True type font tables

True Type Font Tables
Omer Salih Dawood Omer,
College of computer Science and Information Technology,
Sudan University of Science and Technology,
Email:Omercomail@gmail.com
June 22, 2011

Abstract P latf orm F ontT ype RequiredF iles
TrueType 1
TTF play major roles in operating system because Windows TrueType Collection 1
it represents fonts that contained in the system and PostScript Type 1 2
you can add your own font, TTF consist from set OpenType 1
of tables each table responsible from specific func- Windows style TT 1
tion which collectively provide the main functional- Mac OS X OpenType 1
ity of the TTF. This paper aimed to provide general PostScript Type 1 2
overview of TTF and how to read the TTF content Linux TrueType 1
to be readied by human. Linux PostScript Type 1 2

Table 1: TTF in different OS
1 Introduction.
1.1 True Type Font. ent smart rendering system producing the Apple Ad-
vanced Typography (AAT) font specification. SILs
The primary font technology used on Microsoft Win- Graphite smart rendering system works by adding
dows and the Mac OS is based on the TrueType spec- tables, too. This section is only concerned with the
ification. TrueType fonts are scalable which means tables which were part of the original TrueType spec-
the glyphs can be displayed at any resolution and ification and which are still used in OpenType, AAT,
any point size (though the glyphs may not look good and Graphite to describe glyphs and provide general
in extreme cases). A TrueType font is a binary font data [1].
file containing a number of tables. There is a di-
rectory of tables at the start of the file. The file 1.1.1 True Type Font tables in different Op-
may contain only one table of each type, and the erating System.
type is indicated by a case-sensitive four letter tag.
Each table and the whole font have checksums. The The table 1 shows information about the various font
TrueType specification was developed by Apple and types on each platform [2].
adopted by Microsoft. Later Microsoft and Adobe
expanded the specification to support smart render- 1.2 Open Type Fonts.
ing and PostScript glyphs. The new specification,
which added more tables, was called OpenType. Ap- An OpenType font file contains data, in table format,
ple also added tables to TrueType to support a differ- that comprises either a TrueType or a PostScript out-

1

DataT ype Description 3. Unicode support
BYTE 8-bit unsigned integer
CHAR 8-bit signed integer 4. Glyph alternates supported
USHORT 16-bit unsigned integer 5. Advanced typography supported
SHORT 16-bit signed integer
UINT24 24-bit unsigned integer 6. Better protection of font data
ULONG 32-bit unsigned integer
7. Font embedding controls
LONG 32-bit signed integer
LONG 32-bit signed integer

Table 2: OTF Data Type
2 Background.
2.1 development of True Type Font
line font. Rasterizers use combinations of data from • Back in the late 1980s, it was clear to most of the
the tables contained in the font to render the True- major players in the personal computer world
Type or PostScript glyph outlines. Some of this sup- that scalable font technology was going to be
porting data is used no matter which outline format an important part of future operating systems.
is used; some of the supporting data is specific to ei- Adobe was trying to get Apple and Microsoft to
ther TrueType or PostScript.[3] OpenType fonts may license its PostScript code for this purpose. Ap-
have the extension .OTF or .TTF, depending on the ple and Microsoft agreed a cross-licensing and
kind of outlines in the font and the creator’s desire for product development deal, the fruits of which
compatibility on systems without native OpenType would be available to both parties: Microsoft
support. would bring a PostScript-style graphics engine to
• In all cases, fonts with only CFF data (no True- the table (TrueImage), while Apple would create
Type outlines) always have an .OTF extension. a font system even better than Adobe’s

• Fonts containing TrueType outlines may have ei- • In mid-1989, when they learned that Apple
ther .OTF or .TTF, depending on the desire for would not be requiring its technology, they an-
backward compatibility on older systems or with nounced a program, Adobe Type Manager, be-
previous versions of the font. TrueType Collec- fore it had even been written,About a year later,
tion fonts should have a .TTC extension whether you could buy ATM to display Adobe Type 1
or not the fonts have OpenType layout tables fonts on the Macintosh, without any help from
present.[3] Apple. ATM was sold cheaply, or was bundled
with fonts bought from Adobe.
1.2.1 OTF Data Type • Apple had been developing what was to become
TrueType from late 1987 At that time there were
table 2 show and describe open type font (OTF) data
many competing font scaling technologies, and
types [3]
several would have been suitable for the Macin-
tosh. Kaasila completed his work on TrueType,
1.2.2 Benefits of Open Type Font [4] though it didn’t yet have that name, in August
There are many benefits from Open Type Font,as 1989.
Follows : • Apple released TrueType to the world in March
1. Support for large character sets 1991 - the core engine in much the same form
that Kaasila left it back in 1989. This first cus-
2. Multi-script character sets tomer version was an 80K add-on to System 6.0,

