On 18/06/2020 17:53, Henry S. Thompson via Cygwin wrote:
[Warning, gnarly X-windows issues below, read at your own risk]
I run XEmacs on several Linux servers, and sometimes (always for the
time being) access them via (Cygwin) ssh -Y and/or (Windows)TigerVNC.
I'm not sure if you're using 'XEmacs' here to refer to 'GNU Emacs as an
X11 client' or 'XEmacs (the fork derived from Lucid Emacs)'
XEmacs and fonts are problematic in their own right, but I'm struggling
to understand the X-windows-as-such issues of this configuration, to try
to isolate my problem, which is that I'm not seeing things displayed in
the fonts I want.
In particular, I'm trying to understand as between the X servers running
on my remote servers (there has to be one, however simple, whichever way
I connect, because that's where my XEmacs instances are running, right?)
and the Cygwin/X server on my machine at home.
Sort of. When using ssh forwarding, the sshd provides a 'proxy X
server', which forwards the X protocol across the ssh tunnel to the ssh
client (where the real X server is located).
(Typically these proxy X servers are listening on ports corresponding to
display numbers starting at :10 (see X11DisplayOffset in 'man
sshd_config'. If you inspect the DISPLAY env var inside a 'ssh -Y'
session, you'll typically see it is something like 'localhost:10.0')
Configuration 1)
I _think_ I understand that if I launch XEmacs inside an Xvnc instance
on a server, viewed using a vncviewer instance on my home machine, the
fonts available to it are determined by what fonts are available within
the remote Xvnc instance, in whatever form.
Am I also right in thinking that it does _not_ matter what fonts
TigerVNC-for-Windows finds on my Cygwin box at home?
Configuration 2)
If OTOH I launch Cygwin/XWin, and ssh -Y from a local xterm to a remote
server, where I launch XEmacs, I really don't know what happens. Does
the sshd X server include a font server, or search for font.dirs, or???
Or does _all_ font-related activity depend on the Cygwin/X server?
Sort of. The core (legacy) fonts depend on the X server.
All modern applications will be rendering fonts inside the X client, so
it's the fonts available where that runs which are significant.
See the end of [1] for the last lot of more words I wrote about that.
[1] https://cygwin.com/pipermail/cygwin-xfree/2014-July/036712.html
Configuration 3)
Unfortunately, the configuration I like best is a mixture. I launch
XEmacs inside an Xvnc instance on a server, viewed using a vncviewer
instance on my home machine, and fire up gnuserv inside it. I close the
viewer, and ssh -Y back to the server from home, then run gnuclient from
the resulting shell, which brings up a separate window on the original
XEmacs instance. I have no idea whose fonts matter in this case, can
anyone explain?
I think that gnuclient will be starting a 'frame' on the display
indicated by the DISPLAY env var. If the client is using core fonts,
then they are from the X server.
A related question: when running setup and looking at font packages, how
can I tell whether they contain new-style (fc-list will will list them,
they have names such as "DejaVu Sans Mono", or old-style (xlsfonts will
list them, they have names such as "-b&h-lucidatypewriter-medium-r...")?
I'm not sure if we have a convention which lets you tell this by name.
I think the majority, if not all, of the core fonts have names starting
'xorg-x11-fonts-'.
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