TrueType is an outline font standard originally developed by
Computer in the late 1980s as a competitor to Adobe's Type 1 fonts used in PostScript. The primary
strength of TrueType is that it offers font developers a high
degree of control over precisely how their fonts are displayed,
right down to particular pixels, at various font heights.
TrueType history: Apple
On the Macintosh, fonts were drawn from hand-tuned font files
that specified individual pixel locations for a font at a
particular size. If the user wanted to see a font at another size,
the Font Manager found the closest match and applied a basic
scaling algorithm. When scaled to large sizes the effect was
comical– since these fonts were bitmapped, they would scale
the way a JPEG image does, becoming blocky.
In contrast, printer fonts for the popular Apple
LaserWriter were based on PostScript Type 1 (and 3) outlines, resulting in
excellent output at any size. Although Adobe provided the
Type Manager software to use the same fonts on-screen, the
software was fairly expensive. Nevertheless it became a de facto
standard for anyone involved in desktop publishing, to the point
where Apple wanted to have a similar system built-in. Making
matters difficult was the fact that Type 1 fonts were encrypted,
and Adobe made considerable amount of their income from licensing
the format to interested parties. They were not about to simply
allow Apple to include the software for free.
Instead Sampo Kaasila at Apple decided to write an entirely new
format, which he worked on under the name Bass (as in
Bass-o-matic from the Saturday Night Live sketch) and
later Royal. The system developed and was eventually
released as TrueType with the launch of Mac
OS System 7 in May 1991.
The fonts, four-weight families of Times Roman, Helvetica, Courier,
and a handful of others, replaced the older bitmap fonts that
previous Macintosh System versions had used.
One huge drawback of the TrueType system is that it could not
use Type 1 fonts on-screen -- not surprising given its genesis.
However this meant that the system was in fact not used by the very
people it was intended to help, the DTP users. They had already
invested considerable money in commercial Type 1 fonts, which they
were not interested in replacing, and therefore had to continue
using Type Manager. Adding to the problem was that there were very
few fonts available in TrueType format, so even if one wanted to
start fresh there was no real way to do so.
As part of Apple's new tactic of distancing itself from Adobe,
Apple licensed TrueType to Microsoft, in exchange for a license for TrueImage, a Microsoft-developed PostScript-compatible
printer driver that Apple planned to use in their laser printers.
This driver was never actually included in any Apple products.
When TrueType was released, John Warnock of Adobe gave an impassioned speech
in which he claimed Apple and Microsoft were selling snake oil, and then
instantly released the Type 1 format as a published standard for
anyone to use. This put even more pressure on TrueType. Apple
eventually renewed agreements with Adobe for the use of PostScript
in its printers; it is speculated that Apple's tactics resulted in
lower royalty payments to Adobe as part of its new licensing
Apple extended TrueType with the launch of TrueType GX in
1994, as part of QuickDraw GX. This
offered powerful extensions in two main areas. First was font
morphing, for example
allowing fonts to be smoothly adjusted from light to bold or from
narrow to extended — competition for Adobe's "multiple
master" technology. Second was substitution, where particular
sequences of characters can be coded to flip to different designs
in certain circumstances, useful for example to offer ligatures for
'fi', 'ffi', 'ct', etc. while maintaining the backing store of
characters necessary for spell-checkers and text searching. However, the
lack of user-friendly tools for making TrueType GX fonts meant
there were no more than a handful of GX fonts. Much of the
technology in TrueType GX, including morphing and substitution,
lives on as AAT (Apple Advanced Typography) in OS X. Few font
developers outside Apple attempt to make AAT fonts.
