Editing Screensaver

{{short description|Computer program that blanks the screen or fills it with moving images}}
{{about|the computer software|other uses|Screen Savers (disambiguation)}}
{{redir|.scr|CAD scripts|CadSoft EAGLE}}[[File:Einstein@Home.gif|border|thumb|400x400px|[[Einstein@Home]] interactive screensaver]]

A '''screensaver''' (or '''screen saver''') is a [[computer program]] that blanks the display screen or fills it with moving images or patterns when the computer has been idle for a designated time. The original purpose of screensavers was to prevent [[phosphor]] [[screen burn-in|burn-in]] on [[Cathode-ray tube|CRT]] or [[plasma display|plasma]] [[computer monitor]]s (hence the name).<ref name="Technovelgy">{{Cite web |title=Screensaver (Inventor of) by Robert Heinlein from Stranger in a Strange Land |url=http://www.technovelgy.com/ct/content.asp?Bnum=184 |archive-url=https://web.archive.org/web/20150318155626/http://www.technovelgy.com/ct/content.asp?Bnum=184 |archive-date=March 18, 2015 |website=Technovelgy.com}}</ref> Though most modern monitors are not susceptible to this issue (with the notable exception of [[OLED]] technology, which has individual pixels vulnerable to burnout), screensaver programs are still used for other purposes. Screensavers are often set up to offer a basic layer of [[computer security|security]] by requiring a password to re-access the device. Some screensaver programs also use otherwise-idle computer resources to do useful work, such as processing for [[volunteer computing]] projects.<ref>{{Citation |title=Einstein@Home Screensaver {{!}} Multi-Directional 2.07 | date=21 September 2020 |url=https://www.youtube.com/watch?v=kGWsTnmk1lw |access-date=2022-09-18 |archive-url=https://web.archive.org/web/20220903134636/https://www.youtube.com/watch?v=kGWsTnmk1lw |archive-date=2022-09-03 |url-status=live |language=en |via=[[YouTube]]}}</ref>

As well as computers, modern television operating systems, media players, and other digital entertainment systems may include optional screensavers.

== Purpose ==
=== Screen protection ===
Before the advent of [[LCD]] screens, most computer screens were based on [[cathode-ray tube]]s (CRTs). When the same image is displayed on a CRT screen for long periods, the properties of the exposed areas of the phosphor coating on the inside of the screen gradually and permanently change, eventually leading to a darkened shadow or "ghost" image on the screen, called a [[screen burn-in]]. Cathode-ray tube [[television]]s, [[oscilloscope]]s and other devices that use CRTs are all susceptible to [[phosphor burn-in]], as are [[plasma display]]s to some extent.<ref>{{Cite web |last=Phillips |first=Gavin |date=January 24, 2020 |title=How to Fix Screen Burn-In on TVs: Plasma, LCD, and OLED |url=https://www.makeuseof.com/tag/why-do-images-get-burned-into-lcd-and-plasma-displays-and-how-you-can-fix-it/ |url-status=live |archive-url=https://web.archive.org/web/20240126211617/https://www.makeuseof.com/tag/why-do-images-get-burned-into-lcd-and-plasma-displays-and-how-you-can-fix-it/ |archive-date=2024-01-26 |access-date=2022-09-18 |website=MakeUseOf.com |language=en-US}}</ref>

Screen-saver programs were designed to help avoid these effects by automatically changing the images on the screen during periods of user inactivity.

For CRTs used in public, such as [[automated teller machine|ATMs]] and railway ticketing machines, the risk of burn-in is especially high because a stand-by display is shown whenever the machine is not in use. Older machines designed without burn-in problems taken into consideration often display evidence of screen damage, with images or text such as "Please insert your card" (in the case of ATMs) visible even when the display changes while the machine is in use. Blanking the screen is not a valid option as the machine can be perceived as out of service. In these applications, burn-in can be prevented by shifting the position of the display contents every few seconds, or by having a number of different images that are changed regularly.

Later CRTs were much less susceptible to [[phosphor burn-in|burn-in]] than older models due to improvements in phosphor coatings, and because modern computer images are generally lower contrast than the stark green- or white-on-black text and graphics of earlier machines. LCD computer monitors, including the display panels used in [[laptop]] computers, are not susceptible to burn-in because the image is not directly produced by phosphors (although they can suffer from a less extreme and usually non-permanent form of [[image persistence]]).

