Merge pull request #3203 from radarhere/size

Changed Image size property to be read-only by default

Author: hugovk

Tests/test_file_icns.py

@@ -64,6 +64,10 @@ def test_sizes(self):
             self.assertEqual(im2.mode, 'RGBA')
             self.assertEqual(im2.size, (wr, hr))
 
+        # Check that we cannot load an incorrect size
+        with self.assertRaises(ValueError):
+            im.size = (1, 1)
+
     def test_older_icon(self):
         # This icon was made with Icon Composer rather than iconutil; it still
         # uses PNG rather than JP2, however (since it was made on 10.9).

Tests/test_file_ico.py

@@ -47,6 +47,11 @@ def test_save_to_bytes(self):
         self.assert_image_equal(reloaded,
                                 hopper().resize((32, 32), Image.LANCZOS))
 
+    def test_incorrect_size(self):
+        im = Image.open(TEST_ICO_FILE)
+        with self.assertRaises(ValueError):
+            im.size = (1, 1)
+
     def test_save_256x256(self):
         """Issue #2264 https://github.com/python-pillow/Pillow/issues/2264"""
         # Arrange

Tests/test_file_tiff.py

@@ -69,6 +69,14 @@ def test_set_legacy_api(self):
         self.assertEqual(str(e.exception),
                          "Not allowing setting of legacy api")
 
+    def test_size(self):
+        filename = "Tests/images/pil168.tif"
+        im = Image.open(filename)
+
+        def set_size():
+            im.size = (256, 256)
+        self.assert_warning(DeprecationWarning, set_size)
+
     def test_xyres_tiff(self):
         filename = "Tests/images/pil168.tif"
         im = Image.open(filename)

Tests/test_image.py

@@ -56,9 +56,8 @@ def test_width_height(self):
         self.assertEqual(im.width, 1)
         self.assertEqual(im.height, 2)
 
-        im.size = (3, 4)
-        self.assertEqual(im.width, 3)
-        self.assertEqual(im.height, 4)
+        with self.assertRaises(AttributeError) as e:
+            im.size = (3, 4)
 
     def test_invalid_image(self):
         if py3:

Tests/test_imagefile.py

@@ -154,7 +154,7 @@ class MockImageFile(ImageFile.ImageFile):
     def _open(self):
         self.rawmode = 'RGBA'
         self.mode = 'RGBA'
-        self.size = (200, 200)
+        self._size = (200, 200)
         self.tile = [("MOCK", (xoff, yoff, xoff+xsize, yoff+ysize), 32, None)]
 
 

docs/example/DdsImagePlugin.py

@@ -221,7 +221,7 @@ def _open(self):
         header = BytesIO(header_bytes)
 
         flags, height, width = struct.unpack("<3I", header.read(12))
-        self.size = (width, height)
+        self._size = (width, height)
         self.mode = "RGBA"
 
         pitch, depth, mipmaps = struct.unpack("<3I", header.read(12))

docs/handbook/writing-your-own-file-decoder.rst

@@ -69,7 +69,7 @@ true color.
             header = string.split(header)
 
             # size in pixels (width, height)
-            self.size = int(header[1]), int(header[2])
+            self._size = int(header[1]), int(header[2])
 
             # mode setting
             bits = int(header[3])

docs/releasenotes/5.3.0.rst

@@ -39,6 +39,22 @@ and size, new method ``ImageOps.pad`` pads images to fill a requested aspect
 ratio and size, filling new space with a provided ``color`` and positioning the
 image within the new area through a ``centering`` argument.
 
+Image Size
+==========
+
+If you attempt to set the size of an image directly, e.g.
+``im.size = (100, 100)``, you will now receive an ``AttributeError``. This is
+not about removing existing functionality, but instead about raising an
+explicit error to prevent later consequences. The ``resize`` method is the
+correct way to change an image's size.
+
+The exceptions to this are:
+* The ICO and ICNS image formats, which use ``im.size = (100, 100)`` to select
+a subimage.
+* The TIFF image format, which now has a ``DeprecationWarning`` for this
+action, as direct image size setting was previously necessary to work around an
+issue with tile extents.
+
 Other Changes
 =============
 

src/PIL/BlpImagePlugin.py

@@ -270,7 +270,7 @@ def _read_blp_header(self):
         self._blp_alpha_encoding, = struct.unpack("<b", self.fp.read(1))
         self._blp_mips, = struct.unpack("<b", self.fp.read(1))
 
-        self.size = struct.unpack("<II", self.fp.read(8))
+        self._size = struct.unpack("<II", self.fp.read(8))
 
         if self.magic == b"BLP1":
             # Only present for BLP1

src/PIL/BmpImagePlugin.py

@@ -143,7 +143,7 @@ def _bitmap(self, header=0, offset=0):
                           file_info['header_size'])
         # ------------------ Special case : header is reported 40, which
         # ---------------------- is shorter than real size for bpp >= 16
-        self.size = file_info['width'], file_info['height']
+        self._size = file_info['width'], file_info['height']
         # -------- If color count was not found in the header, compute from bits
         file_info['colors'] = file_info['colors'] if file_info.get('colors', 0) else (1 << file_info['bits'])
         # -------------------------------- Check abnormal values for DOS attacks