Glyph Info

Glyph Info

This dialog allows you to set the name and unicode encoding of a given glyph. If you know the name of the glyph then FontForge can tell you the encoding (if you press Set From Name), similarly if you know the encoding then FontForge can tell you the name.

The name field contains a pull down list with (possibly) several synonyms for the name of this unicode code point.

The Glyph class field is for the opentype 'GDEF' table. You can usually leave it set to automatic. FontForge will then figure out the class, and whether it should be output into GDEF. You can see what FontForge does in View->Show ATT.

You can assign an arbitrary (unicode) comment to the glyph. Simply type any text into this field. The comment is for your use, it will not go into any generated fonts. You may also assign a color to a glyph to make it stand out in the font view.

There are 6 separate sub-dialogs to help you edit the lookups of the GPOS and GSUB tables (some of these data can be converted into various of Apple's AAT tables, particularly 'morx'). Lookups and their subtables are described in some detail here, and may be manipulated and created with the Element->Font Info commmand.

The first of sub-dialogs is the alternate position pane which allows you to associate certain modifications to a glyph's metrics with a feature in the GPOS table.

In the example at right the first lookup subtable (which is associated with the Scientific Inferiors feature) will move the y position of the glyph down by 900 em-units, while the second subtable will move it down by 560 em-units. Positioning subtables can also move glyphs horizontally and can adjust the horizontal and vertical advances of the glyph. If you have configured FontForge to support them you can also add device tables for pixel level corrections to these adjustments. Most subtables will use only a few of the possibilities open to them and FontForge generally hides unused columns -- but if you want to see them just turn off [*] Hide Unused Columns.

A new entry in the list may be created by pressing the <New> button and a popup menu will appear with all possible lookup subtables you could add data to.

The pairwise positioning sub-dialog allows you to change the positions of two glyphs when they occur next to one another -- better know as kerning. I think the Metrics View provides a better place to do kerning, but you can do it here if you wish.

A simple substitution replaces one glyph with another. Here the glyph "one" has a series of substitutions to various glyphs depending on what lookup subtable is invoked.

The multiple and alternate substitution sub-dialogs are very similar to this one except that they can take multiple glyph names. In a multiple substitution subtable each glyph is replaced by several other glyphs (sort of the reverse of a ligature), while in the alternate substitution sub-dialog each glyph is to be replaced by exactly one glyph from a list and the user is to be given a choice as to which glyph is to be chosen.

"Hello Rabbit," he said, "is that you?"

"Let's pretend it isn't," said Rabbit, "and see what happens."

Winnie-The-Pooh
A. A. Milne, 1926


The ligature pane allows you to tell FontForge that the current glyph is a ligature composed of several other glyphs. FontForge will sometimes be able to fill this in with the right default value, but not always. The value should be a list of postscript glyph names separated by spaces. If a glyph may be viewed as two different ligatures then they may both be specified in different lines. For example "ffi" may be viewed as a ligature of "f" "f" and "i" or of "ff" and "i".


In complicated Asian glyphs, postscript has a mechanism for controlling the width of counters between stems. These are called counter mask hints. In Latin, Cyrillic, Greek fonts only glyphs like "m" are allowed to have counter masks, and only in very controlled conditions. See the description of counter masks.

Some glyphs (ligatures, accented glyphs, Hangul syllables, etc.) are built up out of other glyphs (at least according to unicode). This pane of the dlg shows the components that Unicode says make up the current glyph, if those components are in the font then you can use FontForge's Element->Build->Build Accented or Element->Build->Build Composite commands to create the current glyph. The information displayed here is informative only, you may not change this field directly (it changes when you change the unicode value or glyph name associated with this glyph).

The TeX pane allows you to specify glyph specific information used in TeX tmf files. The height and depth fields are often the same as the glyph's bounding box (if you don't fill these in that's what fontforge will use by default), but they should be corrected for optical distortion, so in glyphs like "o" these fields should be clipped to the x-height and baseline (ff isn't smart enough to do this for you).

The Subscript and Superscript Positions are only used in TeX Math (and Math-extension) fonts.

The Next and Prev buttons allow you to move from one glyph to the next (if, for example, you need to enter encodings for a range of glyphs).

The Done (or Cancel) button only Cancels work in the current glyph. If you have already used Next or Prev then those earlier changes will not be cancelled.

See Also:

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