GNOME Bugzilla – Bug 132378
Problem with Arabic Orphan Marks
Last modified: 2004-12-22 21:47:04 UTC
We were working on Fall-Back rendering for Arabic language, but there are
some problems for Arabic Orphan Marks:
1- Pango doesn't find any valid shape engine for Orpahn marks, because, the
script specified for Arabic marks in "pango_script_table" is
"PANGO_SCRIPT_INHERITED" not "PANGO_SCRIPT_ARABIC".
2- FriBIDI gives an Odd level number for Arabic Orphan marks, so, even if
Pango shape them with Arabic shape engine, positioning rules can not be
applied to them, because in OpenType lookup and rules (OTL), Arabic runs
are assumed to be RTL.
From what I see in the code, Pango renders all marks on the previous
character in the visual stream. So never assumes that a mark is used
in an RTL context. Moreover, I really doubt that FriBidi assigns an
odd level to an orphan mark. Marks simply get the level of their base
Moreover, ASAIK Arabic module in Pango does nothing about marks, so I
cannot see what the bug is.
I don't think trying to make sure that "orphan" Arabic fonts
always go to the Arabic shaper makes sense, so this just
duplicates bug 103938 or bug 127176; whatever engine gets
the orphan mark needs to handle it the best it can.
*** This bug has been marked as a duplicate of 103938 ***