[Bug 1722508] Re: Font hinting appears broken on 17.10 beta

[gldickens3]

One of the primary differences in freetype-2.8 and prior Ubuntu versions
of freetype is the introduction of TT_CONFIG_OPTION_SUBPIXEL_HINTING in
/include/freetype/config/ftoption.h in freetype-2.7.X and later. The
default value is:

#define TT_CONFIG_OPTION_SUBPIXEL_HINTING  2

This needs to be undefined (uncommented) in order for freetype-2.7 and
2.8 to render fonts identically to prior versions of Ubuntu freetype
(freetype-2.6.X and earlier).

The diff file (freetype_2.8-0.2ubuntu2.diff.gz) at
https://launchpad.net/ubuntu/+source/freetype/2.8-0.2ubuntu2 enables
FT_CONFIG_OPTION_SUBPIXEL_RENDERING in
/include/freetype/config/ftoption.h with:

#define FT_CONFIG_OPTION_SUBPIXEL_RENDERING

This properly enables subpixel rendering to render fonts identical to MS
cleartype, however, if TT_CONFIG_OPTION_SUBPIXEL_HINTING is also set
then the fonts are rendered differently than before.  So, this problem
is fixed simply by undefining TT_CONFIG_OPTION_SUBPIXEL_HINTING.

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https://bugs.launchpad.net/bugs/1722508

Title:
  Font hinting appears broken on 17.10 beta

Status in Qt:
  New
Status in freetype package in Ubuntu:
  Confirmed
Status in qtbase-opensource-src package in Ubuntu:
  Confirmed
Status in freetype source package in Artful:
  Confirmed
Status in qtbase-opensource-src source package in Artful:
  Confirmed

Bug description:
  It appears that font hinting in 17.10 (beta) doesn't work as expected.
  The issue is easy to miss if you have antialiasing enabled system-
  wise. However, if you install "gnome-tweak-tool" and disable
  antialiasing there, the problem becomes obvious.

  Here is how it looks on 17.10 beta:
  https://postimg.org/image/3auqsbkqtn/

  And here is how it looks on my 16.04 machine (and this is pretty much how it's supposed to look):
  https://postimg.org/image/85n5ss3l4b/

  * When comparing the pictures make sure you "Open image in new tab"
  and see them without browser zoom, otherwise the problem may no be
  obvious.

  I suspect that this issue is caused by a bug in some base font
  rendering package that Ubuntu uses (edit: the problem is probably
  caused by FreeType 2.8.0, see my comments below). A couple of months
  ago a similar issue was reported (and promptly fixed) in Chromium
  after they had changed something in FreeType rendering
  (https://bugs.chromium.org/p/chromium/issues/detail?id=748997).

  lsb_release -rd
  Description: Ubuntu Artful Aardvark (development branch)
  Release:     17.10

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