only in 8.5-point size.
The LaserJet font files included with groff assume that all printers
since the LaserJet 4 are identical. There are some differences
between fonts in the earlier and more recent printers, however. The
LaserJet 4 printer used Agfa Intellifont technology for 35 of the
internal scalable fonts; the remaining 10 scalable fonts were
TrueType. Beginning with the LaserJet 4000–series printers
introduced in 1997, all scalable internal fonts have been TrueType.
The number of printable glyphs differs slightly between Intellifont
and TrueType fonts (generally, the TrueType fonts include more
glyphs), and there are some minor differences in glyph metrics.
Differences among printer models are described in the PCL 5
Comparison Guide and the PCL 5 Comparison Guide Addendum (for
printers introduced since approximately 2001).
LaserJet printers reference a glyph by a combination of a 256-glyph
symbol set and an index within that symbol set. Many glyphs appear
in more than one symbol set; all combinations of symbol set and index
that reference the same glyph are equivalent. For each glyph,
hpftodit(1) searches a list of symbol sets, and selects the first set
that contains the glyph. The printing code generated by hpftodit(1)
is an integer that encodes a numerical value for the symbol set in
the high byte(s), and the index in the low byte. See groff_font(5)
for a complete description of the font file format; symbol sets are
described in greater detail in the PCL 5 Printer Language Technical
Reference Manual.
Two of the scalable fonts, Symbol and Wingdings, are bound to
256-glyph symbol sets; the remaining scalable fonts, as well as the
Lineprinter font, support numerous symbol sets, sufficient to enable
printing of more than 600 glyphs.
The metrics generated by hpftodit(1) assume that the DESC file
contains values of 1200 for res and 6350 for unitwidth (or any
combination (e.g., 2400 and 3175) for which
res × unitwidth = 7620000). Although HP PCL 5 LaserJet printers
support an internal resolution of 7200 units per inch, they use a
16-bit signed integer for cursor positioning; if devlj4 is to support
U.S. ledger paper (11" × 17"), the maximum usable resolution is
32767 / 17, or 1927, units per inch, which rounds down to 1200 units
per inch. If the largest required paper size is less (e.g.,
8.5" × 11" or A5), a greater resolution (and lesser unitwidth) can be
specified.
Font metrics for Intellifont fonts were provided by Tagged Font
Metric (TFM) files originally developed by Agfa/Compugraphic. The
TFM files provided for these fonts supported 600+ glyphs and
contained extensive lists of kern pairs.
To accommodate developers who had become accustomed to TFM files, HP
also provided TFM files for the 10 TrueType fonts included in the
LaserJet 4. The TFM files for TrueType fonts generally included less
information than the Intellifont TFMs, supporting fewer glyphs, and
in most cases, providing no kerning information. By the time the
LaserJet 4000 printer was introduced, most developers had migrated to
other means of obtaining font metrics, and support for new TFM files
was very limited. The TFM files provided for the TrueType fonts in
the LaserJet 4000 support only the Latin 2 (ISO 8859-2) symbol set,
and include no kerning information; consequently, they are of little
value for any but the most rudimentary documents.
Because the Intellifont TFM files contain considerably more
information, they generally are preferable to the TrueType TFM files
even for use with the TrueType fonts in the newer printers. The
metrics for the TrueType fonts are very close, though not identical,
to those for the earlier Intellifont fonts of the same names.
Although most output using the Intellifont metrics with the newer
printers is quite acceptable, a few glyphs may fail to print as
expected. The differences in glyph metrics may be particularly
noticeable with composite parentheses, brackets, and braces used by
eqn(1). A script, located in
/usr/local/share/groff/1.22.3/font/devlj4/generate, can be used to
adjust the metrics for these glyphs in the special font S for use
with printers that have all TrueType fonts.
At the time HP last supported TFM files, only Version 1 of the
Unicode standard was available. Consequently, many glyphs lacking
assigned code points were assigned by HP to the Private Use Area
(PUA). Later versions of the Unicode standard included code points
outside the PUA for many of these glyphs. The HP-supplied TrueType
TFM files use the PUA assignments; TFM files generated from more
recent TrueType font files require the later Unicode values to access
the same glyphs. Consequently, two different mapping files may be
required: one for the HP-supplied TFM files, and one for more recent
TFM files.
/usr/local/share/groff/1.22.3/font/devlj4/DESC
Device description file.
/usr/local/share/groff/1.22.3/font/devlj4/F
Font description file for font F.
groff(1), groff_diff(1), hpftodit(1), grolj4(1), groff_font(5)
Copyright © 2004-2014 Free Software Foundation, Inc.
Permission is granted to make and distribute verbatim copies of this
manual provided the copyright notice and this permission notice are
preserved on all copies.
Permission is granted to copy and distribute modified versions of
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Groff Version 1.22.3 4 November 2014 LJ4_FONT(5)
Pages that refer to this page: groff(1), grolj4(1), hpftodit(1)