Cursor (user interface)

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A blinking text cursor while typing Wikipedia.

In computer user interfaces, a cursor is an indicator used to show the current position for user interaction on a computer monitor or other display device that will respond to input from a text input or pointing device. The mouse cursor is also called a pointer,[1] owing to its resemblance in usage to a pointing stick.

Etymology[edit]

Cursor is Latin for 'runner'. A cursor is a name given to the transparent slide engraved with a hairline used to mark a point on a slide rule. The term was then transferred to computers through analogy.

On 14 November 1963, while attending a conference on computer graphics in Reno, Nevada, Douglas Engelbart of Augmentation Research Center (ARC) first expressed his thoughts to pursue his objective of developing both hardware and software computer technology to "augment" human intelligence by pondering how to adapt the underlying principles of the planimeter to inputting X- and Y-coordinate data, and envisioned something like the cursor of a mouse he initially called a "bug", which, in a "3-point" form, could have a "drop point and 2 orthogonal wheels".[2] He wrote that the "bug" would be "easier" and "more natural" to use, and unlike a stylus, it would stay still when let go, which meant it would be "much better for coordination with the keyboard."[2]

According to Roger Bates, a young hardware designer at ARC under Bill English, the cursor on the screen was for some unknown reason also referred to as "CAT" at the time, which led to calling the new pointing device a "mouse" as well.[3][4]

Text cursor[edit]

The cursor for the Windows Command Prompt (appearing as an underscore at the end of the line)

In most command-line interfaces or text editors, the text cursor, also known as a caret,[5] is an underscore, a solid rectangle, or a vertical line, which may be flashing or steady, indicating where text will be placed when entered (the insertion point). In text mode displays, it was not possible to show a vertical bar between characters to show where the new text would be inserted, so an underscore or block cursor was used instead. In situations where a block was used, the block was usually created by inverting the pixels of the character using the boolean math exclusive or function.[6] On text editors and word processors of modern design on bitmapped displays, the vertical bar is typically used instead.

In a typical text editing application, the cursor can be moved by pressing various keys. These include the four arrow keys, the Page Up and Page Down keys, the Home key, the End key, and various key combinations involving a modifier key such as the Control key. The position of the cursor also may be changed by moving the mouse pointer to a different location in the document and clicking.

The blinking of the text cursor is usually temporarily suspended when it is being moved; otherwise, the cursor may change position when it is not visible, making its location difficult to follow.

Some interfaces use an underscore or thin vertical bar to indicate that the user is in insert mode, a mode where text will be inserted in the middle of the existing text, and a larger block to indicate that the user is in overtype mode, where inserted text will overwrite existing text. In this way, a block cursor may be seen as a piece of selected text one character wide, since typing will replace the text "in" the cursor with the new text.

Bi-directional text[edit]

A vertical line text cursor with a small left-pointing or right-pointing appendage is for indicating the direction of text flow on systems that support bi-directional text, and is thus usually known among programmers as a 'bidi cursor'. In some cases, the cursor may split into two parts, each indicating where left-to-right and right-to-left text would be inserted.[7]

Pointer[edit]

The common cursor roles for a cursor set.
Common pointer types (enlarged)

In computing, a pointer or mouse cursor (as part of a personal computer WIMP style of interaction)[8][9][10] is a symbol or graphical image on the computer monitor or other display device that echoes movements of the pointing device, commonly a mouse, touchpad, or stylus pen. It signals the point where actions of the user take place. It can be used in text-based or graphical user interfaces to select and move other elements. It is distinct from the cursor, which responds to keyboard input. The cursor may also be repositioned using the pointer.

The pointer commonly appears as an angled arrow (angled because historically that improved appearance on low-resolution screens[11]), but it can vary within different programs or operating systems. The use of a pointer is employed when the input method, or pointing device, is a device that can move fluidly across a screen and select or highlight objects on the screen. In GUIs where the input method relies on hard keys, such as the five-way key on many mobile phones, there is no pointer employed, and instead, the GUI relies on a clear focus state.

The pointer or mouse cursor echoes movements of the pointing device, commonly a mouse, touchpad or trackball. This kind of cursor is used to manipulate elements of graphical user interfaces such as menus, buttons, scrollbars or any other widget. It may be called a "mouse pointer" because the mouse is the dominant type of pointing device used with desktop computers.

Appearance[edit]

A wait cursor replaces the pointer with an hourglass.

