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Qt Virtual Frame Buffer / VNC on Qt Desktop?

  • Hello,

    Can the "Qt embedded vnc": system be used by Qt Desktop applications?

    The use case is that I have a beefy Windows 7 box that can run several instances of my application indefinitely, and I'd like to let a couple of users from nearby machines access them. (On different port numbers, obviously.)

    I know that Microsoft's Terminal Server is an option, but that's getting too complex for my simple application. Plus, I'd like to move to Linux eventually, and this time/money investment would be wasted.

    Just being able to spin up in instance of my app and have it export it's display to VNC rather than the local screen would be awesome.

    Thank you

  • Not tried it on windows but you could try building Qt as an embedded build with the vnc driver enabled. Not sure if it is possible to configure Qt this way or not on windows but it should work on Linux.

  • What is the difference between Qt Embedded and Qt Desktop?

    Is Qt Embedded a super-set or sub-set of Qt Desktop?

  • Mainly, configuring Qt with -embedded just enables the building of the QWS (Qt window system) subsystem of which the vnc driver is a part. The embedded builds are meant to be run in the absence of any X11 server (usually on the framebuffer device).

    All the usual Qt facilities are also available.

  • Great, thank you. I'll give that a try.

    Having only ever used the windows SDK (and mingw) install of Qt, where can I find documentation on how to build and use Qt from source?

  • Download it from "here": Choose LGPL then on the right hand side pick the platform of your choice.

    Once you have the source unpack it somewhere and configure it with something similar to what is shown in this "article": in the Host Build section but remember to add in the -qt-gfx-vnc option too since you need that for your requirements.

    Come back with questions if it is not clear.

    Good luck!

  • ZapB,

    I tried to build using the source and MinGW I downloaded from the Qt site, and got this error:

    @C:\Qt\4.7.3-mingw-src>configure -prefix C:\Qt\4.7.3 -embedded -qt-gfx-vnc
    Unknown option -qt-gfx-vnc
    Usage: configure [-buildkey <key>]
    [-release] [-debug] [-debug-and-release] [-shared] [-static]
    [-no-fast] [-fast] [-no-exceptions] [-exceptions]
    [-no-accessibility] [-accessibility] [-no-rtti] [-rtti]
    [-no-stl] [-stl] [-no-sql-<driver>] [-qt-sql-<driver>]
    [-plugin-sql-<driver>] [-system-sqlite] [-arch <arch>]

    I also tried the full configure command as listed in that page you linked to, but to no avail.

    What should I try next?

    Thank you

  • Try it on Linux. As I said I didn't think this would work on Windows as QWS is for Qt Embedded Linux.

  • Ahh, OK. Yeah. I need this on Windows.

    Is this at all possible?

    Maybe this thread should be moved to the Qt Embedded forum?

  • I don't think so directly. You could look into incorporating VNC into your app yourself or maybe extracting the VNC stuff from the QWS support. MIght be a good time to recompile your app on Linux though since you said you were aiming for that in the long-term anyway?

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