[isabelle-dev] Isabelle DejaVu against old Isabelle Text font

Christian Sternagel c.sternagel at gmail.com
Sun Feb 10 20:01:26 CET 2019

This is just to confirm that the result looks really great on my linux
(Fedora 29 with i3) setup. Thanks!


On 2/10/19 7:47 PM, Makarius wrote:
> On 08/02/2019 10:03, Christian Sternagel wrote:
>> I am glad to hear that others have the same experience, I thought my
>> eyes were going bad ;)
>> But seriously, "buy a new screen" is not always possible. For example,
>> in the upcoming summer term I am teaching an Isabelle class at the
>> University of Innsbruck. In my experience (and I just reconfirmed this
>> for the room I will be teaching in), the projectors we have here a
>> typically rather old (and have low resolution, but that is a different
>> story).
>> At the moment there is a palpable difference (font rendering crispness
>> wise) between using Isabelle2018 with projector (which I will do anyway
>> for my class) and some recent development version (sorry I didn't note
>> down what changeset I used for testing my setup).
> Classic JDK 8 from Oracle and OpenJDK 11 (e.g. from AdoptOpenJDK) are
> different in many ways, and it is definitely required to get used to the
> new look of font rendering. (For me Isabelle2018 already looks very
> strange.)
> With proper parameters -- in software and hardware -- fonts should come
> out better than before.
> First of all, sub-pixel rendering should be enabled, see this NEWS entry
> from Isabelle/f714114b0571 (25-Oct-2018):
>   *** Isabelle/jEdit Prover IDE ***
>   * Improved sub-pixel font rendering (especially on Linux), thanks to
> OpenJDK 11.
> (In Java 8, sub-pixel rendering made things worse.)
> Since that that NEWS entry is a bit too implicit, I have now changed the
> default to enable "Subpixel HRGB" always on all platforms
> (Isabelle/f610115ca3d0). I have checked my usual test machines for
> Windows and macOS, to see that it all looks fine.
> Secondly, I have done some more research on FreeType, the renderer used
> for OpenJDK on Linux. It appears that the DejaVu family gets some
> special treatment if it shows up under its original name, but not if it
> is a renamed copy. So I have fine-tuned the Isabelle DejaVu fonts in
> Isabelle/4791988fcbc4 to impose the FreeType auto-hinting beforehand to
> the TrueType file: this leads to isabelle_fonts-20190210 in
> Isabelle/7e5a7a11d5d1.
> In summary:
>   * Isabelle font rendering should be once again slightly better on Linux.
>   * There is a small risk that it has slightly degraded on Windows and
> macOS.
> In other words: early adopters should look closely if it is all fine. We
> are (very slowly) moving towards the Isabelle2019 release (presumably
> June 2019), and everything needs to be beyond doubt when released.
> 	Makarius

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