Scrolling

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In computer graphics and television, scrolling (screen rolling) aka "text crawling" is the act of sliding a horizontal or vertical presentation of contents (text, drawing, image) across the screen or display window. Scrolling is often used to show reams of data longer than the screen/window.

Scrolling may be performed by software running on a computer's CPU, or it may be done by performing some operation on a dedicated 2D computer graphics chip. The verb "to scroll" , is derived from the way in which people read scrolls. Visually the act is fairly similar. On the home computer demo scene of the 1980s, as well as the period's computer and video games, scrolling was often an integral feature.

In video games scrolling of the playing field is important to allow the player to control a character or vehicle in a large area. The first scrolling video game was Super Bug. Another important term is parallax scrolling, meaning several semi-transparent layers that scroll on top of each other to create an illusion of depth. The first parallax scrolling game was Moon Patrol. The alternative to video game scrolling is the flip screen method.

For reading in a document or similar, a text line wider than fits on the screen (thus requiring horizontal scrolling), is impractical and therefore mostly avoided (an exception to this is in spreadsheets, where horizontal columns is more orderly arranged). On the other hand, a page/body of text higher than fits on the screen, like many web pages, is more common and not problematic; it requires vertical scrolling to see all of it.

In a WIMP style GUI, scrolling is done with the help of a scrollbar or using keyboard shortcuts, (often the arrow keys). Scrolling is often a key feature in TUI and CLI style interfaces, though some older computer terminals used page-mode instead. Modern mice may also have a scroll wheel.