ttx: Convert fonts to XML and back
TTX – From OpenType and TrueType to XML and Back
Once installed you can use the ttx command to convert binary font files (.otf, .ttf, etc) to the TTX XML format, edit them, and convert them back to binary format. TTX files have a .ttx file extension:
ttx /path/to/font.otf
ttx /path/to/font.ttx
The TTX application can be used in two ways, depending on what platform you run it on:
As a command line tool (Windows/DOS, Unix, macOS)
By dropping files onto the application (Windows, macOS)
TTX detects what kind of files it is fed: it will output a .ttx
file when it sees a .ttf
or .otf
, and it will compile a .ttf
or .otf
when the input file is a .ttx
file. By default, the output file is created in the same folder as the input file, and will have the same name as the input file but with a different extension. TTX will never overwrite existing files, but if necessary will append a unique number to the output filename (before the extension) such as Arial#1.ttf
.
When using TTX from the command line there are a bunch of extra options. These are explained in the help text, as displayed when typing ttx -h
at the command prompt. These additional options include:
specifying the folder where the output files are created
specifying which tables to dump or which tables to exclude
merging partial .ttx files with existing .ttf or .otf files
listing brief table info instead of dumping to .ttx
splitting tables to separate .ttx files
disabling TrueType instruction disassembly
The TTX file format
The following tables are currently supported:
BASE, CBDT, CBLC, CFF, CFF2, COLR, CPAL, DSIG, Debg, EBDT, EBLC,
FFTM, Feat, GDEF, GMAP, GPKG, GPOS, GSUB, Glat, Gloc, HVAR, JSTF,
LTSH, MATH, META, MVAR, OS/2, SING, STAT, SVG, Silf, Sill, TSI0,
TSI1, TSI2, TSI3, TSI5, TSIB, TSIC, TSID, TSIJ, TSIP, TSIS, TSIV,
TTFA, VARC, VDMX, VORG, VVAR, ankr, avar, bsln, cidg, cmap, cvar,
cvt, feat, fpgm, fvar, gasp, gcid, glyf, gvar, hdmx, head, hhea,
hmtx, kern, lcar, loca, ltag, maxp, meta, mort, morx, name, opbd,
post, prep, prop, sbix, trak, vhea and vmtx
Other tables are dumped as hexadecimal data.
TrueType fonts use glyph indices (GlyphIDs) to refer to glyphs in most places. While this is fine in binary form, it is really hard to work with for humans. Therefore we use names instead.
The glyph names are either extracted from the CFF
table or the post
table, or are derived from a Unicode cmap
table. In the latter case the Adobe Glyph List is used to calculate names based on Unicode values. If all of these methods fail, names are invented based on GlyphID (eg glyph00142
)
It is possible that different glyphs use the same name. If this happens, we force the names to be unique by appending #n to the name (n being an integer number.) The original names are being kept, so this has no influence on a “round tripped” font.
Because the order in which glyphs are stored inside the binary font is important, we maintain an ordered list of glyph names in the font.