Manual page for AFM(7)
AFM - Adobe POSTSCRIPT font metrics file format
DESCRIPTION
AFM files are a standard interchange format for communicating
POSTSCRIPT font metric information to people and programs.
The format is ASCII encoded (for both human and machine
readability), machine independent, extensible, simple to
parse, and simple to generate.
AFM files are available for all of Adobe Systems'
POSTSCRIPT fonts.
While somewhat verbose, the format is intended to be easily
parsed, with the ability for applications to quickly
skip over items that are not of interest. It should be
possible to create simple line-oriented
parsing programs, or tools based on
awk.1
or
sed.1
Each AFM file contains the information for only one font
face. The file begins with global information about the
font, followed by sections with character metrics. The file
format is line-oriented, each line beginning with a property
(key) name, followed by the values for that property. The
general idea is to give key-value tuples (much like in a POSTSCRIPT
font dictionary).
The format is:
-
Key [value value ...]
Key names are case-sensitive. All keys beginning with a
capital letter are reserved by Adobe Systems.
The standard keys are detailed below, but other keys should
be allowed and safely ignored by programs not recognizing
them. All standard keys begin with a capital letter.
User-defined non-standard entries should begin with a lower-case letter.
The file begins with the line:
-
StartFontMetrics
version
The version described here is 1.0.
The last line of the file is:
-
EndFontMetrics
The following global font keys are defined.
Many of them are defined as in the top level or
FontInfo subdictionary of a POSTSCRIPT font dictionary;
their meanings are described in Appendix A of the
POSTSCRIPT Language Manual. All numeric values are in the
(1000 unit per em) character coordinate system.
- FontName string
-
The name of the font as presented to the POSTSCRIPT
findfont
operator.
- FullName string
-
The ``print name'' of the font.
- FamilyName string
-
The font family name.
- Weight string
-
The weight of the font.
- ItalicAngle real
-
The angle (in degrees counter-clockwise
from the vertical) of the dominant staffs of the font.
- IsFixedPitch boolean
-
Indicates monospaced (typewriter) fonts.
- FontBBox llx lly urx ury
-
Four integers giving the lower left
corner and the upper right corner of the font bounding box.
Note:
the bounding box given here is that of the flattened
paths, not of the Bezier curve descriptions.
- UnderlinePosition number
-
The position (from the baseline) to place
an underline.
- UnderlineThickness number
-
Thickness of an underline stroke.
- Version string
-
Font version identifier.
- Notice string
-
Font name trademark or copyright notice.
- Comment string
-
Comment strings may be ignored.
- EncodingScheme string
-
a string indicating the default encoding
vector for this font. The most common one is
AdobeStandardEncoding.
Special fonts may simply state
``FontSpecific''. In the future, other schemes may be
employed.
- CapHeight number
-
Top of capital H.
- XHeight number
-
Top of lower case x.
- Ascender number
-
Top of lower case d.
- Descender number
-
Bottom of lower case p.
The individual character metrics are surrounded with the lines
StartCharMetrics and EndCharMetrics and consist of a list of
keys and values separated by semicolons. The characters are
sorted (numeric ascending) by character code. Unencoded characters
follow all of the encoded ones and are distinguished by
having character code -1. Each character gets one line
of description. Standard keys are:
- C number
-
decimal value of default POSTSCRIPT
character code (-1 if unencoded).
- WX width-x
-
Character width in x (y is 0).
- W width-x width-y
-
Character width vector.
- N name
-
POSTSCRIPT character name.
- B llx lly urx ury
-
The character bounding box.
- L successor ligature
-
A ligature sequence; The current
character may join with the character named successor to
form the character named ligature. Note that characters
may have more than one such entry.
Most western language fonts have WX entries rather
than W ones.
Note that keys are one letter for brevity. Here too,
the set is extensible, with unknown entries ignored. (This leaves room for
addition of new information, for example.)
A future revision of this format will have a specification for
kerning information.
FILES
- /usr/llib/lw/*.afm
-
AFM files in the TRANSCRIPT distribution.
SEE ALSO
awk(1), sed(1).
AUTHOR
Adobe Systems Incorporated
NOTES
POSTSCRIPT and TRANSCRIPT are trademarks of Adobe Systems Incorporated.
Created by unroff & hp-tools.
© by Hans-Peter Bischof. All Rights Reserved (1997).
Last modified 21/April/97
