<s>
QuickDraw	B-Operating_System
GX	I-Operating_System
was	O
a	O
replacement	O
for	O
the	O
QuickDraw	B-Operating_System
(	O
QD	O
)	O
2D	O
graphics	O
engine	O
and	O
Printing	O
Manager	O
inside	O
the	O
classic	B-Application
Mac	I-Application
OS	I-Application
.	O
</s>
<s>
Its	O
underlying	O
drawing	O
platform	O
was	O
a	O
object	B-Language
oriented	I-Language
resolution-independent	O
retained	O
mode	O
system	O
,	O
making	O
it	O
much	O
easier	O
for	O
programmers	O
to	O
perform	O
common	O
tasks	O
(	O
compared	O
to	O
the	O
original	O
QuickDraw	B-Operating_System
)	O
.	O
</s>
<s>
This	O
,	O
coupled	O
with	O
opposition	O
from	O
an	O
important	O
fraction	O
of	O
the	O
developer	O
market	O
,	O
especially	O
PostScript	B-Language
owner	O
Adobe	O
,	O
and	O
a	O
lack	O
of	O
communication	O
from	O
Apple	O
about	O
the	O
benefits	O
of	O
GX	O
and	O
why	O
users	O
should	O
adopt	O
it	O
,	O
led	O
to	O
the	O
technology	O
being	O
sidelined	O
.	O
</s>
<s>
QuickDraw	B-Operating_System
GX	I-Operating_System
saw	O
little	O
development	O
after	O
its	O
initial	O
release	O
,	O
and	O
was	O
formally	O
"	O
killed	O
"	O
with	O
the	O
purchase	O
of	O
NeXT	O
and	O
the	O
eventual	O
adoption	O
of	O
the	O
Quartz	B-Operating_System
imaging	O
model	O
in	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
.	O
</s>
<s>
Many	O
of	O
its	O
component	O
features	O
lived	O
on	O
and	O
are	O
now	O
standard	O
in	O
the	O
current	O
Macintosh	B-Device
platform	O
;	O
TrueType	O
GX	O
in	O
particular	O
has	O
,	O
with	O
a	O
few	O
tweaks	O
,	O
become	O
a	O
broadly	O
used	O
modern	O
standard	O
in	O
the	O
form	O
of	O
OpenType	O
Variable	O
Fonts	O
.	O
</s>
<s>
As	O
the	O
80s	O
wore	O
on	O
,	O
QuickDraw	B-Operating_System
's	O
architectural	O
limitations	O
began	O
to	O
impose	O
limits	O
on	O
Apple	O
and	O
third-party	O
developers	O
.	O
</s>
<s>
All	O
of	O
QuickDraw	B-Operating_System
's	O
public	O
data	O
structures	O
assume	O
a	O
16-bit	O
integer	O
coordinate	O
space	O
,	O
with	O
no	O
provision	O
for	O
fractional	O
coordinates	O
.	O
</s>
<s>
Adding	O
new	O
features	O
to	O
QuickDraw	B-Operating_System
was	O
extremely	O
difficult	O
due	O
to	O
lack	O
of	O
data	O
hiding	O
in	O
the	O
API	B-General_Concept
.	O
</s>
<s>
The	O
central	O
data	O
structure	O
in	O
QuickDraw	B-Operating_System
was	O
the	O
GrafPort	B-Operating_System
,	O
a	O
structure	O
with	O
all	O
of	O
the	O
member	O
variables	O
exposed	O
.	O
</s>
<s>
Worse	O
,	O
the	O
GrafPort	B-Operating_System
structure	O
was	O
designed	O
to	O
be	O
directly	O
embedded	O
in	O
third-party	O
developer	O
data	O
structures	O
,	O
so	O
Apple	O
could	O
not	O
add	O
new	O
variables	O
.	O
</s>
<s>
Color	B-Operating_System
QuickDraw	I-Operating_System
,	O
introduced	O
in	O
1987	O
,	O
was	O
a	O
tremendous	O
kludge	O
on	O
top	O
of	O
the	O
original	O
black	O
and	O
white	O
QuickDraw	B-Operating_System
.	O
</s>
<s>
For	O
example	O
,	O
QuickDraw	B-Operating_System
could	O
not	O
easily	O
support	O
advanced	O
graphics	O
transformations	O
such	O
as	O
rotations	O
and	O
shears	O
,	O
and	O
introducing	O
new	O
data	O
types	O
such	O
as	O
curves	O
