SECTION 5.4
411
Introduction to Font Data Structures
ports two classes of font-related objects, called
CIDFonts
and
CMaps,
described in
cause, like fonts, they are collections of glyphs; however, a CIDFont is never used
directly but only as a component of a Type 0 font.
TABLE 5.7 Font types
TYPE
SUBTYPE VALUE
DESCRIPTION
Type 0
Type 1
Type0
(PDF 1.2)
A
composite
font—a font composed of glyphs from a descendant
CIDFont (see Section 5.6, “Composite Fonts”)
A font that defines glyph shapes using Type 1 font technology (see Section
A
multiple master
font—an extension of the Type 1 font that allows the gen-
eration of a wide variety of typeface styles from a single font (see “Multiple
A font that defines glyphs with streams of PDF graphics operators (see Sec-
A font based on the TrueType font format (see Section 5.5.2, “TrueType
(PDF 1.2)
A CIDFont whose glyph descriptions are based on Type 1 font
technology (see Section 5.6.3, “CIDFonts”)
(PDF 1.2)
A CIDFont whose glyph descriptions are based on TrueType font
technology (see Section 5.6.3, “CIDFonts”)
Type1
MMType1
Type 3
TrueType
CIDFont
Type3
TrueType
CIDFontType0
CIDFontType2
For all font types, the term
font dictionary
refers to a PDF dictionary containing
information about the font; likewise, a
CIDFont dictionary
contains information
about a CIDFont. Except for Type 3, this dictionary is distinct from the
font pro-
gram
that defines the font’s glyphs. That font program may be embedded in the
PDF file as a stream object or be obtained from some external source.
Note:
This terminology differs from that used in the PostScript language. In Post-
Script, a font dictionary is a PostScript data structure that is created as a direct re-
sult of interpreting a font program. In PDF, a font program is always treated as if it
were a separate file, even if its contents are embedded in the PDF file. The font pro-
gram is interpreted by a specialized font interpreter when necessary; its contents
never materialize as PDF objects.