Added EXIF support

Tests/test_file_png.py

@@ -590,6 +590,25 @@ class TestFilePng(PillowTestCase):
         im = Image.open("Tests/images/hopper_idat_after_image_end.png")
         self.assertEqual(im.text, {'TXT': 'VALUE', 'ZIP': 'VALUE'})
 
+    def test_exif(self):
+        im = Image.open("Tests/images/pil_sample_rgb.jpg")
+
+        test_file = self.tempfile("temp.png")
+        im.save(test_file)
+
+        reloaded = Image.open(test_file)
+        exif = reloaded._getexif()
+        self.assertEqual(exif[305], "Adobe Photoshop CS Macintosh")
+
+    def test_exif_argument(self):
+        im = Image.open(TEST_PNG_FILE)
+
+        test_file = self.tempfile("temp.png")
+        im.save(test_file, exif=b"exifstring")
+
+        reloaded = Image.open(test_file)
+        self.assertEqual(reloaded.info["exif"], b"Exif\x00\x00exifstring")
+
     @unittest.skipUnless(HAVE_WEBP and _webp.HAVE_WEBPANIM,
                          "WebP support not installed with animation")
     def test_apng(self):

src/PIL/PngImagePlugin.py

@@ -529,6 +529,11 @@ class PngStream(ChunkStream):
 
         return s
 
+    def chunk_eXIf(self, pos, length):
+        s = ImageFile._safe_read(self.fp, length)
+        self.im_info["exif"] = b"Exif\x00\x00"+s
+        return s
+
     # APNG chunks
     def chunk_acTL(self, pos, length):
         s = ImageFile._safe_read(self.fp, length)
@@ -683,6 +688,10 @@ class PngImageFile(ImageFile.ImageFile):
         self.png.close()
         self.png = None
 
+    def _getexif(self):
+        from .JpegImagePlugin import _getexif
+        return _getexif(self)
+
 
 # --------------------------------------------------------------------
 # PNG writer
@@ -861,6 +870,12 @@ def _save(im, fp, filename, chunk=putchunk):
                 chunks.remove(cid)
                 chunk(fp, cid, data)
 
+    exif = im.encoderinfo.get("exif", im.info.get("exif"))
+    if exif:
+        if exif.startswith(b"Exif\x00\x00"):
+            exif = exif[6:]
+        chunk(fp, b"eXIf", exif)
+
     ImageFile._save(im, _idat(fp, chunk),
                     [("zip", (0, 0)+im.size, 0, rawmode)])