[OpenJDK 2D-Dev] [PATCH FOR REVIEW] fix for fontmanager when no fonts are installed - RHBZ#862355,

Jiri Vanek jvanek at redhat.com
Tue Nov 13 14:47:57 UTC 2012

Thank you both for valuable feedback,

Yes, this was very straight-forward fix, but also the less harmful. I tested it quite heavvily, and 
it does not move failure to "just later". Jre is working pretty find (as all calls to 
FontManagerFactory are returning this stub, which is making its job quite fine:)
This fix was really intended for small (but maybe bigger then we think) group of headless devices, 
where openjdk have its place. Such a device can have pretty good output eg via html, but no need for 
fonts at "server" at all. This headless device will definitely have no need for fonts at all.
Except eg generating captcha which can be exactly the usage you have described.

However your contra-usecase with  misconfigured system or JRE is more then true, and I agree with 
it. The workaround for user, to provide his ttf as default font can be maybe best solution.

The approach of OracleJDK is well known to me - It have its default fonts. In world of opensource 
the fonts were always little bit painful topic, but still this solution may be working to.

Anyway both solution above are  workarounds and does not fix the issue that createFont(or even most 
of jre)  should work no meter what fonts are installed.

Another suggested patch was make it configurable - but then it already is, as one can easily provide 
custom font manager via sun.font.fontmanager property. Then we can maybe make life little bit more 
easier by adding such "improved"  fontmanager implementation.

I'm sorry for providing just linux implementation, but linux is probably target platform in such a 
devices. It was also serving as proof of concept. I'm definitely going to implement this also for 
win/mac when possible solution will be clarified.

Currently I'm definitely for adding NoFontsFound exception (better then NullPointException, and 
maybe extend it also for case that this Array have 0 length[just idea during writing]?), and think 
little bit more about it.
  Although I still like "my approach" the most, I'm going to obey yours advice but I still believe 
this issue is worthy to be fixed.

Best regards,

> 2012/11/12 Phil Race <philip.race at oracle.com <mailto:philip.race at oracle.com>>
>     Well this seems like a really narrow use case for an extremely rare system
>     misconfiguration. It wouldn't help the 99.999% of apps which expect to
>     kick off AWT or Swing.
>     And can you ensure that nothing in the app, or in the implementation makes
>     the (reasonable) expectation that there are other fonts installed ?
>     The most you could do is render to a BufferedImage or similar using the explicitly
>     loaded font. The default logical font installed on a SG2D will be backed by a non-existent
>     physical font, so you'd need to swap that in sooner rather than later.
>     At some point you have to say that if JRE or system components are missing,
>     then the source of the problem is what you should fix rather than make the
>     JRE work around it.
>     If you do want to try something, then in this case you get a much more usable
>     runtime by providing a default font that the JRE can ensure is available so
>     that the other 99.999% of apps can get by.
>     The "Oracle" JDK gets by in this case precisely because it has a real physical font
>     to fall back on.
>     -phil.
> Hi Phil,
> I'm thinking here of Headless or embedded devices where the full Swing/AWT support may not be needed.
> Anyway, I see your point that those cases are definitely the minority and if OpenJDK doesn't want to
> work on those system, then I can only say that whoever is going to have such use case can just apply
> this patch and live with it.
> I totally agree however that if this comes from a misconfiguration rather than a conscious decision
> the JDK should probably protect itself by failing earlier (it will fail anyway, as you noted though).
> Perhaps a better patch would be to allow this to be configurable, by still introducing this new
> FontManager but making it a named class and allow this as an option, defaulting on the old
> behaviour, and at the same time giving a better error message.
> Also, like you suggest, ship a fallback in jre/lib/fonts sound a better idea in most cases.
> Cheers,
> Mario
>     On 11/12/2012 12:29 PM, Mario Torre wrote:
>         Hi Phil,
>         I believe that the underlying problem here is that it should be legal to create a font from
>         a file, even if the FontManager doesn't have any fonts installed.
>         So, code like the one in the example:
>         public class Test {
>               public static void main(String[] args) throws Exception {
>                   Font.createFont(Font.TRUETYPE___FONT, new File("example.ttf"));
>               }
>         }
>         When passed a real, valid font (example.ttf in this case) would still fail with the old
>         code, and instead would work with the given patch (at least, I think this is the idea here,
>         Jiri can probably explain in more details his intentions?).
>         Cheers,
>         Mario
>         2012/11/12 Phil Race <philip.race at oracle.com <mailto:philip.race at oracle.com>
>         <mailto:philip.race at oracle.com <mailto:philip.race at oracle.com>__>>
>              Hello Jiri,
>              Doesn't this just move the point of failure to a bit later ?
>              I can't see how having zero fonts on the system is survivable for an
>              app that uses fonts. That's the principal reason we haven't tried
>              to do something like this already.
>              When facing system configuration issues maybe we just need to
>              print a better message for the exception such as
>              throw new InternalError("Can't find any fonts installed on this
>              system.");
>              Or make the default font more configurable and distros could ship
>              one in jre/lib/fonts.
>              BTW it appears you are only trying to solve the problem for
>              Linux/Unix.
>              Nothing for Windows or OS X.
>              -phil.
>              On 11/12/2012 10:07 AM, Jiri Vanek wrote:
>                  Hi!
>                  This is attempt to fix
>         https://bugzilla.redhat.com/__show_bug.cgi?id=862355
>         <https://bugzilla.redhat.com/show_bug.cgi?id=862355>
>                  The patch is introducing new exception
>                  src/share/classes/sun/font/__NoFontsFoundException.java, which
>                  is thrown from
>                  /src/solaris/classes/sun/awt/__X11FontManager.java    instead of
>                  null pointer exception when no fonts are found on system.
>                  Exception is then catch in
>                  src/share/classes/sun/font/__FontManagerFactory.java, and in
>                  this case it returns (and not caching the instance of it)
>                  dummy font manager instead of continue in failure.
>                  the dummy manager do nothing, except that it is able to create
>                  java.awt.Font in same way as SunFontManager is doing, but is
>                  not doing any caching.
>                  To avoid duplicate code with
>                  src/share/classes/sun/font/__SunFontManager.java, i have
>                  extracted code from method createFont2D to new method here -
>                  prepareFont2D - which is responsible for creating font until
>                  caching..
>                  Best regards,
>                    J.
>                  webrev
>         http://jvanek.fedorapeople.__org/oracle/jdk8/webrevs/__fontProperties/
>         <http://jvanek.fedorapeople.org/oracle/jdk8/webrevs/fontProperties/>
>                  with test  (although it will probably need some tuning and I'm
>                  not sure where is the best place for it)
>         http://jvanek.fedorapeople.__org/oracle/jdk8/webrevs/__fontProperties/test/src/__nofontsreproducer/
>         <http://jvanek.fedorapeople.org/oracle/jdk8/webrevs/fontProperties/test/src/nofontsreproducer/>
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