was	O
impossible	O
.	O
</s>
<s>
GX	O
appears	O
to	O
have	O
started	O
in	O
a	O
roundabout	O
fashion	O
,	O
originally	O
as	O
an	O
outline	O
font	O
system	O
that	O
would	O
be	O
added	O
to	O
the	O
Mac	B-Application
OS	I-Application
.	O
</s>
<s>
The	O
system	O
also	O
included	O
a	O
system	O
for	O
"	O
wrapping	O
"	O
existing	O
PostScript	B-Language
Type	O
1	O
fonts	O
into	O
its	O
own	O
internal	O
format	O
,	O
which	O
added	O
bitmap	O
preview	O
versions	O
for	O
quick	O
on-screen	O
rendering	O
.	O
</s>
<s>
This	O
project	O
later	O
took	O
on	O
an	O
expanded	O
role	O
when	O
Apple	O
and	O
Microsoft	O
agreed	O
to	O
work	O
together	O
to	O
form	O
an	O
alternative	O
to	O
PostScript	B-Language
fonts	O
,	O
which	O
were	O
extremely	O
expensive	O
,	O
creating	O
the	O
TrueType	O
effort	O
based	O
on	O
Apple	O
's	O
existing	O
efforts	O
.	O
</s>
<s>
Another	O
project	O
,	O
apparently	O
unrelated	O
at	O
first	O
,	O
attempted	O
to	O
address	O
problems	O
with	O
the	O
conversion	O
from	O
QuickDraw	B-Operating_System
into	O
various	O
printer	O
output	O
formats	O
.	O
</s>
<s>
Whereas	O
developers	O
had	O
earlier	O
been	O
forced	O
to	O
write	O
their	O
own	O
code	O
to	O
convert	O
their	O
QuickDraw	B-Operating_System
on-screen	O
display	O
to	O
PostScript	B-Language
for	O
printing	O
,	O
under	O
the	O
new	O
printer	O
architecture	O
such	O
conversions	O
would	O
be	O
provided	O
by	O
the	O
OS	O
.	O
</s>
<s>
Additionally	O
the	O
new	O
system	O
was	O
deliberately	O
engineered	O
to	O
be	O
as	O
flexible	O
as	O
possible	O
,	O
supporting	O
not	O
only	O
QD	O
and	O
PS	B-Language
printers	O
,	O
but	O
potentially	O
other	O
standards	O
such	O
as	O
Hewlett	O
Packard	O
's	O
PCL	B-Language
as	O
well	O
.	O
</s>
<s>
QuickDraw	B-Operating_System
GX	I-Operating_System
was	O
one	O
such	O
victim	O
,	O
and	O
delays	O
and	O
changes	O
of	O
direction	O
in	O
TrueType	O
and	O
other	O
problems	O
greatly	O
delayed	O
the	O
introduction	O
of	O
GX	O
.	O
</s>
<s>
Version	O
1.1.1	O
was	O
bundled	O
with	O
System	B-Operating_System
7.5	I-Operating_System
later	O
that	O
year	O
.	O
</s>
<s>
The	O
package	O
was	O
large	O
enough	O
to	O
strain	O
the	O
memory	O
of	O
most	O
existing	O
Macintosh	B-Device
computers	O
of	O
the	O
era	O
,	O
and	O
arguments	O
like	O
"	O
you	O
can	O
now	O
print	O
to	O
PostScript	B-Language
"	O
were	O
less	O
than	O
impressive	O
considering	O
many	O
existing	O
programs	O
had	O
already	O
added	O
such	O
support	O
.	O
</s>
<s>
Speed	O
was	O
also	O
an	O
issue	O
,	O
limiting	O
it	O
to	O
running	O
only	O
on	O
Macs	O
with	O
a	O
Motorola	B-Device
68020	I-Device
or	O
better	O
.	O
</s>
<s>
Given	O
that	O
the	O
installed	O
Mac	O
base	O
at	O
the	O
time	O
still	O
contained	O
large	O
numbers	O
of	O
68000	O
based	O
machines	O
like	O
the	O
Mac	B-Device
Plus	I-Device
,	O
these	O
requirements	O
restricted	O
the	O
number	O
of	O
machines	O
it	O
could	O
run	O
on	O
.	O
</s>
<s>
When	O
it	O
was	O
first	O
released	O
,	O
one	O
review	O
noted	O
,	O
"	O
QuickDraw	B-Operating_System
GX	I-Operating_System
is	O
n't	O
for	O
everyone	O
and	O
requires	O
more	O
RAM	O
than	O
many	O
