Makes single-instance check optional

Author: MaxBQb

CHANGELOG.md

@@ -1,5 +1,8 @@
 # Changelog
 ## [Unreleased](https://github.com/MaxBQb/InversionFilterManager/releases/tag/latest) (2022-07-29)
+Features:
+- Single-app-instance check can be disabled with `--allow-multiple`/`-m` start param  
+
 Stability:
 - Drop support of non-privileged run (Requires run as Administrator)
 

main.py

@@ -1,18 +1,22 @@
+import argparse
 from asyncio import run
 
 import inject
 import win32api
+import win32con
 import win32event
 from winerror import ERROR_ALREADY_EXISTS
 
 from app_start import AppStartManager
 
 
-def lock_instance():
+def lock_instance(allow_multiple=False):
     from _meta import __instance_lock_key__
     mutex = win32event.CreateMutex(None, False, __instance_lock_key__)
     if win32api.GetLastError() != ERROR_ALREADY_EXISTS:
         return mutex
+    elif allow_multiple:
+        return win32event.OpenMutex(win32con.SYNCHRONIZE, False, __instance_lock_key__)
 
 
 @inject.autoparams()
@@ -22,8 +26,17 @@ async def main(app: AppStartManager):
     await app.run()
 
 
+def get_args():
+    parser = argparse.ArgumentParser(description="App, that inverts colors when you opens blinding white windows")
+    parser.add_argument('--allow-multiple', '-m',
+                        action='store_true',
+                        help="Disable single-instance check")
+    return parser.parse_args()
+
+
 def bootstrap():
-    lock = lock_instance()
+    args = get_args()
+    lock = lock_instance(args.allow_multiple)
     if not lock:
         print("WARNING: Program already started!")
         return