Re: (re)display problems after font backend merge

[David De La Harpe Golden <david@harpegolden.net>]

Stephen Berman wrote:

> For ascii:
> 
> -unknown-DejaVu Sans Mono-normal-normal-normal-*-12-*-*-*-m-0-iso8859-1
>

Call it (a)

> For the non-ascii characters:
> 
> -gnu-unifont-medium-r-normal--16-160-75-75-p-80-iso10646-1
>

Call it (b)

This is mostly me trying to understand something:

Those (a) and (b) look like XLFD font specs, as used by X core 1-bit
fonts - see output of command xlsfonts [*]

> This is post-merge, in the pre-merge buffer, the corresponding line of
> the character description for both ascii and non-ascii characters is
> this:
> 
> dejavu sans mono:pixelsize=12:foundry=unknown:weight=medium:slant=r:width=normal
>

Call it (c).   That looks like a fontconfig font spec, as used by xft
antialiased fonts - see output of fc-list [*]

Are you setting X resource "Emacs.FontBackend: xft"? I've found that
without that, I get a strange mix of decent and horrible font rendering
as xft fonts (yay) and x core fonts (boo) are apparently both used somehow?

:::::: I've just found that, at least post font-backend merge and
possibly for some time before, emacs /even with/ FontBackend: xft
returns XLFD-style specs even when it's clearly using xft rendering and
fonts that I _know_ I didn't make available to X core font handling - I
find that kind of confusing, emacs must be just inventing and using
XLFDs internally ???
e.g. describe-char gives me, which looks like your (a), though I naively
expected something like (c):

-unknown-DejaVu Sans Mono-normal-normal-normal-*-14-*-*-*-m-0-iso10646-1

A sort of "synthetic XLFD" that emacs has invented.


::::: I would speculate that you [Stephen] don't have FontBackend: xft
and your (a)  is one of these synthetic XLFDs and (b) is a "real" XLFD
corresponding to an X core font ??

So some of your characters (those in (b)) are getting drawn with
X core font rendering and some with Xft font rendering (those in (a)),
leading to at least some of the visually ugly appearance that is a
"feature" of all X core font handling (e.g. lack of antialiasing, poor
alignment)  ???



[*] Sometimes the same font dirs are added to paths for both core fonts
and fontconfig, so the same fonts show up in both xlsfonts and fc-list,
but that's a bad assumption to make in general.