Add .cur writer

win2xcur/cursor.py

@@ -4,6 +4,9 @@ from wand.sequence import SingleImage
 
 
 class CursorImage:
+    image: SingleImage
+    hotspot: Tuple[int, int]
+
     def __init__(self, image: SingleImage, hotspot: Tuple[int, int]) -> None:
         self.image = image
         self.hotspot = hotspot
@@ -13,6 +16,9 @@ class CursorImage:
 
 
 class CursorFrame:
+    images: List[CursorImage]
+    delay: int
+
     def __init__(self, images: List[CursorImage], delay: int = 0) -> None:
         self.images = images
         self.delay = delay

win2xcur/parser/cur.py

@@ -9,6 +9,7 @@ from win2xcur.parser.base import BaseParser
 
 class CURParser(BaseParser):
     MAGIC = b'\0\0\02\0'
+    ICO_TYPE_CUR = 2
     ICON_DIR = struct.Struct('<HHH')
     ICON_DIR_ENTRY = struct.Struct('<BBBBHHII')
 
@@ -27,7 +28,7 @@ class CURParser(BaseParser):
     def _parse_header(self) -> List[Tuple[int, int]]:
         reserved, ico_type, image_count = self.ICON_DIR.unpack(self.blob[:self.ICON_DIR.size])
         assert reserved == 0
-        assert ico_type == 2
+        assert ico_type == self.ICO_TYPE_CUR
         assert image_count == len(self._image.sequence)
 
         offset = self.ICON_DIR.size

win2xcur/writer/windows.py

@@ -0,0 +1,26 @@
+from itertools import chain
+from typing import List
+
+from win2xcur.cursor import CursorFrame
+from win2xcur.parser import CURParser
+
+
+def to_cur(frame: CursorFrame) -> bytes:
+    header = CURParser.ICON_DIR.pack(0, CURParser.ICO_TYPE_CUR, len(frame))
+    directory: List[bytes] = []
+    image_data: List[bytes] = []
+    offset = CURParser.ICON_DIR.size + len(frame) * CURParser.ICON_DIR_ENTRY.size
+
+    for image in frame:
+        clone = image.image.clone()
+        if clone.width > 256 or clone.height > 256:
+            raise ValueError(f'Image too big for CUR format: {clone.width}x{clone.height}')
+        blob = clone.make_blob('png')
+        image_data.append(blob)
+        x_offset, y_offset = image.hotspot
+        directory.append(CURParser.ICON_DIR_ENTRY.pack(
+            clone.height & 0xFF, clone.height & 0xFF, 0, 0, x_offset, y_offset, len(blob), offset
+        ))
+        offset += len(blob)
+
+    return b''.join(chain([header], directory, image_data))