chris@harlqn.co.uk (chris richardson) (07/14/89)
SCRIPTWORKS
The Product
ScriptWorks is Harlequin's software package for previewing and
printing PostScript(R) descriptions of text and graphics images.
The product runs on a wide range of standard hardware platforms and
delivers monochrome, greyscale and colour PostScript images in
X-Windows(TM) and a variety of other windowing environments.
ScriptWorks is a very fast and flexible system. The package combines
full support for the PostScript standard with proprietary techniques
for overcoming the limitations of traditional implementations. The
result is a system which performs complex clipping, large image
handling, colour rendering and high quality font handling at
remarkable speed.
The Approach
Harlequin has incorporated sophisticated memory management techniques
into ScriptWorks to provide extra flexibility. Traditional
limitations on the sizes of available stacks, the amount of PostScript
virtual memory and the number of permissible graphic points do not
apply. Instead, the ScriptWorks internal memory manager extends such
facilities to cope with application requirements. This is effective
both with and without virtual memory support from the host operating
system.
ScriptWorks has been designed to take full advantage of available
co-processors, such as floating point and graphics units. The package
is written in conservative C (and PostScript), thus enhancing
portability and maintainability. Through ScriptWorks, Harlequin has
shown that portability does not necessarily entail a loss of either
performance or quality.
PostScript
PostScript is a simple interpreted programming language with powerful
graphics capabilities. Its primary application is to describe the
appearance of text, graphical shapes and sampled images on printed
pages in a way which is independent of the resolution of output
devices.
ScriptWorks is completely compatible with the PostScript language from
Adobe Systems Incorporated. There are two key references for this
language: the PostScript Language Reference Manual by Adobe and the
Apple LaserWriter(R). ScriptWorks essentially provides a superset of
these, removing the restrictions which each may impose and, in case of
irreconcilable conflict, ensuring that the LaserWriter industry
standard is supported.
This support for industry standards and usage has been a major
concern. Several widely used software packages in desk top
publishing, CAD and related fields do not quite produce pure
PostScript. ScriptWorks has been adapted to accommodate their
requirements.
Fonts
Harlequin has evaluated 'hinted' fonts from a range of vendors,
selecting a very high quality hinting system which has been integrated
into ScriptWorks. This technology adjusts the shape of characters to
make allowances for rounding errors that occur as re-sizing takes
place onto a raster of discrete pixels. The outcome is recognisable
and aesthetically pleasing text at different sizes, resolutions and
orientations. The effect is particularly apparent at small point sizes
or low resolutions.
Font Storage
In its standard configuration, ScriptWorks takes its fonts from disk,
allowing new fonts to be added easily to the system. It is also
possible to save fonts described in PostScript terms with the standard
fonts. ScriptWorks employs a multi-level font-caching system to
enhance performance. These caches may themselves be saved on disk for
further performance gains. Thus characters of commonly used sizes
from any desired font may be permanently cached. (A similar effect is
obtained by using ROM cache in printers.)
Previewing and Windowing
ScriptWorks supports both the previewing and printing of PostScript
pages on multiple output devices. Previewing is best carried out in a
windowing environment, although this is not essential. X-Windows is
the standard environment but support is also available for native
window systems such as SunTools and the Apollo Display Manager. In
some environments, ScriptWorks can access the display's frame store
directly, thereby greatly enhancing performance.
Printing
Taking full advantage of double buffering techniques, ScriptWorks
supports Canon SX/CX laser printers. These operate at 300 dots per
inch through a VME card supplied by De Facto Industries for Sun
workstations. Standard configurations of ScriptWorks may be used to
compute images at user-specified resolutions of up to 600 dots per
inch. Even higher resolutions can be handled using ScriptWorks Plus,
a separately available product, or through Harlequin's specialist
services.
Colour
>From the outset, full support for colour has been designed into
ScriptWorks. For example, Harlequin's advanced error diffusion
dithering technique is employed to provide 24-bit natural colour
simulation for appropriate output devices. Care has been taken to
ensure that the product conforms to the standard PostScript
specification for colour as it has emerged.
Portability
ScriptWorks has been successfully ported to many different machines
using a variety of ANSI standard and more traditional C compilers.
Specific systems running ScriptWorks include the Sun family - Sun3,
Sun4 and Sun386i, the Apollo Domain family including the DN10000,
transputer systems, the Sony NEWS workstation, CLIPPER(R)-based Orion
machines and InterPro(R) workstations from High Level Hardware and
Intergraph Corporation respectively, and MIPS-based machines from MIPS
themselves.
Dependence on host operating systems has been kept to a minimum.
Operating systems which have been employed include both Berkeley and
System V UNIX(R) and those proprietary to specific machine vendors.
MultiScript(TM)
Harlequin also provides a related product called MultiScript, which is
compatible with but extends the functionality offered by
TranScript(R). MultiScript translates and filters a variety of
printer and graphics formats into PostScript, ready for processing by
ScriptWorks or any PostScript interpreter. Both MultiScript and
ScriptWorks are available as networked or standalone systems.
Enhancements
Harlequin is committed to an extensive programme of development for
ScriptWorks which will maintain the product's position on the leading
edge of PostScript technology. The package is being ported to an even
wider variety of platforms, displays, devices and systems. In
particular, it is being incorporated into a PostScript imaging model
with active windowing. Integration with LispWorks(TM), Harlequin's
Common Lisp programming system and environment, is also taking place.
Further Information
For more information about ScriptWorks, any of the related products,
pricing or availability please contact:
ScriptWorks Support
Harlequin Limited
Barrington Hall
Barrington
Cambridge CB2 5RG
England
Tel. : +44-223-872522
Fax. : +44-223-872519
Telex : 818440 harlqn g
Email : scriptworks-request@uk.co.harlqn
or mcvax!ukc!harlqn!scriptworks-request
Harlequin's products including ScriptWorks will be demonstrated at
IJCAI 89 in Detroit.
_______________________________________________________
ScriptWorks, LispWorks and MultiScript are trademarks of Harlequin Limited.
The X Window System is a trademark of the Massachusetts Institute of
Technology.
PostScript and TranScript are registered trademarks of Adobe Systems
Incorporated.
LaserWriter is a registered trademark of Apple Computer Inc.
UNIX is a registered trademark of AT&T Bell Laboratories.
Other brand or product names are trademarks of their respective holders.
Harlequin reserves the right to alter the specification of ScriptWorks
without notice.