[Bug 1545149] New: OTF/CFF conts no longer hinted horizontally

https://bugzilla.redhat.com/show_bug.cgi?id=1545149

Bug ID: 1545149
           Summary: OTF/CFF conts no longer hinted horizontally
           Product: Fedora
           Version: 27
         Component: freetype
          Assignee: [e-mail]
          Reporter: [e-mail]
        QA Contact: [e-mail]
                CC: [e-mail], [e-mail],
                    [e-mail],
                    [e-mail], [e-mail],
                    [e-mail], [e-mail],
                    [e-mail], [e-mail],
                    [e-mail], [e-mail]

I upgraded from Fedora 26 to Fedora 27 and all of a sudden OTF/CFF fonts such
as Cantarell are no longer hinted horizontally, making them appear blurry and
out of focus.

A similar change was done for TTF fonts previously, but that could be reverted
by setting "FREETYPE_PROPERTIES=truetype:interpreter-version=35".

Is there a similar setting hidden for this latest change? The normal font
hinting settings have no effect on this.

[Bug 1545149] OTF/CFF conts no longer hinted horizontally

https://bugzilla.redhat.com/show_bug.cgi?id=1545149

Nikolaus Waxweiler  changed:

What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |[e-mail]

--- Comment #1 from Nikolaus Waxweiler  ---
OTFs weren't hinted horizontally before, what was turned off was stem
darkening. If you prefer a thicker look, try

FREETYPE_PROPERTIES="truetype:interpreter-version=35 cff:no-stem-darkening=0"

See
https://www.freetype.org/freetype2/docs/text-rendering-general.html#disabled....

[Bug 1545149] OTF/CFF conts no longer hinted horizontally

https://bugzilla.redhat.com/show_bug.cgi?id=1545149

--- Comment #2 from Pierre Ossman  ---
Hmm... I don't think that was it.

Crap. I can't really reproduce any issue. I should have taken screen shots back
in February.

Perhaps there was something wrong with the auto-hinter that got fixed? Right
now Cantarell looks like shit with the standard hinting. But the autohinter
sorts that out, and it most definitely does some horizontal hinting, at least
for Cantarell.

[Bug 1545149] OTF/CFF conts no longer hinted horizontally

https://bugzilla.redhat.com/show_bug.cgi?id=1545149

--- Comment #3 from Pierre Ossman  ---
Scratch that, even with the auto hinter it still is pretty bad when you
actually start using it. And fortunately I found an old screen shot of how it
used to render. So please see the attachment for a comparison. In the old
version it used to hint horizontally very aggressively.

[Bug 1545149] OTF/CFF conts no longer hinted horizontally

https://bugzilla.redhat.com/show_bug.cgi?id=1545149

--- Comment #4 from Pierre Ossman  ---
Created attachment 1501958
  --> https://bugzilla.redhat.com/attachment.cgi?id=1501958&action=edit
rendering comparison

[Bug 1545149] OTF/CFF conts no longer hinted horizontally

https://bugzilla.redhat.com/show_bug.cgi?id=1545149

--- Comment #5 from Nikolaus Waxweiler  ---
Interesting. I can't immediately find which FreeType F26 shipped with, your F26
image however looks like you had full hinting and autohinting active at the
same time. Try adding this to your fontconfig config:

<match target="font">
    <test name="family">
      <string>Cantarell</string>
    </test>
    <edit mode="assign" name="hinting">
      <bool>true</bool>
    </edit>
    <edit mode="assign" name="autohint">
      <bool>true</bool>
    </edit>
    <edit mode="assign" name="hintstyle">
      <const>hintfull</const>
    </edit>
  </match>

(Not sure if you need to use 'match target="font"' or '...="pattern"')

If that doesn't match what you had before, another possibility was that your FT
was using the previous CFF renderer before Adobe contributed the one in current
use. I don't think you can select the old one through fontconfig, it's a
compile time option iirc.

[Bug 1545149] OTF/CFF conts no longer hinted horizontally

https://bugzilla.redhat.com/show_bug.cgi?id=1545149

--- Comment #6 from Pierre Ossman  ---
(In reply to Nikolaus Waxweiler from comment #5)
> Interesting. I can't immediately find which FreeType F26 shipped with, your
> F26 image however looks like you had full hinting and autohinting active at
> the same time. Try adding this to your fontconfig config:
>
> ...

I already had such a file to force the autohinter. But the other additions had
no effect.

But I was already enabling full hinting through gnome tweak tool. Anything
other than full hinting gives blurry text almost by definition.
> If that doesn't match what you had before, another possibility was that your
> FT was using the previous CFF renderer before Adobe contributed the one in
> current use. I don't think you can select the old one through fontconfig,
> it's a compile time option iirc.

I doubt it. Fedora 26 uses 2.7 according to the Fedora repo. And the Adobe
engine was added in 2.5 if I understand things correctly.

