freetype2/docs/formats.txt

This  file contains  a list  of various  font formats.   It gives  the
reference document and whether it is supported in FreeType 2.

Table fields
------------

  wrapper format
    The format used to represent the font data.  In the table below it
    is  used only  if the  font format  differs.  Possible  values are

      SFNT  binary
      PFB   binary
      PS    a text header, followed by  binary or text data
      LZW   compressed with  either `gzip' or `compress'
      BZ2   compressed with `bzip2'.

  font format
    How the font is to be accessed, possibly after converting the file
    type and wrapper  format into a generic form.   Bitmap formats are
    `BDF',  `PCF', and  one form  of `WINFNT';  all others  are vector
    formats.   `PS' indicates  third-order,  `TT' second-order  Bézier
    curves.

  font type
    Sub-formats of the  font format.  `SBIT' and  `MACSBIT' are bitmap
    formats,  `MM' and  `VAR' support  optical axes.   `CFF2' supports
    optical axes also.

  glyph access
    If  not specified,  the glyph  access  is `standard'  to the  font
    format.   Values are  `CID' for  CID-keyed fonts,  `SYNTHETIC' for
    fonts that  are modified  versions of  other fonts  by means  of a
    transformation matrix, and  `TYPE_0' for PS fonts which  are to be
    accessed in a tree-like structure.

  FreeType driver
    The module in the FreeType library which handles the specific font
    format.  A missing  entry means that FreeType  doesn't support the
    font format (yet).


Notes
-----

  The  SFNT  container  format also  provides  `collections'  (usually
  having the file extension `.ttc'  or `.otc').  A collection contains
  multiple font faces that share some tables to avoid redundancy, thus
  reducing the file  size.  In FreeType, elements of  a collection can
  be accessed with a proper face index.

  Both  the GX  and the  OpenType 1.8  variation fonts  provide `named
  instances'.  FreeType  maps them to  face indices (they can  also be
  accessed with the standard MM interface).

  Other  font  formats  (not  using the  SFNT  wrapper)  also  provide
  multiple faces  within one  file; they are  marked with  an asterisk
  (`*') in the table below.

  FreeType can  be configured to  support Mac  files (on older  Mac OS
  versions, a `file' is stored as a data and a resource fork, that is,
  within two  separate data chunks).  If  a file can't be  opened as a
  font, FreeType then checks whether it  is a resource fork, trying to
  extract  the contained  font data  from  either a  `POST' or  `sfnt'
  resource.


Please  send additions  and/or  corrections to  wl@gnu.org  or to  the
FreeType   developer's   list    at   freetype-devel@nongnu.org   (for
subscribers only).   If you can  provide a  font example for  a format
which isn't supported yet please send a mail too.


  wrapper font    font    glyph      FreeType reference
  format  format  type    access     driver   documents
 -----------------------------------------------------------------------------

  ---     BDF     ---     ---        bdf      5005.BDF_Spec.pdf, X11


  SFNT    PS      TYPE_1  ---        type1    Type 1 GX Font Format [7]
                                              (for the Mac; not supported)
  SFNT    PS      TYPE_1  CID        cid      5180.sfnt.pdf (for the Mac) [3]
  SFNT    PS      CFF     ---        cff      OT spec, 5176.CFF.pdf
                                              (`OTTO' format)
  SFNT    PS      CFF     CID        cff      OT spec, 5176.CFF.pdf
  SFNT    PS      CFF     SYNTHETIC  ---      OT spec, 5176.CFF.pdf
  SFNT    PS      CFF2    ---        cff      OT spec 1.8

  SFNT    TT      SBIT    ---        sfnt     XFree86 (bitmaps only;
                                              with `head' table)
  SFNT    TT      MACSBIT ---        sfnt     OT spec (for the Mac;
                                              bitmaps only; `bhed' table)
  SFNT    TT      ---     ---        truetype OT spec (`normal' TT font)
  SFNT    TT      VAR     ---        truetype GX spec (`?var' tables)
  SFNT    TT      VAR     ---        truetype OT spec 1.8
                                              (`?var' + `?VAR' tables)


  WOFF    ---     ---     ---        cff,     Compressed SFNT, ver. 1.0 [6]
                                     truetype
  WOFF2   ---     ---     ---        cff,     Compressed SFNT, ver. 2.0 [6]
                                     truetype


