The UniMIFfer Tool

The UniMIFfer tool examines a font to determine whether or not it has all the pieces needed to display fully decomposed Unicode using precomposed glyphs for the Unicode characters it covers. It generates two text files���an "add" file and a "morph input file" (MIF)���to be used by the AAT Font Tool (q.v.) to add the proper support for this functionality to the font.

The Problem

The Unicode character set standard is becoming increasingly pervasive on computers. One feature of Unicode is that many symbols can be represented in more than one way. For example, the accented letter "��" can be represented in Unicode by an intact "��" (the precomposed form) or by a letter "e" with the accent "��" following it (the decomposed form).

On the Mac OS, the HFS+ file system uses Unicode names for files, and these names are fully decomposed. If your file name is "R��sum��", therefore, it will be stored on your HFS+ disk as "R-e-��-s-u-m-e-��". If the Finder, a disk utility such as Norton Disk Doctor or some other application were to list your file by name, it would be best if the name came out as "R��sum��."

The Unicode drawing system on the Mac OS���Apple Type Services for Unicode�Ѣ Imaging (ATSUI)���will allow for this. It can automatically draw "R-e-��-s-u-m-e-��" as "R��sum��" if the font being used supports it.The problem is, not all fonts support it.

The solution

UniMIFfer is one step in the solving of this problem. If a precomposed Unicode character is supported by a particular font, it will check to see if all the Unicode characters used for the decomposed form are also supported by the font. In the case of "��", it will check to see that the font has both an "e" and a "��". If any of these are missing, it will note the fact and include the missing characters in the add file it generates.

UniMIFfer will also add the equivalence of "��" and "e-��" to the morph input file (MIF) it also generates. These two files can be used with the AAT Font Tool to make sure that the text will be shown in the proper composed form even if the decomposed form is actually found in the text.

Notes

UniMIFfer doesn't know enough to produce a properly designed glyph for every character that needs to be added. Rather, it tries to find a glyph in the font that looks like the one needed and indicates that it should be cloned for the new character. If it can't find something appropriate, it will direct that the space character be cloned. The presumption is that these newly added characters will never, or rarely, be seen by themselves so giving them invisible glyphs is relatively harmless.

The proper solution, however, is for the font designer to double check that every glyph added is designed properly. (The add list is used instead of directly adding the characters to the font, too, so that the font designer has a chance to override UniMIFfer's choices for the glyphs to clone.) This can be done by manually adding all the needed glyphs before using the AAT Font Tool (and then not using the add list) or by editing the font generated by the AAT Font Tool.

If you encounter problems with UniMIFfer, please contact the Apple Font Group.

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