System.IO.Compression.ZipArchiveEntry.GetDataCompressor C# (CSharp) Метод

        private CheckSumAndSizeWriteStream GetDataCompressor(Stream backingStream, bool leaveBackingStreamOpen, EventHandler onClose)
        {
            //stream stack: backingStream -> DeflateStream -> CheckSumWriteStream

            //we should always be compressing with deflate. Stored is used for empty files, but we don't actually
            //call through this function for that - we just write the stored value in the header
            Debug.Assert(CompressionMethod == CompressionMethodValues.Deflate);

            Stream compressorStream = _compressionLevel.HasValue
                                            ? new DeflateStream(backingStream, _compressionLevel.Value, leaveBackingStreamOpen)
                                            : new DeflateStream(backingStream, CompressionMode.Compress, leaveBackingStreamOpen);
            bool isIntermediateStream = true;

            bool leaveCompressorStreamOpenOnClose = leaveBackingStreamOpen && !isIntermediateStream;
            var checkSumStream = new CheckSumAndSizeWriteStream(
                compressorStream,
                backingStream,
                leaveCompressorStreamOpenOnClose,
                this,
                onClose,
                (long initialPosition, long currentPosition, uint checkSum, Stream backing, ZipArchiveEntry thisRef, EventHandler closeHandler) =>
                {
                    thisRef._crc32 = checkSum;
                    thisRef._uncompressedSize = currentPosition;
                    thisRef._compressedSize = backing.Position - initialPosition;

                    if (closeHandler != null)
                        closeHandler(thisRef, EventArgs.Empty);
                });

            return checkSumStream;
        }