Merge branch 'python-pillow:main' into p2pa_images_conversion

CHANGES.rst

@@ -5,6 +5,15 @@ Changelog (Pillow)
 9.2.0 (unreleased)
 ------------------
 
+- Improve transparency handling when saving GIF images #6176
+  [radarhere]
+
+- Do not update GIF frame position until local image is found #6219
+  [radarhere]
+
+- Netscape GIF extension belongs after the global color table #6211
+  [radarhere]
+
 - Only write GIF comments at the beginning of the file #6300
   [raygard, radarhere]
 

Tests/test_file_gif.py

@@ -354,16 +354,23 @@ def test_seek_rewind():
             assert_image_equal(im, expected)
 
 
-def test_n_frames():
-    for path, n_frames in [[TEST_GIF, 1], ["Tests/images/iss634.gif", 42]]:
-        # Test is_animated before n_frames
-        with Image.open(path) as im:
-            assert im.is_animated == (n_frames != 1)
+@pytest.mark.parametrize(
+    "path, n_frames",
+    (
+        (TEST_GIF, 1),
+        ("Tests/images/comment_after_last_frame.gif", 2),
+        ("Tests/images/iss634.gif", 42),
+    ),
+)
+def test_n_frames(path, n_frames):
+    # Test is_animated before n_frames
+    with Image.open(path) as im:
+        assert im.is_animated == (n_frames != 1)
 
-        # Test is_animated after n_frames
-        with Image.open(path) as im:
-            assert im.n_frames == n_frames
-            assert im.is_animated == (n_frames != 1)
+    # Test is_animated after n_frames
+    with Image.open(path) as im:
+        assert im.n_frames == n_frames
+        assert im.is_animated == (n_frames != 1)
 
 
 def test_no_change():
@@ -632,7 +639,8 @@ def test_dispose2_background(tmp_path):
         assert im.getpixel((0, 0)) == (255, 0, 0)
 
 
-def test_transparency_in_second_frame():
+def test_transparency_in_second_frame(tmp_path):
+    out = str(tmp_path / "temp.gif")
     with Image.open("Tests/images/different_transparency.gif") as im:
         assert im.info["transparency"] == 0
 
@@ -642,6 +650,14 @@ def test_transparency_in_second_frame():
 
         assert_image_equal_tofile(im, "Tests/images/different_transparency_merged.png")
 
+        im.save(out, save_all=True)
+
+    with Image.open(out) as reread:
+        reread.seek(reread.tell() + 1)
+        assert_image_equal_tofile(
+            reread, "Tests/images/different_transparency_merged.png"
+        )
+
 
 def test_no_transparency_in_second_frame():
     with Image.open("Tests/images/iss634.gif") as img:
@@ -653,6 +669,22 @@ def test_no_transparency_in_second_frame():
         assert img.histogram()[255] == 0
 
 
+def test_remapped_transparency(tmp_path):
+    out = str(tmp_path / "temp.gif")
+
+    im = Image.new("P", (1, 2))
+    im2 = im.copy()
+
+    # Add transparency at a higher index
+    # so that it will be optimized to a lower index
+    im.putpixel((0, 1), 5)
+    im.info["transparency"] = 5
+    im.save(out, save_all=True, append_images=[im2])
+
+    with Image.open(out) as reloaded:
+        assert reloaded.info["transparency"] == reloaded.getpixel((0, 1))
+
+
 def test_duration(tmp_path):
     duration = 1000
 
@@ -772,9 +804,16 @@ def test_number_of_loops(tmp_path):
     im = Image.new("L", (100, 100), "#000")
     im.save(out, loop=number_of_loops)
     with Image.open(out) as reread:
-
         assert reread.info["loop"] == number_of_loops
 
+    # Check that even if a subsequent GIF frame has the number of loops specified,
+    # only the value from the first frame is used
+    with Image.open("Tests/images/duplicate_number_of_loops.gif") as im:
+        assert im.info["loop"] == 2
+
+        im.seek(1)
+        assert im.info["loop"] == 2
+
 
 def test_background(tmp_path):
     out = str(tmp_path / "temp.gif")

Tests/test_image.py

@@ -609,6 +609,20 @@ def test_remap_palette(self):
             with pytest.raises(ValueError):
                 im.remap_palette(None)
 
+    def test_remap_palette_transparency(self):
+        im = Image.new("P", (1, 2))
+        im.putpixel((0, 1), 1)
+        im.info["transparency"] = 0
+
+        im_remapped = im.remap_palette([1, 0])
+        assert im_remapped.info["transparency"] == 1
+
+        # Test unused transparency
+        im.info["transparency"] = 2
+
+        im_remapped = im.remap_palette([1, 0])
+        assert "transparency" not in im_remapped.info
+
     def test__new(self):
         im = hopper("RGB")
         im_p = hopper("P")

docs/handbook/image-file-formats.rst

@@ -156,7 +156,8 @@ The :py:meth:`~PIL.Image.open` method sets the following
     it will loop forever.
 
