Screensaver

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This article is about the computer software. For other uses, see Screen Savers (disambiguation).
".scr" redirects here. For CAD scripts, see
CadSoft EAGLE.
Einstein@Home
interactive screensaver

A screensaver (or screen saver) is a

CRT or plasma computer monitors (hence the name).[citation needed] 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 security by requiring a password to re-access the device.[1] Some screensaver programs also use otherwise-idle computer resources to do useful work, such as processing for volunteer computing projects.[2]

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

phosphor burn-in, as are plasma displays to some extent.[3]

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 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 out of the question as the machine would appear to be 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

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

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

virus scan or a volunteer computing application (such as the SETI@home project).[4] This allows applications to use resources only when the computer would be otherwise idle. The 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,

Stranger In A Strange Land (1961):[6]

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

Apple's Lisa
, in 1983.

The

LCD models. These are examples of screensavers in ROM or the firmware
of a computer.

Android 4.2 introduced "daydreams", screensavers that activate while the device is docked or charging.[8][9]

In 2015 the screensaver "Event listeners"[10] 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.[11]

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

Screensavers are usually designed and coded using a variety of programming languages as well as graphics interfaces. Typically the authors of screensavers use the

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

If the system detects inactivity lasting longer than the time specified in the control panel, check if the active program is a simple program (and not another screensaver) by sending the "WM_SYSCOMMAND" message with the "SC_SCREENSAVE" argument. If the program calls in response the standard system function (DefWindowProc), the screensaver defined in the control panel screen runs.

A Windows screensaver is a regular

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 parameters:[12]

With no parameter – shows the Settings dialog box or do nothing. 

ScreenSaver.scr /s

Runs the screensaver. 

ScreenSaver.scr /p or /l <HWND>

Previews the screensaver as child of window. <HWND> (presented as unsigned

decimal number) is an identifier (handle
) of the window in which the preview should appear. 

ScreenSaver.scr /c

Shows the Settings dialog box, modal to the foreground window. 

ScreenSaver.scr /a <HWND>

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

macOS

Under macOS, screensavers are regular macOS application bundles with the .saver file extension.[13]

Internally, the screensaver must define a class that is subclass of ScreenSaverView. The new class must be assigned as NSPrincipalClass 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 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 watts 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 most modern operating systems, though it must also be supported by the computer hardware and monitor itself.

Using a screensaver with a flat panel or 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.[14][15] 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.[citation needed]

Entertainment

XScreenSaver displaying a Matrix-style screensaver

fractals, Fourier transforms or other means) as in the Electric Sheep
screensaver.

At least one screensaver, Johnny Castaway, told a humorous animated story over many months.[16] The ability of screensavers to divert and entertain is used for promotion, especially to build buzz for "event-based" products such as feature films.

The screensaver is also a creative outlet for computer programmers. The

demo scene
.

Microsoft Windows

On older versions of

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.[17]

By launching the "bubbles" screensaver executable through the bubbles.scr /p65552 command-line parameter, it runs as

desktop wallpaper, the bubbles are smaller, and there are more bubbles on screen.[18] You must use the Task Manager to stop the screensaver.[19]

See also

References

  1. ^ "OKthePK - Screensaver". www.okthepk.ca. Retrieved 2022-09-18.
  2. ^ Einstein@Home Screensaver | Multi-Directional 2.07, retrieved 2022-09-18
  3. ^ Phillips, Gavin (2020-01-24). "How to Fix Screen Burn-In on TVs: Plasma, LCD, and OLED". MUO. Retrieved 2022-09-18.
  4. ^ SETI@home screensaver | Enhanced 5.27, retrieved 2022-09-18
  5. ^ Screensaver (Inventor of) by Robert Heinlein from Stranger in a Strange Land Archived March 18, 2015, at the Wayback Machine
  6. ISBN 9780441790340
    .
  7. ^ Chin, Kathy (1983-04-11). "Z-29, a new computer terminal from Zenith Data Systems". InfoWorld. p. 13.
  8. ^ Walter, Derek (29 December 2015). "How to Set Up Android's Daydream Screensaver". Tom's Guide. Retrieved 14 December 2021.
  9. ^ Hoffman, Chris. "5+ Cool Uses for Android's Daydream Mode". How-To Geek. Retrieved 14 December 2021.
  10. ^ [https://sammlung.mak.at/en/collection_online?id=collect-372479 MAK Collection Online: Event Listeners by van den Dorpel
  11. ^ [https://www.artnews.com/art-news/market/mak-vienna-becomes-first-museum-to-acquire-art-using-bitcoin-a-harm-van-den-dorpel-3995/ MAK Vienna Becomes First Museum to Use Bitcoin to Acquire Art, a Harm van den Dorpel
  12. ^ "INFO: Screen Saver Command Line Arguments". Microsoft.
  13. ^ "ScreenSaverView - ScreenSaver | Apple Developer Documentation". developer.apple.com. Retrieved 2018-09-25.
  14. ^ "CBC.ca | Quirks & Quarks | Dinosaur Speed Demon Dawn at Vesta Chivalrous Crickets Hybrid Humans Science Fact or Science Fiction: Fluorescent Lights". www.cbc.ca. Archived from the original on 28 October 2011. Retrieved 12 January 2022.
  15. ^ "When to Turn off Your Lights".
  16. ^ Emrich, Alan; Wilson, Johnny L. (January 1993). "The Misadventures of Johnny Castaway". Computer Gaming World. p. 16. Retrieved 5 July 2014.
  17. ^ "Warning on search engine safety". BBC News. 2006-05-12. Retrieved 2010-06-07.
  18. ^ "How to run Screensaver as Wallpaper in Windows 11/10". 18 March 2019.
  19. ^ "Run screensaver as wallpaper in Windows 11/10". 29 October 2023.


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