The current implementation uses System.Windows.Media.Imaging.BitmapImage class in order to take the image pixels for the PDF export. However, BitmapImage class throws NotSupportedException when being initialized with a WMF or EMF image.

WORKAROUND: WMF and EMF images may be converted to PNG images before the PDF export. The following code snippet shows how to convert all inline WMF image to PNG images by using System.Drawing.Image class:

private static void ConvertInlineWmfImagesToPng(RadFlowDocument document)
{
    foreach (ImageInline image in document.EnumerateChildrenOfType<ImageInline>())
    {
        if (image.Image.ImageSource.Extension.Equals("wmf", StringComparison.InvariantCultureIgnoreCase))
        {
            using (MemoryStream wmfImageStream = new MemoryStream(image.Image.ImageSource.Data))
            {
                using (MemoryStream pngImageStream = new MemoryStream())
                {
                    var imageDrawing = System.Drawing.Image.FromStream(wmfImageStream);
                    imageDrawing.Save(pngImageStream, ImageFormat.Png);
                    byte[] pngBytes = pngImageStream.ToArray();
 
                    image.Image.ImageSource = new ImageSource(pngBytes, "png");
                }
            }
        }
    }
}