This function performs basic operations for "shaping" Arabic text. It is most * useful for use with legacy data formats and legacy display technology * (simple terminals). All operations are performed on Unicode characters.
* *Text-based shaping means that some character code points in the text are * replaced by others depending on the context. It transforms one kind of text * into another. In comparison, modern displays for Arabic text select * appropriate, context-dependent font glyphs for each text element, which means * that they transform text into a glyph vector.
* *Text transformations are necessary when modern display technology is not * available or when text needs to be transformed to or from legacy formats that * use "shaped" characters. Since the Arabic script is cursive, connecting * adjacent letters to each other, computers select images for each letter based * on the surrounding letters. This usually results in four images per Arabic * letter: initial, middle, final, and isolated forms. In Unicode, on the other * hand, letters are normally stored abstract, and a display system is expected * to select the necessary glyphs. (This makes searching and other text * processing easier because the same letter has only one code.) It is possible * to mimic this with text transformations because there are characters in * Unicode that are rendered as letters with a specific shape * (or cursive connectivity). They were included for interoperability with * legacy systems and codepages, and for unsophisticated display systems.
* *A second kind of text transformations is supported for Arabic digits: * For compatibility with legacy codepages that only include European digits, * it is possible to replace one set of digits by another, changing the * character code points. These operations can be performed for either * Arabic-Indic Digits (U+0660...U+0669) or Eastern (Extended) Arabic-Indic * digits (U+06f0...U+06f9).
* *Some replacements may result in more or fewer characters (code points). * By default, this means that the destination buffer may receive text with a * length different from the source length. Some legacy systems rely on the * length of the text to be constant. They expect extra spaces to be added * or consumed either next to the affected character or at the end of the * text.
* *For details about the available operations, see the description of the
* U_SHAPE_... options.
source.
*
* @param dest The destination buffer that will receive the results of the
* requested operations. It may be NULL only if
* destSize is 0. The source and destination must not
* overlap.
*
* @param destSize The size (capacity) of the destination buffer in UChars.
* If destSize is 0, then no output is produced,
* but the necessary buffer size is returned ("preflighting").
*
* @param options This is a 32-bit set of flags that specify the operations
* that are performed on the input text. If no error occurs,
* then t