Merge pull request #1384 from radarhere/gifparams

GIF 89a and animation parameters

PIL/GifImagePlugin.py

@@ -24,7 +24,8 @@
 # See the README file for information on usage and redistribution.
 #
 
-from PIL import Image, ImageFile, ImagePalette, ImageChops, ImageSequence, _binary
+from PIL import Image, ImageFile, ImagePalette, \
+                ImageChops, ImageSequence, _binary
 
 __version__ = "0.9"
 
@@ -300,14 +301,17 @@ RAWMODE = {
 }
 
 
-def _convert_mode(im):
+def _convert_mode(im, initial_call=False):
     # convert on the fly (EXPERIMENTAL -- I'm not sure PIL
     # should automatically convert images on save...)
     if Image.getmodebase(im.mode) == "RGB":
+        if initial_call:
             palette_size = 256
             if im.palette:
                 palette_size = len(im.palette.getdata()[1]) // 3
             return im.convert("P", palette=1, colors=palette_size)
+        else:
+            return im.convert("P")
     return im.convert("L")
 
 
@@ -317,6 +321,7 @@ def _save_all(im, fp, filename):
 
 def _save(im, fp, filename, save_all=False):
 
+    im.encoderinfo.update(im.info)
     if _imaging_gif:
         # call external driver
         try:
@@ -328,7 +333,7 @@ def _save(im, fp, filename, save_all=False):
     if im.mode in RAWMODE:
         im_out = im.copy()
     else:
-        im_out = _convert_mode(im)
+        im_out = _convert_mode(im, True)
 
     # header
     try:
@@ -340,6 +345,7 @@ def _save(im, fp, filename, save_all=False):
     if save_all:
         previous = None
 
+        first_frame = None
         for im_frame in ImageSequence.Iterator(im):
             im_frame = _convert_mode(im_frame)
 
@@ -347,22 +353,30 @@ def _save(im, fp, filename, save_all=False):
             # e.g. getdata(im_frame, duration=1000)
             if not previous:
                 # global header
-                for s in getheader(im_frame, palette, im.encoderinfo)[0] + getdata(im_frame):
+                first_frame = getheader(im_frame, palette, im.encoderinfo)[0]
-                    fp.write(s)
+                first_frame += getdata(im_frame, (0, 0), **im.encoderinfo)
             else:
+                if first_frame:
+                    for s in first_frame:
+                        fp.write(s)
+                    first_frame = None
+
                 # delta frame
-                delta = ImageChops.subtract_modulo(im_frame, previous)
+                delta = ImageChops.subtract_modulo(im_frame, previous.copy())
                 bbox = delta.getbbox()
 
                 if bbox:
                     # compress difference
-                    for s in getdata(im_frame.crop(bbox), offset=bbox[:2]):
+                    for s in getdata(im_frame.crop(bbox),
+                                     bbox[:2], **im.encoderinfo):
                         fp.write(s)
                 else:
                     # FIXME: what should we do in this case?
                     pass
-            previous = im_frame.copy()
+            previous = im_frame
-    else:
+        if first_frame:
+            save_all = False
+    if not save_all:
         header = getheader(im_out, palette, im.encoderinfo)[0]
         for s in header:
             fp.write(s)
@@ -533,8 +547,19 @@ def getheader(im, palette=None, info=None):
 
     # Header Block
     # http://www.matthewflickinger.com/lab/whatsinagif/bits_and_bytes.asp
+
+    version = b"87a"
+    for extensionKey in ["transparency", "duration", "loop"]:
+        if info and extensionKey in info and \
+                not (extensionKey == "duration" and info[extensionKey] == 0):
+            version = b"89a"
+            break
+    else:
+        if im.info.get("version") == "89a":
+            version = b"89a"
+
     header = [
-        b"GIF87a" +             # signature + version
+        b"GIF"+version +        # signature + version
         o16(im.size[0]) +       # canvas width
         o16(im.size[1])         # canvas height
     ]
@@ -591,7 +616,16 @@ def getheader(im, palette=None, info=None):
     # size of global color table + global color table flag
     header.append(o8(color_table_size + 128))
     # background + reserved/aspect
-    background = im.info["background"] if "background" in im.info else 0
+    if info and "background" in info:
+        background = info["background"]
+    elif "background" in im.info:
+        # This elif is redundant within GifImagePlugin
+        # since im.info parameters are bundled into the info dictionary
+        # However, external scripts may call getheader directly
+        # So this maintains earlier behaviour
+        background = im.info["background"]
+    else:
+        background = 0
     header.append(o8(background) + o8(0))
     # end of Logical Screen Descriptor
 

