The Gravity type represents the orientation of glyphs in a segment of text. This is useful when rendering vertical text layouts. In those situations, the layout is rotated using a non-identity PangoMatrix, and then glyph orientation is controlled using Gravity. Not every value in this enumeration makes sense for every usage of Gravity; for example, AUTO only can be passed to set_base_gravity and can only be returned by get_base_gravity.
See also: GravityHint