[Bug 58314] New: GetGlyphOutlineW returns a negative number sometimes

[WineHQ Bugzilla]

http://bugs.winehq.org/show_bug.cgi?id=58314

Bug ID: 58314
           Summary: GetGlyphOutlineW returns a negative number sometimes
           Product: Wine
           Version: 10.8
          Hardware: x86-64
                OS: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: gdi32
          Assignee: [e-mail]
          Reporter: [e-mail]
      Distribution: ---

Created attachment 78672
  --> http://bugs.winehq.org/attachment.cgi?id=78672
Source code for a repro, an exe build, Windows and Wine sample logs, and the
necessary font.

In an application I'm developing, I've found that GetGlyphOutlineW returns a
negative number under specific circumstances in Wine. According to the
documentation, it should return a positive number, with the exception of
GDI_ERROR (-1). My program therefore treats the return value as unsigned (as
specified in the documentation) and checks against -1, which doesn't work when
it returns -32 instead. It's not clear to me why this value is being returned,
but I've only seen it reproduce with a specific character (¯) in a specific
font.

I've put together a minimal reproducing sample. The issue reproduces on both 32
and 64 bit, and does not reproduce on Windows. Source code and a copy of the
necessary font (https://ggbot.itch.io/raster-forge-font) are attached, as are
expected and actual logs. In this sample, -8 is returned instead of -32, but I
suspect the root cause is similar - it shouldn't be returning anything lower
than -1 in either case.

For what it's worth, I'm running on EndeavourOS, which hasn't received 10.9 yet
at the time of writing, but I've checked the commit logs for gdi32 and haven't
seen anything that looks relevant.

[Bug 58314] GetGlyphOutlineW returns a negative number sometimes

[WineHQ Bugzilla]

http://bugs.winehq.org/show_bug.cgi?id=58314

Nikolay Sivov  changed:

What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1

--- Comment #1 from Nikolay Sivov  ---
The sample program is asking for a glyph for 0xaf (macron) that does not exist
in the font. Linked font is used instead, Tahoma in this case.

Next in freetype_get_glyph_outline() in metrics fixup:

---
         metrics.horiBearingY = top;
         metrics.height = top - bottom;
---

things go wrong and resulting box gets inverted yMin and yMax. This produces
negative height later and negative "needed" buffer size.

I don't have time right now to look deeper at what's happening with this
metrics adjustment, but that's the problem I think. I don't know if it's a
general fixup issue or is caused by a linked font and metrics are mixed up
somewhere between the fonts.