=== Modern usage ===
[[File:Gnome-screensaver.png|thumb|[[GNOME Screensaver]] has an option for password protection.]]
While modern screens are not susceptible to the issues discussed above, screensavers are still used. Primarily these are for decorative/entertainment purposes, or for password protection. They usually feature moving images or patterns and sometimes sound effects.

As screensavers are generally expected to activate when users are away from their machines, many screensavers can be configured to ask users for a [[password]] before permitting the user to resume work. This is a basic security measure against another person accessing the machine while the user is absent.

Some screensavers activate a useful background task, such as a [[anti-virus software|virus scan]] or a [[volunteer computing]] application (such as the [[SETI@home]] project).<ref>{{Cite AV media |url=https://www.youtube.com/watch?v=IfeGNAZY92k |title=SETI@home Screensaver {{!}} Enhanced 5.27 |language=en |access-date=2022-09-18 |archive-url=https://web.archive.org/web/20220929181755/https://www.youtube.com/watch?app=desktop&v=IfeGNAZY92k |archive-date=2022-09-29 |url-status=live |via=[[YouTube]]}}</ref> This allows applications to use resources only when the computer would be otherwise idle. The [[Ken Burns effect|Ken Burns panning and zooming effect]] is sometimes used to bring the image to life.

== History ==
Decades before the first computers using this technology were invented, [[Robert A. Heinlein]] gave an example of how they might be used<ref name="Technovelgy" /> in his novel ''[[Stranger in a Strange Land]]'' (1961):<ref>{{Cite book |last=Heinlein |first=Robert |url=https://books.google.com/books?id=jBtDSf1VzQkC |title=Stranger in a Strange Land |publisher=[[Penguin Group|Penguin]] |year=1987 |isbn=9780441790340 |location=[[New York, New York]] |pages=448 |via=[[Google Books]]}}</ref>
{{blockquote|Opposite his chair was a stereovision tank disguised as an aquarium; he switched it on, guppies and tetras gave way to the face of the well-known Winchell Augustus Greaves.}}

The first screensaver was allegedly written for the original [[IBM PC]] by [[John Socha]], best known for creating [[Norton Commander]]; he also coined the term ''screen saver''. The screensaver, named ''scrnsave'', was published in the December 1983 issue of the ''[[Softalk]]'' magazine. It simply blanked the screen after three minutes of inactivity (an interval which could be changed by recompiling the program).

By 1983 a [[Zenith Data Systems]] executive included "screen-saver" among the new Z-29 [[computer terminal]]'s features, telling ''[[InfoWorld]]'' that it "blanks out the display after 15 minutes of nonactivity, preventing burned-in character displays."<ref name="chin19830411">{{Cite magazine |last=Chin |first=Kathy |date=April 11, 1983 |title=Z-29, a New Computer Terminal from Zenith Data Systems |url=https://books.google.com/books?id=8S8EAAAAMBAJ&pg=PA13 |magazine=[[InfoWorld]] |page=13 |language=en |via=[[Google Books]]}}</ref> The first screensaver that allowed users to change the activating time was released on [[Apple Computer|Apple]]'s [[Apple Lisa|Lisa]], in 1983.

The [[Atari 400]] and [[Atari 800|800's]] screens would also go through random screensaver-like color changes if they were left inactive for about 8 minutes. Normal users had no control over this, though programs did. These computers, released in 1979, are technically earlier "screen savers". Prior to these computers, games for the 1977 [[Atari 2600|Atari VCS/2600]] gaming console such as Combat and [[Breakout (video game)|Breakout]], included color cycling in order to prevent burn-in of game images into 1970s-era televisions. In addition, the first model of the [[TI-30]] calculator from 1976 featured a screensaver, which consisted of a decimal point running across the display after 30 seconds of inactivity. This was chiefly used to save battery power, as the TI-30 [[LED]] display was more power intensive than later LCD models. These are examples of screensavers in [[Read-only memory|ROM]] or the [[firmware]] of a computer.