Macs	O
have	O
to	O
spare.	O
"	O
</s>
<s>
Additionally	O
,	O
the	O
API	B-General_Concept
for	O
the	O
system	O
was	O
very	O
large	O
,	O
filling	O
several	O
books	O
.	O
</s>
<s>
The	O
number	O
of	O
GX-based	O
(	O
as	O
opposed	O
to	O
GX-compatible	O
)	O
programs	O
numbered	O
less	O
than	O
six	O
,	O
including	O
Pixar	O
's	O
Typestry	O
and	O
Softpress	O
's	O
UniQorn	B-Operating_System
.	O
</s>
<s>
While	O
PostScript	B-Language
printing	O
had	O
never	O
been	O
easy	O
,	O
over	O
the	O
years	O
since	O
the	O
release	O
of	O
the	O
original	O
LaserWriter	O
,	O
developers	O
had	O
built	O
up	O
a	O
library	O
of	O
solutions	O
to	O
common	O
problems	O
.	O
</s>
<s>
It	O
might	O
have	O
seen	O
widespread	O
use	O
as	O
a	O
part	O
of	O
the	O
Copland	B-Application
project	O
,	O
but	O
Copland	B-Application
never	O
launched	O
.	O
</s>
<s>
Mac	B-Operating_System
OS	I-Operating_System
8	I-Operating_System
dropped	O
support	O
for	O
the	O
GX	O
printing	O
architecture	O
,	O
though	O
the	O
text	O
management	O
and	O
color	O
management	O
architectures	O
survived	O
.	O
</s>
<s>
With	O
the	O
advent	O
of	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
,	O
portions	O
of	O
GX	O
live	O
on	O
in	O
Apple	B-Operating_System
Type	I-Operating_System
Services	I-Operating_System
for	I-Operating_System
Unicode	I-Operating_System
Imaging	I-Operating_System
(	O
ATSUI	B-Operating_System
)	O
,	O
and	O
in	O
ColorSync	O
,	O
whose	O
file	O
format	O
is	O
identical	O
to	O
the	O
original	O
format	O
developed	O
for	O
GX	O
.	O
</s>
<s>
QuickDraw	B-Operating_System
GX	I-Operating_System
is	O
based	O
on	O
an	O
object	B-Language
oriented	I-Language
model	O
in	O
which	O
graphics	O
objects	O
are	O
aware	O
of	O
and	O
responsible	O
for	O
their	O
own	O
state	O
.	O
</s>
<s>
Unlike	O
QuickDraw	B-Operating_System
,	O
there	O
is	O
no	O
universal	O
"	O
state	O
"	O
,	O
every	O
drawing	O
command	O
can	O
re-construct	O
the	O
state	O
from	O
data	O
stored	O
within	O
it	O
,	O
or	O
various	O
"	O
parent	O
"	O
objects	O
.	O
</s>
<s>
Since	O
this	O
state	O
was	O
private	O
,	O
and	O
sent	O
to	O
GX	O
if	O
and	O
when	O
needed	O
,	O
GX	O
theoretically	O
allowed	O
the	O
Mac	B-Application
OS	I-Application
to	O
support	O
protected	O
memory	O
,	O
as	O
state	O
was	O
no	O
longer	O
shared	O
directly	O
between	O
the	O
programs	O
and	O
graphics	O
system	O
.	O
</s>
<s>
This	O
contrasts	O
strongly	O
with	O
the	O
original	O
QuickDraw	B-Operating_System
,	O
where	O
the	O
programmer	O
was	O
responsible	O
for	O
all	O
state	O
changes	O
.	O
</s>
<s>
This	O
was	O
a	O
3-by-3	O
matrix	B-Architecture
which	O
could	O
express	O
arbitrary	O
linear	B-Architecture
transformations	I-Architecture
in	O
two	O
dimensions	O
,	O
including	O
perspective	B-Architecture
distortions	O
.	O
</s>
<s>
Although	O
all	O
of	O
this	O
state	O
was	O
held	O
in	O
the	O
gxMapping	O
for	O
that	O
object	O
,	O
GX	O
also	O
provided	O
"	O
wrapper	O
"	O
commands	O
like	O
"	O
rotate	O
"	O
to	O
make	O
the	O
API	B-General_Concept
simpler	O
to	O
use	O
.	O
</s>
<s>
Unlike	O
QuickDraw	B-Operating_System
,	O
QuickDraw	B-Operating_System
