Metadata is null for GIF images on Windows XP SP3 (works fine on Windows 7)

I have the following piece of code, which prints the metadata of an image using the WPF imaging API:

void Main()
{
    Uri imageUri = new Uri(@"E:\tmp\bomb.gif");
    var decoder = BitmapDecoder.Create(imageUri, BitmapCreateOptions.None, BitmapCacheOption.OnLoad);
    var f = decoder.Frames[0];
    var m = f.Metadata as BitmapMetadata;
    DumpMetadata(m);
}

void DumpMetadata(BitmapMetadata metadata)
{
    DumpMetadata(metadata, 0);
}

void DumpMetadata(BitmapMetadata metadata, int indentLevel)
{
    if (metadata == null)
    {
        Console.WriteLine ("(No metadata)");
        return;
    }
    string indent = new string('开发者_开发技巧\t', indentLevel);
    foreach (var propertyName in metadata)
    {
        object value = metadata.GetQuery(propertyName);
        BitmapMetadata complexProperty = value as BitmapMetadata;
        if (complexProperty != null)
        {
            Console.WriteLine("{0}{1} =", indent, propertyName);
            DumpMetadata(complexProperty, indentLevel + 1);
        }
        else
        {
            Type type = null;
            if (value != null)
                type = value.GetType();
            Console.WriteLine("{0}{1} = {2} ({3})", indent, propertyName, value, type);
        }
    }
}

On Windows 7, it gives correct results:

/imgdesc =
  /Left = 0 (System.UInt16)
  /Top = 0 (System.UInt16)
  /Width = 78 (System.UInt16)
  /Height = 121 (System.UInt16)
  /LocalColorTableFlag = False (System.Boolean)
  /InterlaceFlag = False (System.Boolean)
  /SortFlag = False (System.Boolean)
  /LocalColorTableSize = 7 (System.Byte)
/grctlext =
  /Disposal = 2 (System.Byte)
  /UserInputFlag = False (System.Boolean)
  /TransparencyFlag = True (System.Boolean)
  /Delay = 10 (System.UInt16)
  /TransparentColorIndex = 0 (System.Byte)

But on Windows XP (SP3), the Metadata property is always null for GIF images (animated or not).

I think the issue might be related to Windows Imaging Component, but WIC is supposed to be installed with SP3 (and also as part of .NET 3.0; I have 3.5 SP1 and 4.0 on that PC), so it should work on XP too.

Not sure what's going on here... Is it just a missing codec? Is there a way to make this code work on XP?

EDIT: the information I need is the Delay field (duration of the frame); if I can't get the BitmapMetadata, is there another way to extract this information? Ideally I would prefer to use only the WPF imaging API (i.e. not GDI/System.Drawing).

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UPDATE: I posted the same question on the MSDN forums, and according to the answer I received, GIF metadata are only supported on Windows 7, and on Vista with Platform Update (see here and there). So I guess it's just not possible to make it work on XP using the WPF imaging API. I will probably end up using System.Drawing, but I'm open to better suggestions...

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You are right, the issue is with WIC in XP. This thread also mentions that problem.

However using the old System.Drawing from GDI+ you could do something like this:

private static int ReadGifDelayInMiliseconds(string gifFile, int frameIndex = 0)
{
    System.Drawing.Image img = System.Drawing.Image.FromFile(gifFile);
    int numFrames = img.GetFrameCount(FrameDimension.Time);
    byte[] bytes = img.GetPropertyItem(0x5100).Value;
    if (frameIndex < numFrames)
    {
        var raw = BitConverter.ToInt32(bytes, frameIndex *  4);
        return raw * 10;
    }
    else
    {
        return -1;
    }       
}

Note that you can modify the function to read the delay of every frame all at once since the bytes array has all the delays.

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I eventually solved this by writing a custom GIF decoder, which is not unreasonably hard since I only need the metadata...