fix: Stop LED flash when tag is removed (v1.2.2)

- Add per-pad stop event system (_flash_stop_events dictionary)
- Add stop_flash(pad) method to cancel active flash animations
- flash_pad now checks stop events at multiple points in loop
- Tag removal handler calls stop_flash before setting pad to OFF
- Fixes issue where LED flash continued indefinitely after figure removed

lego_dimensions_reader.py

@@ -74,7 +74,7 @@ VENDOR_ID = 0x0e6f
 PRODUCT_ID = 0x0241
 
 # Module version
-__version__ = "1.2.1"
+__version__ = "1.2.2"
 
 
 def get_usb_backend():
@@ -183,6 +183,9 @@ class LegoDimensionsReader:
         # Active tags currently on pads (pad_num -> TagInfo)
         self._active_tags: Dict[int, TagInfo] = {}
         
+        # Flash stop events per pad (for cancelling software flash)
+        self._flash_stop_events: Dict[int, threading.Event] = {}
+        
         # Callbacks
         self.on_tag_insert: Optional[Callable[[TagInfo], None]] = None
         self.on_tag_remove: Optional[Callable[[TagInfo], None]] = None
@@ -590,6 +593,22 @@ class LegoDimensionsReader:
         command = [0x55, 0x06, 0xc0, 0x02, pad.value, color[0], color[1], color[2]]
         self._send_command(command)
     
+    def stop_flash(self, pad: Pad):
+        """
+        Stop any active flash animation on a pad.
+        
+        Args:
+            pad: Which pad to stop flashing (Pad.ALL stops all pads)
+        """
+        if pad == Pad.ALL:
+            pads_to_stop = [Pad.CENTER, Pad.LEFT, Pad.RIGHT]
+        else:
+            pads_to_stop = [pad]
+        
+        for p in pads_to_stop:
+            if p.value in self._flash_stop_events:
+                self._flash_stop_events[p.value].set()
+    
     def flash_pad(self, pad: Pad, color: list, on_time: int = 10, 
                   off_time: int = 10, count: int = 5):
         """
@@ -618,19 +637,44 @@ class LegoDimensionsReader:
         else:
             pads_to_flash = [pad]
         
+        # Stop any existing flash on these pads
+        for p in pads_to_flash:
+            if p.value in self._flash_stop_events:
+                self._flash_stop_events[p.value].set()
+        
+        # Create new stop events for this flash
+        stop_events = {}
+        for p in pads_to_flash:
+            stop_events[p.value] = threading.Event()
+            self._flash_stop_events[p.value] = stop_events[p.value]
+        
         def _flash_thread():
             for _ in range(actual_count):
+                # Check if we should stop (device disconnected or stop requested)
                 if not self._running and not self.dev:
                     break
+                # Check if stop was requested for any of our pads
+                if any(stop_events[p.value].is_set() for p in pads_to_flash):
+                    break
                 # ON
                 for p in pads_to_flash:
+                    if not stop_events[p.value].is_set():
                         self.set_pad_color(p, color)
                 time.sleep(on_secs)
+                # Check again before OFF
+                if any(stop_events[p.value].is_set() for p in pads_to_flash):
+                    break
                 # OFF
                 for p in pads_to_flash:
+                    if not stop_events[p.value].is_set():
                         self.set_pad_color(p, COLORS['OFF'])
                 time.sleep(off_secs)
             
+            # Cleanup stop events when done
+            for p in pads_to_flash:
+                if p.value in self._flash_stop_events and self._flash_stop_events[p.value] == stop_events[p.value]:
+                    del self._flash_stop_events[p.value]
+        
         # Run flash in background thread so it doesn't block
         flash_thread = threading.Thread(target=_flash_thread, daemon=True)
         flash_thread.start()
@@ -720,7 +764,8 @@ class LegoDimensionsReader:
                     if pad_num in self._active_tags:
                         del self._active_tags[pad_num]
                     
-                    # Turn off pad LED
+                    # Stop any active flash and turn off pad LED
+                    self.stop_flash(pad)
                     self.set_pad_color(pad, COLORS['OFF'])
                     
                     if self.on_tag_remove: