Unable to overwrite image file... I think...

[lidds]

I have written some code to capture a image of the desktop and preview it within a picturebox, this works fine. The problem comes when I try to repeat the process and the following error is produced

 

"An unhandled exception of type 'System.Runtime.InteropServices.ExternalException' occurred in system.drawing.dll

 

Additional information: A generic error occurred in GDI+."

 

I can only presume this is because my picturebox is still keeping the file open. There is not problem in overwritting the file if I close my program and open it again. I have tried pointing the picturebox image to nothing but this does not work.

 

   Private Sub btnCapture_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCapture.Click
       Dim SC As New ScreenShot.ScreenCapture
       Me.picPreview.Image = Nothing

       Dim MyBitMap As Bitmap = SC.CaptureDeskTopRectangle(New Rectangle(MRCSData.Instance.X1, MRCSData.Instance.Y1, _
       MRCSData.Instance.X2, MRCSData.Instance.Y2), Math.Abs(MRCSData.Instance.X1 - MRCSData.Instance.X2), Math.Abs(MRCSData.Instance.Y1 - MRCSData.Instance.Y2))
       MyBitMap.Save("c:\desktopregion.jpg", Imaging.ImageFormat.Jpeg)

       Dim path As String = "c:\desktopregion.jpg"
       Me.picPreview.Image = Image.FromFile(path)

       Dim myBMP As Bitmap = New Bitmap(path)
       Me.pnlPreview.Size = New Size(520, 420)

       If myBMP.Width < Me.pnlPreview.Width Then
           Me.pnlPreview.Width = myBMP.Width
       End If

       If myBMP.Height < Me.pnlPreview.Height Then
           Me.pnlPreview.Height = myBMP.Height
       End If

       Me.pnlPreview.AutoScroll = True
       Me.pnlPreview.AutoScrollMinSize = myBMP.Size
   End Sub

 

Thanks

 

Simon

[PlausiblyDamp]

You will need to dispose of the image assigned to the picturebox rather than just setting it to nothing.

[lidds]

You will need to dispose of the image assigned to the picturebox rather than just setting it to nothing.

 

I added the dispose to my script but it produced the same error. Any ideas, or have I made a mistake??

 

   Private Sub btnCapture_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCapture.Click
       Dim SC As New ScreenShot.ScreenCapture
       Me.picPreview.Image = Nothing
       Me.picPreview.Dispose()

       Dim MyBitMap As Bitmap = SC.CaptureDeskTopRectangle(New Rectangle(MRCSData.Instance.X1, MRCSData.Instance.Y1, _
       MRCSData.Instance.X2, MRCSData.Instance.Y2), Math.Abs(MRCSData.Instance.X1 - MRCSData.Instance.X2), Math.Abs(MRCSData.Instance.Y1 - MRCSData.Instance.Y2))
       MyBitMap.Save("c:\desktopregion.jpg", Imaging.ImageFormat.Jpeg)

       Dim path As String = "c:\desktopregion.jpg"
       Me.picPreview.Image = Image.FromFile(path)

       Dim myBMP As Bitmap = New Bitmap(path)
       Me.pnlPreview.Size = New Size(520, 420)

       If myBMP.Width < Me.pnlPreview.Width Then
           Me.pnlPreview.Width = myBMP.Width
       End If

       If myBMP.Height < Me.pnlPreview.Height Then
           Me.pnlPreview.Height = myBMP.Height
       End If

       Me.pnlPreview.AutoScroll = True
       Me.pnlPreview.AutoScrollMinSize = myBMP.Size
   End Sub

 

Thanks

 

Simon

[PlausiblyDamp]

try

Me.picPreview.Image.Dispose()

[lidds]

Still came up with the same error message, I'm at a loss with this.

 

Simon

[snarfblam]

If you need to access an image file repeatedly you can not use the constructor overload that accepts a filename or the Image.FromFile function. Whether by design or as the result of a bug, the image file is not freed for access (at least not for write access, not sure about read access) until the image is finalized (not when it is disposed).

 

An easy workaround for this is to create a FileStream on the image file and pass this FileStream to the Bitmap constructor instead of using Image.FromFile. Immediately after creating the Bitmap object, close the FileStream to free it up to be deleted/read/written again.

[lidds]

Thanks you. However would it be possible for you to give me an example of how to do this.

 

Thanks

 

Simon

[Cags]

Dim path As String = "c:\\image.jpg"
Dim fs As New IO.FileStream(path, IO.FileMode.Open)
Dim bmp As New Bitmap(fs)
fs.Close()
PictureBox1.Image = bmp