[Bug 1767499] New: Very bad kerning for Tahoma in Fedora 31

https://bugzilla.redhat.com/show_bug.cgi?id=1767499

Bug ID: 1767499
           Summary: Very bad kerning for Tahoma in Fedora 31
           Product: Fedora
           Version: 31
            Status: NEW
         Component: pango
          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]
  Target Milestone: ---
    Classification: Fedora

Created attachment 1631087
  --> https://bugzilla.redhat.com/attachment.cgi?id=1631087&action=edit
Tahoma as rendered by Pango 1.44 in Fedora 31

This is how Tahoma font is rendered in Fedora 31.

After downgrading to pango-1.43.0-4.fc30.x86_64.rpm the issue disappears.

[Bug 1767499] Very bad kerning for Tahoma in Fedora 31

https://bugzilla.redhat.com/show_bug.cgi?id=1767499

--- Comment #1 from Artem S. Tashkinov  ---
Created attachment 1631088
  --> https://bugzilla.redhat.com/attachment.cgi?id=1631088&action=edit
~/.config/fontconfig/fonts.conf

[Bug 1767499] Very bad kerning for Tahoma in Fedora 31

https://bugzilla.redhat.com/show_bug.cgi?id=1767499

--- Comment #2 from Artem S. Tashkinov  ---
Created attachment 1631089
  --> https://bugzilla.redhat.com/attachment.cgi?id=1631089&action=edit
Font itself

[Bug 1767499] Very bad kerning for Tahoma in Fedora 31

https://bugzilla.redhat.com/show_bug.cgi?id=1767499

--- Comment #3 from Artem S. Tashkinov  ---
My DE is XFCE.

screen #0:
  dimensions:    1920x1080 pixels (508x286 millimeters)
  resolution:    96x96 dots per inch

[Bug 1767499] Very bad kerning for Tahoma in Fedora 31

https://bugzilla.redhat.com/show_bug.cgi?id=1767499

Jens Petersen  changed:

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

[Bug 1767499] Very bad kerning for Tahoma in Fedora 31

https://bugzilla.redhat.com/show_bug.cgi?id=1767499

--- Comment #4 from Peng Wu  ---
Could you try the following patch?

https://gitlab.gnome.org/pwu/pango/commit/3cea6d3e2526f4900a180d75717be30d36...

The patch is only trying to find the cause of this problem.

Koji: https://koji.fedoraproject.org/koji/taskinfo?taskID=39192026

[Bug 1767499] Very bad kerning for Tahoma in Fedora 31

https://bugzilla.redhat.com/show_bug.cgi?id=1767499

--- Comment #5 from Artem S. Tashkinov  ---
Tried the build at https://koji.fedoraproject.org/koji/taskinfo?taskID=39192041
- no changes whatsoever.

You can install Tahoma in any Linux distro. I don't quite understand why I
should be debugging this issue on my end: it's reproducible in a few seconds.

[Bug 1767499] Very bad kerning for Tahoma in Fedora 31

https://bugzilla.redhat.com/show_bug.cgi?id=1767499

--- Comment #6 from Artem S. Tashkinov  ---
Created attachment 1639217
  --> https://bugzilla.redhat.com/attachment.cgi?id=1639217&action=edit
Tahoma

[Bug 1767499] Very bad kerning for Tahoma in Fedora 31

https://bugzilla.redhat.com/show_bug.cgi?id=1767499

--- Comment #7 from Nicolas Mailhot  ---
Tahoma and other parts of Microsoft’s “fonts for the web” are very early
display fonts with lots of technical mistakes.

So, they are challenging to display correctly, because they are, basically,
incorrect (they were built around the bugs of the Windows text engine, and the
screen pixel resolutions, of the time, both of which do not apply on a 2019
Linux system).

The version Microsoft ships in Windows has been fixed a long time ago (or they
may special-case it, I don’t remember).

The version people keep installing on Linux is the same 1990’s Microsoft dump.
Because they do not have access to the fixed font files for legal reasons.

