Skip to main content
_
_mostafa_mohamed_
Participant
April 2, 2009
Question

Cmaps and characters code

  • April 2, 2009
  • 1 reply
  • 2483 views
i try to extract glyphIndex from cmap tables ,I'd like to ask about if a character code maybe appear in many cmap tables for Ex: a character code can appear in both cmap0 and cmap4 tables? and if this case happened then should the glyphIndex of the character be extracted from the higher cmap
This topic has been closed for replies.

1 reply

T
Thomas Phinney
Inspiring
April 3, 2009
Yes, a character code may appear in multiple cmap subtables.

See the OpenType spec: http://www.microsoft.com/Typography/otspec/cmap.htm

Which cmap subtable you would use to access the character would depend on your particular needs. What kind of codepoint are you trying to look up the glyph with? You say "cmap0" and "cmap4" but you don't specify whether the 0 and 4 refer to platform, encoding, or format.

I'm going to guess that you are referring to format 0 and format 4. First, I would say that one would normally pick a cmap based first on platform/encoding, and only secondarily on format.

Cmap format 0 is an old Apple format, limited to 256 encoded glyphs, seen in conjunction with platform=specific encoding(s), notably MacRoman.

Format 4 is one of several ways of representing Unicode codepoints, with the limitation that it can only deal with codepoints in the Basic Multilingual Plane or BMP.

Cheers,

T
Terms & ConditionsAccessibility statement
Using the community Terms of use Privacy Cookie preferences Do not sell or share my personal information ad choicesAdChoices