Got VNC platform plugin working on Qt 5

[ganeshv]

Hello,

I took the old VNC plugin code from Qt 4.x and massaged it into a Qt 5 platform plugin. You can export QT_QPA_PLATFORM=vnc, have your Qt desktop application run headless, and connect to it using a VNC client.

The code is here. It runs on Mac OS Mountain Lion, should work on Linux. Just got it working, so it's not tested very much.

Thinking of adding websocket support, which will let you connect to "headless" Qt apps using a browser-based VNC viewer.

Feedback welcome.

Ganesh

[SGaist]

Hi and welcome to devnet,

What about contributing that QPA to the Qt project ? That way everybody using Qt would easily have access to it

[ganeshv]

I plan to do that, once I have some more testing done.

[ganeshv]

Websocket support is now working. You can start an app with

qtapp -platform vnc:mode=websocket

Navigate to http://localhost:5900 and you will be automatically redirected to an HTML5 VNC client.

More in the README

[Julien C.]

That's great to have a QPA VNC plugin support.
I've just built your plugin on my i.MX6 based platform over Qt5.5.0 and test it but unfortunately running failed

VNC Websockets

# /usr/lib/qt/examples/qpa/windows/windows -platform "vnc:size=800x600:addr=0.0.0.0:mode=websocket"
QVNCServer created on "0.0.0.0" port 5900 mode websocket
QVNCServer: no password configured!
Client protocol version RFB 003.003

Want format: 32 24 0 1 8 8 8 16 8 0
QVNCServer::setEncodings: 1
QVNCServer::setEncodings: 7
QVNCServer::setEncodings: -260
QVNCServer::setEncodings: 5
QVNCServer::setEncodings: using hextile
QVNCServer::setEncodings: 2
QVNCServer::setEncodings: 0
QVNCServer::setEncodings: -223
QVNCServer::setEncodings: -239
QVNCServer::setEncodings: -26
QVNCServer::setEncodings: -247
QVNCServer::setEncodings: -224
QVNCServer::setEncodings: -309
QVNCServer::setEncodings: -308
Segmentation fault

VNC RAW

# /usr/lib/qt/examples/qpa/windows/windows -platform "vnc:size=800x600:addr=0.0.role = 1 tID = 00.0:mode=raw"
QVNCServer created on "0.0.0.0" port 5900 mode raw
QVNCServer: no password configured!
Client protocol version RFB 003.003

Want format: 8 8 0 1 3 3 2 0 3 6
QVNCServer::setEncodings: 7
QVNCServer::setEncodings: 16
QVNCServer::setEncodings: 9
QVNCServer::setEncodings: -65527
QVNCServer::setEncodings: 1
QVNCServer::setEncodings: 5
QVNCServer::setEncodings: using hextile
QVNCServer::setEncodings: 6
QVNCServer::setEncodings: 4
QVNCServer::setEncodings: 2
QVNCServer::setEncodings: 0
QVNCServer::setEncodings: -247
QVNCServer::setEncodings: -32
QVNCServer::setEncodings: -240
QVNCServer::setEncodings: -239
QVNCServer::setEncodings: -232
QVNCServer::setEncodings: -131072
QVNCServer::setEncodings: -223
QVNCServer::setEncodings: -224
QVNCServer::setEncodings: -131071
QVNCServer::setEncodings: -131070
QVNCServer::setEncodings: -131069
Segmentation fault

[Aster5]

Thats absolutely very good news, that we have vnc plugin for QT5.

Although examples work fine as intended, When I configure and build my Qt Application with this source code, it gives error as:-

"This plugin does not support createPlatformOpenGLContext!
Failed to create OpenGL context for format QSurfaceFormat(version 2.0, options QFlags(), depthBufferSize 24, redBufferSize -1, greenBufferSize -1, blueBufferSize -1, alphaBufferSize -1, stencilBufferSize 8, samples -1, swapBehavior 2, swapInterval 1, profile 0) "

System Details are as below:-
OS: Ubuntu 14.04 LTS 32-bit
Compiler: gcc (Ubuntu 4.8.4-2ubuntu1~14.04) 4.8.4
mkspecs :- linux-g++

when checked the configure output it reads as :-
opengl-desktop
vnc-yes
egl-yes

and even the libgles1-mesa and libgles1-mesa-dev are also installed.
please suggest what could have been the problem.

[Aster5]

@ganeshv

Hi Ganesh,

Any update on contributing the QPA to the Qt Project?

BR,
Aster

[SGaist]

@Aster5 IIRC, there's a VNC plugin in the dev branch of the qtbase module.

[Julien C.]

@ganeshv

Hi ganesh,

Do you plan to bump your version of websocket based VNC on top of official Qt VNC plugin? It would be great because it's a great feature to get rid of any specific software to access embedded screenless device.

Regards,

Julien

[RJV B]

@Julien-C said in Got VNC platform plugin working on Qt 5:

@ganeshv

Hi ganesh,

Do you plan to bump your version of websocket based VNC on top of official Qt VNC plugin? It would be great because it's a great feature to get rid of any specific software to access embedded screenless device.

+++

And the README also states that

display=<num> VNC display number. Server listens to port 5900 + <num>
 Default: display=0

That's a very useful feature on hosts that also run a VNC server (e.g. any Mac with screen sharing turned on) and thus already have port 5900 in use. Or simply if you want to be able to run multiple applications over VNC.

[MatthiasU]

For those who find this via web search, the port can be set via a … drum roll … port=INTEGER parameter, as in

#!/bin/sh
export QT_QPA_PLATFORM=vnc:size=480x300:addr=127.0.0.1:port=$(expr 5900 + ${SCREEN:-1})
export QT_PLUGIN_PATH=/usr/lib/qt/plugins

here="$(dirname "$0")"
exec "${here}"/gui.real