[[Android 4.2]] introduced "daydreams", screensavers that activate while the device is [[dock connector|docked]] or charging.<ref name="Walter">{{Cite web |last=Walter |first=Derek |date=December 29, 2015 |title=How to Set Up Android's Daydream Screensaver |url=https://www.tomsguide.com/us/android-daydream,review-3306.html |url-status=live |archive-url=https://web.archive.org/web/20211214202212/https://www.tomsguide.com/us/android-daydream,review-3306.html |archive-date=2021-12-14 |access-date=2021-12-14 |website=[[Tom's Guide]] |language=en}}</ref><ref name="Hoffman">{{Cite web |last=Hoffman |first=Chris |date=August 26, 2013 |title=5+ Cool Uses for Android's Daydream Mode |url=https://www.howtogeek.com/170990/5-cool-uses-for-androids-daydream-mode/ |url-status=live |archive-url=https://web.archive.org/web/20211214202211/https://www.howtogeek.com/170990/5-cool-uses-for-androids-daydream-mode/ |archive-date=2021-12-14 |access-date=2021-12-14 |website=HowToGeek.com |language=en}}</ref>

In 2015 the screensaver "Event Listeners"<ref>{{Cite web |title=MAK Collection Online: Event Listeners by van den Dorpel |url=https://sammlung.mak.at/en/collection_online?id=collect-372479 |url-status=live |archive-url=https://web.archive.org/web/20220205115254/https://sammlung.mak.at/en/collection_online?id=collect-372479 |archive-date=2022-02-05 |website=Sammlung.mak.at}}</ref> of van den Dorpel became the first [[work of art]] that was purchased by a [[museum]] ([[Museum of Applied Arts, Vienna]]) using the cryptocurrency [[bitcoin]].<ref>{{Cite web |last=Ghorashi |first=Hannah |date=April 24, 2015 |title=MAK Vienna Becomes First Museum to Use Bitcoin to Acquire Art, a Harm van den Dorpel |url=https://www.artnews.com/art-news/market/mak-vienna-becomes-first-museum-to-acquire-art-using-bitcoin-a-harm-van-den-dorpel-3995/ |archive-url=https://web.archive.org/web/20230409232002/https://www.artnews.com/art-news/market/mak-vienna-becomes-first-museum-to-acquire-art-using-bitcoin-a-harm-van-den-dorpel-3995/ |archive-date=2023-04-09 |access-date=2024-07-13 |website=ArtNews.com}}</ref>

Modern graphics technologies such as [[3D computer graphics]] have allowed a wide variety of screensavers to be made. Screensavers with realistic 3D environments can be programmed and run on modern computers.

== Underlying architecture ==
{{Expand list|date=February 2014}}

Screensavers are usually designed and coded using a variety of programming languages as well as graphics interfaces. Typically the authors of screensavers use the [[C (programming language)|C]] or [[C++]] programming languages, along with [[Graphics Device Interface]] (GDI), such as [[OpenGL]] ("Open Graphics Library", which works on many, if not most, platforms capable of [[3D rendering]]), or alternatives such as [[Microsoft DirectX]] (which is limited to [[Microsoft]] platforms, mainly [[Microsoft Windows]] and the [[Microsoft Xbox]]), to craft their final products. Several [[OS X]] screensavers are created and designed using [[Quartz Composer]]. The screensaver interfaces indirectly with the operating system to cause the physical display screen to be overlaid with one or more graphic "scenes". The screensaver typically terminates after receiving a message from the operating system that a key has been pressed or the mouse has been moved.

=== Microsoft Windows ===
[[File:StarfieldSimulation.gif|alt=Animation of stars becoming bigger and moving away from the center of the image, simulating moving towards the stars.|thumb|A recreation of Starfield Simulation, one of the screensavers added in [[Windows 95]].]]
If the system detects inactivity lasting longer than the time specified in the [[Control Panel (Windows)|control panel]], check if the active program is a simple program (and not another screensaver) by sending the "<code>WM_SYSCOMMAND</code>" message with the "<code>SC_SCREENSAVE</code>" argument. If the program calls in response the standard system function (<code>DefWindowProc</code>), the screensaver defined in the control panel screen runs.

