GenValue: 1 GenValue Features

Depending upon the specific UI, the GenValue object can look like one of many things. It may be a spin gadget, a slider, a dial, or some other gadget. A GenValue typically allows the user to set a value within a specified range through keyboard or mouse input. For example, many GenValue objects in OSF/Motif are comprised of a text field showing the current value, an incrementor and a decrementor, and possibly a moniker. (Scroll bars are also GenValues, though they have very different appearance.)

In OSF/Motif, the user can enter the value by keyboard input into the text field or by clicking the mouse on the incrementor or decrementor.

The GenValue provides the following capabilities:

A user interface object to enter values into your application.
Application defined minimum and maximum values.
The increment value to increase or decrease values by.
Ability for the value to be represented in a variety of forms, including integer, decimal, or a unit of distance.
An action to apply any value to.

The user may change a value in a GenValue in one of two ways. It can be entered with the keyboard by typing directly into the display area, or it can be entered graphically by using the arrows, dials, or sliders that the specific UI provides. To enter a value by typing directly into the text field, first the user clicks on the area, bringing up a cursor. Then a value may be typed into the GenValue. To enter a value graphically, the user clicks on either the incrementor or decrementor, thus changing the value of the GenValue.

Once the value is changed, the value may become set immediately (if the object is operating in immediate mode), and the GenValue will perform its action (if any) every time the value is changed. As an alternative, the GenValue may be operating in delayed mode, and the value will not be set until a MSG_GEN_APPLY is received through an "Apply" or "OK" button. The mode (delayed or immediate) of the GenValue is controlled by the parent. Usually a GenValue will operate in immediate mode unless it is placed as a child of a GIT_PROPERTIES GenInteraction.

GenValue only allows the user to set a value within a specific range; this range consists of a minimum and maximum value that the GenValue may display. These values are set by the application and cannot be directly modified by the user, but they can be changed by your application. If the user enters a value above the maximum, the GenValue simply takes on its maximum possible value. If the user enters a value below the minimum, the GenValue takes on its least possible value.

In addition to the limits upon the range of values entered by the user, the GenValue also has a defined increment value. The increment value is the specific amount to increment or decrement the GenValue's value when using graphical input. The user cannot directly modify this value, but it can be changed by your application.

The GenValue object always displays a numerical value within its text field. The units of that numerical value may be set by your application. By default, any value within a GenValue is an integer, but that value could also be a decimal value, or even a unit of distance such as centimeters, points, or inches. The GenValue automatically provides whatever notation is required by the display units (decimal points, the words "pt" and "cm," or any other distance notation in the text field).

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