sub-cluster selection
Submitted by Behdad Esfahbod
Link to original bug (#460832)
Description
From Owen's notes from pango bof at GUADEC:
- Taking advantage of the sub-cluster selection, cursor movement, hit-testing available in Graphite. (Might involve caching "user data" from the shaping run on PangoRun. Same infrastructure would be useful for non-linear OpenType carets.)
Essentially we need something parallel to pango_glyph_string_get_logical_widths() to return a rectangle or something, but the information is just not available in glyphstrings. So it needs to move to some other level (PangoRun, etc).
Another question is what to return? IIRC Owen said ATSUI returns a path. Can be useful when we take font slant into account for cursor drawing etc, but we don't have a generic path type anyway.