You can use one of these constants to set or obtain glyph direction in a line of text or an entire text layout object, regardless of their font-specified direction; see the functions ATSUSetLayoutControls, ATSUSetLineControls, ATSUGetLayoutControl, and ATSUGetLineControl.
enum {
kATSULeftToRightBaseDirection = 0,
kATSURightToLeftBaseDirection = 1
};
Constant descriptions
kATSULeftToRightBaseDirection
Imposes left-to-right direction on glyphs in a line of horizontal text; for vertical text, imposes top-to-bottom direction.
kATSURightToLeftBaseDirection
Imposes right-to-left direction on glyphs in a line of horizontal text; for vertical text, imposes bottom-to-top direction.
