Pointer (user interface)
In computing, a pointer or mouse cursor 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, as part of a personal computer WIMP style of interaction. 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 (because historically the angled shape improved appearance on low resolution screens), but it can vary within different programs or operating systems. 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, the GUI relies on a clear focus state.
Moving the pointer around the screen may reveal screen hotspots as the pointer changes shape depending on the circumstances. For example, the corners and edges of the screen may 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.
Common situational pointer shapes include:
- Text manipulation pointer: In text boxes containing text, 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.
- Hand pointer: When displaying a document, the pointer can appear as a hand (with all fingers extended), allowing scrolling by "pushing" the displayed page around.
- Resizing pointer: 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 or corner in an indicated direction to adjust the size of the window.
- "Busy" or "wait" pointer: While a computer program is performing tasks and cannot accept user input, a wait pointer is displayed when the mouse pointer is in the corresponding window. The Windows wait pointer is a spinning ring, although before Windows Vista, it was an hourglass. The macOS wait pointer is known as the spinning pinwheel.
- Finger pointer: 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 depend 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.
Windows 7 added support for touchscreens. As such, a touch pointer is displayed instead of the mouse pointer. The touch pointer resembles a small diamond shape. A tap performs the same function as a click. When the screen is tapped, a blue ripple appears around the touch pointer to provide visual touch feedback. When swiping, the touch pointer follows the finger. Windows can be configured so that "touching and holding" (maintaining touch for one second) can perform the same function as a right-click. In this case, Windows shows a thick white ring around the touch pointer, letting the user know that disconnecting the contact would emulate the right-click action. When using a pen instead of a finger, the mentioned visual feedback is less pronounced.
Pointer trails and animation
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 in 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.
Introduced with Windows NT, an animated pointer was a small looping animation that was played at the location of the pointer. This is used, for example, to provide a visual cue that the computer is busy with a task. 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 pointer load routine of Windows.
A pointer editor is an application for creating and editing static or animated mouse pointers. Pointer editors usually support both static and animated pointers, but there are exceptions. An animated pointer is a sequence of static pointers representing individual frames of an animation. A pointer editor should be able to:
- Modify pixels of a static pointer or of each individual frame in an animated pointer
- Set the pointer hotspot
- Add or remove frames in an animated pointer and set their animation speed
Pointer editors are may be combined with icon editors, because in Microsoft Windows, computer icons and pointers share similar properties. Both contain small raster images and the file format used to store icons and static pointer is similar.
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