GX	I-Operating_System
allowed	O
for	O
fractional	O
coordinates	O
.	O
</s>
<s>
However	O
,	O
these	O
were	O
fixed-point	O
values	O
,	O
rather	O
than	O
floating-point	B-Algorithm
.	O
</s>
<s>
At	O
the	O
time	O
GX	O
was	O
being	O
developed	O
(	O
late	O
1980s	O
to	O
early	O
1990s	O
)	O
,	O
there	O
was	O
still	O
a	O
significant	O
performance	O
penalty	O
in	O
using	O
floating-point	B-Algorithm
arithmetic	I-Algorithm
.	O
</s>
<s>
The	O
GX	O
graphics	O
architecture	O
was	O
built	O
around	O
a	O
number	O
of	O
types	O
of	O
objects	O
which	O
were	O
premade	O
,	O
though	O
a	O
full	O
set	O
of	O
API	B-General_Concept
calls	O
was	O
available	O
for	O
examining	O
and	O
manipulating	O
them	O
:	O
</s>
<s>
API	B-General_Concept
calls	O
allowed	O
the	O
interrogation	O
of	O
the	O
properties	O
of	O
a	O
font	O
,	O
including	O
the	O
determination	O
of	O
what	O
encodings	O
(	O
Unicode	O
,	O
language-specific	O
etc	O
.	O
)	O
</s>
<s>
GX	O
supported	O
all	O
the	O
QuickDraw	B-Operating_System
pixel	O
layouts	O
;	O
this	O
allowed	O
both	O
a	O
GX	O
view	O
device	O
and	O
a	O
QuickDraw	B-Operating_System
GrafPort	B-Operating_System
to	O
point	O
to	O
the	O
same	O
pixels	O
,	O
thereby	O
allowing	O
applications	O
to	O
mix	O
both	O
sets	O
of	O
drawing	O
calls	O
.	O
</s>
<s>
Each	O
tag	O
had	O
an	O
OSType	B-Application
type	O
code	O
,	O
but	O
there	O
could	O
be	O
multiple	O
tags	O
of	O
the	O
same	O
type	O
attached	O
to	O
the	O
same	O
object	O
.	O
</s>
<s>
Glyph	B-Application
shapes	O
were	O
a	O
way	O
to	O
use	O
character	O
shapes	O
(	O
"	O
glyphs	B-Application
"	O
)	O
as	O
pure	O
geometry	O
,	O
for	O
instance	O
as	O
Clipping	O
paths	O
.	O
</s>
<s>
The	O
GX	O
API	B-General_Concept
also	O
provided	O
hit-testing	O
functions	O
,	O
so	O
that	O
for	O
example	O
if	O
the	O
user	O
clicked	O
on	O
a	O
layout	O
shape	O
in	O
the	O
middle	O
of	O
a	O
ligature	O
,	O
or	O
in	O
the	O
region	O
between	O
a	O
change	O
of	O
text	O
direction	O
,	O
GX	O
itself	O
would	O
provide	O
the	O
smarts	O
to	O
determine	O
which	O
character	O
position	O
in	O
the	O
original	O
text	O
corresponded	O
to	O
the	O
click	O
.	O
</s>
<s>
An	O
important	O
distinction	O
in	O
GX	O
was	O
drawn	O
between	O
a	O
character	O
and	O
a	O
glyph	B-Application
,	O
a	O
distinction	O
also	O
found	O
in	O
the	O
Unicode	O
Standard	O
.	O
</s>
<s>
Whereas	O
a	O
glyph	B-Application
was	O
a	O
specific	O
graphic	O
shape	O
from	O
a	O
particular	O
font	O
,	O
whether	O
the	O
shape	O
represented	O
a	O
single	O
character	O
or	O
a	O
set	O
of	O
characters	O
.	O
</s>
<s>
Thus	O
,	O
for	O
example	O
,	O
the	O
Hoefler	O
Text	O
font	O
had	O
glyphs	B-Application
to	O
represent	O
the	O
letters	O
"	O
f	O
"	O
and	O
"	O
l	O
"	O
.	O
</s>
<s>
It	O
also	O
had	O
another	O
glyph	B-Application
to	O
represent	O
the	O
ligature	O
,	O
which	O
could	O
be	O
automatically	O
composed	O
(	O
instead	O
of	O
the	O
individual	O
glyphs	B-Application
)	O
wherever	O
the	O
two	O
abstract	O
characters	O
"	O
f	O
"	O
and	O
"	O
l	O
"	O
occurred	O
in	O
sequence	O
in	O
the	O
source	O
text	O
.	O
</s>
<s>
PostScript	B-Language
Type	O
1	O
font	O
