framebuffer-vncserver

VNC server for Linux framebuffer devices.

The goal is to access remote embedded Linux systems without X. Implemented features: remote display, touchscreen, keyboard, rotation Not implemented: file transfer, ..

Working configurations:

without rotation:

with rotation:

The code is based on a LibVNC example for Android: https://github.com/LibVNC/libvncserver/blob/master/examples/androidvncserver.c

build

Dependency:

sudo apt-get install libvncserver-dev

There are 2 options: CMake or qmake

Using cmake:

mkdir -p build && cd build
cmake ..
make

Using qmake:

mkdir -p build && cd build
qmake ../framebuffer-vncserver.pro
make

command-line help

./framebuffer-vncserver [-f device] [-p port] [-t touchscreen] [-k keyboard] [-r rotation] [-R touchscreen rotation] [-F FPS] [-v] [-h]
-p port: VNC port, default is 5900
-f device: framebuffer device node, default is /dev/fb0
-k device: keyboard device node (example: /dev/input/event0)
-t device: touchscreen device node (example:/dev/input/event2)
-r degrees: framebuffer rotation, default is 0
-R degrees: touchscreen rotation, default is same as framebuffer rotation
-F FPS: Maximum target FPS, default is 10
-v: verbose
-h: print this help

Run on startup as service

To run at startup as a service using systemd, edit the file fbvnc.service make sure the path and command line arguments are correct and then run:

sudo cp fbvnc.service /etc/systemd/system/
sudo systemctl enable fbvnc.service
sudo systemctl start fbvcn.service

Vfb test

Linux Virtual Frame Buffer kernel object (vfb.ko) is used for this test. https://cateee.net/lkddb/web-lkddb/FB_VIRTUAL.html

Local computer:

# install
sudo apt install vagrant virtualbox xtightvncviewer

# after framebuffer-vncserver start
vncviewer localhost

vagrant up
vagrant ssh

Inside vagrant box:

sudo su
cd /home/vagrant/buildc/

# build framebuffer-vncserver
make

# set resolution, color depth
fbset -g 640 480 640 480 16

# restart framebuffer-vncserver
killall framebuffer-vncserver;./framebuffer-vncserver -t /dev/input/ms -k /dev/input/kbd &

# set test pattern or ..
fb-test

# draw random rectangles or ..
rect

# display a GUI or ...
qmlscene -platform linuxfb -plugin evdevmouse:/dev/input/ms:abs -plugin evdevkeyboard:/dev/input/kbd:grab=1

Automatic test

This generates patterns with different resolutions and color depths (on local computer):

python3 -m pip install fabric vncdotool python-vagrant entrypoint2
python3 vfb.py

rotation	color	fbtest	qmlscene	gradient
0	1
0	8
0	16
0	24
0	32
90	16
180	16
270	16

Testing single-touch

$ (evtest /dev/input/event0 &) ;./framebuffer-vncserver -t /dev/input/event0 -v
...
Initializing touch device /dev/input/event0 ...
x:(0 4095)  y:(0 4095) 
...
Supported events:
Event type 0 (EV_SYN)
Event type 1 (EV_KEY)
	Event code 330 (BTN_TOUCH)
Event type 3 (EV_ABS)
	Event code 0 (ABS_X)
	Value   1970
	Min        0
	Max     4095
	Event code 1 (ABS_Y)
	Value   1745
	Min        0
	Max     4095
	Event code 24 (ABS_PRESSURE)
	Value      0
	Min        0
	Max      255
...
Got ptrevent: 0001 (x=186, y=570)
Event: time 1580221917.655639, type 1 (EV_KEY), code 330 (BTN_TOUCH), value 1
Event: time 1580221917.655639, type 3 (EV_ABS), code 0 (ABS_X), value 1586
Event: time 1580221917.655639, type 3 (EV_ABS), code 1 (ABS_Y), value 2733
Event: time 1580221917.655639, -------------- SYN_REPORT ------------
injectTouchEvent (screen(186,570) -> touch(1586,2733), mouse=1)
...
Got ptrevent: 0000 (x=186, y=570)
Event: time 1580221918.516897, type 1 (EV_KEY), code 330 (BTN_TOUCH), value 0
Event: time 1580221918.516897, -------------- SYN_REPORT ------------
injectTouchEvent (screen(186,570) -> touch(1586,2733), mouse=0)

Testing multi-touch

$ (evtest /dev/input/event2 &) ;./framebuffer-vncserver -t /dev/input/event2 -v
...
Supported events:
Event type 0 (EV_SYN)
Event type 1 (EV_KEY)
	Event code 330 (BTN_TOUCH)
Event type 3 (EV_ABS)
	Event code 0 (ABS_X)
	Value    245
	Min        0
	Max      480
	Event code 1 (ABS_Y)
	Value    485
	Min        0
	Max      854
	Event code 47 (ABS_MT_SLOT)
	Value      4
	Min        0
	Max        4
	Event code 48 (ABS_MT_TOUCH_MAJOR)
	Value      0
	Min        0
	Max      255
	Event code 50 (ABS_MT_WIDTH_MAJOR)
	Value      0
	Min        0
	Max      255
	Event code 53 (ABS_MT_POSITION_X)
	Value      0
	Min        0
	Max      480
	Event code 54 (ABS_MT_POSITION_Y)
	Value      0
	Min        0
	Max      854
	Event code 57 (ABS_MT_TRACKING_ID)
	Value      0
	Min        0
	Max    65535
...
Initializing touch device /dev/input/event2 ...
x:(0 480)  y:(0 854) 
...
Got ptrevent: 0001 (x=237, y=528)
Event: time 1580221680.870277, type 3 (EV_ABS), code 57 (ABS_MT_TRACKING_ID), value 0
Event: time 1580221680.870277, type 1 (EV_KEY), code 330 (BTN_TOUCH), value 1
Event: time 1580221680.870277, type 3 (EV_ABS), code 53 (ABS_MT_POSITION_X), value 237
Event: time 1580221680.870277, type 3 (EV_ABS), code 54 (ABS_MT_POSITION_Y), value 528
Event: time 1580221680.870277, type 3 (EV_ABS), code 0 (ABS_X), value 237
Event: time 1580221680.870277, type 3 (EV_ABS), code 1 (ABS_Y), value 528
Event: time 1580221680.870277, -------------- SYN_REPORT ------------
injectTouchEvent (screen(237,528) -> touch(237,528), mouse=1)
...
Got ptrevent: 0000 (x=237, y=528)
Event: time 1580221681.190716, type 3 (EV_ABS), code 57 (ABS_MT_TRACKING_ID), value -1
Event: time 1580221681.190716, type 1 (EV_KEY), code 330 (BTN_TOUCH), value 0
Event: time 1580221681.190716, -------------- SYN_REPORT ------------
injectTouchEvent (screen(237,528) -> touch(237,528), mouse=0)

nexa/framebuffer-vncserver