This manual page is not meant to be exhaustive. The complete documentation for this version of TEX can be found in the info file or manual Web2C: A TeX implementation.
The gftodvi program converts a generic font (gf) file output by, for example, mf(1), to a device independent (DVI) file (that can then be typeset using the same software that has already been written for TEX). The characters in the gf file will appear one per page, with labels, titles, and annotations as specified in Appendix H (Hardcopy Proofs) of The M ETAFONT book.
gftodvi uses other fonts in addition to the main gf file. A `gray' font is used to typeset the pixels that actually make up the character. (We wouldn't want all the pixels to be simply black, since then labels, key points, and other information would be lost.) A `title' font is used for the information at the top of the page. A `label' font is used for the labels on key points of the figure. A `slant' font is used to typeset diagonal lines, which otherwise have to be simulated using horizontal and vertical rules. The default gray, title, and label fonts are gray, cmr8, and cmtt10, respectively; there is no default slant font.
To change the default fonts, you can give special commands in your M ETAFONT source file, or you can change the fonts online. An online dialog ensues if you end the gf_file_name with a `/'. For example,
Special font substitution: grayfont black
OK; any more? grayfontarea /home/art/don/
OK; any more? slantfont /home/fonts/slantimagen6
OK; any more?
will use /home/art/don/black as the `gray' font and /home/fonts/slantimagen6 as the `slant' font (this name indicates a font for lines with slope 1/6 at the resolution of an Imagen printer).
The argument to -overflow-label-offset specifies the distance from the right edge of the character bounding box at which the overflow equations (if any) are typeset. The value is given in TEX points. The default is a little over two inches.
gftodvi looks for gf_file_name using the environment variable GFFONTS. If that is not set, it uses the variable TEXFONTS. If that is not set, it uses the system default.
The default fonts.