files	O
have	O
one	O
to	O
one	O
mapping	O
only	O
,	O
and	O
as	O
ligatures	O
are	O
many	O
to	O
one	O
mappings	O
,	O
they	O
can	O
not	O
be	O
inserted	O
into	O
the	O
composition	O
without	O
changing	O
the	O
source	O
character	O
string	O
,	O
for	O
instance	O
,	O
the	O
ligature	O
ffi	O
is	O
placed	O
at	O
the	O
position	O
of	O
capital	O
Y	O
in	O
Adobe	O
font	O
products	O
,	O
and	O
"	O
Adobe	O
Offices	O
"	O
is	O
composed	O
by	O
typing	O
"	O
Adobe	O
O	O
"	O
<change font> "Y" <change font>	O
"	O
ces	O
"	O
.	O
</s>
<s>
In	O
the	O
layout	O
the	O
character	O
string	O
is	O
broken	O
,	O
and	O
in	O
PDF	O
made	O
from	O
streamed	O
PostScript	B-Language
the	O
characters	O
f+f+i	O
can	O
only	O
be	O
reconstructed	O
,	O
if	O
the	O
name	O
of	O
the	O
glyph	B-Application
follows	O
a	O
glyph	B-Application
naming	O
list	O
.	O
</s>
<s>
Contextual	O
substitutions	O
can	O
be	O
controlled	O
by	O
enabling	O
or	O
disabling	O
the	O
composition	O
options	O
of	O
a	O
TrueType	O
GX	O
font	O
in	O
WorldText	O
on	O
the	O
Mac	B-Application
OS	I-Application
9	O
CD	O
or	O
in	O
TextEdit	O
in	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
.	O
Fonts	O
commonly	O
have	O
features	O
called	O
"	O
common	O
ligatures	O
"	O
(	O
such	O
as	O
the	O
"	O
fl	O
"	O
example	O
)	O
,	O
"	O
rare	O
ligatures	O
"	O
(	O
such	O
as	O
inscriptional	O
ME	O
and	O
MD	O
ligatures	O
)	O
,	O
"	O
archaic	O
non-terminal	O
s	O
"	O
(	O
for	O
automatically	O
substituting	O
the	O
letter	O
"	O
s	O
"	O
with	O
the	O
archaic	O
form	O
that	O
looked	O
more	O
like	O
an	O
"	O
f	O
"	O
,	O
except	O
at	O
the	O
ends	O
of	O
words	O
)	O
,	O
and	O
even	O
choices	O
between	O
entirely	O
separate	O
sets	O
of	O
glyph	B-Application
designs	O
,	O
such	O
as	O
more	O
and	O
less	O
ornate	O
forms	O
.	O
</s>
<s>
The	O
rules	O
for	O
performing	O
contextual	O
substitutions	O
are	O
implemented	O
as	O
state	B-Architecture
machines	I-Architecture
built	O
into	O
the	O
font	O
,	O
and	O
interpreted	O
by	O
the	O
LLM	O
Line	O
Layout	O
Manager	O
,	O
the	O
counterpart	O
of	O
the	O
CMM	O
Color	O
Management	O
Module	O
for	O
ColorSync	O
services	O
.	O
</s>
<s>
Text	O
management	O
in	O
the	O
operating	O
system	O
allowed	O
QuickDraw	B-Operating_System
GX	I-Operating_System
to	O
accept	O
character	O
strings	O
with	O
any	O
mix	O
of	O
writing	O
systems	O
and	O
scripts	O
,	O
and	O
compose	O
the	O
strings	O
automatically	O
,	O
whether	O
the	O
encoding	O
was	O
Unicode	O
1.0	O
or	O
8bit	O
and	O
8/16bit	O
encodings	O
.	O
</s>
<s>
Cary	O
Clark	O
was	O
the	O
architect	O
and	O
technical	O
lead	O
for	O
QuickDraw	B-Operating_System
GX	I-Operating_System
.	O
</s>
<s>
He	O
had	O
worked	O
on	O
Color	B-Operating_System
QuickDraw	I-Operating_System
,	O
and	O
went	O
on	O
to	O
become	O
an	O
early	O
member	O
of	O
Rocket	O
Science	O
Games	O
and	O
WebTV	O
.	O
</s>
<s>
Keith	O
McGreggor	O
was	O
the	O
manager	O
of	O
the	O
graphics	O
group	O
and	O
the	O
primary	O
developer	O
of	O
the	O
color	O
architecture	O
for	O
QuickDraw	B-Operating_System
GX	I-Operating_System
,	O
and	O
Robert	O
Johnson	O
was	O
the	O
resident	O
mathematician	O
.	O
</s>