[Bug 1767499] Very bad kerning for Tahoma in Fedora 31

https://bugzilla.redhat.com/show_bug.cgi?id=1767499

--- Comment #8 from Artem S. Tashkinov  ---
I've just installed the Tahoma font from Windows 10 LTSC - the result is
absolutely the same.

You can freely get the font by downloading Windows 10 ISO from Microsoft
website, then using 7zip to extract the fonts from install.wim

In case that's two difficult for you I've uploaded the font to my Google Drive:

https://drive.google.com/drive/folders/1d8l1OP08LCSBMrCpKLxniOR9Q_bFuoDV

[Bug 1767499] Very bad kerning for Tahoma in Fedora 31

https://bugzilla.redhat.com/show_bug.cgi?id=1767499

--- Comment #9 from Artem S. Tashkinov  ---
Created attachment 1639251
  --> https://bugzilla.redhat.com/attachment.cgi?id=1639251&action=edit
Tahoma from Windows 10 with pango 1.44.7

[Bug 1767499] Very bad kerning for Tahoma in Fedora 31

https://bugzilla.redhat.com/show_bug.cgi?id=1767499

--- Comment #10 from Peng Wu  ---
Actually I think the patch will make the text rendering one pixel positioning
different.

Please provide whether this test version of pango works as old version or not.

Please try it with re-login or reboot.

[Bug 1767499] Very bad kerning for Tahoma in Fedora 31

https://bugzilla.redhat.com/show_bug.cgi?id=1767499

--- Comment #11 from Artem S. Tashkinov  ---
(In reply to Peng Wu from comment #10)

I did re-login.

The results are already posted.

I don't have a 20/20 vision to see a one pixel difference but overall it looks
the same to me. You're free to use GIMP or any other graphics editor to spot
the difference.

[Bug 1767499] Very bad kerning for Tahoma in Fedora 31

https://bugzilla.redhat.com/show_bug.cgi?id=1767499

--- Comment #12 from Artem S. Tashkinov  ---
Created attachment 1639435
  --> https://bugzilla.redhat.com/attachment.cgi?id=1639435&action=edit
WMT with the official update 1.44.7

[Bug 1767499] Very bad kerning for Tahoma in Fedora 31

https://bugzilla.redhat.com/show_bug.cgi?id=1767499

--- Comment #13 from Artem S. Tashkinov  ---
Created attachment 1639436
  --> https://bugzilla.redhat.com/attachment.cgi?id=1639436&action=edit
WMT with the test update 1.44.7

[Bug 1767499] Very bad kerning for Tahoma in Fedora 31

https://bugzilla.redhat.com/show_bug.cgi?id=1767499

--- Comment #14 from Artem S. Tashkinov  ---
Yes the PNG files turned out to be slightly different which means there's a
difference in output.

[Bug 1767499] Very bad kerning for Tahoma in Fedora 31

https://bugzilla.redhat.com/show_bug.cgi?id=1767499

--- Comment #15 from Artem S. Tashkinov  ---
Created attachment 1639437
  --> https://bugzilla.redhat.com/attachment.cgi?id=1639437&action=edit
The difference between the official update and the test version

[Bug 1767499] Very bad kerning for Tahoma in Fedora 31

https://bugzilla.redhat.com/show_bug.cgi?id=1767499

--- Comment #16 from Peng Wu  ---
Please provide the screenshot of the expected result.

[Bug 1767499] Very bad kerning for Tahoma in Fedora 31

https://bugzilla.redhat.com/show_bug.cgi?id=1767499

--- Comment #17 from Artem S. Tashkinov  ---
Created attachment 1639774
  --> https://bugzilla.redhat.com/attachment.cgi?id=1639774&action=edit
WMT with pango 1.43

(In reply to Peng Wu from comment #16)
> Please provide the screenshot of the expected result.

[Bug 1767499] Very bad kerning for Tahoma in Fedora 31

https://bugzilla.redhat.com/show_bug.cgi?id=1767499

Constantine Gavrilov  changed:

What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |constantine.gavrilov@gmail.
                   |                            |com

--- Comment #18 from Constantine Gavrilov  ---
I have finally found what is the reason. For me, the switch from Fedora 29 with
freetype-freeworld from RPMFUSION to Fedora-31 with freetype with supposedly
included sub-pixel rendering was really painful, especially on 4k screen, and
especially when screen scaling was done.
The reason is that the freetype build Fedora 31 enables subpixel rendering, but
disables LCD filter. This breaks the rendering. I believe this is an error,
since both are covered by the same patent, and both must be enabled for
subpixel rendering to work corretcly.

