Added scale argument to IcnsImageFile load()

Tests/test_file_icns.py

@@ -63,8 +63,8 @@ def test_save_append_images(tmp_path: Path) -> None:
         assert_image_similar_tofile(im, temp_file, 1)
 
         with Image.open(temp_file) as reread:
-            reread.size = (16, 16, 2)
-            reread.load()
+            reread.size = (16, 16)
+            reread.load(2)
             assert_image_equal(reread, provided_im)
 
 
@@ -92,9 +92,15 @@ def test_sizes() -> None:
             assert im.mode == "RGBA"
             assert im.size == (wr, hr)
 
+            # Test using load() with scale
+            im.size = (w, h)
+            im.load(scale=r)
+            assert im.mode == "RGBA"
+            assert im.size == (wr, hr)
+
         # Check that we cannot load an incorrect size
         with pytest.raises(ValueError):
-            im.size = (1, 1)
+            im.size = (1, 2)
 
 
 def test_older_icon() -> None:
@@ -105,8 +111,8 @@ def test_older_icon() -> None:
             wr = w * r
             hr = h * r
             with Image.open("Tests/images/pillow2.icns") as im2:
-                im2.size = (w, h, r)
-                im2.load()
+                im2.size = (w, h)
+                im2.load(r)
                 assert im2.mode == "RGBA"
                 assert im2.size == (wr, hr)
 
@@ -122,8 +128,8 @@ def test_jp2_icon() -> None:
             wr = w * r
             hr = h * r
             with Image.open("Tests/images/pillow3.icns") as im2:
-                im2.size = (w, h, r)
-                im2.load()
+                im2.size = (w, h)
+                im2.load(r)
                 assert im2.mode == "RGBA"
                 assert im2.size == (wr, hr)
 

docs/handbook/image-file-formats.rst

@@ -331,6 +331,18 @@ sets the following :py:attr:`~PIL.Image.Image.info` property:
     ask for ``(512, 512, 2)``, the final value of
     :py:attr:`~PIL.Image.Image.size` will be ``(1024, 1024)``).
 
+.. _icns-loading:
+
+Loading
+~~~~~~~
+
+You can call the :py:meth:`~PIL.Image.Image.load` method with the following parameter.
+
+**scale**
+    Affects the scale of the resultant image. If the size is set to ``(512, 512)``,
+    after loading at scale 2, the final value of :py:attr:`~PIL.Image.Image.size` will
+    be ``(1024, 1024)``.
+
 .. _icns-saving:
 
 Saving

src/PIL/IcnsImagePlugin.py

@@ -281,31 +281,30 @@ class IcnsImageFile(ImageFile.ImageFile):
 
     @size.setter
     def size(self, value) -> None:
-        info_size = value
-        if info_size not in self.info["sizes"] and len(info_size) == 2:
-            info_size = (info_size[0], info_size[1], 1)
-        if (
-            info_size not in self.info["sizes"]
-            and len(info_size) == 3
-            and info_size[2] == 1
-        ):
-            simple_sizes = [
-                (size[0] * size[2], size[1] * size[2]) for size in self.info["sizes"]
-            ]
-            if value in simple_sizes:
-                info_size = self.info["sizes"][simple_sizes.index(value)]
-        if info_size not in self.info["sizes"]:
-            msg = "This is not one of the allowed sizes of this image"
-            raise ValueError(msg)
-        self._size = value
+        if len(value) == 3:
+            if value in self.info["sizes"]:
+                self._size = value
+                return
+        else:
+            # Check that a matching size exists,
+            # or that there is a scale that would create a size that matches
+            for size in self.info["sizes"]:
+                simple_size = size[0] * size[2], size[1] * size[2]
+                scale = simple_size[0] // value[0]
+                if simple_size[1] / value[1] == scale:
+                    self._size = value
+                    return
+        msg = "This is not one of the allowed sizes of this image"
+        raise ValueError(msg)
 
-    def load(self) -> Image.core.PixelAccess | None:
-        if len(self.size) == 3:
-            self.best_size = self.size
-            self.size = (
-                self.best_size[0] * self.best_size[2],
-                self.best_size[1] * self.best_size[2],
-            )
+    def load(self, scale: int | None = None) -> Image.core.PixelAccess | None:
+        if scale is not None or len(self.size) == 3:
+            if scale is None and len(self.size) == 3:
+                scale = self.size[2]
+            assert scale is not None
+            width, height = self.size[:2]
+            self.size = width * scale, height * scale
+            self.best_size = width, height, scale
 
         px = Image.Image.load(self)
         if self._im is not None and self.im.size == self.size: