|
NeXT Computer Inc. designed Display PostScript (or DPS) as a display system for their series of Unix-based personal computers starting around 1987. While early versions of Postscript display systems were developed at Adobe, the full implementation of Display PostScript was developed in cooperation with Adobe Systems, and made an official Adobe product with its own standards documents and licensing requirements. The NeXT logo, designed by Paul Rand. ...
Unix or UNIX is a computer operating system originally developed in the 1960s and 1970s by a group of AT&T Bell Labs employees including Ken Thompson, Dennis Ritchie, and Douglas McIlroy. ...
1987 is a common year starting on Thursday of the Gregorian calendar. ...
Adobe Systems (NASDAQ: ADBE) is a computer software company headquartered in San Jose, California that was founded in December 1982 by John Warnock and Charles Geschke. ...
As the name implies, DPS uses the PostScript (PS) imaging model and language to generate on-screen graphics. In order to support interactive, on-screen use with reasonable performance, a few changes were needed: A postscript (from post scriptum, a Latin expression meaning after writing and abbreviated P.S.) is a sentence, paragraph, or occasionally many paragraphs added, often hastily and incidentally, after the signature of a letter or (sometimes) the main body of an essay or book. ...
- multiple execution contexts: unlike a printer setting where the PS interpreter had only one job at a time, DPS would be used in a number of windows at the same time, each with their own settings (colors, brush settings, scale, etc.). This required a modification to the system to allow it to keep several "contexts" (sets of state data) active, one for each process (window).
- encoded names: many of the procedures and data structures in PostScript are looked up by name. In DPS these names could be replaced by small numbers, which are much faster for a computer to find.
- interaction support: a number of procedures were defined to handle interaction, including hit detection.
- halftone phase: in order to improve scrolling performance, DPS only drew the small portion of the window that became visible, shifting the rest of the image instead of re-drawing it. However this meant that the halftones would not line up, producing visible lines and boxes in the display of graphics. DPS included additional code to properly handle these cases. Modern full-color displays with no halftones have made this idea mostly obsolete.
- incremental updates: in printing applications the PS code is interpreted until it gets a
showpage at which point it is actually printed out. This is not suitable for a display situation where a large number of minor updates are needed all the time. DPS included modes to allow semi-realtime display as the instructions were received from the user programs. - bitmap font support: DPS added the ability to map PS fonts onto hand-drawn bitmap fonts and change from one to the other on the fly. While PS's ability to display fonts on "low resolution" devices was good, "low resolution" meant something on the order of 300dpi, not the 96dpi that a NeXT screen used. This required hand-built fonts for reasonable output.
- programming language support: DPS introduced the concept of a "
pswrap", which allowed developers to wrap PostScript code into a C language function which could then be called from an application. DPS did not, however, add a windowing system. That was left to the implementation to provide, and DPS was meant to be used in conjunction with an existing windowing engine. This was often the X Window System, and in this form Display PostScript was later adopted by companies such as IBM and SGI for their workstations. Often the code needed to get from an X window to a DPS context was much more complicated than the entire rest of the DPS interface. This greatly limited the popularity of DPS when any alternative was available. Highly decorative Window in a Japanese Onsen in Hakone A window is an opening in an otherwise solid, opaque surface through which light can pass. ...
Halftoning is a method of printing shades using a single color ink. ...
An assortment of bitmap fonts from the first version of the Macintosh operating system A bitmap font is one that stores each glyph as an array of pixels (that is, a bitmap). ...
Dots per inch (DPI) is a measure of printing resolution, in particular the number of individual dots of ink a printer or toner can produce within a linear one-inch space. ...
A developer can be one of: A software developer, one who programs computers or designs the system to match the requirements of a systems analyst. ...
The C Programming Language, Brian Kernighan and Dennis Ritchie, the original edition that served for many years as an informal specification of the language The C programming language is a standardized imperative computer programming language developed in the early 1970s by Ken Thompson and Dennis Ritchie for use on the...
In computing, the X Window System (commonly X11 or X) is a windowing system for bitmap displays. ...
International Business Machines Corporation (IBM, or colloquially, Big Blue) (NYSE: IBM) (incorporated June 15, 1911, in operation since 1888) is headquartered in Armonk, New York, USA. The company manufactures and sells computer hardware, software, and services. ...
This article needs to be cleaned up to conform to a higher standard of quality. ...
The developers of NeXT wrote a completely new windowing engine to take full advantage of NeXT's object oriented operating system. A number of commands were added to DPS to actually create the windows and to react to events, similar to but simpler than NeWS. The single API made programming at higher levels much easier and made NeXT one of the few systems to extensively use DPS. The user-space windowing system library NeXTStep used PostScript to draw items like titlebars and scrollers. This, in turn, made extensive use of pswraps, which were in turn wrapped in objects and presented to the programmer in object form. The NeXT logo, designed by Paul Rand. ...
Object-oriented programming (OOP) is a computer programming paradigm in which a software system is modeled as a set of objects that interact with each other. ...
In computing, an operating system (OS) is the system software responsible for the direct control and management of hardware and basic system operations. ...
News is essentially new information or current events. ...
NeXTSTEP Desktop NeXTSTEP is the original object-oriented, multitasking operating system that NeXT Computer, Inc. ...
Apple's Mac OS X operating system now makes use of a similar imaging model to Display PostScript, but does not have the same level of programmability. The new system, known as Quartz, is based on the PDF model in which the source of the image is not the PostScript code itself, but the result of interpreting that code. It keeps the basic graphics primitives, font handling and measurements, and in many cases looks and feels like DPS. The PDF format also features several enhancements over PostScript, including superior color management, compression, and font management. It is not entirely clear why this switch happened, but speculation suggests that Adobe was asking for a high licensing fee. Adobe's copyright stipulations regarding their PDF standard are much less restrictive, granting conditional copyright permission to anyone to use the format in software applications, free of charge. Apple Computer, Inc. ...
Mac OS X is the latest version of the Mac OS, the operating system software for Macintosh computers. ...
Quartz is the graphics layer that sits on top of the Darwin core of Mac OS X, sometimes also referred to as CoreGraphics. ...
Portable Document Format (PDF) is a file format developed by Adobe Systems for representing documents in a manner that is independent of the original application software, hardware, and operating system used to create those documents. ...
In computer science, data compression or source coding is the process of encoding information using fewer bits (or other information-bearing units) than a more obvious representation would use, through use of specific encoding schemes. ...
See also News is essentially new information or current events. ...
Portable Document Format (PDF) is a file format developed by Adobe Systems for representing documents in a manner that is independent of the original application software, hardware, and operating system used to create those documents. ...
Two quickdraws. ...
External link
References |
Feeds |
Contact