Character Reordering

Character Re ordering

Principles of text ordering differ according to the type of script under

consideration. With Roman and simple scripts (such as Greek and Cyrillic) as

well as bidirectional scripts (such as Arabic and Hebrew), phonetic and

writing order are synonymous except for vowel signs and other marks. With

certain Southeast Asian scripts, there may be significant differences between

phonetic and writing order.

The Figure below shows an example of the reordering of vowels for the word

hindi in the Devanagari script. The box on the left illustrates the phonetic

order of the characters, whereas the box on the right depicts their writing

order. The consonants in this example take a default vowel (a). To modify the

vowel, you add a vowel marker. Some vowel markers are written to the right of

the consonant they modify; others are written to the left, above, or below.

Character reordering in Devanagari script (for the word hindi )

Word Demarcation

Words in Roman scripts are generally delimited by spaces and punctuation

marks. In contrast, many Asian scripts (for example, Japanese and Thai)

typically have no word delimiters, so the Script Manager provides a more

sophisticated method of finding word boundaries. (For details, see Macintosh

Worldwide Development: Guide to System Software.) System software version

7.0 generalizes and speeds up the Script Manager procedure (FindWord)

that supplies the word demarcation mechanism. For details, see the section

Alignment and Justification of Text

Alignment is the horizontal placement of lines of text with respect to the left

and right edges of the destination rectangle. Alignment can be flush left, flush

right, centered, or justified (that is, flush on both left and right edges of the

destination rectangle). TextEdit supports text alignment that is flush left,

centered, flush right, and flush according to the line direction of the script.

TextEdit does not support fully justified alignment.

The Script Manager supplies routines you can use to provide support for

fully justified text in your applications.

Justification (or fully justified alignment) is the spreading or

compressing of printed text to fit a given line width. It is usually performed in

Roman text primarily by altering the size of the interword spaces. Arabic,

however, inserts extension bar characters between joined characters and

widens blank characters to fill any remaining gaps. Scripts that do not use

interword spaces must modify the intercharacter spacing.

The Script Manager provides routines that take these justification methods

into account when drawing, measuring, or selecting text. The justification is

done by the script systems themselves.