CJKV Information Processing, 2nd Edition

Outline Font Formats

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Other ways to aect the glyph metrics in OpenType fonts can be made via other tables, the

most notable of which is the ‘vmtx’ table. Almost all CJKV character set standards include

full-width Latin, Greek, and Cyrillic characters, and the fonts that are based on these same

character set standards include full-width glyphs that correspond to the characters. When

in horizontal writing mode, these full-width glyphs are expected to use a Latin baseline.

But, if the same glyphs, positioned along the Y-axis such that they rest on a Latin baseline,

are used in vertical writing mode, the results are less than pleasing. One solution is to

include separate glyphs for these characters, for horizontal and vertical writing. A better

solution is to make adjustments to the position of these glyphs along the Y-axis, speci-

cally to center them along the Y-axis. is means that the same glyphs can be used for

horizontal and vertical writing. When these glyphs are used in horizontal writing mode,

they rest on a Latin baseline, but when used in Vertical writing mode, they are centered

along the Y-axis. e settings of the ‘vmtx’ table are considered default behavior.

OpenType ‘cmap’ tables

Although not specic to OpenType fonts, due to its TrueType heritage, the ‘cmap’ table is

composed of subtables, each of which are tagged by format, platform ID, and language ID.

Two types ...