[OpenJDK 2D-Dev] RFR: 7017058: Malayalam glyph substitution is failing for Malayalam with Windows Kartika font.
Sergey.Bylokhov at oracle.com
Tue Sep 11 00:56:20 UTC 2018
On 04/09/2018 17:40, Philip Race wrote:
> This fixes 3 submitted bugs
> https://bugs.openjdk.java.net/browse/JDK-7017058 : the Malayalam bug above
> And also
> https://bugs.openjdk.java.net/browse/JDK-8191130 :
> Sinhala text rendering problem with C+VIRAMA+ZWJ+RA/YA+V
> opentype:Bengali: "Khanda Ta" shaping issue with U+09A4 TA, U+09CD
> virama, U+200D ZWJ
> Webrev: http://cr.openjdk.java.net/~prr/7017058/
> As discussed in the evaluation of 7017058, this is because of some code
> always maps several unicode formatting characters to the invisible glyph to
> ensure it is never rendered as a missing glyph box.
> But if the opentype tables in a font have glyph substitution looks ups that
> depend on that font's actual mapping of those glyphs then they are broken.
> We have had several reports of this (above) and also complaints this breaks
> Emoji family ligature substitution.
> The fix changes this to first consult the font to see if it does map
> these codepoints.
> If it does not then we still will map to the empty glyph in which case
> clearly the
> font can't have any lookup that depends on it.
> The variable origCharCode is added because several of the methods mutate
> and we avoid risk with this approach.
> The tab, NL and CR code points are still always mapped to the empty glyph
> since they are never going to be used by layout in this way and some fonts
> map TAB to a space char which is not what we want.
Best regards, Sergey.
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