The pointer hotspot is the active pixel of the pointer, used to target a click or drag. The hotspot is normally along the pointer edges or in its center, though it may reside at any location in the pointer.[12][13]

In many GUIs, moving the pointer around the screen may reveal other screen hotspots as the pointer changes shape depending on the circumstances. For example:

  • In-the text that the user can select or edit, the pointer changes to a vertical bar with little cross-bars (or curved serif-like extensions) at the top and bottom — sometimes called an "I-beam" since it resembles the cross-section of the construction detail of the same name.
  • When displaying a document, the pointer can appear as a hand with all fingers extended allowing scrolling by "pushing" the displayed page around.
  • Graphics-editing pointers such as brushes, pencils, or paint buckets may display when the user edits an image.
  • On an edge or corner of a window the pointer usually changes into a double arrow (horizontal, vertical, or diagonal) indicating that the user can drag the edge/corner in an indicated direction to adjust the size and shape of the window.
  • The corners and edges of the whole screen may also act as hotspots. According to Fitts's law, which predicts the time it takes to reach a target area, moving mouse and stylus pointers to those spots is easy and fast. As the pointer usually stops when reaching a screen edge, the size of those spots can be considered of virtual infinite size, so the hot corners and edges can be reached quickly by throwing the pointer toward the edges.[14][15]
  • While a computer process is performing tasks and cannot accept user input, a wait pointer (an hourglass in Windows before Vista and many other systems, spinning ring in Windows Vista and later, watch in classic Mac OS, or spinning pinwheel in macOS) is displayed when the mouse pointer is in the corresponding window.
  • When the pointer hovers over a hyperlink, a mouseover event changes the pointer into a hand with an outstretched index finger. Often some informative text about the link may pop up in a tooltip, which disappears when the user moves the pointer away. The tooltips revealed in the box depending on the implementation of the web browser; many web browsers will display the "title" of the element, the "alt" attribute, or the non-standard "tooltips" attribute. This pointer shape was first used for hyperlinks in Apple Computer's HyperCard.
  • In Windows 7, when Windows Touch was introduced in the mainstream to make Windows more touch-friendly, a touch pointer is displayed instead of the mouse pointer. The touch pointer can be switched off in Control Panel and resembles a small diamond shape. When the screen is touched a blue ripple appears around the touch pointer to provide visual touch feedback. When swiping to scroll etc., the touch pointer would follow the finger as it moves. If touch and hold to right-click is enabled, touching and holding will show a thick white ring around the touch pointer. When this ring appears, releasing one's finger would perform a right-click.
    • If a pen is used the left-click ripple is colorless instead of blue and the right-click ring is a thinner ring that appears closer to the pen tip making contact with the screen. A click (either left or right) will not show the touch pointer, but swiping would still show the pointer which would follow the pen tip.
    • Also, the touch pointer would only appear on the desktop once a user has signed in to Windows 7. On the sign-in screen, the mouse cursor would simply jump to the point touched and a left click would be sent on a tap, similar to when a touch input is used on operating systems before Windows 7.
  • In Windows 8 and above, visual touch feedback displays a translucent circle where the finger makes contact with the screen, and a square when attempting to touch and hold to right-click. A swipe is shown by a translucent line of varying thickness. Feedback can be switched on and off in Pen and Touch settings of the Control Panel in Windows 8 and Windows 8.1 or in the Settings app on Windows 10, and feedback can also be made darker and larger where it needs to be emphasized, such as when presenting. However, the touch pointer is normally less commonly visible in touchscreen environments of Windows operating systems later than Windows 7.
  • The mouse-over or hover gesture can also show a tooltip, which presents information about what the pointer is hovering over; the information is a description of what selecting an active element is for or what it will do. The tooltip appears only when stationary over the content. A common use of viewing the information is when browsing the internet to know the destination of a link before selecting it, if the URL of the text is not recognizable.
    • When using touch or a pen with Windows, hovering when supported or performing a set gesture or flick may show the tooltip

I-beam pointer[edit]

The I-beam pointer.

The I-beam pointer (also called the I-cursor) is a cursor shaped like a serifed capital letter "I". The purpose of this cursor is to indicate that the text beneath the cursor can be highlighted and sometimes inserted or changed.[16]

Pointer trails and animation[edit]

An example of mouse pointer trails.

Pointer trails can be used to enhance its visibility during movement. Pointer trails are a feature of GUI operating systems to enhance the visibility of the pointer. Although disabled by default, pointer trails have been an option in every version of Microsoft Windows since Windows 3.1x.

When pointer trails are active and the mouse or stylus is moved, the system waits a moment before removing the pointer image from the old location on the screen. A copy of the pointer persists at every point that the pointer has visited at that moment, resulting in a snake-like trail of pointer icons that follow the actual pointer. When the user stops moving the mouse or removes the stylus from the screen, the trails disappear and the pointer returns to normal.

Pointer trails have been provided as a feature mainly for users with poor vision and for screens where low visibility may become an issue, such as LCD screens in bright sunlight.

In Windows, pointer trails may be enabled in the Control Panel, usually under the Mouse applet.

Introduced with Windows NT, an animated pointer was a small looping animation that was played at the location of the pointer.[17] This is used, for example, to provide a visual cue that the computer is busy with a task.[18] After their introduction, many animated pointers became available for download from third party suppliers. Unfortunately, animated pointers are not without their problems. In addition to imposing a small additional load on the CPU, the animated pointer routines did introduce a security vulnerability. A client-side exploit known as the Windows Animated Cursor Remote Code Execution Vulnerability used a buffer overflow vulnerability to load malicious code via the animated cursor load routine of Windows.[19]

Editor[edit]

A pointer editor is software for creating and editing static or animated mouse pointers. Pointer editors usually support both static and animated mouse cursors, but there are exceptions. An animated cursor is a sequence of static cursors representing individual frames of an animation. A pointer editor should be able to:

  • Modify pixels of a static cursor or each frame in an animated cursor.
  • Set the hot spot of a static cursor or a frame of an animated cursor. The hot spot is a designated pixel that defines the clicking point.
  • Add or remove frames in an animated cursor and set their animation speed.