A Windows screensaver is a regular [[Portable Executable]] (PE) with the <code>.scr</code> file extension. This enables [[malware]] authors to add ".scr" to the name of any [[win32]] [[executable]] file, and thereby increase likelihood that users of [[Microsoft Windows]] will run it unintentionally. In addition, this program should support the following [[Command-line interface|command line]] parameters:<ref>{{Cite web |title=INFO: Screen Saver Command Line Arguments |url=http://support.microsoft.com/kb/182383 |url-status=live |archive-url=https://web.archive.org/web/20140202212351/http://support.microsoft.com/kb/182383 |archive-date=2014-02-02 |access-date=2014-02-01 |publisher=[[Microsoft]]}}</ref>

With no parameter – shows the Settings dialog box or do nothing.
 ScreenSaver.scr <code>/s</code>
Runs the screensaver.
 ScreenSaver.scr <code>/p</code> or <code>/l</code> <HWND>
Previews the screensaver as child of window. <code><HWND></code> (presented as unsigned [[decimal number]]) is an identifier ([[Handle (computing)|handle]]) of the window in which the preview should appear.
 ScreenSaver.scr <code>/c</code>
Shows the Settings dialog box, modal to the foreground window.
 ScreenSaver.scr <code>/a </code><HWND>

Changes password, modal to window <code><HWND></code>. Windows 95 screensavers must handle it.

=== macOS ===
Under macOS, screensavers are regular macOS application bundles with the <code>.saver</code> file extension.<ref>{{Cite web |title=ScreenSaverView - ScreenSaver {{!}} Apple Developer Documentation |url=https://developer.apple.com/documentation/screensaver/screensaverview |url-status=live |archive-url=https://web.archive.org/web/20180925180703/https://developer.apple.com/documentation/screensaver/screensaverview |archive-date=2018-09-25 |access-date=2018-09-25 |website=Developer.Apple.com |publisher=[[Apple Inc.]] |language=en}}</ref>

Internally, the screensaver must define a class that is subclass of <code>ScreenSaverView</code>. The new class must be assigned as <code>NSPrincipalClass</code> in the xcode project, so that when the screensaver is launched by the system, this class gets instantiated.

=== Atari ===
As one of the first screensavers appeared in [[8-bit]] Atari computers, forcing systemic color changes when the computer is idle lasting a few minutes (different times depending on the model), stored in the system [[Read-only memory|ROM]] of the computer.

== Considerations ==
Monitors running screensavers consume the same amount of power as when running normally, which can be anywhere from a few [[watt]]s for small LCD monitors to several hundred for large plasma displays. Most modern computers can be set to switch the monitor into a lower power mode, blanking the screen altogether. A power-saving mode for monitors is usually part of the power management options supported in modern [[operating system]]s, though it must also be supported by the computer hardware and monitor itself.

Using a screensaver with a flat panel or [[TFT LCD]] screen not powering down the screen can actually decrease the lifetime of the display, since the fluorescent backlight remains lit and ages faster than it would if the screen is turned off and on frequently.<ref>{{Cite web |title=Science Fact or Science Fiction: Fluorescent Lights |url=http://www.cbc.ca/quirks/episode/2011/10/22/october-22-2011 |url-status=dead |archive-url=https://web.archive.org/web/20111028205846/http://www.cbc.ca/quirks/episode/2011/10/22/october-22-2011 |archive-date=2011-10-28 |access-date=2022-01-12 |website=CBC.ca |publisher=[[Canadian Broadcasting Corporation]]}}</ref><ref>{{Cite web |title=When to Turn Off Your Lights |url=https://www.energy.gov/energysaver/save-electricity-and-fuel/lighting-choices-save-you-money/when-turn-your-lights |url-status=live |archive-url=https://web.archive.org/web/20190322150508/https://www.energy.gov/energysaver/save-electricity-and-fuel/lighting-choices-save-you-money/when-turn-your-lights |archive-date=2019-03-22 |access-date=2019-03-22 |website=Energy.gov |publisher=[[United States Department of Energy]]}}</ref> As fluorescent tubes age they grow progressively dimmer, and they can be expensive or difficult to replace. A typical LCD screen loses about 50% of its brightness during a normal [[product lifetime]]. In most cases, the tube is an integral part of the LCD and the entire assembly needs to be replaced. This is not true of LED backlit displays.

