/// <summary>
/// Decode a shared encoded image to a shared image.
/// </summary>
/// <param name="sharedEncodedImage">The shared encoded image to decode.</param>
/// <returns>The decoded shared image.</returns>
internal static Shared <Image> Decode(this Shared <EncodedImage> sharedEncodedImage)
{
Shared <Image> sharedImage = null;
if (sharedEncodedImage.Resource != null)
{
// The code below maintains back-compatibility with encoded images which did not store the pixel format
// on the instance, but only in the stream. If the pixel format is unknown, we call upon the decoder to
// retrieve the pixel format. This might be less performant, but enables decoding in the right format
// even from older versions of encoded images.
var decoder = new ImageFromStreamDecoder();
var pixelFormat = sharedEncodedImage.Resource.PixelFormat == PixelFormat.Undefined ?
decoder.GetPixelFormat(sharedEncodedImage.Resource.ToStream()) : sharedEncodedImage.Resource.PixelFormat;
// If the decoder does not return a valid pixel format, we throw an exception.
if (pixelFormat == PixelFormat.Undefined)
{
throw new ArgumentException("The encoded image does not contain a supported pixel format.");
}
sharedImage = ImagePool.GetOrCreate(sharedEncodedImage.Resource.Width, sharedEncodedImage.Resource.Height, pixelFormat);
decoder.DecodeFromStream(sharedEncodedImage.Resource.ToStream(), sharedImage.Resource);
}
return(sharedImage);
}