2

available until recently on the Apple website! number of TrueType tables[6]. The TTC Header
The system needed fonts of course, and the first must be located at the beginning of the TTC file.
TrueType fonts - Times Roman, Helvetica and The TTC file must contain a complete Table Direc-
Courier - were great examples of what could be tory for each different font design. A TTC file Table
done with the technology. Directory has exactly the same format as a TTF file
Table Directory. The table offsets in all Table Di-
• Microsoft introduced TrueType into Windows rectories within a TTC file are measured from the
with version 3.1 in early 1992. Working with beginning of the TTC file. Each TrueType table in
Monotype, they had created the superb core set a TTC file is referenced through the Table Directo-
of fonts - TrueType versions of Times New Ro- ries of all fonts which use that table. Some of the
man, Arial and Courier. These fonts showed, TrueType tables must appear multiple times, once
just as Apple’s TrueTypes had, that scalable for each font included in the TTC; while other ta-
fonts could generate bitmaps virtually as though bles should be shared by all fonts in the TTC. As
each size had been designed by hand. an example, consider a TTC file which combines two
• Only in August 1995, with the release of Win- Japanese fonts (Font1 and Font2). The fonts have
dows 95, did Microsoft’s TrueType engine be- different kana designs (Kana1 and Kana2) but use
come 32-bit, complete and reliable. Indeed, the same design for kanji. The TTC file contains a
it now features greyscale rasterization (anti- single glyf table which includes both designs of kana
aliasing), enhancing on-screen text substan- together with the kanji; both fonts Table Directories
tially. Microsoft have commissioned some superb point to this glyf table. But each fonts Table Direc-
new[5]. TrueType fonts that they give out free tory points to a different cmap table, which identifies
on their website. The rehabilitation of TrueType the glyph set to use. Font1s cmap table points to
is well underway [5]. the Kana1 region of the loca and glyf tables for kana
glyphs, and to the kanji region for the kanji. Font2s
cmap table points to the Kana2 region of the loca and
2.2 TrueType Collection (TTC) glyf tables for kana glyphs, and to the same kanji re-
A TrueType Collection (TTC) is a means of deliv- gion for the kanji.
ering multiple TrueType fonts in a single file struc- The tables that should have a unique copy per font
ture. TrueType Collections are most useful when the are those that are used by the system in identifying
fonts to be delivered together share many glyphs in the font and its character mapping, including cmap,
common. By allowing multiple fonts to share glyph name, and OS/2. The tables that should be shared
sets, TTCs can result in a significant saving of file by all fonts in the TTC are those that define glyph
space. For example, a group of Japanese fonts may and instruction data or use glyph indices to access
each have their own designs for the kana glyphs, but data: glyf, loca, hmtx, hdmx, LTSH, cvt , fpgm, prep,
share identical designs for the kanji. With ordinary EBLC, EBDT, EBSC, maxp, and so on. In practice,
TrueType font files, the only way to include the com- any tables which have identical data for two or more
mon kanji glyphs is to copy their glyph data into each fonts may be shared. Creating a TrueType Collec-
font. Since the kanji represent much more data than tion by combining existing TrueType font files is a
the kana, this results in a great deal of wasteful du- non-trivial process. It involves paying close atten-
plication of glyph data. TTCs were defined to solve tion the issue of glyph renumbering in a font and
this problem . the side effects that can result, in the cmap table
and elsewhere. The fonts to be merged must also
have compatible TrueType instructionsthat is, their
2.2.1 TTC File Structure
preprograms, function definitions, and control values
A TrueType Collection file consists of a single TTC must not conflict[6].
Header table, two or more Table Directories, and a TrueType Collection files use the filename suffix