Thus the term "screen saver" is now something of a [[misnomer]] – the best way to save the screen and also save electricity consumed by screen would simply be to have the computer turn off the monitor. Screensavers displaying complex 3D graphics might even add to overall power draw.<ref>{{Cite web |last=Hoffman |first=Chris |date=September 16, 2016 |title=Why Screen Savers Are No Longer Necessary |url=https://www.howtogeek.com/128644/htg-explains-why-screen-savers-are-no-longer-necessary/ |website=HowToGeek.com |access-date=2024-07-13}}</ref>

== Entertainment ==
[[File:Xscreensaver xmatrix.png|thumb|XScreenSaver displaying a [[Matrix digital rain|''Matrix'']]-style screensaver]]

''[[After Dark (software)|After Dark]]'' was an early screensaver for the [[Mac (computer)|Macintosh]] platform, and later PC/Windows, which prominently featured whimsical designs such as "flying toasters". Perhaps in response to the workplace environment in which they are often viewed, many screensavers continue this legacy of whimsy by populating the idle monitor with animals or fish, [[video game]]s, and visual expressions of [[mathematics]] equations (through the use of [[fractal]]s, [[Fourier transform]]s or other means) as in the [[Electric Sheep]] screensaver.

At least one screensaver, ''[[Johnny Castaway]]'', told a humorous animated story over many months.<ref name="cgw199301">{{Cite magazine |last1=Emrich |first1=Johnny L. |last2=Wilson |date=January 1993 |title=The Misadventures of Johnny Castaway |url=http://www.cgwmuseum.org/galleries/index.php?year=1993&pub=2&id=102 |url-status=live |archive-url=https://web.archive.org/web/20160702201302/http://www.cgwmuseum.org/galleries/index.php?year=1993&pub=2&id=102 |archive-date=2016-07-02 |access-date=2014-07-05 |magazine=[[Computer Gaming World]] |pages=16}}</ref> The ability of screensavers to divert and entertain is used for [[Promotion (marketing)|promotion]], especially to build [[Marketing buzz|buzz]] for "event-based" products such as [[film|feature films]].

The screensaver is also a creative outlet for computer programmers. The [[Unix]]-based screensaver [[XScreenSaver]] collects the display effects of other Unix screensavers, which are termed "display hacks" in the ''[[Jargon File]]'' tradition of US computer science academics. It also collects forms of computer graphics effects called ''[[demo effect]]s'', such as were originally produced by the [[demoscene]].

=== Microsoft Windows ===
On older versions of [[Microsoft Windows]] the native screensaver format had the potential to install a virus when run (as a screen saver was just an ordinary application with a different extension). When any file with the [[file suffix]] ".scr" was opened, for example from an [[email attachment]], Windows would execute the .scr (screensaver) file automatically: this had the potential to allow a [[virus (computer)|virus]] or [[malware]] to install itself. Modern versions of Windows can read tags left by applications such as Internet Explorer and [[code signing|verify the publisher of the file]], presenting a confirmation to the user.

On August 5, 2006, the [[BBC]] reported that "free screensavers" and "screensavers" respectively were the first and third most likely search terms to return links to malware, the second being [[BearShare]].<ref>{{Cite news |date=May 12, 2006 |title=Warning on Search Engine Safety |url=http://news.bbc.co.uk/1/hi/technology/4765199.stm |url-status=live |archive-url=https://web.archive.org/web/20090224174032/http://news.bbc.co.uk/1/hi/technology/4765199.stm |archive-date=2009-02-24 |access-date=2010-06-07 |work=[[BBC News]]}}</ref>

By launching the "bubbles" screensaver executable through the <code>bubbles.scr /p65552</code> command-line parameter, it runs as [[wallpaper (computing)|desktop wallpaper]], the bubbles are smaller, and there are more bubbles on screen.<ref name="Khanse">{{Cite web |last=Khanse |first=Anand |date=March 18, 2019 |title=How to Run Screensaver As Wallpaper in Windows 11/10 |url=https://www.thewindowsclub.com/run-screensaver-as-wallpaper-windows |url-status=live |archive-url=https://web.archive.org/web/20220121010518/https://www.thewindowsclub.com/run-screensaver-as-wallpaper-windows |archive-date=2022-01-21 |access-date=2022-01-21 |website=TheWindowsClub.com}}</ref> The user must use the [[Task Manager (Windows)|Task Manager]] to stop the screensaver.<ref name="Khanse" />

== See also ==
* [[Degaussing]]

== References ==
{{Reflist}}


{{Wiktionary}}
{{Commons category|Screensavers}}

[[Category:Screensavers| ]]
[[Category:Computer-related introductions in the 1970s]]
[[Category:1970s neologisms]]
[[Category:Display technology]]
[[Category:Utility software types]]
[[Category:Volunteer computing]]