/// <summary>
/// Function to load an image from a stream.
/// </summary>
/// <param name="stream">The stream containing the image data to read.</param>
/// <param name="size">The size of the image within the stream, in bytes.</param>
/// <returns>A <see cref="IGorgonImage"/> containing the image data from the stream.</returns>
/// <exception cref="GorgonException">Thrown when the image data in the stream has a pixel format that is unsupported.</exception>
protected override IGorgonImage OnDecodeFromStream(Stream stream, long size)
{
var wic = new WicUtilities();
Stream streamAlias = stream;
try
{
// If we have a stream position that does not begin exactly at the start of the stream, we have to wrap that stream in a
// dummy stream wrapper. This is to get around a problem in the underlying COM stream object used by WIC that throws an
// exception when the stream position is not exactly 0.
if (streamAlias.Position != 0)
{
streamAlias = new GorgonStreamWrapper(stream, 0, size);
}
IGorgonImage result = wic.DecodeImageData(streamAlias, size, SupportedFileFormat, DecodingOptions, FrameOffsetMetadataNames);
if (result == null)
{
throw new IOException(string.Format(Resources.GORIMG_ERR_FILE_FORMAT_NOT_CORRECT, Codec));
}
if (stream.Position != streamAlias.Position)
{
stream.Position += streamAlias.Position;
}
return(result);
}
finally
{
if (streamAlias != stream)
{
streamAlias?.Dispose();
}
wic.Dispose();
}
}
