From 31638ee29aae89452adf30acd41620d8c8d91373 Mon Sep 17 00:00:00 2001
From: Andrew Murray <radarhere@users.noreply.github.com>
Date: Thu, 5 Sep 2024 23:07:40 +1000
Subject: [PATCH] Added type hints

---
 Tests/test_file_gif.py    |  4 +++-
 src/PIL/PngImagePlugin.py | 46 ++++++++++++++++++++++-----------------
 2 files changed, 29 insertions(+), 21 deletions(-)

diff --git a/Tests/test_file_gif.py b/Tests/test_file_gif.py
index 7c332149d..571fe1b9a 100644
--- a/Tests/test_file_gif.py
+++ b/Tests/test_file_gif.py
@@ -1392,7 +1392,9 @@ def test_lzw_bits() -> None:
         ),
     ),
 )
-def test_extents(test_file, loading_strategy) -> None:
+def test_extents(
+    test_file: str, loading_strategy: GifImagePlugin.LoadingStrategy
+) -> None:
     GifImagePlugin.LOADING_STRATEGY = loading_strategy
     try:
         with Image.open("Tests/images/" + test_file) as im:
diff --git a/src/PIL/PngImagePlugin.py b/src/PIL/PngImagePlugin.py
index a87e1a625..c268d7b1a 100644
--- a/src/PIL/PngImagePlugin.py
+++ b/src/PIL/PngImagePlugin.py
@@ -370,21 +370,27 @@ class PngInfo:
 # PNG image stream (IHDR/IEND)
 
 
+class _RewindState(NamedTuple):
+    info: dict[str | tuple[int, int], Any]
+    tile: list[ImageFile._Tile]
+    seq_num: int | None
+
+
 class PngStream(ChunkStream):
-    def __init__(self, fp):
+    def __init__(self, fp: IO[bytes]) -> None:
         super().__init__(fp)
 
         # local copies of Image attributes
-        self.im_info = {}
-        self.im_text = {}
+        self.im_info: dict[str | tuple[int, int], Any] = {}
+        self.im_text: dict[str, str | iTXt] = {}
         self.im_size = (0, 0)
-        self.im_mode = None
-        self.im_tile = None
-        self.im_palette = None
-        self.im_custom_mimetype = None
-        self.im_n_frames = None
-        self._seq_num = None
-        self.rewind_state = None
+        self.im_mode = ""
+        self.im_tile: list[ImageFile._Tile] = []
+        self.im_palette: tuple[str, bytes] | None = None
+        self.im_custom_mimetype: str | None = None
+        self.im_n_frames: int | None = None
+        self._seq_num: int | None = None
+        self.rewind_state = _RewindState({}, [], None)
 
         self.text_memory = 0
 
@@ -398,16 +404,16 @@ class PngStream(ChunkStream):
             raise ValueError(msg)
 
     def save_rewind(self) -> None:
-        self.rewind_state = {
-            "info": self.im_info.copy(),
-            "tile": self.im_tile,
-            "seq_num": self._seq_num,
-        }
+        self.rewind_state = _RewindState(
+            self.im_info.copy(),
+            self.im_tile,
+            self._seq_num,
+        )
 
     def rewind(self) -> None:
-        self.im_info = self.rewind_state["info"].copy()
-        self.im_tile = self.rewind_state["tile"]
-        self._seq_num = self.rewind_state["seq_num"]
+        self.im_info = self.rewind_state.info.copy()
+        self.im_tile = self.rewind_state.tile
+        self._seq_num = self.rewind_state.seq_num
 
     def chunk_iCCP(self, pos: int, length: int) -> bytes:
         # ICC profile
@@ -461,11 +467,11 @@ class PngStream(ChunkStream):
     def chunk_IDAT(self, pos: int, length: int) -> NoReturn:
         # image data
         if "bbox" in self.im_info:
-            tile = [("zip", self.im_info["bbox"], pos, self.im_rawmode)]
+            tile = [ImageFile._Tile("zip", self.im_info["bbox"], pos, self.im_rawmode)]
         else:
             if self.im_n_frames is not None:
                 self.im_info["default_image"] = True
-            tile = [("zip", (0, 0) + self.im_size, pos, self.im_rawmode)]
+            tile = [ImageFile._Tile("zip", (0, 0) + self.im_size, pos, self.im_rawmode)]
         self.im_tile = tile
         self.im_idat = length
         msg = "image data found"