[OpenJDK 2D-Dev] [9] RFR JDK-8147002:[macosx] Arabic character cannot be rendered on MacOS X

Phil Race philip.race at oracle.com
Wed Feb 15 17:10:12 UTC 2017

I don't know what versions of MacOS X either of you (Dmitry+Prasanta) 
used but I am going to guess they are different
(can you both report these, for the record).

In https://bugs.openjdk.java.net/browse/JDK-8147002, Prasanta enumerates
the cascade list for the Italic case and I don't see .NotoSansUniversal 
anywhere on that list.

So although if enumerated it likely still won't work (since it is not 
enumerated by the other APIs),
there does not appear to be any font in the cascade list reported by 
Prasanta that "would not work",
so the fix still seems fine to me as it is plugging a gap.

A fix for using "hidden" fonts in the cascade list seems like a JDK 10 
candidate unless there
is some critical case we are still missing.


On 02/13/2017 01:56 AM, Dmitry Batrak wrote:
> > Yes, we are aware this fixed it only for Oracle JDK.
> > The bit I missed is that GeezaProInterface was then used on OpenJDK by JRS.
> > So we could add that as well.
> > If you have any other fonts you think should be added to the tail of that list we
> > can add them too.
> I ran JRSFontCreateFallbackFontForCharacters against all Unicode code 
> points with Menlo-Italic as base font,
> and got 63 possible fallback fonts - vs 29 present in cascade list, 
> currently used by JDK 9 (given in JDK-8147002).
> So the mismatch is quite large. But the interesting thing is that 
> cascade list returned by
> CTFontCopyDefaultCascadeListForLanguages still covers that whole 
> Unicode range. The problem is that JDK
> doesn't use that list fully. In particular, Arabic alef letter U+0627 
> can be displayed using the font
> .NotoSansUniversal from that list. This font doesn't get into 
> composite font, as it's not found among the fonts
> known to Java. So a better fix (and still quite small) will probably 
> be using those 'hidden' fonts as part of
> cascade composites - by creating a new, 'local' CFont instance if 
> lookup in the known font list fails
> (this, btw, seems to work fine for us). If even this is considered 
> risky for JDK 9, then probably adding
> .NotoSansUniversal with or instead of .GeezaProInterface as a 
> hardcoded component makes sense.
> Best regards,
> Dmitry Batrak
> On Fri, Feb 10, 2017 at 8:19 PM, Phil Race <philip.race at oracle.com 
> <mailto:philip.race at oracle.com>> wrote:
>     I think that so long as we are using JRS* in some places and
>     CoreText's cascading list
>     in others there is the likelihood of some inconsistency where JRS
>     introduces some magic
>     that we don't know about
>     So canDisplay() needs to be fixed to be consistent and perhaps we
>     also need to see
>     if we are always getting the glyphs from the same fonts for the
>     cases where there
>     is no missing glyph.
>     I do agree that getting away from JRS* support is the way to go so
>     we are in control.
>     However not at this time in JDK 9.
>     Yes "." fonts are not enumerated by OS X but if you can find them
>     they work.
>     This is how the UI fonts are handled.
>     Yes, we are aware this fixed it only for Oracle JDK.
>     The bit I missed is that GeezaProInterface was then used on
>     OpenJDK by JRS.
>     So we could add that as well.
>     If you have any other fonts you think should be added to the tail
>     of that list we
>     can add them too.
>     -phil.
>     On 02/10/2017 07:59 AM, Dmitry Batrak wrote:
>         Hi,
>         I've tried to build OpenJDK from 'client' repository with the
>         fix, and the
>         issue is still reproducible for me. Are you fixing it only for
>         Oracle JDK
>         (including Lucida Sans Regular font), and not for OpenJDK? The
>         problem is not
>         that some character cannot be rendered using a particular
>         font, it's that
>         rendering behaviour doesn't match what 'canDisplay' returns.
>         If you're interested I can share the way we've fixed this
>         issue in our
>         OpenJDK-based runtime.
