The PangoDirection type represents a direction in the Unicode bidirectional algorithm; not every value in this enumeration makes sense for every usage of PangoDirection; for example, the return value of pango_unichar_direction() and pango_find_base_dir() cannot be PANGO_DIRECTION_WEAK_LTR or PANGO_DIRECTION_WEAK_RTL, since every character is either neutral or has a strong direction; on the other hand PANGO_DIRECTION_NEUTRAL doesn't make sense to pass to pango_itemize_with_base_dir().
The PANGO_DIRECTION_TTB_LTR, PANGO_DIRECTION_TTB_RTL values come from an earlier interpretation of this enumeration as the writing direction of a block of text and are no longer used; See PangoGravity for how vertical text is handled in Pango.
If you are interested in text direction, you should really use fribidi directly. PangoDirection is only retained because it is used in some public apis.
A strong left-to-right direction
A strong right-to-left direction
Deprecated value; treated the same as PANGO_DIRECTION_RTL.
Deprecated value; treated the same as PANGO_DIRECTION_LTR
A weak left-to-right direction
A weak right-to-left direction
No direction specified