Retrieves an array of logical attributes for each character in
the layout. This function will return a table that contains
a subtable for each character in the layout. Each subtable will
be have the following fields initialized:
IsLineBreak-
If set, can break line in front of character.
IsMandatoryBreak-
If set, must break line in front of character.
IsCharBreak-
If set, can break here when doing character wrapping.
IsWhite-
Is whitespace character.
IsCursorPosition-
If set, cursor can appear in front of character. i.e. this is a grapheme boundary, or the first character in the text.
This flag implements Unicode's Grapheme Cluster Boundaries semantics.
IsWordStart-
Is first character in a word.
IsWordEnd-
Is first non-word char after a word. Note that in degenerate cases, you could have both
IsWordStart and IsWordEnd set for some character.
IsSentenceBoundary-
Is a sentence boundary. There are two ways to divide sentences. The first assigns all inter-sentence whitespace/control/format chars
to some sentence, so all chars are in some sentence;
IsSentenceBoundary denotes the boundaries there. The second way doesn't assign
between-sentence spaces, etc. to any sentence, so IsSentenceStart / IsSentenceEnd mark the boundaries of those sentences.
IsSentenceStart-
Is first character in a sentence.
IsSentenceEnd-
Is first char after a sentence. Note that in degenerate cases, you could have both
IsSentenceStart and IsSentenceEnd set for some
character. (e.g. no space after a period, so the next sentence starts right away).
BackspaceDeletesCharacter-
If set, backspace deletes one character rather than the entire grapheme cluster. This field is only meaningful on grapheme boundaries
(where
IsCursorPosition is set). In some languages, the full grapheme (e.g. letter + diacritics) is considered a unit, while in others,
each decomposed character in the grapheme is a unit. In the default implementation of pango break, this bit is set on all grapheme
boundaries except those following Latin, Cyrillic or Greek base characters.
IsExpandableSpace-
Is a whitespace character that can possibly be expanded for justification purposes.
IsWordBoundary-
Is a word boundary, as defined by UAX#29. More specifically, means that this is not a position in the middle of a word. For example,
both sides of a punctuation mark are considered word boundaries. This flag is particularly useful when selecting text word-by-word.
This flag implements Unicode’s Word Boundaries semantics.
The number of attributes returned in the table will be one more
than the total number of characters in the layout, since there
need to be attributes corresponding to both the position before
the first character and the position after the last character.