Incomputer displays,filmmaking,television production,video games and other kinetic displays,scrolling is sliding text, images or video across a monitor or display, vertically or horizontally. "Scrolling," as such, does not change the layout of the text or pictures but moves (pans ortilts) the user's view across what is apparently a larger image that is not wholly seen.[1] A common television and movie special effect is to scroll credits, while leaving the background stationary. Scrolling may take place completely without user intervention (as in film credits) or, on an interactive device, be triggered bytouchscreen or a keypress and continue without further intervention until a further user action, or be entirely controlled byinput devices.
Scrolling may take place in discrete increments (perhaps one or a few lines of text at a time), or continuously (smooth scrolling).Frame rate is the speed at which an entire image is redisplayed. It is related to scrolling in that changes to text and image position can only happen as often as the image can be redisplayed. When frame rate is a limiting factor, one smooth scrolling technique is to blur images during movement that would otherwise appear to "jump".
Scrolling is often carried out on a computer by the CPU (software scrolling) or by agraphics processor. Some systems featurehardware scrolling, where an image may be offset as it is displayed, without anyframe buffer manipulation (see alsohardware windowing). This was especially common in 8 and 16bit video game consoles.
In aWIMP-stylegraphical user interface (GUI), user-controlled scrolling is carried out by manipulating ascrollbar with a mouse, or usingkeyboard shortcuts, often thearrow keys. Scrolling is often supported bytext user interfaces andcommand line interfaces. Oldercomputer terminals changed the entire contents of the display one screenful ("page") at a time; this paging mode requires fewer resources than scrolling. Scrolling displays often also support page mode. Typically certain keys orkey combinations page up or down; onPC-compatible keyboards thepage up and page down keys or thespace bar are used; earlier computers often usedcontrol key combinations.[notes 1] Somecomputer mice have ascroll wheel, which scrolls the display, often vertically, when rolled; others havescroll balls ortilt wheels which allow both vertical and horizontal scrolling.
Some software supports other ways of scrolling.Adobe Reader has a mode identified by a small hand icon ("hand tool") on the document, which can then be dragged by clicking on it and moving the mouse as if sliding a large sheet of paper. When this feature is implemented on atouchscreen it is calledkinetic scrolling.Touch-screens often useinertial scrolling, in which the scrolling motion of an object continues in a decaying fashion after release of the touch, simulating the appearance of an object withinertia. An early implementation of such behavior was in the "Star7"PDA ofSun Microsystems ca. 1991–1992.[2]
Scrolling can be controlled in other software-dependent ways by a PC mouse. Some scroll wheels can be pressed down, functioning like a button. Depending on the software, this allows both horizontal and vertical scrolling by dragging in the direction desired; when the mouse is moved to the original position, scrolling stops. A few scroll wheels can also be tilted, scrolling horizontally in one direction until released. Ontouchscreen devices, scrolling is amulti-touch gesture, done by swiping a finger on the screen vertically in the direction opposite to where the user wants to scroll to.
If any content is too wide to fit on a display, horizontal scrolling is required to view all of it. In applications such asgraphics andspreadsheets there is often more content than can fit either the width or the height of the screen at a comfortable scale, and scrolling in both directions is necessary.
In contrast tomaterial divided into discrete pages, the web design approach ofinfinite scrolling dynamically adds new material to the user display, leading to a continuous, apparently bottomless or endless scrolling experience.
Inlanguages written horizontally, such as most Western languages, text documents longer than will fit on the screen are often displayedwrapped and sized to fit the screen width, and scrolled vertically to bring desired content into view. It is possible to display lines too long to fit the display without wrapping, scrolling horizontally to view each entire line. However, this requires inconvenient constant line-by-line scrolling, while vertical scrolling is only needed after reading a full screenful.
Software such asword processors andweb browsers normally uses word-wrapping to display as many words in a single line as will fit the width of the screen or window or, for text organised in columns, each column.
Scrolling texts, also referred to asscrolltexts orscrollers, played an important part in the birth of the computerdemo culture. Thesoftware crackers often used their deep knowledge ofcomputer platforms to transform the information that accompanied their releases intocrack intros. The sole role of these intros was to scroll the text on the screen in an impressive way.[3]
Scrolling is commonly used to display the credits at the end offilms andtelevision programs.
Scrolling is often used in the form of anews ticker towards the bottom of the picture for content such astelevision news, scrolling sideways across the screen, delivering short-form content.
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In the dynamic layout ofkinetic typography, scrolling typography can scroll across the flat screen, or can appear to recede or advance.An iconic example is theStar Wars opening crawl inspired by theFlash Gordon serials.
Incomputer and video games, scrolling of a playing field allows the player to control an object in a large contiguous area. Early examples of this method includeTaito's 1974 vertical-scrollingracing video gameSpeed Race,[4]Sega's 1976forward-scrollingracing gamesMoto-Cross[5] (Fonz)[6] andRoad Race,[7] andSuper Bug. Previously theflip-screen method was used to indicate moving backgrounds.
TheNamco Galaxianarcade system board introduced withGalaxian in 1979 pioneered asprite system that animated pre-loaded sprites over a scrolling background, which became the basis forNintendo'sRadar Scope andDonkey Kong arcade hardware andhome consoles such as theNintendo Entertainment System.[8]
Parallax scrolling, which was first featured inMoon Patrol, involves severalsemi-transparent layers (called playfields), which scroll on top of each other at varying rates in order to give an earlypseudo-3D illusion of depth.[9]
Belt scrolling is a method used in side-scrollingbeat 'em up games with a downward camera angle where players can move up and down in addition to left and right.
A 1993 article by George Fitzmaurice studied spatially awarepalmtop computers. These devices had a 3D sensor, and moving the device caused the contents to move as if the contents were fixed in place. This interaction could be referred to as “moving to scroll.” Also, if the user moved the device away from their body, they would zoom in; conversely, the device would zoom out if the user pulled the device closer to them.Smartphonecameras and “optical flow” image analysis utilize this technique nowadays.[10]
A 1996 research paper byJun Rekimoto analyzed tilting operations as scrolling techniques on small screen interfaces. Users could not only tilt to scroll, but also tilt to select menu items. These techniques proved especially useful for field workers, since they only needed to hold and control the device with one hand.[11]
A study from 2013 by Selina Sharmin, Oleg Špakov, and Kari-Jouko Räihä explored the action of reading text on a screen while the text auto-scrolls based on the user'seye tracking patterns. The control group simply read text on a screen and manually scrolled. The study found that participants preferred to read primarily at the top of the screen, so the screen scrolled down whenever participants’ eyes began to look toward the bottom of the screen. This auto-scrolling caused no statistically significant difference in reading speed or performance.[12]
A undated study occurring during or after 2010 by Dede Frederick, James Mohler, Mihaela Vorvoreanu, and Ronald Glotzbach noted that parallax scrolling "may cause certain people to experience nausea."[13]
