I need to remotely control a Qt / QML application on an embedded ARM instrument. I intended to do that using VNC. This doesn't work. An USB keyboard plugged in the instrument doesn't work either.
NB: Normally this application is controlled by the hard keys on the instrument connected to GPIO and converted through custom application code to send Qt events:
QCoreApplication::postEvent(..., new QKeyEvent(QEvent::KeyPress, ...));
Now, I'm trying to send keys remotely using VNC. To test the remote session, I type the following command on the instrument console:
x11vnc -rawfb map:/dev/fb0@800x480x32 -forever -rotate -90 -dk
After getting a Wifi connection between my Linux PC and the instrument (whose IP address is 192.168.1.1), I type the following command on my Linux PC:
gvncviewer 192.168.1.1:0
I do see the screen of the instrument correctly displayed on my PC in a window with the right geometry, color, and orientation...
BUT...
My Qt application doesn't care about the key strokes. It doesn't seem to receive any keyboard event.
More context: the Qt application is started on the instrument using a systemd service. I tried to attach the systemd service to a TTY so it would have a stdin.. The service looks like this:
[Unit]
Description=Instrument IHM
After=network.target
[Service]
StandardInput=tty-force
StandardOutput=tty
StandardError=tty
TTYPath=/dev/tty0
Restart=always
ExecStartPost=/path/to/my_application --platform linuxfb:fb=/dev/fb0:rotation=90 -plugin evdevkeyboard:/dev/input/event0
Restart=on-failure
RestartSec=2s
[Install]
WantedBy=multi-user.target
When I type the keys corresponding to the instrument's hardkeys on my VNC client, the VNC server on the instrument receives correctly the keyboard events, as shown by this extract of the logs of the VNC server:
05/03/2024 09:17:23 Using tight encoding for client 192.168.1.10
05/03/2024 09:17:24 Sending rfbEncodingExtDesktopSize for size (480x800)
05/03/2024 09:17:24 client 1 network rate 119.5 KB/sec (6395.0 eff KB/sec)
05/03/2024 09:17:24 client 1 latency: 0.9 ms
05/03/2024 09:17:24 dt1: 0.0575, dt2: 0.1834 dt3: 0.0009 bytes: 28741
05/03/2024 09:17:24 link_rate: LR_BROADBAND - 1 ms, 119 KB/s
05/03/2024 09:17:24 client_set_net: 192.168.1.10 0.0066
05/03/2024 09:17:30 # keyboard(down, 0xff54 "Down") uip=0 14.6279
05/03/2024 09:17:31 # keyboard(up, 0xff54 "Down") uip=0 14.7875
05/03/2024 09:17:32 # keyboard(down, 0xff52 "Up") uip=0 15.7994
05/03/2024 09:17:32 # keyboard(up, 0xff52 "Up") uip=0 15.8880
05/03/2024 09:17:32 # keyboard(down, 0x20 "space") uip=0 16.6078
05/03/2024 09:17:33 # keyboard(up, 0x20 "space") uip=0 16.6684
05/03/2024 09:17:33 # keyboard(down, 0xff1b "Escape") uip=0 17.5182
05/03/2024 09:17:33 # keyboard(up, 0xff1b "Escape") uip=0 17.5997
05/03/2024 09:17:34 # keyboard(down, 0xff0d "Return") uip=0 18.3625
05/03/2024 09:17:34 # keyboard(up, 0xff0d "Return") uip=0 18.4278
But still my Qt application doesn't care.
Thanks you so much for your reading. Thanks in advance for your insights!
