Referencing positions and ranges in a character string

TTextRegion and TTextRange provide the protocol for referencing a range of text in an address-independent manner. A TTextRegion instance consists of one or more TTextRange instances. You can iterate through the TTextRange instances contained by a TTextRegion using a TTextRegionIterator. Each TTextRange stores the beginning text offset and the length of the range. Use TTextRange or TTextRegion to specify part or all of the text within a text object.

The classes for representing these character ranges are based on three primitive types:

• TTextIndex references the position of a single character and is typically used to access an individual character within a text object. Text indexes are zero-based. Use TTextIndex as you would use an array index to access a data array.
• TTextOffset references the position between two characters and is typically used to specify an insertion point between two characters or the endpoint of a range of characters. Text offsets are zero-based; a text offset of zero is the position immediately before the first character in the text object. You can use text offsets as a relative measure. For example, you can shift a text offset by either a positive or negative number.
• TTextCount contains the number of Unicode characters, or UniChars, in a text range. TTextCount is typically used to represent the length of an entire text object or a particular range.