The following simple patch fixes it:

-- src/smooth/ftsmooth.c.orig  2020-01-26 19:29:22.287267057 +0200
+++ src/smooth/ftsmooth.c       2020-01-26 19:35:55.302516806 +0200
@@ -44,7 +44,7 @@
     sub[2].x = 21;
     sub[2].y = 0;

-#elif 0   /* or else, once ClearType patents expire */
+#else

FT_Library_SetLcdFilter( render->root.library, FT_LCD_FILTER_DEFAULT );

And the code block in question is:

/* initialize renderer -- init its raster */
  static FT_Error
  ft_smooth_init( FT_Renderer  render )
  {

#ifndef FT_CONFIG_OPTION_SUBPIXEL_RENDERING

FT_Vector*  sub = render->root.library->lcd_geometry;

/* set up default subpixel geometry for striped RGB panels. */
    sub[0].x = -21;
    sub[0].y = 0;
    sub[1].x = 0;
    sub[1].y = 0;
    sub[2].x = 21;
    sub[2].y = 0;

#elif 0   /* or else, once ClearType patents expire */ <<< BOOM ISSUE HERE

FT_Library_SetLcdFilter( render->root.library, FT_LCD_FILTER_DEFAULT );

#endif

Recompiling the freetype with the fix, brings back very crips fonts, as opposed
to stock ugly fat Fedora 31 fonts.

[Bug 1767499] Very bad kerning for Tahoma in Fedora 31

https://bugzilla.redhat.com/show_bug.cgi?id=1767499

Peng Wu  changed:

What    |Removed                     |Added
----------------------------------------------------------------------------
              Flags|                            |needinfo?(constantine.gavri
                   |                            |[e-mail])

--- Comment #19 from Peng Wu  ---
Could you provide the result screenshot with your patch?

[Bug 1767499] Very bad kerning for Tahoma in Fedora 31

https://bugzilla.redhat.com/show_bug.cgi?id=1767499

--- Comment #20 from Artem S. Tashkinov  ---
Created attachment 1667695
  --> https://bugzilla.redhat.com/attachment.cgi?id=1667695&action=edit
Microsoft core fonts broken kerning with Pango 1.44/patched freetype2

This patch doesn't work for this issue. Microsoft core fonts kerning is still
utterly broken with the new Pango.

[Bug 1767499] Very bad kerning for Tahoma in Fedora 31

https://bugzilla.redhat.com/show_bug.cgi?id=1767499

Artem S. Tashkinov  changed:

What    |Removed                     |Added
----------------------------------------------------------------------------
              Flags|needinfo?(constantine.gavri |
                   |[e-mail])              |

[Bug 1767499] Very bad kerning for Tahoma in Fedora 31

https://bugzilla.redhat.com/show_bug.cgi?id=1767499

Artem S. Tashkinov  changed:

What    |Removed                     |Added
----------------------------------------------------------------------------
            Link ID|                            |GNOME Gitlab
                   |                            |GNOME/pango/issues/463

[Bug 1767499] Very bad kerning for Tahoma in Fedora 31

https://bugzilla.redhat.com/show_bug.cgi?id=1767499

--- Comment #21 from Peng Wu  ---
In pango 1.44, pango switched from freetype to harfbuzz for kerning, etc.

I think freetype kerning supports grid fitting, maybe harfbuzz kerning not
support grid fitting, BICBW.

I dunno whether this is the root cause.

[Bug 1767499] Very bad kerning for Tahoma in Fedora 31

https://bugzilla.redhat.com/show_bug.cgi?id=1767499

--- Comment #22 from Peng Wu  ---
Upstream URL: https://github.com/harfbuzz/harfbuzz/issues/2268

[Bug 1767499] Very bad kerning for Tahoma in Fedora 31

https://bugzilla.redhat.com/show_bug.cgi?id=1767499

--- Comment #23 from Artem S. Tashkinov  ---
(In reply to Peng Wu from comment #22)
> Upstream URL: https://github.com/harfbuzz/harfbuzz/issues/2268

Are you sure? It's closed.

