[vbox-dev] Subject: Com api. Cannot use IDisplay. It's null

Pavel Murygin pavel.murygin at gmail.com
Sat Mar 9 06:12:40 GMT 2013


Hi everybody!

I wrote a virtual box frontend in C# using com api. I haven't touched my
code for about a year. During that year I've moved to a laptop from pc.
Last time I ran my code it worked fine. Now I cannot access IDisplay
because it's null;
here is my code:

    var vb = new VirtualBoxClass();
    _machine = vb.FindMachine(machineName);

    var monitors = _machine.MonitorCount;

    Monitors = new MMFFrameBuffer[monitors];
    for (byte i = 0; i < monitors; i++)
    {
        var name = string.Format("monitor{0}", i + 1);
        Monitors[i] = MMFFrameBuffer.CreateNew(name)
;
    }

    _session = new SessionClass();
    _machine.LockMachine(_session, LockType.LockType_Shared);

    for (int i = 0; i < MonitorsCount; i++)
    {
        _session.Console.Display.SetFramebuffer((uint) i, Monitors[i]);
    }

My program fails on the line where I'm trying to set framebuffer. I get
NullreferenceException: _session.Console.Display is null.
My current version of Vbox is the latest: 4.2.8 r83876. I can't remember
the exact version on which my code ran correctly. I can only say It was the
latest one about 1 year ago. Host OS is Win7 pro x64 (same as it was on my
previous PC)

I'm completely clueless about my issue. Any help would be highly
appreciated!

Regrads,
Pavel Murygin.
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