Re: [ft-devel] [PATCH] Always check the checksum to identify tricky fonts

[Kan-Ru Chen]

address@hidden writes:

> Dear Kan-Ru Chen,
>
> On Sat, 23 Apr 2011 18:37:53 +0800
> Kan-Ru Chen <address@hidden> wrote:
>>example PDF file attached.
>
> Thank you very much for providing interesting sample,
> I have to fix this issue. Your suggestion to prioritize
> the tricky font detection checksum than that by family
> name helps another issue (tricky font with non-ASCII
> family),
>       http://lists.gnu.org/archive/html/freetype-devel/2011-01/msg00003.html
> so I will apply your patch.

Thank you.

I find you changed the order of the checks. I think it is better to keep
the original order, because the family_name check is faster than the
checksum check (string comparison vs. some 32-bit arithmetic), and more
accurate, consider that checksums may have collisions.

> But, there was a discussion that the tricky font detection
> by the checksum might be inaccurate for too short table,
>       http://lists.gnu.org/archive/html/freetype-devel/2010-11/msg00033.html
> so there is a possiblity that I have to revert the change
> and improve the condition to detect mangled family name.

I see. Would it help if we use stronger hash method?

> # Among the bugzillas of poppler library and its client
> # applications, "please enable freetype hinting always",
> # "please disable freetype hinting always" are popular
> # requests.
>
> Your sample PDF seems to be generated by "Crystal Reports",
> if you know any other softwares generating a PDF including
> mangled family names, please let me know.

OK.

Cheers,
Kanru