Motion capture: camera selection dropdown

Replace camera index spinbox with a combo listing detected cameras by
name. On Linux enumerates /dev/video* and reads device names from sysfs
(fast, no probing). Fallback probes cv2.VideoCapture indices 0-7 on
other platforms. Simulation entry always appended as last option.

Also adds explicit simulation mode (index -1) to tracker.start() and a
rescan button (⟳) in both the main window and the Settings > Plugins
widget.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

1 files changed, 51 insertions, 0 deletions

diff --git a/plugins/motion_capture/tracker.py b/plugins/motion_capture/tracker.py
index 847a170..d65aca1 100644
--- a/plugins/motion_capture/tracker.py
+++ b/plugins/motion_capture/tracker.py
@@ -99,6 +99,13 @@ class CameraTracker:
         self.stop()
         self._running = True
 
+        if camera_index == -1:
+            with self._lock:
+                self._simulated = True
+            self._thread = threading.Thread(target=self._run_sim, daemon=True)
+            self._thread.start()
+            return True
+
         try:
             import cv2
             cap = cv2.VideoCapture(camera_index)
@@ -287,6 +294,50 @@ class CameraTracker:
             time.sleep(1 / 30)
 
 
+# ── Camera enumeration ────────────────────────────────────────────────────────
+
+def list_cameras():
+    """
+    Return list of (index, label) for all detected camera devices.
+
+    On Linux: reads /dev/video* and pulls human-readable names from sysfs.
+    Falls back to probing cv2.VideoCapture indices 0-7 on other platforms.
+    Always appends a Simulation entry.
+    """
+    cameras = []
+
+    import os, glob
+
+    video_nodes = sorted(glob.glob("/dev/video*"))
+    if video_nodes:
+        for path in video_nodes:
+            try:
+                idx = int(path.replace("/dev/video", ""))
+            except ValueError:
+                continue
+            name_path = f"/sys/class/video4linux/video{idx}/name"
+            try:
+                with open(name_path) as f:
+                    name = f.read().strip()
+            except OSError:
+                name = path
+            cameras.append((idx, f"{name}  [/dev/video{idx}]"))
+    else:
+        # Non-Linux fallback: probe indices
+        try:
+            import cv2
+            for idx in range(8):
+                cap = cv2.VideoCapture(idx)
+                if cap.isOpened():
+                    cameras.append((idx, f"Camera {idx}"))
+                    cap.release()
+        except ImportError:
+            pass
+
+    cameras.append((-1, "Simulation (no camera)"))
+    return cameras
+
+
 # ── Helper ────────────────────────────────────────────────────────────────────
 
 def _make_cv_tracker():