Serialize Path objects to QML

- media_cache.get_(thumbnail/media) now return a Path instead of str
- When converted to strings in the serialization, the "file://" prefix
  is prepended. This fixes problems when the app is built in release
  mode with QRC resources.

TODO.md

@@ -1,6 +1,5 @@
 - Media
   - Verify things work with chat.privacytools.io (subdomain weirdness)
-  - Allow multiple file selection
   - Confirmation box after picking file to upload
   - Handle upload errors: non existent path, path is a dir, file too big, etc
   - Show real progression for mxc thumbnail loadings, uploads and downloads

src/python/media_cache.py

@@ -223,8 +223,8 @@ class MediaCache:
         await Media(self, mxc, data, {}).create()
 
 
-    async def get_media(self, mxc: str, crypt_dict: CryptDict = None) -> str:
+    async def get_media(self, mxc: str, crypt_dict: CryptDict = None) -> Path:
-        return str(await Media(self, mxc, None, crypt_dict).get())
+        return await Media(self, mxc, None, crypt_dict).get()
 
 
     async def create_thumbnail(
@@ -236,10 +236,10 @@ class MediaCache:
 
     async def get_thumbnail(
         self, mxc: str, width: int, height: int, crypt_dict: CryptDict = None,
-    ) -> str:
+    ) -> Path:
 
         thumb = Thumbnail(
             # QML sometimes pass float sizes, which matrix API doesn't like.
             self, mxc, None, crypt_dict, (round(width), round(height)),
         )
-        return str(await thumb.get())
+        return await thumb.get()

src/python/utils.py

@@ -3,6 +3,7 @@ import html
 import xml.etree.cElementTree as xml_etree  # FIXME: bandit warning
 from enum import Enum
 from enum import auto as autostr
+from pathlib import Path
 from typing import IO, Any, Tuple, Union
 
 import filetype
@@ -68,4 +69,7 @@ def serialize_value_for_qml(value: Any) -> Any:
     if hasattr(value, "__class__") and issubclass(value.__class__, Enum):
         return value.value
 
+    if isinstance(value, Path):
+        return f"file://{value!s}"
+
     return value