Inside Macintosh: Programming With the Text Encoding Conversion Manager /

Chapter 4 - Unicode Converter Reference / Unicode Converter Constants

Fallback-Handler Control Flags

A fallback mapping is a sequence of one or more characters in the destination encoding that are not exactly equivalent to the source characters but which preserve some of the information of the original. For example, (C) is a possible fallback mapping for ©.

A fallback handler is a function that the Unicode Converter uses to perform fallback mapping. The Unicode Converter supplies a default fallback handler. You can provide your own fallback handler and use it alone, or you can use both. Using fallback control flags, described in "Fallback-Handler Control Flags" (page 115), you can specify the order in which both handlers are called if one fails.

You can set control flags to specify which fallback handler the Unicode Converter should use. If both are to be used, you can set the order in which they are called.

The following enumeration defines constants for the setting the controlFlags parameter of the functions SetFallbackUnicodeToText (page 172) and SetFallbackUnicodeToTextRun (page 175).

enum {
   kUnicodeFallbackDefaultOnly = 0L,
   kUnicodeFallbackCustomOnly= 1L,
   kUnicodeFallbackDefaultFirst= 2L,
   kUnicodeFallbackCustomFirst= 3L
};

Constant descriptions

kUnicodeFallbackDefaultOnly

Use the default fallback handler only.

kUnicodeFallbackCustomOnly

Use the custom fallback handler only.

kUnicodeFallbackDefaultFirst

Use the default fallback handler first, then the custom one.

kUnicodeFallbackCustomFirst

Use the custom fallback handler first, then the default one.