  ---     PS      TYPE_1  ---        type1    T1_SPEC.pdf
                                              (PFA, Type 1 font resource)
  PFB     PS      TYPE_1  ---        type1    T1_SPEC.pdf,
                                              5040.Download_Fonts.pdf
                                              (`normal' Type 1 font)
  ---     PS      TYPE_1  CID        cid      PLRM.pdf (CID Font Type 0;
                                              Type 9 font)
  ---     PS      MM      ---        type1    5015.Type1_Supp.pdf
                                              (Multiple Masters)
  ---     PS      CFF     ---        cff      5176.CFF.pdf (`pure' CFF)
  ---     PS*     CFF     CID        cff      5176.CFF.pdf (`pure' CFF)
  ---     PS      CFF     SYNTHETIC  ---      5176.CFF.pdf (`pure' CFF)
  ---     PS      CFF/MM  ---        cff      old 5167.CFF.pdf (`pure' CFF)
                                              [3]
  ---     PS*     CFF/MM  CID        cff      old 5167.CFF.pdf (`pure' CFF)
                                              [3]
  ---     PS      CFF/MM  SYNTHETIC  ---      old 5167.CFF.pdf (`pure' CFF)
                                              [3]
  PS      PS      CFF     ---        ---      PLRM.pdf (Type 2) [1]
  PS      PS*     CFF     CID        ---      PLRM.pdf (Type 2) [1]
  PS      PS      CFF     SYNTHETIC  ---      PLRM.pdf (Type 2) [1]
  PS      PS      CFF/MM  ---        ---      PLRM.pdf (Type 2) [1]
  PS      PS*     CFF/MM  CID        ---      PLRM.pdf (Type 2) [1]
  PS      PS      CFF/MM  SYNTHETIC  ---      PLRM.pdf (Type 2) [1]
  ---     PS      ---     TYPE_0     ---      PLRM.pdf
  ---     PS      TYPE_3  ---        ---      PLRM.pdf (never supported)
  ---     PS      TYPE_3  CID        ---      PLRM.pdf (CID Font Type 1;
                                              Type 10 font; never supported)
  PS      PS      TYPE_14 ---        ---      PLRM.pdf (Chameleon font;
                                              Type 14 font; never supported?)
  ---     PS      TYPE_32 CID        ---      PLRM.pdf (CID Font Type 4;
                                              Type 32 font; never supported?)
  PS      TT      ---     ---        type42   5012.Type42_Spec.pdf
                                              (Type 42 font)
  PS      TT      ---     CID        ---      PLRM.pdf (CID Font Type 2;
                                              Type 11 font)


  ?       ?       CEF     ?          cff      ?


  ---     PCF     ---     ---        pcf      X11 [4]
  LZW     PCF     ---     ---        pcf      X11 [4]
  BZ2     PCF     ---     ---        pcf      X11 [4]


  ---     PFR*    PFR0    ---        pfr      [2]
  ---     PFR     PFR1    ---        ---      (undocumented, proprietary;
                                              probably never supported)


  ---     WINFNT* ---     ---        winfonts Windows developer's notes [5]
  ---     WINFNT  VECTOR  ---        ---      Windows developer's notes [5]


[1] Support should  be rather simple since this is  identical to `CFF'
    but in a PS wrapper.

[2] The  official  PFR  specification  is  no  longer  available,  but
    archive.org has archived it:

      https://web.archive.org/web/20091014062300/http://www.bitstream.com/font_rendering/products/truedoc/pfrspec.html
      https://web.archive.org/web/20081115152605/http://www.bitstream.com/font_rendering/pdfs/pfrspec1.3.pdf

    The syntax  of the  auxiliary data  is not  defined there,  but is
    partially defined in MHP 1.0.3 (also called ETSI TS 101812 V1.3.1)
    section 7.4.

      https://www.etsi.org/
      https://webapp.etsi.org/workprogram/Report_WorkItem.asp?WKI_ID=18799

[3] Support  is rudimentary  currently; some  tables or  data are  not
    loaded yet.

[4] See

      THE X WINDOW SYSTEM SERVER: X VERSION 11, RELEASE 5
      Elias Israel, Erik Fortune, Digital Press, 1992
      ISBN 1-55558-096-3

    for a specification given in Appendix D on pgs. 436-450.  However,
    this information might be out  of date; unfortunately, there is no
    PCF specification available online, and this book is out of print.
    George Williams deduced  the font format from the  X11 sources and
    documented it for his FontForge font editor:

      https://fontforge.github.io/pcf-format.html

[5] This is from MS Windows 3;  see Microsoft's Knowledge Base article
    at

      https://support.microsoft.com/kb/65123

[6] Supported  font  formats  are   TrueType  and  OpenType  fonts  as
    defined in the OpenType specification 1.6 and newer.

[7] `The Type 1 GX Font Format' (dated 1995-09-27)  was distributed in
    Apple Developer CD-ROM in those days.  The content of `TYP1' table
    is a PostScript Type 1 font without the eexec encryption.  Current
    versions of FreeType don't not support this format,  but FontForge
    can load it.

------------------------------------------------------------------------

Copyright (C) 2004-2024 by
David Turner, Robert Wilhelm, and Werner Lemberg.

This  file is  part  of the  FreeType  project, and  may  only be  used,
modified,  and  distributed under  the  terms  of  the FreeType  project
license, LICENSE.TXT.  By continuing  to use, modify, or distribute this
file  you indicate that  you have  read the  license and  understand and
accept it fully.


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