cursor
The cursor is by a pointing device , typically a mouse on a computer - screen moving symbol (usually a arrow ; technically a Sprite ), can be shown with an illustrated detail. Subsequent activation of a mouse button triggers a certain process, depending on the position of the mouse pointer. The mouse pointer is an integral part of many graphical user interfaces (GUI).
Function and properties
If one of the mouse buttons is clicked or double-clicked after pointing or the mouse pointer is moved while the mouse button is pressed ( drag and drop ), the mere sighting of a displayed object can become a selection, processing or local shift. In modern graphical user interfaces, the mere lingering of the mouse pointer on a displayed object can result in information about this object being displayed (so-called tooltips or tooltips) or the object being automatically brought to the foreground of a multilayer display.
Most operating systems allow you to define the appearance of the mouse pointer yourself. In most cases, a small raster graphic or animation is defined together with a pixel as an active pointing point (hotspot) in the program. In the case of the usual arrow, for example, the tip is this point. In an image editing program , the mouse pointer can take on an appearance that symbolizes the currently selected tool for editing the image. A Windows cursor file also contains a second graphic in black and white (this is only effective for cursor files with an alpha channel for operating systems prior to Windows XP that do not support alpha channels). At the points where it is white, the content of the first image is not simply drawn, but linked to the screen content at the corresponding point via bit-by-bit XOR , which means transparency (first image black) and complementary color (first image white ) become possible.
- Typical pointer shapes
The following mouse pointer variants are most common in desktop environments:
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| Standard shape (arrow) | Waiting form ( hourglass , wristwatch , ...) | Text form (I-bar) | Move (cross) | Pointer (index finger) |
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history
Originally a cursor is just an input mark: it can be moved with the arrow keys . If a character is then entered via the keyboard, it appears at the current cursor position. As a rule, the cursor is then moved one position to the right or - if it is already on the right edge of the display area - at the beginning of the next line.
In the 1970s , the mouse was invented as a more convenient input medium in certain cases. The cursor could now be moved not only with the arrow keys but also by moving the mouse. Later even two cursors could be seen on the screen: a keyboard cursor , which could not be moved with the mouse and which marks the text input position, and a mouse cursor which the keyboard usually has no influence on. Most graphical user interface operating systems today use both cursors.
