asked on

Object Disposed Exception

I'm getting this error...

System.ObjectDisposedException: Cannot access a closed Stream. at System.IO.__Error.StreamIsClosed() at System.IO.MemoryStream.Seek(Int64 offset, SeekOrigin loc)

I haven't disposed of the stream in question.. so who has ?

Are streams cleaned up differently ? The stream in question is defined at class level.

Any ideas?

kaufmed

It would help to see the code in question.

Dodsworth

ASKER

I've chopped the code down so it's easier to read, which has prompted a thought..
When I dispose of e.ImageStream is mainStream also being disposed because I'm using '=' ?

Partial Public Class Camera

    Private mainStream As Stream    'This is where I'm holding the image stream from the camera
    Private saveNow As Boolean = True   'Save the image straight away or on click of save button

    Private Sub cam_CaptureImageAvailable(ByVal sender As Object, ByVal e As Microsoft.Devices.ContentReadyEventArgs)
        Try
            mainStream = e.ImageStream
            If saveNow Then
                saveImage() 'This call does not error
            End If
        Catch err As Exception
            Stop
        Finally
            e.ImageStream.Close()
        End Try
    End Sub

    Private Sub saveImage()
        mainStream.Seek(0, SeekOrigin.Begin)
        library.SavePictureToCameraRoll(Date.UtcNow.Ticks.ToString & ".jpg", mainStream)
    End Sub

    Private Sub Ok_Click(sender As Object, e As EventArgs)
        saveImage() 'Here Errors :(
    End Sub
End Class

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ASKER CERTIFIED SOLUTION

Carl Tawn

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Dodsworth

ASKER

Thought that might be the case. So I need to copy the e.Imagestream to mainStream somehow?

Carl Tawn

Or remove the line:

e.ImageStream.Close()

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From your Finally clause, and then close the stream when you are done with it (probably in your SaveImage() method.

kaufmed

So I need to copy the e.Imagestream to mainStream somehow?

You can use the Clone method for this purpose.

and then close the stream when you are done with it (probably in your SaveImage() method.

But you'll also want to include some checking on the state of that variable, in case someone clicks the button twice. I'd suggest setting the variable to Nothing after you close the image, and then add a check for Is Nothing in your save code.

Dodsworth

ASKER

It would seem that e.ImageStream goes out of scope outside cam_CaptureImageAvailable.

I tried

e.ImageStream.CopyTo(mainStream)

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but got a ArgumentNullException which the documentation indicates that is because the destination is Nothing.

Private mainStream As New Stream

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Resulted in
'New' cannot be used on a class that is declared 'MustInhert'
So I changed it to

Private mainStream As New MemoryStream

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And all is well :)