Image.Save(..) throws a GDI+ exception because the

问题:

i\'ve got some binary data which i want to save as an image. When i try to save the image, it throws an exception if the memory stream used to create the image, was closed before the save. The reason i do this is because i\'m dynamically creating images and as such .. i need to use a memory stream.

this is the code:

[TestMethod]
public void TestMethod1()
{
    // Grab the binary data.
    byte[] data = File.ReadAllBytes(\"Chick.jpg\");

    // Read in the data but do not close, before using the stream.
    Stream originalBinaryDataStream = new MemoryStream(data);
    Bitmap image = new Bitmap(originalBinaryDataStream);
    image.Save(@\"c:\\test.jpg\");
    originalBinaryDataStream.Dispose();

    // Now lets use a nice dispose, etc...
    Bitmap2 image2;
    using (Stream originalBinaryDataStream2 = new MemoryStream(data))
    {
        image2 = new Bitmap(originalBinaryDataStream2);
    }

    image2.Save(@\"C:\\temp\\pewpew.jpg\"); // This throws the GDI+ exception.
}

Does anyone have any suggestions to how i could save an image with the stream closed? I cannot rely on the developers to remember to close the stream after the image is saved. In fact, the developer would have NO IDEA that the image was generated using a memory stream (because it happens in some other code, elsewhere).

I\'m really confused :(

回答1:

As it\'s a MemoryStream, you really don\'t need to close the stream - nothing bad will happen if you don\'t, although obviously it\'s good practice to dispose anything that\'s disposable anyway. (See this question for more on this.)

However, you should be disposing the Bitmap - and that will close the stream for you. Basically once you give the Bitmap constructor a stream, it \"owns\" the stream and you shouldn\'t close it. As the docs for that constructor say:

You must keep the stream open for the lifetime of the Bitmap.

I can\'t find any docs promising to close the stream when you dispose the bitmap, but you should be able to verify that fairly easily.

回答2:

A generic error occurred in GDI+. May also result from incorrect save path! Took me half a day to notice that. So make sure that you have double checked the path to save the image as well.

回答3:

Perhaps it is worth mentioning that if the C:\\Temp directory does not exist, it will also throw this exception even if your stream is still existent.

回答4:

I had the same problem but actually the cause was that the application didn\'t have permission to save files on C. When I changed to \"D:\\..\" the picture has been saved.

回答5:

Copy the Bitmap. You have to keep the stream open for the lifetime of the bitmap.

When drawing an image: System.Runtime.InteropServices.ExternalException: A generic error occurred in GDI

    public static Image ToImage(this byte[] bytes)
    {
        using (var stream = new MemoryStream(bytes))
        using (var image = Image.FromStream(stream, false, true))
        {
            return new Bitmap(image);
        }
    }

    [Test]
    public void ShouldCreateImageThatCanBeSavedWithoutOpenStream()
    {
        var imageBytes = File.ReadAllBytes(\"bitmap.bmp\");

        var image = imageBytes.ToImage();

        image.Save(\"output.bmp\");
    }

回答6:

This error occurred to me when I was trying from Citrix. The image folder was set to C:\\ in the server, for which I do not have privilege. Once the image folder was moved to a shared drive, the error was gone.

回答7:

You can try to create another copy of bitmap:

using (var memoryStream = new MemoryStream())
{
    // write to memory stream here

    memoryStream.Position = 0;
    using (var bitmap = new Bitmap(memoryStream))
    {
        var bitmap2 = new Bitmap(bitmap);
        return bitmap2;
    }
}

回答8:

A generic error occurred in GDI+. It can occur because of image storing paths issues,I got this error because my storing path is too long, I fixed this by first storing the image in a shortest path and move it to the correct location with long path handling techniques.

回答9:

I was getting this error, because the automated test I was executing, was trying to store snapshots into a folder that didn\'t exist. After I created the folder, the error resolved

回答10:

One strange solution which made my code to work. Open the image in paint and save it as a new file with same format(.jpg). Now try with this new file and it works. It clearly explains you that the file might be corrupted in someway. This can help only if your code has every other bugs fixed

回答11:

It has also appeared with me when I was trying to save an image into path

C:\\Program Files (x86)\\some_directory

and the .exe wasn\'t executed to run as administrator, I hope this may help someone who has same issue too.

回答12:

For me the code below crashed with A generic error occurred in GDI+on the line which Saves to a MemoryStream. The code was running on a web server and I resolved it by stopping and starting the Application Pool that was running the site.

Must have been some internal error in GDI+

    private static string GetThumbnailImageAsBase64String(string path)
    {
        if (path == null || !File.Exists(path))
        {
            var log = ContainerResolver.Container.GetInstance<ILog>();
            log.Info($\"No file was found at path: {path}\");
            return null;
        }

        var width = LibraryItemFileSettings.Instance.ThumbnailImageWidth;

        using (var image = Image.FromFile(path))
        {
            using (var thumbnail = image.GetThumbnailImage(width, width * image.Height / image.Width, null, IntPtr.Zero))
            {
                using (var memoryStream = new MemoryStream())
                {
                    thumbnail.Save(memoryStream, ImageFormat.Png); // <= crash here 
                    var bytes = new byte[memoryStream.Length];
                    memoryStream.Position = 0;
                    memoryStream.Read(bytes, 0, bytes.Length);
                    return Convert.ToBase64String(bytes, 0, bytes.Length);
                }
            }
        }
    }

回答13:

I came across this error when I was trying a simple image editing in a WPF app.

Setting an Image element\'s Source to the bitmap prevents file saving. Even setting Source=null doesn\'t seem to release the file.

Now I just never use the image as the Source of Image element, so I can overwrite after editing!

EDIT

After hearing about the CacheOption property(Thanks to @Nyerguds) I found the solution: So instead of using the Bitmap constructor I must set the Uri after setting CacheOption BitmapCacheOption.OnLoad.(Image1 below is the Wpf Image element)

Instead of

Image1.Source = new BitmapImage(new Uri(filepath));

Use:

var image = new BitmapImage();
image.BeginInit();
image.CreateOptions = BitmapCreateOptions.IgnoreImageCache;
image.CacheOption = BitmapCacheOption.OnLoad;
image.UriSource = new Uri(filepath);
image.EndInit();
Image1.Source = image;

See this: WPF Image Caching

回答14:

Try this code:

static void Main(string[] args)
{
    byte[] data = null;
    string fullPath = @\"c:\\testimage.jpg\";

    using (MemoryStream ms = new MemoryStream())
    using (Bitmap tmp = (Bitmap)Bitmap.FromFile(fullPath))
    using (Bitmap bm = new Bitmap(tmp))
    {
        bm.SetResolution(96, 96);
        using (EncoderParameters eps = new EncoderParameters(1))
        {   
            eps.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, 100L);
            bm.Save(ms, GetEncoderInfo(\"image/jpeg\"), eps);
        }

        data = ms.ToArray();
    }

    File.WriteAllBytes(fullPath, data);
}

private static ImageCodecInfo GetEncoderInfo(string mimeType)
{
        ImageCodecInfo[] encoders = ImageCodecInfo.GetImageEncoders();

        for (int j = 0; j < encoders.Length; ++j)
        {
            if (String.Equals(encoders[j].MimeType, mimeType, StringComparison.InvariantCultureIgnoreCase))
                return encoders[j];
        }
    return null;
}