Changed Image mode property to be read-only by default

Tests/test_image.py

@@ -135,6 +135,12 @@ def test_width_height(self):
         with pytest.raises(AttributeError):
             im.size = (3, 4)
 
+    def test_set_mode(self):
+        im = Image.new("RGB", (1, 1))
+
+        with pytest.raises(AttributeError):
+            im.mode = "P"
+
     def test_invalid_image(self):
         im = io.BytesIO(b"")
         with pytest.raises(UnidentifiedImageError):

Tests/test_imagefile.py

@@ -136,7 +136,7 @@ def test_no_format(self):
 
         class DummyImageFile(ImageFile.ImageFile):
             def _open(self):
-                self.mode = "RGB"
+                self._mode = "RGB"
                 self._size = (1, 1)
 
         im = DummyImageFile(buf)
@@ -217,7 +217,7 @@ def cleanup(self):
 class MockImageFile(ImageFile.ImageFile):
     def _open(self):
         self.rawmode = "RGBA"
-        self.mode = "RGBA"
+        self._mode = "RGBA"
         self._size = (200, 200)
         self.tile = [("MOCK", (xoff, yoff, xoff + xsize, yoff + ysize), 32, None)]
 

Tests/test_pickle.py

@@ -75,13 +75,13 @@ def test_pickle_la_mode_with_palette(tmp_path):
 
     # Act / Assert
     for protocol in range(0, pickle.HIGHEST_PROTOCOL + 1):
-        im.mode = "LA"
+        im._mode = "LA"
         with open(filename, "wb") as f:
             pickle.dump(im, f, protocol)
         with open(filename, "rb") as f:
             loaded_im = pickle.load(f)
 
-        im.mode = "PA"
+        im._mode = "PA"
         assert im == loaded_im
 
 

docs/example/DdsImagePlugin.py

@@ -225,7 +225,7 @@ def _open(self):
 
         flags, height, width = struct.unpack("<3I", header.read(12))
         self._size = (width, height)
-        self.mode = "RGBA"
+        self._mode = "RGBA"
 
         pitch, depth, mipmaps = struct.unpack("<3I", header.read(12))
         struct.unpack("<11I", header.read(44))  # reserved

docs/handbook/writing-your-own-image-plugin.rst

@@ -72,11 +72,11 @@ true color.
             # mode setting
             bits = int(header[3])
             if bits == 1:
-                self.mode = "1"
+                self._mode = "1"
             elif bits == 8:
-                self.mode = "L"
+                self._mode = "L"
             elif bits == 24:
-                self.mode = "RGB"
+                self._mode = "RGB"
             else:
                 msg = "unknown number of bits"
                 raise SyntaxError(msg)

src/PIL/BlpImagePlugin.py

@@ -266,7 +266,7 @@ def _open(self):
             msg = f"Bad BLP magic {repr(self.magic)}"
             raise BLPFormatError(msg)
 
-        self.mode = "RGBA" if self._blp_alpha_depth else "RGB"
+        self._mode = "RGBA" if self._blp_alpha_depth else "RGB"
         self.tile = [(decoder, (0, 0) + self.size, 0, (self.mode, 0, 1))]
 
 

src/PIL/BmpImagePlugin.py

@@ -163,7 +163,7 @@ def _bitmap(self, header=0, offset=0):
             offset += 4 * file_info["colors"]
 
