Explanation
DIRECT MANIPULATION :-
Direct manipulation (DM) is an interaction style in which users act on displayed objects of interest using physical, incremental, reversible actions whose effects are immediately visible on the screen. Direct manipulation is one of the central concepts of graphical user interfaces (GUIs) and is sometimes equated with “what you see is what you get” (WYSIWYG). These interfaces combine menu-based interaction with physical actions such as dragging and dropping in order to help the user use the interface with minimal learning.
The term direct manipulation is given by Shneiderman (1982) as they possess the following characteristics:
i. The system is portrayed as an extension of the real world.
ii. Continuous visibility of objects and actions.
iii. Actions are rapid and incremental with visible display of results.
iv. Incremental actions are easily reversible.
Example for direct manipulation:
On a mobile phone you can pinch out to zoom into an image and pinch in to zoom out. The action of using your fingertips to zoom in and out of the image is an example of a direct-manipulation interaction. Another classic example is dragging a file from a folder to another one in order to move it.
INDIRECT MANIPULATION :-
Indirect manipulation substitutes words and text, such as pull-down or pop-up menus, for symbols and substitutes typing for pointing. Most window systems are a combination of both direct manipulation and indirect manipulation.
In practice, direct manipulation of all screen objects and actions may not be feasible because of the following:
i. The operation may be difficult to conceptualize in graphical system.
ii. The graphics capability of the system may be limited.
iii. The amount of space available for placing manipulation controls in the window border may be limited.
iv. It may be difficult for people to learn and remember all the necessary operations and actions.
