WPF BitmapImage Doesn't Dispose

Question

I have loaded a list of images out of a filestream database. When I load them initially the memory jump isn't that large. When I display them on the screen my memory usage spikes and doesn't go away even after I dispose of the BitmapImage streamsource and set it to Nothing.

    Dim newItem As New MIdentifiedImage
    Dim data As Byte() = dt.Rows(i).Item("ScannedImage")
    Dim strm As New MemoryStream(data)

    Dim bi As New BitmapImage()
    bi.BeginInit()
    bi.StreamSource = strm
    bi.EndInit()
    bi.Freeze()
    newItem.ScannedImage = bi

And here is my dispose code

  For Each img In InvoiceObj.ImageList
    img.ScannedImage.StreamSource.Dispose()
    img.ScannedImage.StreamSource = Nothing

  Next

So my profiler says that the memory usage is low but when I check in my task manager the memory usage is quite high. If I continue to load images beyond 1.5GB of memory it just stops showing the images on screen.

Answer 1

You need to clear out the ImageList, as well. Just setting the StreamSource to null doesn't cause it to remove the data that's already loaded. By clearing the ImageList when you're done with it, you allow the GC to clean up the actual BitmapImage instances, as well.