Comment Feed for Display and save image file to SQL Server simultaneously (TechOff on Channel 9)

Re: Display and save image file to SQL Server simultaneously

stevo_ — Tue, 06 Nov 2007 09:18:46 GMT

Does that have an effect on the memory usage?

Re: Display and save image file to SQL Server simultaneously

Sven Groot — Tue, 06 Nov 2007 07:22:29 GMT

Tommy, the method you're using to do this probably works in most cases, but it is not generically safe.

You see, the reason Image.FromFile keeps the file locked is because GDI+ can (depending on the codec, the size of the file, and other factors) delay decoding (parts of) the image until they are actually needed (e.g. when you draw them). The Image.FromStream method will for the same reason keep a reference to the stream you passed it. If you close the stream and you run into one of these delayed-decoding scenarios, GDI+ will access the stream and fail with an ObjectDisposedException.

The only way that I know of to achieve this that is 100% safe in all cases is to load the image from file, create a new image, draw the original image into the new image, and then close the original one (which unlocks the file).

Public Module Utils
   Public Function ImageFromFile(ByVal fileName As String) As Image
      Using image As Image = image.FromFile(fileName)
         Dim result As New Bitmap(image.Width, image.Height, Imaging.PixelFormat.Format32bppArgb)
         Using g As Graphics = Graphics.FromImage(result)
            g.DrawImage(image, 0, 0, image.Width, image.Height)
         End Using
         Return result
      End Using
   End Function
End Module

Re: Display and save image file to SQL Server simultaneously

ed_de_wind — Tue, 06 Nov 2007 07:12:50 GMT

Finally, IT WORKS........... Thanks for your guide.
I only did a tiny modification in my code and it instantly worked. What I change is the declaration of FileStream, so now it looks like this:

Dim fs As FileStream = New FileStream(FilePath, FileMode.Open, FileAccess.Read)

The underlined words are all changes I've made to get it done. Thanks again, Tommy.......

Re: Display and save image file to SQL Server simultaneously

Tommy Carlier — Tue, 06 Nov 2007 06:25:34 GMT

Last year I wrote a blog post about this. The code is in C#, but I think it's not hard to translate to VB. It's only a few lines of code. http://tommycarlier.blogspot.com/2006/06/reading-image-from-file-without.html