Checking and closing HANDLE

Question

I am working with HANDLES, the first one, nextColorFrameEvent is an event handler and the second one is a stream handler. They are being initialized in the following piece of code:

nextColorFrameEvent = CreateEvent( NULL, TRUE, FALSE, NULL );
hr = nui->NuiImageStreamOpen(
            NUI_IMAGE_TYPE_COLOR,
            NUI_IMAGE_RESOLUTION_640x480,
            0,
            2,
            nextColorFrameEvent,
            &videoStreamHandle);

I want to properly deal with them on destruction, while not creating errors at the same time. Sometimes the initializer wont be called, so both HANDLEs are still NULL when the software comes to an end. Thats why I want to check first if the HANDLEs are properly initialized etc. and if they are, I want to close them. I got my hands on the following piece of code for this:

    if (nextColorFrameEvent && nextColorFrameEvent != INVALID_HANDLE_VALUE)CloseHandle(nextColorFrameEvent);
#ifdef QT_DEBUG
    DWORD error = GetLastError();
    qDebug()<< error;
#endif
    if (videoStreamHandle && videoStreamHandle != INVALID_HANDLE_VALUE)CloseHandle(videoStreamHandle);
#ifdef QT_DEBUG
    error = GetLastError();
    qDebug()<< error;
#endif

But this is apperently incorrect: if I do not run the initializer and then close the software this piece of code runs and gives me a 6:

Starting C:\...\Qt\build-simpleKinectController-Desktop_Qt_5_0_2_MSVC2012_64bit-Debug\debug\simpleKinectController...
6 
6 
C:\...\Qt\build-simpleKinectController-Desktop_Qt_5_0_2_MSVC2012_64bit-Debug\debug\simpleKinectController exited with code 0

which means:

ERROR_INVALID_HANDLE 6 (0x6) The handle is invalid. Which means that closeHandle ran anyway despite the tests. What tests should I do to prevent closing when the handle is not a valid HANDLE?

Bonus question: if I run the initializer this error will no longer appear when only closing colorFrameEvent, but will still appear when closing videoStreamHandle:

Starting C:\...\Qt\build-simpleKinectController-Desktop_Qt_5_0_2_MSVC2012_64bit-Debug\debug\simpleKinectController...
0 
6 
C:\...\Qt\build-simpleKinectController-Desktop_Qt_5_0_2_MSVC2012_64bit-Debug\debug\simpleKinectController exited with code 0

Do I need a diffent function to close a stream handler?

Answer 1

nui->NuiImageStreamOpen(...) does not create a valid Windows handle for the stream but instead it creates an internal handle inside the driver side.
So you can not use windows API to release/close stream handle !!!

• To do that just call nui->NuiShutdown(). I have not yet used the callback event but I think its a valid windows handle and should be closed normally.
• if you need just to change settings you can always call nui->NuiImageStreamOpen(...) with new settings. No need to shutdown ...
• I would also welcome function nui->NuiImageStreamClose(...); because current state of API complicates things for long term running aps with changing sensor configurations.