Add .ani writer

win2xcur/parser/ani.py

@@ -10,7 +10,12 @@ from win2xcur.parser.cur import CURParser
 class ANIParser(BaseParser):
     SIGNATURE = b'RIFF'
     ANI_TYPE = b'ACON'
+    HEADER_CHUNK = b'anih'
+    LIST_CHUNK = b'LIST'
+    SEQ_CHUNK = b'seq '
+    RATE_CHUNK = b'rate'
     FRAME_TYPE = b'fram'
+    ICON_CHUNK = b'icon'
     RIFF_HEADER = struct.Struct('<4sI4s')
     CHUNK_HEADER = struct.Struct('<4sI')
     ANIH_HEADER = struct.Struct('<IIIIIIIII')
@@ -52,7 +57,7 @@ class ANIParser(BaseParser):
         return name, size, offset
 
     def _parse(self, offset: int) -> List[CursorFrame]:
-        _, size, offset = self._read_chunk(offset, expected=[b'anih'])
+        _, size, offset = self._read_chunk(offset, expected=[self.HEADER_CHUNK])
 
         if size != self.ANIH_HEADER.size:
             raise ValueError('Unexpected anih header size %d, expected %d' % (size, self.ANIH_HEADER.size))
@@ -60,6 +65,9 @@ class ANIParser(BaseParser):
         size, frame_count, step_count, width, height, bit_count, planes, display_rate, flags = self.ANIH_HEADER.unpack(
             self.blob[offset:offset + self.ANIH_HEADER.size])
 
+        if size != self.ANIH_HEADER.size:
+            raise ValueError('Unexpected size in anih header %d, expected %d' % (size, self.ANIH_HEADER.size))
+
         if not flags & self.ICON_FLAG:
             raise NotImplementedError('Raw BMP images not supported.')
 
@@ -70,8 +78,8 @@ class ANIParser(BaseParser):
         delays = [display_rate for _ in range(step_count)]
 
         while offset < len(self.blob):
-            name, size, offset = self._read_chunk(offset, expected=[b'LIST', b'seq ', b'rate'])
-            if name == b'LIST':
+            name, size, offset = self._read_chunk(offset, expected=[self.LIST_CHUNK, self.SEQ_CHUNK, self.RATE_CHUNK])
+            if name == self.LIST_CHUNK:
                 list_end = offset + size
                 if self.blob[offset:offset + 4] != self.FRAME_TYPE:
                     raise ValueError('Unexpected RIFF list type: %r, expected %r' %
@@ -79,18 +87,18 @@ class ANIParser(BaseParser):
                 offset += 4
 
                 for i in range(frame_count):
-                    _, size, offset = self._read_chunk(offset, expected=[b'icon'])
+                    _, size, offset = self._read_chunk(offset, expected=[self.ICON_CHUNK])
                     frames.append(CURParser(self.blob[offset:offset + size]).frames[0])
                     offset += size
 
                 if offset != list_end:
                     raise ValueError('Wrong RIFF list size: %r, expected %r' % (offset, list_end))
-            elif name == b'seq ':
+            elif name == self.SEQ_CHUNK:
                 order = [i for i, in self.UNSIGNED.iter_unpack(self.blob[offset:offset + size])]
                 if len(order) != step_count:
                     raise ValueError('Wrong animation sequence size: %r, expected %r' % (len(order), step_count))
                 offset += size
-            elif name == b'rate':
+            elif name == self.RATE_CHUNK:
                 delays = [i for i, in self.UNSIGNED.iter_unpack(self.blob[offset:offset + size])]
                 if len(delays) != step_count:
                     raise ValueError('Wrong animation rate size: %r, expected %r' % (len(delays), step_count))

win2xcur/writer/windows.py

@@ -1,8 +1,9 @@
+from io import BytesIO
 from itertools import chain
 from typing import List
 
 from win2xcur.cursor import CursorFrame
-from win2xcur.parser import CURParser
+from win2xcur.parser import ANIParser, CURParser
 
 
 def to_cur(frame: CursorFrame) -> bytes:
@@ -24,3 +25,38 @@ def to_cur(frame: CursorFrame) -> bytes:
         offset += len(blob)
 
     return b''.join(chain([header], directory, image_data))
+
+
+def get_ani_cur_list(frames: List[CursorFrame]) -> bytes:
+    io = BytesIO()
+    for frame in frames:
+        cur_file = to_cur(frame)
+        io.write(ANIParser.CHUNK_HEADER.pack(ANIParser.ICON_CHUNK, len(cur_file)))
+        io.write(cur_file)
+        if len(cur_file) & 1:
+            io.write(b'\0')
+    return io.getvalue()
+
+
+def get_ani_rate_chunk(frames: List[CursorFrame]) -> bytes:
+    io = BytesIO()
+    io.write(ANIParser.CHUNK_HEADER.pack(ANIParser.RATE_CHUNK, ANIParser.UNSIGNED.size * len(frames)))
+    for frame in frames:
+        io.write(ANIParser.UNSIGNED.pack(int(round(frame.delay * 60))))
+    return io.getvalue()
+
+
+def to_ani(frames: List[CursorFrame]) -> bytes:
+    ani_header = ANIParser.ANIH_HEADER.pack(
+        ANIParser.ANIH_HEADER.size, len(frames), len(frames), 0, 0, 32, 1, 1, ANIParser.ICON_FLAG
+    )
+
+    cur_list = get_ani_cur_list(frames)
+    chunks = [
+        ANIParser.CHUNK_HEADER.pack(ANIParser.HEADER_CHUNK, len(ani_header)),
+        ani_header,
+        ANIParser.RIFF_HEADER.pack(ANIParser.LIST_CHUNK, len(cur_list) + 4, ANIParser.FRAME_TYPE),
+        cur_list,
+    ]
+    body = b''.join(chunks)
+    return ANIParser.RIFF_HEADER.pack(ANIParser.SIGNATURE, len(body) + 4, ANIParser.ANI_TYPE) + body