[Nix-dev] How to downgrade or patch freetype-2.7 ?

[Volth]

There are still at least one place where
"environment.sessionVariables.LD_LIBRARY_PATH = ..." does not replace
freetype with a custom-built version: in cgi-scripts run under
lighttpd service:

RRD rendered with stock freetype-2.7.1 http://i.imgur.com/HVZ5iPa.png
RRD rendered with freetype-2.7.1 compiled without subpixel rendering
(#define TT_CONFIG_OPTION_SUBPIXEL_HINTING 0):
http://i.imgur.com/Qj4W0Lx.png


On 4/20/17, Volth <volth at volth.com> wrote:
> On 4/20/17, Thomas Tuegel <ttuegel at mailbox.org> wrote:
>> Volth <volth at volth.com> writes:
>>
>>> The second (http://imgur.com/MDiydzS) is what we get with these
>>> fontconfig rules on NixOS-17.09 (freetype-2.7.1) with default v40.
>>> Antialias is off, but hinting is not in action.
>>
>> Did you intentionally turn off hinting in that sample, or is it just not
>> working? Even with v40, it should be possible to achieve good results
>> with full hinting and no antialiasing.
>
> Hinting is on, the difference between the 2nd and the 3rd images is
> only 35 vs. 40 in the environment variable.
> If you want to reproduce, you may disable antialiasing and enable full
> hinting for pkgs.ubuntu_font_family or pkgs.liberation_ttf_v1_binary
> which are in nixpkgs.
>
>>> PS. v38 works similar to v40. It easy to turn in off by
>>> "config.fonts.fontconfig.ultimate.enable = false;".
>>> What I was looking for is a similar easy way to turn off v40 appeared
>>> in NixOS-unstable.
>>
>> That setting doesn't actually turn off v38! It turns off the
>> fontconfig-ultimate settings, but FreeType 2.6 is still patched to use
>> v38 instead of v35. So, if you could get acceptable rendering with
>> FreeType 2.6 on NixOS (which used v38), we should also be able to fix it
>> with FreeType 2.7 (v40) too.
>
> There was a visually similar issue in 17.03 with liberation_ttf_2.xx
> [1] which forced me to downgrade to 1.07. In 17.09 even
> liberation_ttf_1.07.xx became broken.
>
> There are clearly two diverging ways: the mainstream with
> antialiasing, subpixel rendering, gray-on-white texts, ... and the
> minority people who want to stay with contrast fonts rendered using
> only two colors (foreground and background). In order to stay the
> ground both the fonts and freetype are to be downgraded to their
> previous versions, so it won't be so long to lose the battle. Anyway,
> as dpi grows and pixels became invisible, it won't be the matter at
> all.
>
> 1. https://github.com/NixOS/nixpkgs/issues/21806
>