Added Motion Capture plugin

Tracks a user-selected point via webcam (OpenCV CSRT tracker) and
streams x_pos / y_pos pixel coordinates as live channels into the
acquisition pipeline. Falls back to a Lissajous figure simulation
when opencv-python is not installed, so the plugin works immediately
without hardware.

- tracker.py: background thread, real camera + sim modes, thread-safe API
- device.py: BaseDevice reading x/y from tracker, wires into engine
- filter.py: custom pixel_to_mm filter (registered in FILTER_CLASSES)
- window.py: floating tool window, live feed, click-to-track ROI selection
- plugin.py: LabPlugin wiring all pieces together, toolbar button,
  settings widget, profile save/restore

Also: PluginAction.button_ref_callback lets plugins store a ref to their
toolbar button so they can uncheck it when their window closes.

opencv-python install note added to requirements.txt.

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

1 files changed, 85 insertions, 0 deletions

diff --git a/plugins/motion_capture/device.py b/plugins/motion_capture/device.py
new file mode 100644
index 0000000..f0d082c
--- /dev/null
+++ b/plugins/motion_capture/device.py
@@ -0,0 +1,85 @@
+"""
+motion_capture/device.py
+
+BaseDevice that reads x/y position from CameraTracker.
+
+Channels:
+    x_pos  — horizontal position [px]   (left=0, right=frame_width)
+    y_pos  — vertical position   [px]   (top=0, bottom=frame_height)
+
+Apply the  pixel_to_mm  filter in Signals → Channels to convert to mm.
+"""
+
+from __future__ import annotations
+
+import threading
+from typing import Any, Dict
+
+from devices.base_device import (
+    BaseDevice, ChannelConfig, DeviceInfo, DeviceStatus,
+)
+
+
+class MotionCaptureDevice(BaseDevice):
+
+    def __init__(self, tracker, device_id: str = "motion_capture"):
+        super().__init__(DeviceInfo(
+            device_id   = device_id,
+            name        = "Motion Capture",
+            device_type = "virtual",
+            description = "Camera point-tracking — x/y position in pixels.",
+            icon        = "🎥",
+            channels    = [
+                ChannelConfig(
+                    channel_id = "x_pos",
+                    name       = "X Position",
+                    unit       = "px",
+                    min_value  = 0.0,
+                    max_value  = 1920.0,
+                    color      = "#00d4ff",
+                ),
+                ChannelConfig(
+                    channel_id = "y_pos",
+                    name       = "Y Position",
+                    unit       = "px",
+                    min_value  = 0.0,
+                    max_value  = 1080.0,
+                    color      = "#f72585",
+                ),
+            ],
+        ))
+        self._tracker = tracker
+        self._lock    = threading.Lock()
+        self._last    = (0.0, 0.0)
+
+    # ── BaseDevice interface ──────────────────────────────────────────────
+
+    def connect(self) -> bool:
+        self.status = DeviceStatus.SIMULATED
+        return True
+
+    def disconnect(self) -> None:
+        self.status = DeviceStatus.DISCONNECTED
+
+    def read_channels(self) -> Dict[str, float]:
+        pos = self._tracker.get_position()
+        if pos is not None:
+            with self._lock:
+                self._last = pos
+        with self._lock:
+            x, y = self._last
+        return {"x_pos": x, "y_pos": y}
+
+    def write_channel(self, channel_id: str, value: Any) -> bool:
+        return False
+
+    def get_config_widget(self):
+        from PyQt6.QtWidgets import QLabel
+        lbl = QLabel(
+            "Configure via the Motion Capture toolbar window.\n\n"
+            "Apply 'pixel_to_mm' filter in Signals → Channels\n"
+            "to convert pixel coordinates to millimetres."
+        )
+        lbl.setObjectName("traceSource")
+        lbl.setWordWrap(True)
+        return lbl