3

N ame req Description T ype N ame Description
name [req] Font Information USHORT numberOfGlyphs Number of glyphs
glyf [req] Contains glyph outlines CHAR offset[numGlyphs] Difference between
cmap [req] Contains multiple graphic index and
mapping tables standard order of glyph
post [req] contain glyph names
OS/2 [req on spacing, font Table 4: glyph in the font file
Windows] weight and font style
head [req] font metrics
and OpenType fonts with TrueType data. OpenType
and checksum
fonts with TrueType data may also use Version 3.0.
CFF embedded PostScript OpenType fonts with CFF data use Version 3.0 only.
glyphs
kern kerning pair data • Version 1.0
This TrueType-based font file contains exactly
Table 3: TTF Tables the 258 glyphs in the standard Macintosh True-
Type font file
.TTC
• Version 2.0
This is the version required by TrueType-based
2.2.2 TTC Header Table fonts to be used on Windows. This TrueType-
The purpose of the TTC Header table is to locate the based font file contains glyphs not in the stan-
different Table Directories within a TTC file. The dard Macintosh set or the ordering of the glyphs
TTC Header is located at the beginning of the TTC in the TrueType font file is non-standard (again,
file (offset = 0). It consists of an identification tag, a for the Macintosh). The glyph name array maps
version number, a count of the number of TrueType the glyphs in this font to name index. If the
fonts (Table Directories) in the file, and an array of name index is between 0 and 257, treat the name
offsets to each Table Directory. index as a glyph index in the Macintosh stan-
dard order. If the name index is between 258
and 32767, then subtract 258 and use that to in-
3 True Type Font tables. dex into the list of Pascal strings at the end of
the table. Thus a given font may map some of its
Below is a list of the tables used in TrueType glyphs to the standard glyph names, and some
files. Also included are tables added by OpenType, to its own names. Index numbers 32768 through
Graphite, and Apple. The table name is case sensi- 65535 are reserved for future use. If you do not
tive and always consists of four eight-bit characters, want to associate a PostScript name with a par-
which are spaces if the name below is less than four ticular glyph, use index number 0 which points
characters. The [req] label is placed on tables that are the name .notdef.
required in fonts that contain TrueType outlines[7].
• Version 2.5 This version of the ’post’ table has
been deprecated as of OpenType Specification
3.1 PostScript
v1.3. This version provides a space saving ta-
This table contains additional information needed to ble for TrueType-based fonts which contain a
use TrueType or OpenType fonts on PostScript print- pure subset of, or a simple reordering of, the
ers. This includes data for the FontInfo dictionary standard Macintosh glyph set. This version is
entry and the PostScript names of all the glyphs. useful for TrueType-based font files that con-
Versions 1.0, 2.0, and 2.5 refer to TrueType fonts tain only glyphs in the standard Macintosh glyph

4

set but which have those glyphs arranged in a
non-standard order or which are missing some
glyphs. The table contains one byte for each
glyph in the font file. The byte is treated as a
signed offset that maps the glyph index used in
this font into the standard glyph index. In other
words, assuming that the font contains the three
glyphs A, B, and C which are the 37th, 38th, and
39th glyphs in the standard ordering, the ’post’
table would contain the bytes +36, +36, +36.
This format has been deprecated by Apple, as of
February 2000.

• Version 3.0
This version is used by OpenType fonts with
TrueType or CFF data. The version makes
it possible to create a special font that is not
burdened with a large ’post’ table set of glyph
.
names. This version specifies that no PostScript
name information is provided for the glyphs in Figure 1: application Components
this font file. The printing behavior of this ver-
sion on PostScript printers is unspecified, except
that it should not result in a fatal or unrecov-
erable error. Some drivers may print nothing, 4.2 TTF Reader/Analyser
other drivers may attempt to print using a de-
fault naming scheme[8]. The TTF reader reads the TTF File contents and
shows them to the user and it works as follows:
4 Implementation
1. Open the specified TTF table.
As shown in Figure 1 the Implementation consist
from three parts :

1. TTF File 2. Calculate the numbers of table the contained
into TTF File .
2. TTF File Reader/Analyzer.

3. TTF contents.
3. Read TTF tables name according to their num-
The entire application developed using web program- ber
ming language known as PHP which used in this ap-
plication to read and present the TTF content to be
readied by human.
4.3 Show TTF contents
4.1 TTF File
here we specify the TTF file that we want to read its here we display the TTF tables name that generated
contents from the TTF Reader/Analyser

5

5 Result: [8] 7- http://www.microsoft.com/typography/
otspec/post.htm

figure[1]:application Results

6 Conclusions:
TTF File is essential in the system and provide im-
portant functionality to the system ,and you can add
your own TTF file to the system, this paper explain
TTF font and other fonts like open Type Font and
post Script ,and give approach to read the tables of
the TTF File

References
[1] http://scripts.sil.org/cms/scripts/page.php?
item id=IWS-Chapter08#3054f18b

[2] http://www.asy.com/fonts.htm

[3] http://www.microsoft.com/typography/
otspec/otff.htm

[4] www.myanmarnlp.net.mm/doc/.../OpenType

[5] http://www.truetype-
typography.com/tthist.htm

[6] http://www.microsoft.com/typography/tt/ttf
spec/ttch03.doc

[7] http://scripts.sil.org/cms/scripts/page.php?item
id=IWS-AppendixC

6

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