Why won't GDI let me delete large images?

Question

My ASP.NET application has an image cropping and resizing features. This requires that the uploaded temporary image be deleted. Everything works fine, but when I try to delete an image larger than 80px by 80px I get a "File is locked by other process..." error, even though I've released all resources.

Can anyone help? I'm tired of Googling!

Here's a snippet:

    System.Drawing.Image tempimg = System.Drawing.Image.FromFile(temppath);
    System.Drawing.Image img = (System.Drawing.Image) tempimg.Clone(); //advice from another forum
    tempimg.Dispose();

    img = resizeImage(img, 200, 200); //delete only works if it's 80, 80
    img.Save(newpath);
    img.Dispose();

    File.Delete(temppath);

Answer 1

If you create the image this way, it won't be locked:

using (FileStream fs = new FileStream(info.FullName, FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
                {
                    byte[] data = new byte[fs.Length];
                    int read = fs.Read(data, 0, (int)fs.Length);
                    MemoryStream ms = new MemoryStream(data, false);
                    return Image.FromStream(ms, false, false); // prevent GDI from holding image file open
                }

Answer 2

I think you are not disposing the first Image instance assigned to the img variable.

Consider this instead:

System.Drawing.Image tempimg = System.Drawing.Image.FromFile(temppath);
System.Drawing.Image img = (System.Drawing.Image) tempimg.Clone();
tempimg.Dispose();

System.Drawing.Image img2 = resizeImage(img, 200, 200);
img2.Save(newpath);
img2.Dispose();
img.Dispose();

File.Delete(temppath);