bug#11860: 24.1; Arabic - Harakat (diacritics, short vowels) don't appear

[Kenichi Handa]

In article <83vcfhvowu.fsf@gnu.org>, Eli Zaretskii <eliz@gnu.org> writes:

> OK, but in this case we are talking about diacriticals, which are
> always drawn in the same character cell as the base character.  IOW,
> the pen does not advance until the entire gstring is drawn.  In that
> case, whatever Ffont_shape_gstring does will not affect the result on
> the screen, would it?

If a font driver decided to adjust the drawing poistion of a
base character, Ffont_shape_gstring wrongly combines that
character with the previous cluster, which results in wrong
display position of that base character.

For instance, provided upcases are base characters and
downcases are diacriticals, an RTL text "AaBbCc" should be
displayed as "CcBbAa", but if Ffont_shape_gstring wrongly
segment it as "AaBb" and "Cc", it is displayed as "CcAaBb.

---
Kenichi Handa
handa@gnu.org