Use gzip's GzipFile to manage compression/decompression

README.rst

@@ -7,11 +7,11 @@ codecs for use in data storage and communication applications.
 .. image:: https://readthedocs.org/projects/numcodecs/badge/?version=latest
     :target: http://numcodecs.readthedocs.io/en/latest/?badge=latest
 
-.. image:: https://travis-ci.org/alimanfoo/numcodecs.svg?branch=master
-    :target: https://travis-ci.org/alimanfoo/numcodecs
+.. image:: https://travis-ci.org/zarr-developers/numcodecs.svg?branch=master
+    :target: https://travis-ci.org/zarr-developers/numcodecs
 
-.. image:: https://ci.appveyor.com/api/projects/status/r35av34952d9fcyn?svg=true
-    :target: https://ci.appveyor.com/project/alimanfoo/numcodecs
+.. image:: https://ci.appveyor.com/api/projects/status/jhaaaxotvel24n9g?svg=true
+    :target: https://ci.appveyor.com/project/zarr-developers/numcodecs
 
-.. image:: https://coveralls.io/repos/github/alimanfoo/numcodecs/badge.svg?branch=master
-    :target: https://coveralls.io/github/alimanfoo/numcodecs?branch=master
+.. image:: https://coveralls.io/repos/github/zarr-developers/numcodecs/badge.svg?branch=master
+    :target: https://coveralls.io/github/zarr-developers/numcodecs?branch=master

numcodecs/gzip.py

@@ -1,6 +1,7 @@
 # -*- coding: utf-8 -*-
 from __future__ import absolute_import, print_function, division
-import zlib as _zlib
+import gzip as _gzip
+import io
 
 
 import numpy as np
@@ -45,9 +46,12 @@ def encode(self, buf):
             buf = buffer_tobytes(buf)
 
         # do compression
-        compress = _zlib.compressobj(self.level, _zlib.DEFLATED, 16 + 15)
-        compressed = compress.compress(buf)
-        compressed += compress.flush()
+        compressed = io.BytesIO()
+        with _gzip.GzipFile(fileobj=compressed,
+                            mode='wb',
+                            compresslevel=self.level) as compressor:
+            compressor.write(buf)
+        compressed = compressed.getvalue()
 
         return compressed
 
@@ -59,9 +63,11 @@ def decode(self, buf, out=None):
             buf = buffer_tobytes(buf)
 
         # do decompression
-        dec = _zlib.decompress(buf, 15 + 32)
+        buf = io.BytesIO(buf)
+        with _gzip.GzipFile(fileobj=buf, mode='rb') as decompressor:
+            decompressed = decompressor.read()
 
         # handle destination - Python standard library zlib module does not
         # support direct decompression into buffer, so we have to copy into
         # out if given
-        return buffer_copy(dec, out)
+        return buffer_copy(decompressed, out)