         # ---------------------- Check bit depth for unusual unsupported values
-        self.mode, raw_mode = BIT2MODE.get(file_info["bits"], (None, None))
+        self._mode, raw_mode = BIT2MODE.get(file_info["bits"], (None, None))
         if self.mode is None:
             msg = f"Unsupported BMP pixel depth ({file_info['bits']})"
             raise OSError(msg)
@@ -200,7 +200,7 @@ def _bitmap(self, header=0, offset=0):
                     and file_info["rgba_mask"] in SUPPORTED[file_info["bits"]]
                 ):
                     raw_mode = MASK_MODES[(file_info["bits"], file_info["rgba_mask"])]
-                    self.mode = "RGBA" if "A" in raw_mode else self.mode
+                    self._mode = "RGBA" if "A" in raw_mode else self.mode
                 elif (
                     file_info["bits"] in (24, 16)
                     and file_info["rgb_mask"] in SUPPORTED[file_info["bits"]]
@@ -214,7 +214,7 @@ def _bitmap(self, header=0, offset=0):
                 raise OSError(msg)
         elif file_info["compression"] == self.RAW:
             if file_info["bits"] == 32 and header == 22:  # 32-bit .cur offset
-                raw_mode, self.mode = "BGRA", "RGBA"
+                raw_mode, self._mode = "BGRA", "RGBA"
         elif file_info["compression"] in (self.RLE8, self.RLE4):
             decoder_name = "bmp_rle"
         else:
@@ -245,10 +245,10 @@ def _bitmap(self, header=0, offset=0):
 
                 # ------- If all colors are grey, white or black, ditch palette
                 if greyscale:
-                    self.mode = "1" if file_info["colors"] == 2 else "L"
+                    self._mode = "1" if file_info["colors"] == 2 else "L"
                     raw_mode = self.mode
                 else:
-                    self.mode = "P"
+                    self._mode = "P"
                     self.palette = ImagePalette.raw(
                         "BGRX" if padding == 4 else "BGR", palette
                     )

src/PIL/BufrStubImagePlugin.py

@@ -46,7 +46,7 @@ def _open(self):
         self.fp.seek(offset)
 
         # make something up
-        self.mode = "F"
+        self._mode = "F"
         self._size = 1, 1
 
         loader = self._load()

src/PIL/DdsImagePlugin.py

@@ -128,7 +128,7 @@ def _open(self):
 
         flags, height, width = struct.unpack("<3I", header.read(12))
         self._size = (width, height)
-        self.mode = "RGBA"
+        self._mode = "RGBA"
 
         pitch, depth, mipmaps = struct.unpack("<3I", header.read(12))
         struct.unpack("<11I", header.read(44))  # reserved
@@ -141,9 +141,9 @@ def _open(self):
         if pfflags & DDPF_LUMINANCE:
             # Texture contains uncompressed L or LA data
             if pfflags & DDPF_ALPHAPIXELS:
-                self.mode = "LA"
+                self._mode = "LA"
             else:
-                self.mode = "L"
+                self._mode = "L"
 
             self.tile = [("raw", (0, 0) + self.size, 0, (self.mode, 0, 1))]
         elif pfflags & DDPF_RGB:
@@ -153,7 +153,7 @@ def _open(self):
             if pfflags & DDPF_ALPHAPIXELS:
                 rawmode += masks[0xFF000000]
             else:
-                self.mode = "RGB"
+                self._mode = "RGB"
             rawmode += masks[0xFF0000] + masks[0xFF00] + masks[0xFF]
 
             self.tile = [("raw", (0, 0) + self.size, 0, (rawmode[::-1], 0, 1))]
@@ -172,15 +172,15 @@ def _open(self):
             elif fourcc == b"ATI1":
                 self.pixel_format = "BC4"
                 n = 4
-                self.mode = "L"
+                self._mode = "L"
             elif fourcc == b"ATI2":
                 self.pixel_format = "BC5"
                 n = 5
-                self.mode = "RGB"
+                self._mode = "RGB"
             elif fourcc == b"BC5S":
                 self.pixel_format = "BC5S"
                 n = 5
-                self.mode = "RGB"
+                self._mode = "RGB"
             elif fourcc == b"DX10":
                 data_start += 20
                 # ignoring flags which pertain to volume textures and cubemaps
@@ -189,19 +189,19 @@ def _open(self):
                 if dxgi_format in (DXGI_FORMAT_BC5_TYPELESS, DXGI_FORMAT_BC5_UNORM):
                     self.pixel_format = "BC5"
                     n = 5
-                    self.mode = "RGB"
+                    self._mode = "RGB"
                 elif dxgi_format == DXGI_FORMAT_BC5_SNORM:
                     self.pixel_format = "BC5S"
                     n = 5
-                    self.mode = "RGB"
+                    self._mode = "RGB"
                 elif dxgi_format == DXGI_FORMAT_BC6H_UF16:
                     self.pixel_format = "BC6H"
                     n = 6
-                    self.mode = "RGB"
+                    self._mode = "RGB"
                 elif dxgi_format == DXGI_FORMAT_BC6H_SF16:
                     self.pixel_format = "BC6HS"
                     n = 6
-                    self.mode = "RGB"
+                    self._mode = "RGB"
                 elif dxgi_format in (DXGI_FORMAT_BC7_TYPELESS, DXGI_FORMAT_BC7_UNORM):
                     self.pixel_format = "BC7"
                     n = 7

