Graphics Programs Reference
In-Depth Information
Type 1 fonts
Introduced with font type
/Type1
in the font dictionary. Type 1 is an Adobe font
format originally for use with PostScript. The standard 14 fonts are defined as Type
1 fonts. Multiple Master Type 1 fonts (
/MMType1
) are an extension of Type 1 al-
lowing the automatic generation of many font styles from a one set of outlines.
TrueType fonts
Introduced with font type
/TrueType
in the font dictionary. Based on Apple's True-
Type font format (also frequently used in Microsoft Windows).
Type 3 fonts
Introduced with font type
/Type3
. These are fonts composed of streams of PDF
graphics operators. This means they can include colors and shadings, so are more
flexible, but have no hinting mechanisms for clear display at small sizes. Often used
to emulate other font formats (for example, bitmap fonts).
CID fonts
These are
composite fonts
, intended to support multibyte character sets (where a
font has a huge number of glyphs, such as Chinese). They are not discussed in this
text.
Type 1 Fonts
We will use Type 1 fonts as an example.
Table 6-4
summarizes the entries in a Type 1
font dictionary.
Table 6-4. Type 1 font dictionary (*denotes required entry, **denotes required except for the standard
14 fonts)
Key
Value type
Value
/Type
*
name
Must be
/Font
.
/Subtype
*
name
Must be
/Type1
.
/BaseFont
*
name
The PostScript name for the font.
/FirstChar
**
integer
The first code in the
/Widths
array.
/LastChar
**
integer
The last code in the
/Widths
array.
/Widths
**
array of integers
Array of length (
/LastChar
-
/FirstChar
+ 1), giving the glyph
width for those characters in thousandths of text space units.
/FontDescriptor
**
indirect reference to
dictionary
A
font descriptor dictionary
giving the font's metrics (other than the glyph
widths).
name or dictionary
The font's character encoding, for example
/MacRomanEncoding
or
/WinAnsiEncoding
. More complicated ones are described by
dictionaries.
/Encoding
/ToUnicode
stream
A stream containing instructions for the extraction of text content. See
“Extracting Text from a Document” on page 86
.
