Apply XOR mask to 1 and L mode images

Author: radarhere

Tests/images/mask_1.cur

@@ -40,6 +40,22 @@ def test_largest_cursor() -> None:
         assert im.size == (8, 8)
 
 
+@pytest.mark.parametrize("mode", ("1", "L"))
+def test_mask(mode: str) -> None:
+    with Image.open("Tests/images/mask_" + mode + ".cur") as im:
+        assert im.mode == "LA"
+
+        for i, value in enumerate(
+            [
+                (0, 255),  # AND 0 XOR 0 is black
+                (255, 255),  # AND 0 XOR 1 is white
+                (0, 0),  # AND 1 XOR 0 is transparent
+                (0, 0),  # AND 1 XOR 1 is transparent
+            ]
+        ):
+            assert im.getpixel((0, i)) == value
+
+
 def test_invalid_file() -> None:
     invalid_file = "Tests/images/flower.jpg"
 

Tests/images/mask_L.cur

@@ -17,7 +17,7 @@
 #
 from __future__ import annotations
 
-from . import BmpImagePlugin, Image
+from . import BmpImagePlugin, Image, ImageOps
 from ._binary import i16le as i16
 from ._binary import i32le as i32
 
@@ -61,10 +61,38 @@ def _open(self) -> None:
 
         # load as bitmap
         self._bitmap(i32(m, 12) + offset)
+        self._masked = self.mode in ("1", "L")
+        if self._masked:
+            self._rawmode = self.mode
+            self._mode = "LA"
 
         # patch up the bitmap height
-        self._size = self.size[0], self.size[1] // 2
-        self.tile = [self.tile[0]._replace(extents=(0, 0) + self.size)]
+        self._size = self.width, self.height // 2
+        if not self._masked:
+            self.tile = [self.tile[0]._replace(extents=(0, 0) + self.size)]
+
+    def load_prepare(self) -> None:
+        if self._masked:
+            self._mode = self._rawmode
+            self._size = self.width, self.height * 2
+        super().load_prepare()
+
+    def load_end(self) -> None:
+        if not self._masked:
+            return
+        self._mode = "LA"
+        new_height = self.height // 2
+
+        and_mask = self.im.crop((0, 0, self.width, new_height))
+        xor_mask = self.im.crop((0, new_height, self.width, self.height))
+
+        self._size = self.width, new_height
+        self._im = Image.core.fill(self.mode, self.size)
+        self._im.paste(
+            xor_mask.convert(self.mode),
+            (0, 0) + self.size,
+            ImageOps.invert(Image.Image()._new(and_mask)).im,
+        )
 
 
 #

Tests/test_file_cur.py

@@ -1450,6 +1450,7 @@ static struct {
     {IMAGING_MODE_1, IMAGING_MODE_L, bit2l},
     {IMAGING_MODE_1, IMAGING_MODE_I, bit2i},
     {IMAGING_MODE_1, IMAGING_MODE_F, bit2f},
+    {IMAGING_MODE_1, IMAGING_MODE_LA, bit2rgb},
     {IMAGING_MODE_1, IMAGING_MODE_RGB, bit2rgb},
     {IMAGING_MODE_1, IMAGING_MODE_RGBA, bit2rgb},
     {IMAGING_MODE_1, IMAGING_MODE_RGBX, bit2rgb},