It's all kind ugly: Gnome/RH programmers removed bitmap fonts support and broke
kerning for lots of fonts almost a year ago now and no one cares.

[Bug 1767499] Very bad kerning for Tahoma in Fedora 31

https://bugzilla.redhat.com/show_bug.cgi?id=1767499

--- Comment #24 from Peng Wu  ---
That is one potential cause for larger kerning value on small DPI,
and this feature exists in pango 1.43.

I can reproduce this issue now with pango-view.
$ pango-view -t "Tahoma 9" --font="Tahoma 9" --hinting=full --hint-metrics=on
--dpi=72 --antialias=none --subpixel-order=rgb

[Bug 1767499] Very bad kerning for Tahoma in Fedora 31

https://bugzilla.redhat.com/show_bug.cgi?id=1767499

--- Comment #25 from Peng Wu  ---
From pango 1.43 to 1.44, pango switched to use harfbuzz instead of freetype.

[Bug 1767499] Very bad kerning for Tahoma in Fedora 31

https://bugzilla.redhat.com/show_bug.cgi?id=1767499

Artem S. Tashkinov  changed:

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

--- Comment #26 from Artem S. Tashkinov  ---
(In reply to Peng Wu from comment #25)

Knowing what causes this issue isn't much a consolation unfortunately. I'm now
running F32 and I have to use packages from F30 (pango-1.43) and F31 (Thunar)
in order to work around this issue.

Matthias Clasen who broke this feature has remained silent so far, two months
after I reported the issue in Gnome's bugzilla, and half a year after I
reported it here in RH's bugzilla.

He is ostensibly so busy he doesn't even have the time to confirm it.

[Bug 1767499] Very bad kerning for Tahoma after update from Pango 1.43 to 1.44.x

https://bugzilla.redhat.com/show_bug.cgi?id=1767499

Artem S. Tashkinov  changed:

What    |Removed                     |Added
----------------------------------------------------------------------------
            Version|31                          |32
            Summary|Very bad kerning for Tahoma |Very bad kerning for Tahoma
                   |in Fedora 31                |after update from Pango
                   |                            |1.43 to 1.44.x

[Bug 1767499] Very bad kerning for Tahoma after update from Pango 1.43 to 1.44.x

https://bugzilla.redhat.com/show_bug.cgi?id=1767499

Artem S. Tashkinov  changed:

What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |CLOSED
            Link ID|                            |Github
                   |                            |harfbuzz/harfbuzz/issues/23
                   |                            |94 Github
                   |                            |harfbuzz/harfbuzz/issues/18
                   |                            |92
         Resolution|---                         |WONTFIX
        Last Closed|                            |2020-05-09 19:16:41

--- Comment #27 from Artem S. Tashkinov  ---
I was basically told to **** off and stop using Open Source. Maybe you're
right. It doesn't seem entirely fair given how much I've invested in Open
Source over the past 20+ years but it is what it is.

It doesn't seem fair given that Linux is often offered as a better alternative
to Windows but it surely looks like some developers don't share this opinion
and insist users must buy high DPI displays to keep on using Linux. Maybe Linux
has suddenly become a sort of luxury but I surely don't want to participate in
this.

I will downgrade from future Fedora releases which will make using Pango 1.43
impossible to CentOS 8 which still uses the same old "bad" "inefficient"
"outdated" font stack and then when CentOS 8 become unsuitable for me I will
probably give up on Linux altogether. I don't have spare $600 to buy a monitor
just to continue to use Linux. I have much better things in life to spend this
money on. Spending them on pixels is a vanity fair.

I'm deeply sorry for wasting everyone's time here and spamming this bugzilla
with worthless requests. It's the worst interaction I've ever had with Open
Source for the past 24 years but maybe I'm just unlucky since my eyes are my
most prized asset. I will surely choose my eyes over Linux any time of the day.

Thank you for your attention. Have a nice day!