src/PIL/EpsImagePlugin.py

@@ -227,7 +227,7 @@ def _open(self):
         # go to offset - start of "%!PS"
         self.fp.seek(offset)
 
-        self.mode = "RGB"
+        self._mode = "RGB"
         self._size = None
 
         byte_arr = bytearray(255)
@@ -344,10 +344,10 @@ def check_required_header_comments():
                 ]
 
                 if bit_depth == 1:
-                    self.mode = "1"
+                    self._mode = "1"
                 elif bit_depth == 8:
                     try:
-                        self.mode = self.mode_map[mode_id]
+                        self._mode = self.mode_map[mode_id]
                     except ValueError:
                         break
                 else:
@@ -391,7 +391,7 @@ def load(self, scale=1, transparency=False):
         # Load EPS via Ghostscript
         if self.tile:
             self.im = Ghostscript(self.tile, self.size, self.fp, scale, transparency)
-            self.mode = self.im.mode
+            self._mode = self.im.mode
             self._size = self.im.size
             self.tile = []
         return Image.Image.load(self)

src/PIL/FitsImagePlugin.py

@@ -51,14 +51,14 @@ def _open(self):
 
         number_of_bits = int(headers[b"BITPIX"])
         if number_of_bits == 8:
-            self.mode = "L"
+            self._mode = "L"
         elif number_of_bits == 16:
-            self.mode = "I"
+            self._mode = "I"
             # rawmode = "I;16S"
         elif number_of_bits == 32:
-            self.mode = "I"
+            self._mode = "I"
         elif number_of_bits in (-32, -64):
-            self.mode = "F"
+            self._mode = "F"
             # rawmode = "F" if number_of_bits == -32 else "F;64F"
 
         offset = math.ceil(self.fp.tell() / 2880) * 2880

src/PIL/FliImagePlugin.py

@@ -56,7 +56,7 @@ def _open(self):
         self.is_animated = self.n_frames > 1
 
         # image characteristics
-        self.mode = "P"
+        self._mode = "P"
         self._size = i16(s, 8), i16(s, 10)
 
         # animation speed

src/PIL/FpxImagePlugin.py

@@ -106,7 +106,7 @@ def _open_index(self, index=1):
             # note: for now, we ignore the "uncalibrated" flag
             colors.append(i32(s, 8 + i * 4) & 0x7FFFFFFF)
 
-        self.mode, self.rawmode = MODES[tuple(colors)]
+        self._mode, self.rawmode = MODES[tuple(colors)]
 
         # load JPEG tables, if any
         self.jpeg = {}

src/PIL/FtexImagePlugin.py

@@ -77,7 +77,7 @@ def _open(self):
         self._size = struct.unpack("<2i", self.fp.read(8))
         mipmap_count, format_count = struct.unpack("<2i", self.fp.read(8))
 
-        self.mode = "RGB"
+        self._mode = "RGB"
 