Pointer editors are occasionally combined with icon editors because computer icons and cursors share similar properties. Both contain small raster images and the file format used to store icons and static cursors in Microsoft Windows is similar.

Despite the similarities, pointer editors differ from icon editors in several ways. While icons contain multiple images with different sizes and color depths, static cursors (for Windows) only contain a single image. Pointer editors must provide the means to set the hot spot. Animated pointer editors additionally must be able to handle animations.

3D cursor[edit]

An example of a 3D cursor in a 3D modeling environment (center).

The idea of a cursor being used as a marker or insertion point for new data or transformations, such as rotation, can be extended to a 3D modeling environment. Blender, for instance, uses a 3D cursor to determine where future operations are to take place.

See also[edit]

References[edit]

  1. ^ Mouse Pointer Behaves Erratically If Mouse Pointer Speed Is Set Above-Level Five
  2. ^ a b Bardini, Thierry (2000). Bootstrapping: Douglas Engelbart, Coevolution, and the Origins of Personal Computing. Stanford, USA: Stanford University Press. p. 95. ISBN 978-0-80473871-2.
  3. ^ Markoff, John Gregory (2005) [2004-06-11]. "2. Augmentation". What the Dormouse Said: How the Sixties Counterculture Shaped the Personal Computer Industry. Penguin Books / Penguin Random House LLC. pp. 123–124. ISBN 978-1-10120108-4. ISBN 1-10120108-8. Retrieved 2021-08-26. pp. 123–124: […] Although it is commonly believed that the story of how the mouse got its name has been lost in history, Roger Bates, who was a young hardware designer working for Bill English, has a clear recollection of how the name was chosen. […] He remembers that what today is called the cursor on the screen was at the time called a "CAT". Bates has forgotten what CAT stood for, and no one else seems to remember either, but in hindseight, it seems obvious that a CAT would chase the tailed mouse on the desktop. […] (336 pages)
  4. ^ Markoff, John Gregory (2013-07-03). "Douglas C. Engelbart, 1925–2013: Computer Visionary Who Invented the Mouse". The New York Times. Archived from the original on 2021-06-15. Retrieved 2021-08-26. […] When and under what circumstances the term "the mouse" arose is hard to pin down, but one hardware designer, Roger Bates, has contended that it happened under Mr. English's watch. Mr. Bates was a college sophomore and Mr. English was his mentor at the time. Mr. Bates said the name was a logical extension of the term then used for the cursor on a screen: CAT. Mr. Bates did not remember what CAT stood for, but it seemed to all that the cursor was chasing their tailed desktop device. […]
  5. ^ FIX: The caret shape appears as a thick rectangle after you switch from the Korean Input Method Editor (IME) to English in Visual FoxPro 8.0
  6. ^ U.S. Patent #4197590
  7. ^ ATSUI Programming Guide: Caret Handling, page 32.
  8. ^ Markoff, John (2009-02-16). "The Cellphone, Navigating Our Lives". The New York Times. New York. Retrieved 2011-12-14. [...] so-called WIMP interface — for windows, icons, menus, pointer [...]
  9. ^ Hinckley, Ken (December 1996). "Haptic Issues for Virtual Manipulation". Microsoft. Retrieved 2011-12-14. The Windows-Icons-Menus-Pointer (WIMP) interface paradigm dominates modern computing systems.
  10. ^ Hinckley, Ken. "Input Technologies and Techniques" (PDF). Microsoft. Retrieved 2011-12-14. Researchers are looking to move beyond the current "WIMP" (Windows, Icons, Menus, and Pointer) interface [...]
  11. ^ "Document from 1981 reveals why mouse cursor is tilted and not straight". Archived from the original on 2014-02-17. Retrieved 2014-02-18.
  12. ^ "Mouse".
  13. ^ "Setting a Cursor's Hot Spot". 2008-05-02. Archived from the original on 2008-05-02.
  14. ^ Hale, Kevin (2007-10-03). "Visualizing Fitts' Law". Particle Tree.
  15. ^ Atwood, Jeff (2006-08-09). "Fitts' Law and Infinite Width". Coding Horror.
  16. ^ ComputerHope.com
  17. ^ Staff (2007). Encyclopedia Of Information Technology. Atlantic Publishers & Distributors. p. 24. ISBN 978-81-269-0752-6.
  18. ^ Lock & Philander (2009). Michael Sangster (ed.). FCS Systems Analysis & Design L4. Pearson Education South Africa. p. 149. ISBN 978-1-77025-428-2.
  19. ^ McClure, Stuart; Scambray, Joel; Kurtz, George (2009). Hacking exposed: network security secrets & solutions (6th ed.). McGraw Hill Professional. p. 177. ISBN 978-0-07-161374-3.

External links[edit]