[Bug 1545149] OTF/CFF conts no longer hinted horizontally

https://bugzilla.redhat.com/show_bug.cgi?id=1545149

--- Comment #7 from Pierre Ossman  ---
Aha! I think I found the missing detail to test this. You need to enable
subpixel hinting as well. Apparently I disabled that somewhere along the line
of finding a workaround for this issue.

So:

* Forced autohinter for Cantarell
 * Full hinting
 * Subpixel hinting

Then compare Fedora 28 and freetype-2.7.1-10.fc26. You'll see sharp stems with
the 2.7.1, and fuzzy ones with 2.8.

You can test this directly on your Fedora 28 machine. Just download the old RPM
here:

https://koji.fedoraproject.org/koji/buildinfo?buildID=1045246

Unpack it using rpm2cpio, and then point at it using LD_LIBRARY_PATH. Then you
can easily compare then new and old stuff.

[Bug 1545149] OTF/CFF conts no longer hinted horizontally

https://bugzilla.redhat.com/show_bug.cgi?id=1545149

--- Comment #8 from Nikolaus Waxweiler  ---
Do you mean subpixel rendering?

This is interesting. In ftview from that build, If I enable normal
anti-aliasing (A) and forced autohinting (f) and switch to subpixel rendering
(C) and forced autohinting, some glyphs seems to glitch by being a pixel or so
wider at 16px (e.g. i, j, doubles quotes). Aside from that, nothing changes
significantly?

In the newest ftview from git, I can't seem to enable full autohinting with
subpixel rendering.

[Bug 1545149] OTF/CFF conts no longer hinted horizontally

https://bugzilla.redhat.com/show_bug.cgi?id=1545149

--- Comment #9 from Nikolaus Waxweiler  ---
Created attachment 1503145
  --> https://bugzilla.redhat.com/attachment.cgi?id=1503145&action=edit
Comparison shot

Upper left: ftview 2.7.1 with normal grayscale rendering plus forced
autohinting
Lower left: ftview 2.7.1 with RGB subpixel rendering plus forced autohinting
Upper right: ftview git master with normal grayscale rendering plus forced
autohinting

[Bug 1545149] OTF/CFF conts no longer hinted horizontally

https://bugzilla.redhat.com/show_bug.cgi?id=1545149

--- Comment #10 from Nikolaus Waxweiler  ---
Going on a limb here, have you tried enabling warping? Only available in slight
autohinting mode.

[Bug 1545149] OTF/CFF conts no longer hinted horizontally

https://bugzilla.redhat.com/show_bug.cgi?id=1545149

--- Comment #11 from Pierre Ossman  ---
instead. (In reply to Nikolaus Waxweiler from comment #8)
> Do you mean subpixel rendering?

Right, sorry. ftview does its own thing, so I started simply comparing GTK
applications. The setting I was referring to here is "Antialiasing: Subpixel"
in GNOME Tweaks.
> This is interesting. In ftview from that build, If I enable normal
> anti-aliasing (A) and forced autohinting (f) and switch to subpixel
> rendering (C) and forced autohinting, some glyphs seems to glitch by being a
> pixel or so wider at 16px (e.g. i, j, doubles quotes). Aside from that,
> nothing changes significantly?

ftview's rendering doesn't seem to be representative of what GTK does, so it
might not be the best test case. Your image does show a bit of the tendencies
though as there are a lot of single pixel wide stems in the lower left example.

(and the glitch is mentioned on bug 1035486 comment #36)
> In the newest ftview from git, I can't seem to enable full autohinting with
> subpixel rendering.

Isn't that the problem though? Neither ftview nor GTK is able to get that mode
fully working.

(In reply to Nikolaus Waxweiler from comment #10)
> Going on a limb here, have you tried enabling warping? Only available in
> slight autohinting mode.

It seems to have some effect, but it doesn't even compensate for the extra blur
caused by going from full hinting to slight.

[Bug 1545149] OTF/CFF conts no longer hinted horizontally

https://bugzilla.redhat.com/show_bug.cgi?id=1545149

--- Comment #12 from Ben Cotton  ---
This message is a reminder that Fedora 27 is nearing its end of life.
On 2018-Nov-30  Fedora will stop maintaining and issuing updates for
Fedora 27. It is Fedora's policy to close all bug reports from releases
that are no longer maintained. At that time this bug will be closed as
EOL if it remains open with a Fedora  'version' of '27'.

Package Maintainer: If you wish for this bug to remain open because you
plan to fix it in a currently maintained version, simply change the 'version' 
to a later Fedora version.

Thank you for reporting this issue and we are sorry that we were not 
able to fix it before Fedora 27 is end of life. If you would still like 
to see this bug fixed and are able to reproduce it against a later version 
of Fedora, you are encouraged  change the 'version' to a later Fedora 
version prior this bug is closed as described in the policy above.

Although we aim to fix as many bugs as possible during every release's 
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[Bug 1545149] OTF/CFF conts no longer hinted horizontally

https://bugzilla.redhat.com/show_bug.cgi?id=1545149

Pierre Ossman  changed:

What    |Removed                     |Added
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            Version|27                          |28