 **comment**
-    May not be present. A comment about the image.
+    May not be present. A comment about the image. This is the last comment found
+    before the current frame's image.
 
 **extension**
     May not be present. Contains application specific information.

src/PIL/GifImagePlugin.py

@@ -185,8 +185,6 @@ def _seek(self, frame, update_image=True):
         if not s or s == b";":
             raise EOFError
 
-        self.__frame = frame
-
         self.tile = []
 
         palette = None
@@ -244,15 +242,15 @@ def _seek(self, frame, update_image=True):
                         info["comment"] = comment
                     s = None
                     continue
-                elif s[0] == 255:
+                elif s[0] == 255 and frame == 0:
                     #
                     # application extension
                     #
                     info["extension"] = block, self.fp.tell()
                     if block[:11] == b"NETSCAPE2.0":
                         block = self.data()
                         if len(block) >= 3 and block[0] == 1:
-                            info["loop"] = i16(block, 1)
+                            self.info["loop"] = i16(block, 1)
                 while self.data():
                     pass
 
@@ -291,6 +289,8 @@ def _seek(self, frame, update_image=True):
         if interlace is None:
             # self._fp = None
             raise EOFError
+
+        self.__frame = frame
         if not update_image:
             return
 
@@ -399,7 +399,7 @@ def _rgb(color):
 
         if info.get("comment"):
             self.info["comment"] = info["comment"]
-        for k in ["duration", "extension", "loop"]:
+        for k in ["duration", "extension"]:
             if k in info:
                 self.info[k] = info[k]
             elif k in self.info:
@@ -574,10 +574,14 @@ def _write_multiple_frames(im, fp, palette):
             im_frame = _normalize_mode(im_frame.copy())
             if frame_count == 0:
                 for k, v in im_frame.info.items():
+                    if k == "transparency":
+                        continue
                     im.encoderinfo.setdefault(k, v)
-            im_frame = _normalize_palette(im_frame, palette, im.encoderinfo)
 
             encoderinfo = im.encoderinfo.copy()
+            im_frame = _normalize_palette(im_frame, palette, encoderinfo)
+            if "transparency" in im_frame.info:
+                encoderinfo.setdefault("transparency", im_frame.info["transparency"])
             if isinstance(duration, (list, tuple)):
                 encoderinfo["duration"] = duration[frame_count]
             elif duration is None and "duration" in im_frame.info:
@@ -716,18 +720,6 @@ def _write_local_header(fp, im, offset, flags):
             + o8(0)
         )
 
-    if "loop" in im.encoderinfo:
-        number_of_loops = im.encoderinfo["loop"]
-        fp.write(
-            b"!"
-            + o8(255)  # extension intro
-            + o8(11)
-            + b"NETSCAPE2.0"
-            + o8(3)
-            + o8(1)
-            + o16(number_of_loops)  # number of loops
-            + o8(0)
-        )
     include_color_table = im.encoderinfo.get("include_color_table")
     if include_color_table:
         palette_bytes = _get_palette_bytes(im)
@@ -933,6 +925,17 @@ def _get_global_header(im, info):
         # Global Color Table
         _get_header_palette(palette_bytes),
     ]
+    if "loop" in info:
+        header.append(
+            b"!"
+            + o8(255)  # extension intro
+            + o8(11)
+            + b"NETSCAPE2.0"
+            + o8(3)
+            + o8(1)
+            + o16(info["loop"])  # number of loops
+            + o8(0)
+        )
     if info.get("comment"):
         comment_block = b"!" + o8(254)  # extension intro
 

src/PIL/Image.py

@@ -1909,6 +1909,13 @@ def remap_palette(self, dest_map, source_palette=None):
         m_im.putpalette(new_palette_bytes)
         m_im.palette = ImagePalette.ImagePalette("RGB", palette=palette_bytes)
 
+        if "transparency" in self.info:
+            try:
+                m_im.info["transparency"] = dest_map.index(self.info["transparency"])
+            except ValueError:
+                if "transparency" in m_im.info:
+                    del m_im.info["transparency"]
+
         return m_im
 
     def _get_safe_box(self, size, resample, box):