Merge pull request #8366 from radarhere/gif_rgba

Author: hugovk

Tests/test_file_gif.py

@@ -1429,3 +1429,21 @@ def test_saving_rgba(tmp_path: Path) -> None:
  with Image.open(out) as reloaded:
  reloaded_rgba = reloaded.convert("RGBA")
  assert reloaded_rgba.load()[0, 0][3] == 0
+
+
+def test_optimizing_p_rgba(tmp_path: Path) -> None:
+ out = str(tmp_path / "temp.gif")
+
+ im1 = Image.new("P", (100, 100))
+ d = ImageDraw.Draw(im1)
+ d.ellipse([(40, 40), (60, 60)], fill=1)
+ data = [0, 0, 0, 0, 0, 0, 0, 255] + [0, 0, 0, 0] * 254
+ im1.putpalette(data, "RGBA")
+
+ im2 = Image.new("P", (100, 100))
+ im2.putpalette(data, "RGBA")
+
+ im1.save(out, save_all=True, append_images=[im2])
+
+ with Image.open(out) as reloaded:
+ assert reloaded.n_frames == 2

src/PIL/GifImagePlugin.py

@@ -553,7 +553,9 @@ def _normalize_palette(
 
  if im.mode == "P":
  if not source_palette:
- source_palette = im.im.getpalette("RGB")[:768]
+ im_palette = im.getpalette(None)
+ assert im_palette is not None
+ source_palette = bytearray(im_palette)
  else: # L-mode
  if not source_palette:
  source_palette = bytearray(i // 3 for i in range(768))
@@ -629,7 +631,10 @@ def _write_single_frame(
 def _getbbox(
  base_im: Image.Image, im_frame: Image.Image
 ) -> tuple[Image.Image, tuple[int, int, int, int] | None]:
- if _get_palette_bytes(im_frame) != _get_palette_bytes(base_im):
+ palette_bytes = [
+ bytes(im.palette.palette) if im.palette else b"" for im in (base_im, im_frame)
+ ]
+ if palette_bytes[0] != palette_bytes[1]:
  im_frame = im_frame.convert("RGBA")
  base_im = base_im.convert("RGBA")
  delta = ImageChops.subtract_modulo(im_frame, base_im)
@@ -984,7 +989,13 @@ def _get_palette_bytes(im: Image.Image) -> bytes:
  :param im: Image object
  :returns: Bytes, len<=768 suitable for inclusion in gif header
  """
- return bytes(im.palette.palette) if im.palette else b""
+ if not im.palette:
+ return b""
+
+ palette = bytes(im.palette.palette)
+ if im.palette.mode == "RGBA":
+ palette = b"".join(palette[i * 4 : i * 4 + 3] for i in range(len(palette) // 3))
+ return palette
 
 
 def _get_background(

src/PIL/Image.py

@@ -1067,7 +1067,7 @@ def convert_transparency(
  trns_im = new(self.mode, (1, 1))
  if self.mode == "P":
  assert self.palette is not None
- trns_im.putpalette(self.palette)
+ trns_im.putpalette(self.palette, self.palette.mode)
  if isinstance(t, tuple):
  err = "Couldn't allocate a palette color for transparency"
  assert trns_im.palette is not None
@@ -2179,6 +2179,9 @@ def remap_palette(
  source_palette = self.im.getpalette(palette_mode, palette_mode)
  else: # L-mode
  source_palette = bytearray(i // 3 for i in range(768))
+ elif len(source_palette) > 768:
+ bands = 4
+ palette_mode = "RGBA"
 
  palette_bytes = b""
  new_positions = [0] * 256