添加 Box 类及其子类 ItemLocationBox 的实现，包含初始化和解析逻辑

heic_types.py

@@ -0,0 +1,48 @@
+# In heic_types.py
+import struct
+from base import Box  # <-- THIS IS THE KEY CHANGE
+
+class ItemLocation:
+    # ... (rest of this class is unchanged)
+    def __init__(self, item_id, offset, length):
+        self.item_id = item_id
+        self.offset = offset
+        self.length = length
+    def __repr__(self):
+        return f"<ItemLocation ID={self.item_id} offset={self.offset} length={self.length}>"
+
+class ItemLocationBox(Box):
+    # ... (rest of this class is unchanged)
+    def __init__(self, size: int, box_type: str, offset: int, raw_data: bytes):
+        super().__init__(size, box_type, offset, raw_data)
+        self.locations = []
+        self._parse_locations()
+    def _parse_locations(self):
+        # ... (all the parsing logic here is unchanged)
+        stream = self.raw_data
+        version_flags = struct.unpack('>I', stream[:4])[0]
+        sizes = struct.unpack('>H', stream[4:6])[0]
+        offset_size = (sizes >> 12) & 0x0F
+        length_size = (sizes >> 8) & 0x0F
+        base_offset_size = (sizes >> 4) & 0x0F
+        item_count = struct.unpack('>H', stream[6:8])[0]
+        current_pos = 8
+        for _ in range(item_count):
+            item_id = struct.unpack('>H', stream[current_pos : current_pos+2])[0]
+            current_pos += 4 # Skip item_id and construction_method
+            current_pos += 2 # Skip data_reference_index
+            current_pos += base_offset_size
+            extent_count = struct.unpack('>H', stream[current_pos : current_pos+2])[0]
+            current_pos += 2
+            if extent_count > 0:
+                offset = self._read_int(stream, current_pos, offset_size)
+                current_pos += offset_size
+                length = self._read_int(stream, current_pos, length_size)
+                current_pos += length_size
+                self.locations.append(ItemLocation(item_id, offset, length))
+    def _read_int(self, data, pos, size):
+        if size == 1: return data[pos]
+        if size == 2: return struct.unpack('>H', data[pos:pos+2])[0]
+        if size == 4: return struct.unpack('>I', data[pos:pos+4])[0]
+        if size == 8: return struct.unpack('>Q', data[pos:pos+8])[0]
+        return 0