GFtype: Plain text transliteration of generic fonts

GFtype translates a generic font (GF) bitmap file (as output by Metafont, for example) to a plain text file that humans can read. It also serves as a GF-validating program, i.e., if GFtype can read a file, it's correct. Synopsis:

gftype [option]... gfname.dpi[gf]

The font gfname is searched for in the usual places (see section `Glyph lookup' in Kpathsea). To see all the relevant paths, set the environment variable KPATHSEA_DEBUG to `-1' before running the program.

The suffix `gf' is supplied if not already present. This suffix is not an extension; no `.' precedes it: for instance, `cmr10.600gf'.

The translation is written to standard output.

The program accepts the following options, as well as the standard `-help' and `-version' (see section Common options):

`-images'

Show the characters' bitmaps using asterisks and spaces.

`-mnemonics'

Translate all commands in the GF file.

As an example of the output, here is the (abrdiged) translation of the letter `K' in `cmr10', as rendered at 600dpi with the mode `ljfour' from `modes.mf' (available from `ftp://ftp.tug.org/tex/modes.mf'), with both `-mnemonics' and `-images' enabled.

GFtype outputs the information about a character in two places: a main definition and a one-line summary at the end. We show both. Here is the main definition:

2033: beginning of char 75: 3<=m<=60 0<=n<=56
(initially n=56) paint (0)24(12)20
2043: newrow 0 (n=55) paint 24(12)20
2047: newrow 0 (n=54) paint 24(12)20
2051: newrow 0 (n=53) paint 24(12)20
2055: newrow 7 (n=52) paint 10(21)13
2059: newrow 8 (n=51) paint 8(23)9
...
2249: newrow 8 (n=5) paint 8(23)11
2253: newrow 7 (n=4) paint 10(22)12
2257: newrow 0 (n=3) paint 24(11)22
2261: newrow 0 (n=2) paint 24(11)22
2265: newrow 0 (n=1) paint 24(11)22
2269: newrow 0 (n=0) paint 24(11)22
2273: eoc
.<--This pixel's lower left corner is at (3,57) in METAFONT coordinates
************************            ********************
************************            ********************
************************            ********************
************************            ********************
       **********                     *************
        ********                       *********
...
        ********                       ***********
       **********                      ************
************************           **********************
************************           **********************
************************           **********************
************************           **********************
.<--This pixel's upper left corner is at (3,0) in METAFONT coordinates

Explanation:

`2033'

`2043'

`...'

The byte position in the file where each GF command starts.

`beginning of char 75'

The character code, in decimal.

`3<=m<=60 0<=n<=56'

The character's bitmap lies between 3 and 60 (inclusive) horizontally, and between 0 and 56 (inclusive) vertically. (@math{m} is a column position and @math{n} is a row position.) Thus, 3 is the left side bearing. The right side bearing is the horizontal escapement (given below) minus the maximum @math{m}.

`(initially n=56) paint (0)24(12)20'

The first row of pixels: 0 white pixels, 24 black pixels, 12 white pixels, etc.

`newrow 0 (n=55) paint 24(12)20'

The second row of pixels, with zero leading white pixels on the row.

`eoc'

The end of the main character definition.

Here is the GF postamble information that GFtype outputs at the end:

Character 75: dx 4259840 (65), width 815562 (64.57289), loc 2033

Explanation:

`dx'

The device-dependent width, in scaled pixels, i.e., units of horizontal pixels times 2^16. The `(65)' is simply the same number rounded. If the vertical escapement is nonzero, it would appear here as a `dy' value.

`width'

The device-independent (TFM) width of this character. It is 2^24 times the ratio of the true width to the font's design size. The `64.57289' is the same number converted to pixels.

`loc'

The byte position in the file where this character starts.

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