Volume 6A: Motif Programming Manual

25.3.4 Text−related Values

Text is almost always an important part of a graphical user interface. UIL supports string, character set, and font

values, all of which are related to the display of text in your interface. A string consists of displayable text. A string

only makes sense in the context of a character set, which defines the supported characters in a string and the encoding

(or mapping from values to glyphs) of the string. A font contains the actual glyphs that visually represent a character

on the screen or on paper. These three elements are closely related as all are necessary to display text. the figure

illustrates the relationships among these types under UIL.

Relationships among strings, character sets, and fonts in UIL

This figure may look complicated, but UIL and Motif provide default values for character sets and fonts. You don't

have to worry about these values unless you are customizing or internationalizing an application. Of course, you must

always provide the strings, but that's the easy part. Before we can explain strings or fonts, you need to understand

character sets, because both strings and fonts depend on them. The character set of a string determines the string's

parsing direction, writing direction, and the number of bytes per character. For example, character sets for

Latin−based languages like English are read from left to right, are written from left to right, ...