>         As you've mentioned, the problem is that
>         JRSFontCreateFallbackFontForCharacters returns fallback font,
>         which is not on
>         the cascaded font list, and it can be absent even in the whole
>         list of fonts
>         reported by the system. On my machine, with OpenJDK, it's
>         .GeezaProInterface
>         (with name starting with dot). I guess such fonts are treated
>         by macOS as
>         'hidden' (just like files with names starting with dots),
>         still they seem to be
>         usable from application if requested by their name.
>         As JRSFontCreateFallbackFontForCharacters is a 'black box',
>         it's hard to make
>         sure cascade list we're building matches its internal logic,
>         so we've chosen to
>         build the list dynamically based on the output of
>         JRSFontCreateFallbackFontForCharacters itself. I can try to
>         prepare
>         corresponding webrev, if you think that can be useful.
>         Alternative solution (and, probably, a better one
>         strategically), would be not
>         using JRSFontCreateFallbackFontForCharacters at all. The
>         cascade list, that is
>         built currently, can probably be used to perform font fallback
>         in all cases.
>         Best regards,
>         Dmitry Batrak
>         > Hi All,
>         >
>         > Please review a fix for an issue which causes arabic
>         character "alef" to
>         > be not rendered in osx for menlo font in italic style.
>         >
>         > Bug: https://bugs.openjdk.java.net/browse/JDK-8147002
>         <https://bugs.openjdk.java.net/browse/JDK-8147002>
>         >
>         > The issue was actually a regression caused by the fix to
>         JDK-7162125:
>         > [macosx] A font has different behaviour for ligatures
>         depending on its
>         > creation mode
>         > in which we have added cascaded font list to find the real
>         fonts that
>         > CFont uses, so that there is no need to use "negative" glyph
>         code for
>         > finding the fallback fonts
>         > using the "subsititution"/"fallback" mechanism used by osx code.
>         >
>         > However, the above logic of using cascaded font list in
>         CFont does not
>         > take into account of using JRE provided fonts like all those
>         Lucida* ttf
>         > in jdk/lib/fonts/, so
>         > when a glyph (in this intance, arabic 'alef' character) is
>         intended to
>         > be rendered in Menlo font in italic style, osx will not be
>         able to find
>         > the glyph in Menlo-Italic font
>         > and neither in all the cascaded system fonts provided by
>         CoreText, so it
>         > results in empty box.
>         >
>         > Before 7162125 fix, the fallback code in
>         >
>         CoreTextSupport.m#CTS_CopyCTFallbackFontAndGlyphForJavaGlyphCode()
>         uses
>         > JRSFontCreateFallbackFontForCharacters()
>         > was adding jre/lib/fonts to the fallback list which was
>         causing the
>         > glyph to be found in "LucidaBrightRegular.ttf" font and the
>         glyph was
>         > rendered.
>         >
>         > So, the proposed fix is to add jre provided font "Lucida
>         Sans Regular"
>         > to the cascaded list so that we get the "alef" glyph.
>         > The reason for choosing "Lucida Sans Regular" over "Lucida
>         Bright
>         > Regular" is, because it is the largest font file in jre and
>         has all the
>         > glyph codepoints that no other font in the jre has,
>         > so we will not lose out on any codepoints and will help us
>         in not
>         > getting missing glyph.
>         >
>         > webrev:
>         http://cr.openjdk.java.net/~psadhukhan/8147002/webrev.00/
>         <http://cr.openjdk.java.net/%7Epsadhukhan/8147002/webrev.00/>
>         <http://cr.openjdk.java.net/%7Epsadhukhan/8147002/webrev.00/
>         <http://cr.openjdk.java.net/%7Epsadhukhan/8147002/webrev.00/>>
>         >
>         > Regards
>         > Prasanta

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