Tests/test_file_gif.py

@@ -24,6 +24,7 @@ class TestFileGif(PillowTestCase):
         self.assertEqual(im.mode, "P")
         self.assertEqual(im.size, (128, 128))
         self.assertEqual(im.format, "GIF")
+        self.assertEqual(im.info["version"], b"GIF89a")
 
     def test_invalid_file(self):
         invalid_file = "Tests/images/flower.jpg"
@@ -95,6 +96,21 @@ class TestFileGif(PillowTestCase):
 
         self.assertEqual(reread.n_frames, 5)
 
+    def test_headers_saving_for_animated_gifs(self):
+        important_headers = ['background', 'version', 'duration', 'loop']
+        # Multiframe image
+        im = Image.open("Tests/images/dispose_bgnd.gif")
+
+        out = self.tempfile('temp.gif')
+        im.save(out, save_all=True)
+        reread = Image.open(out)
+
+        for header in important_headers:
+            self.assertEqual(
+                im.info[header],
+                reread.info[header]
+            )
+
     def test_palette_handling(self):
         # see https://github.com/python-pillow/Pillow/issues/513
 
@@ -251,6 +267,34 @@ class TestFileGif(PillowTestCase):
 
         self.assertEqual(reread.info['background'], im.info['background'])
 
+    def test_version(self):
+        out = self.tempfile('temp.gif')
+
+        # Test that GIF87a is used by default
+        im = Image.new('L', (100, 100), '#000')
+        im.save(out)
+        reread = Image.open(out)
+        self.assertEqual(reread.info["version"], b"GIF87a")
+
+        # Test that adding a GIF89a feature changes the version
+        im.info["transparency"] = 1
+        im.save(out)
+        reread = Image.open(out)
+        self.assertEqual(reread.info["version"], b"GIF89a")
+
+        # Test that a GIF87a image is also saved in that format
+        im = Image.open(TEST_GIF)
+        im.save(out)
+        reread = Image.open(out)
+        self.assertEqual(reread.info["version"], b"GIF87a")
+
+        # Test that a GIF89a image is also saved in that format
+        im.info["version"] = "GIF89a"
+        im.save(out)
+        reread = Image.open(out)
+        self.assertEqual(reread.info["version"], b"GIF87a")
+
+
 if __name__ == '__main__':
     unittest.main()
 

docs/handbook/image-file-formats.rst

@@ -54,8 +54,11 @@ GIF
 ^^^
 
 PIL reads GIF87a and GIF89a versions of the GIF file format. The library writes
-run-length encoded GIF87a files. Note that GIF files are always read as
+run-length encoded files in GIF87a by default, unless GIF89a features
-grayscale (``L``) or palette mode (``P``) images.
+are used or GIF89a is already in use.
+
+Note that GIF files are always read as grayscale (``L``)
+or palette mode (``P``) images.
 
 The :py:meth:`~PIL.Image.Image.open` method sets the following
 :py:attr:`~PIL.Image.Image.info` properties:
@@ -73,12 +76,32 @@ The :py:meth:`~PIL.Image.Image.open` method sets the following
 **version**
     Version (either ``GIF87a`` or ``GIF89a``).
 
+**duration**
+    May not be present. The time to display each frame of the GIF, in
+    milliseconds.
+
+**loop**
+    May not be present. The number of times the GIF should loop.
+
 Reading sequences
 ~~~~~~~~~~~~~~~~~
 
 The GIF loader supports the :py:meth:`~file.seek` and :py:meth:`~file.tell`
 methods. You can seek to the next frame (``im.seek(im.tell() + 1)``), or rewind
-the file by seeking to the first frame. Random access is not supported. ``im.seek()`` raises an ``EOFError`` if you try to seek after the last frame.
+the file by seeking to the first frame. Random access is not supported.
+
+``im.seek()`` raises an ``EOFError`` if you try to seek after the last frame.
+
+Saving sequences
+~~~~~~~~~~~~~~~~
+
+When calling :py:meth:`~PIL.Image.Image.save`, if a multiframe image is used,
+by default only the first frame will be saved. To save all frames, the
+``save_all`` parameter must be present and set to ``True``.
+
+If present, the ``loop`` parameter can be used to set the number of times
+the GIF should loop, and the ``duration`` parameter can set the number of
+milliseconds between each frame.
 
 Reading local images
 ~~~~~~~~~~~~~~~~~~~~