VNC platform plugin for Qt 5

This fork contains a VNC platform plugin which lets you run any Qt app in headless mode and access it with a VNC client. It has builtin websocket support for pure HTML5 VNC clients like noVNC.

You can view Qt apps in a browser just by navigating to http://host:5900

Build

The default ./configure will build the VNC plugin. Use --no-vnc to disable building the VNC plugin. Your Qt application must be built with this Qt library.

Usage

You can control the platform using environment variables or CLI options. In the shell,

export QT_QPA_PLATFORM=vnc
export QT_DEBUG_PLUGINS=1

before starting the application. Alternately, invoke the application with

/path/to/qtapp -platform vnc

For MacOS app bundles, this may be modified to

/path/to/qtapp.app/Contents/MacOS/qtapp -platform vnc

That's pretty much it. You should see messages appearing on the console, like

QVNCServer created on "127.0.0.1" port 5900 mode websocket

Navigate to http://localhost:5900 on any modern browser and you should be able to view and interact with the application.

Options

Platform options can be supplied with the -platform command line option or the QT_QPA_PLATFORM environment variable. The platform string starts with vnc and a combination of the following options, separated by colons.

• size=<width>x<height> Width and height of the frame buffer.
  • Default: size=800x600
• display=<num> VNC display number. Server listens to port 5900 + <num>
  • Default: display=0
• addr=<IP> IPv4 address on which the server listens.
  • Example: addr=0.0.0.0 listens on all interfaces
  • Default: addr=127.0.0.1
• mode=<str> One of websocket or raw. Use websocket to connect with a browser-based HTML5 VNC viewer, or raw to use a regular VNC client like vncviewer or Chicken of the VNC.
  • Default: mode=websocket
• viewer=<URL> Sets the location of the HTML5 VNC viewer. In websocket mode, any regular HTTP request to the listening port will be issued an HTTP redirect to the viewer URL, appended with a hash fragment containing host and port parameters. Websocket requests from other origins are rejected. Note that the colon needs to be URL-encoded since Qt uses it as an option separator. Websocket requests from origins other than the viewer will be rejected.
  • Default: viewer=http%3A//pigshell.github.io/noVNC/qtvnc.html
• maximize=<bool> Maximize first window. Without this option, apps which don't maximize themselves usually occupy a small window at the top left of the frame buffer.
  • Default: maximize=true

Gotchas

• Does not support authentication.
• Does not support SSL.
• Does not build on Windows.
• If running examples on MacOS, you need to do a make install first. Otherwise you need to copy the $QTBASE/plugins/platforms directory into QtAppName.app/Contents/MacOS/, where $QTBASE is the directory containing this (built) Qt repo.