TrueType history: Microsoft
By around 1991 Microsoft
had built TrueType into the Windows operating system. In
partnership with their contractors Monotype, Microsoft spent much effort creating a set
of high quality TrueType fonts that were compatible with the main
fonts being bundled with PostScript equipment at the time. This
included the fonts that are standard with Windows to this day:
Roman (compatible with Times Roman), Arial (compatible with Helvetica) and Courier New (compatible with
Courier). By "compatible" one should
understand this to mean two things: first, that the fonts are
similar to look at (Arial is by no means identical to Helvetica);
and second, very importantly, the fonts have the same character
widths so can be used to typeset the same documents without
reflowing the text. (The disjunction of the names, particularly
between Arial and Helvetica, led some to believe there was a
general problem of having to determine an "equivalent" Apple or
PostScript font whenever a particular Windows font was called for,
or vice versa. In fact, a given font is almost always available on
both major platforms.) Microsoft and Monotype technicians used
TrueType's hinting technology to make these fonts possibly the best
made up to that time in terms of legibility at small sizes on
Microsoft introduced a major rewrite in Windows 95, and then
added anti-aliasing technology to smooth the edges of
fonts in all applications. More recently ClearType, included with Windows XP, significantly
improves readability on TFT based displays.
TrueType in Mac and Windows today
Today's Mac OS X
and Windows XP
still support TrueType fonts fully, but they also have native
support for Adobe's Type 1 format and the OpenType format of Microsoft and Adobe.
However most of the system fonts included in standard installations
of OS X and Windows are in the TrueType format: system fonts have
to be highly legible under a wide variety of conditions, making
TrueType the natural format choice.
TrueType on Linux and other platforms
The FreeType project of David Turner attempts to create
an independent implementation of the TrueType standard (as well as
other font standards). FreeType is included in Linux distributions.
There are potential patent infringements in FreeType 1 because
parts of the TrueType hinting virtual machine were patented by Apple, a fact not
mentioned in the TrueType standards. (Patent holders who contribute
to standards not published by a major standards body such as
ISO are not required to
disclose the scope of their patents.) More recent FreeType releases
include an automatic hinter that analyzes glyph shapes
and corrects them, thus avoiding the patented technology. (http://freetype.sourceforge.net/patents.html)
FreeType 2 is a font service and doesn't provide APIs to perform higher-level features,
like text layout or graphics processing (e.g., colored text
However, it greatly simplifies these tasks by providing a simple,
easy to use and uniform interface to access the content of font files.
FreeType 2 is released under two free-source licenses: BSD-like FreeType License and the GPL. It can thus be used by any kind of
projects, be they proprietary or not.
Technical note: outlines
The outlines of the characters (or glyphs) in TrueType fonts are made of straight line
segments and quadratic Bzier curves. These curves are slightly more
efficient to process than the cubic Bzier curves prevalent in the
PostScript-centered world of graphic design and used in Type 1 fonts. A
TrueType glyph outline specification typically takes up less space
than a Type 1 outline.
Technical note: hinting language
TrueType systems include a virtual machine that executes programs
inside the font, processing the "hints" of the glyphs. These distort the control
points which define the outline, with the intention that the
rasterizer produces fewer undesirable features on the glyph. Each
glyph's hinting program takes account of the size (in pixels) that
the glyph is being displayed at, as well as other less important
factors of the display environment.
Although incapable of receiving input and producing output as
normally understood in programming, the TrueType hinting language
does offer the other prerequisites of programming languages:
conditional branching (IF statements),
an arbitrary number of times (FOR- and WHILE-type statements),
variables (although these are simply numbered slots in an area of
memory reserved by the font), and encapsulation of code into
functions. Special instructions called "delta hints" are the lowest
level control, moving a control point at just one pixel size.
Good TrueType glyph programming techniques are to do as much as
possible using variables defined just once in the whole font (e.g.,
stem widths, cap height, x-height). This means avoiding delta instructions as
much as possible. This helps the font developer to make major
changes (e.g., the point at which the entire font's main stems jump
from 1 to 2 pixels wide) most of the way through development.
Making a very well-hinted TrueType font is still a significant
amount of work, despite the increased user-friendliness of programs
for adding hints to fonts compared with the early 1990s. Many TrueType fonts
therefore have only rudimentary hints, or have hinting
automatically applied by the font editor, with variable end
This information is based on the article TrueType from the free encyclopedia Wikipedia and is licensed under the GNU Free Documentation License. On Wikipedia is a list of authors available.