bug#22699: 25.0.91; Accented characters truncated with DejaVu Sans Mono

[Eli Zaretskii <eliz@gnu.org>]

> From: Andy Moreton <andrewjmoreton@gmail.com>
> Date: Tue, 16 Feb 2016 15:22:48 +0000
> 
> With DejaVu Sans Mono (version 2.35), accented characters are not
> displayed properly at some sizes, and appear truncated at the top (as if
> a pixel row is missing).
> 
> For example, LATIN SMALL LETTER A WITH RING ABOVE "å"
> 
> Displays properly
> -----------------
> In Windows font dialog, choose "Deja Vu Sans Mono", "Bold", "9"
> 
> `describe-char' shows the font as:
> uniscribe:-outline-DejaVu Sans 
> Mono-bold-normal-normal-mono-12-*-*-*-c-*-iso8859-1 (#xA7)
> 
> Top of ring is clipped
> ----------------------
> In Windows font dialog, choose "Deja Vu Sans Mono", "Book", "9"
> 
> `describe-char' shows the font as:
> uniscribe:-outline-DejaVu Sans Mono-normal-normal-normal-mono-12-*-*-*-c-*-=
> iso8859-1 (#xA7)
> 
> This only appears with DejaVu Sans Mono version 2.35 at this size, with the
> "Book" or "Oblique" font styles (larger or smaller sizes display
> properly).

Thanks.  I wonder how to make sure this is an Emacs problem and not
a problem with the font.  E.g., does some other version of Emacs
display this font at this size correctly?  Bonus points for stepping
through w32term.c:x_draw_glyph_string_foreground and looking for
what's going wrong with these characters of this font, as compared to
some others.  Maybe there's something unusual in the metrics of this
font, and we don't handle that situation correctly?