[Bug]: tigervnc: Can type non_ASCII char, but can't copy paste it in to / from Emacs-x.

[gety9]

Problem description

-, When i copy "я" outside emacs-x (say in browser or google docs) and then paste in emacs-x it gets inserted as "??"

Interestingly i can type "я" (on usb keyboard) in emacs-x, but if try to copy it out (say insert in google docs or browser) it pastes as "??"

-, graphical environment is tigervnc server (v1.10.1-31) + real vnc viewer app (v3.8.0.48261); emacs is v28.2

-, It's no emacs config, cause exactly same init.el works perfectly on windows

-, it migh be connected to this #6266 (comment)
(but this termux-api + xclip.el is the only set-up that made copy paste in Emacs-x work)

What steps will reproduce the bug?

Copy я char outside emacs-x
Paste in emacs-x

What is the expected behavior?

Paste as "я" not "??"

System information

termux-info:

Termux Variables:
TERMUX_API_VERSION=0.50.1
TERMUX_APK_RELEASE=F_DROID
TERMUX_APP_PACKAGE_MANAGER=apt
TERMUX_APP_PID=21079
TERMUX_IS_DEBUGGABLE_BUILD=0
TERMUX_MAIN_PACKAGE_FORMAT=debian
TERMUX_VERSION=0.118.0
Packages CPU architecture:
aarch64
Subscribed repositories:
# sources.list
deb https://packages-cf.termux.org/apt/termux-main stable main
# x11-repo (sources.list.d/x11.list)
deb https://packages.termux.dev/apt/termux-x11 x11 main
Updatable packages:
All packages up to date
termux-tools version:
1.35.0
Android version:
11
Kernel build information:
Linux localhost 4.19.157-perf-g616268c8715f-dirty #134 SMP PREEMPT Wed Nov 10 15:13:53 CST 2021 aarch64 Android
Device manufacturer:
QUALCOMM
Device model:
NoteAir2

[gety9]

@xtkoba you right, thank you for pointing out, added graphical environment details in the description.

[xtkoba]

Seems like the VNC Viewer app ("com.realvnc.viewer.android" version "3.8.0.48261") does not support copy and paste of non-ASCII characters. The same behavior is observed when I connect to a VNC server (TigerVNC version 1.12.90) on Gentoo GNU/Linux from the VNC Viewer app on Android. This implies that this issue cannot be resolved by (only) updating our tigervnc package to the latest upstream version.

[gety9]

@xtkoba will it work with another viewer app? Like MultiVNC, bVNC, etc?

Or is in current state none will work? (cause problem is not only in RealVNC viewer but also in tigervnc server)

[gety9]

@xtkoba i found avnc app, it has setting "Send legacy events (Some servers have limited Unicode support. Legacy key events can help input non-English text.)

But it will only work if vnc server has it inplemented aslo (meaning TigerVNC 1.12.90)

Here they have same issue (Chinese copy paste does not work) and discussion
gujjwal00/avnc#121 (comment)

[xtkoba]

Release notes of TigerVNC 1.10.0 say "clipboard now supports full Unicode in [...] Xvnc/libvnc.so". Xvnc ($PREFIX/bin/Xvnc) is the core of the tigervnc server. In fact, copy and paste of non-ASCII does work with the combination of tigervnc (server) version 1.10.1-32 on Termux + TigerVNC viewer version 1.12.90 on Gentoo GNU/Linux.

[gety9]

@xtkoba thank you for looking into it, so the problem is with vnc client, did i understand it right?

[xtkoba]

@gety9 I understand so.

[xtkoba]

Enhancement on the client side. Strictly this is a third-party issue unless we provide a VNC viewer app on our own.

FYI, there is another issue in which the situation is similar: #14491.

[gety9]

@xtkoba

AVNC viewer mantainer added support for ASCII chars, but it will work only on tiger vnc 1.11+ gujjwal00/avnc#121 (comment)

Could you please upgrade termux's tigervnc?

[xtkoba]

@gety9 PR is welcome. Thanks.