gesture: replace dead is-None guard with proper landmark count check

Signed-off-by: NotAShelf <raf@notashelf.dev>
Change-Id: I4b0e7001bd89bd9a7717e0d949853bd86a6a6964

src/flipoff/gesture.py

@@ -1,16 +1,8 @@
-from dataclasses import dataclass
-from typing import Callable
 from typing import ClassVar
 
 from mediapipe.tasks.python.components.containers.landmark import NormalizedLandmark
 
 
-@dataclass
-class GestureResult:
-    name: str
-    detected: bool
-
-
 class Gesture:
     name: ClassVar[str] = "unknown"
 
@@ -35,26 +27,17 @@ class GestureRegistry:
         return cls._gestures.copy()
 
 
-def _check_y_values(
-    hand: list[NormalizedLandmark],
-    *indices: int,
-) -> bool:
-    for idx in indices:
-        if hand[idx].y is None:
-            return False
-    return True
-
-
 @GestureRegistry.register
 class FlippingOffGesture(Gesture):
     name = "flipping_off"
 
     def detect(self, hand: list[NormalizedLandmark]) -> bool:
-        if not _check_y_values(hand, 12, 10, 8, 6, 16, 14, 20, 18):
+        # MediaPipe always returns 21 landmarks; guard against malformed results.
+        if len(hand) < 21:
             return False
         return bool(
-            hand[12].y < hand[10].y
+            hand[12].y < hand[10].y  # middle tip above middle PIP (extended)
-            and hand[8].y > hand[6].y
+            and hand[8].y > hand[6].y  # index tip below index PIP (curled)
-            and hand[16].y > hand[14].y
+            and hand[16].y > hand[14].y  # ring tip below ring PIP (curled)
-            and hand[20].y > hand[18].y
+            and hand[20].y > hand[18].y  # pinky tip below pinky PIP (curled)
         )