         # Only support single-format files.
         # I don't know of any multi-format file.
@@ -90,7 +90,7 @@ def _open(self):
         data = self.fp.read(mipmap_size)
 
         if format == Format.DXT1:
-            self.mode = "RGBA"
+            self._mode = "RGBA"
             self.tile = [("bcn", (0, 0) + self.size, 0, 1)]
         elif format == Format.UNCOMPRESSED:
             self.tile = [("raw", (0, 0) + self.size, 0, ("RGB", 0, 1))]

src/PIL/GbrImagePlugin.py

@@ -73,9 +73,9 @@ def _open(self):
         comment = self.fp.read(comment_length)[:-1]
 
         if color_depth == 1:
-            self.mode = "L"
+            self._mode = "L"
         else:
-            self.mode = "RGBA"
+            self._mode = "RGBA"
 
         self._size = width, height
 

src/PIL/GdImageFile.py

@@ -51,7 +51,7 @@ def _open(self):
             msg = "Not a valid GD 2.x .gd file"
             raise SyntaxError(msg)
 
-        self.mode = "L"  # FIXME: "P"
+        self._mode = "L"  # FIXME: "P"
         self._size = i16(s, 2), i16(s, 4)
 
         true_color = s[6]

src/PIL/GifImagePlugin.py

@@ -304,11 +304,11 @@ def _seek(self, frame, update_image=True):
         if frame == 0:
             if self._frame_palette:
                 if LOADING_STRATEGY == LoadingStrategy.RGB_ALWAYS:
-                    self.mode = "RGBA" if frame_transparency is not None else "RGB"
+                    self._mode = "RGBA" if frame_transparency is not None else "RGB"
                 else:
-                    self.mode = "P"
+                    self._mode = "P"
             else:
-                self.mode = "L"
+                self._mode = "L"
 
             if not palette and self.global_palette:
                 from copy import copy
@@ -325,10 +325,10 @@ def _seek(self, frame, update_image=True):
                     if "transparency" in self.info:
                         self.im.putpalettealpha(self.info["transparency"], 0)
                         self.im = self.im.convert("RGBA", Image.Dither.FLOYDSTEINBERG)
-                        self.mode = "RGBA"
+                        self._mode = "RGBA"
                         del self.info["transparency"]
                     else:
-                        self.mode = "RGB"
+                        self._mode = "RGB"
                         self.im = self.im.convert("RGB", Image.Dither.FLOYDSTEINBERG)
 
         def _rgb(color):
@@ -424,7 +424,7 @@ def load_prepare(self):
                 self.im.putpalette(*self._frame_palette.getdata())
             else:
                 self.im = None
-        self.mode = temp_mode
+        self._mode = temp_mode
         self._frame_palette = None
 
         super().load_prepare()
@@ -434,9 +434,9 @@ def load_end(self):
             if self.mode == "P" and LOADING_STRATEGY == LoadingStrategy.RGB_ALWAYS:
                 if self._frame_transparency is not None:
                     self.im.putpalettealpha(self._frame_transparency, 0)
-                    self.mode = "RGBA"
+                    self._mode = "RGBA"
                 else:
-                    self.mode = "RGB"
+                    self._mode = "RGB"
                 self.im = self.im.convert(self.mode, Image.Dither.FLOYDSTEINBERG)
             return
         if not self._prev_im:
@@ -449,7 +449,7 @@ def load_end(self):
         frame_im = self._crop(frame_im, self.dispose_extent)
 
         self.im = self._prev_im
-        self.mode = self.im.mode
+        self._mode = self.im.mode
         if frame_im.mode == "RGBA":
             self.im.paste(frame_im, self.dispose_extent, frame_im)
         else:

src/PIL/GribStubImagePlugin.py

@@ -46,7 +46,7 @@ def _open(self):
         self.fp.seek(offset)
 
         # make something up
-        self.mode = "F"
+        self._mode = "F"
         self._size = 1, 1
 
         loader = self._load()

src/PIL/Hdf5StubImagePlugin.py

@@ -46,7 +46,7 @@ def _open(self):
         self.fp.seek(offset)
 
         # make something up
-        self.mode = "F"
+        self._mode = "F"
         self._size = 1, 1
 
         loader = self._load()