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, 177 insertions, 0 deletions

diff --git a/plugins/motion_capture/plugin.py b/plugins/motion_capture/plugin.py
new file mode 100644
index 0000000..d4bf497
--- /dev/null
+++ b/plugins/motion_capture/plugin.py
@@ -0,0 +1,177 @@
+"""
+motion_capture/plugin.py
+
+LabDAQ Motion Capture plugin.
+
+Tracks a user-selected point via webcam (OpenCV CSRT tracker) and
+streams x/y pixel coordinates as live channels into the acquisition
+pipeline.  Falls back to a Lissajous simulation when OpenCV is absent.
+
+Custom filter:
+    pixel_to_mm — convert pixel coords to millimetres using a
+    px_per_mm calibration value.  Add it in Signals → Channels on
+    the x_pos or y_pos channel.
+
+Install OpenCV to use a real camera:
+    Arch Linux:  sudo pacman -S python-opencv
+    Other:       pip install opencv-python
+"""
+
+from __future__ import annotations
+
+from typing import Any, Dict, List, Optional
+
+from PyQt6.QtWidgets import (
+    QDoubleSpinBox, QFormLayout, QLabel, QSpinBox, QWidget,
+)
+
+from plugins.base_plugin import LabPlugin, PluginAction, PluginContext
+
+
+class MotionCapturePlugin(LabPlugin):
+
+    # ── Metadata ──────────────────────────────────────────────────────────
+
+    @property
+    def plugin_id(self) -> str: return "motion_capture"
+
+    @property
+    def name(self) -> str: return "Motion Capture"
+
+    @property
+    def version(self) -> str: return "1.0.0"
+
+    @property
+    def description(self) -> str:
+        return ("Track a point via webcam and stream x/y position as live signals. "
+                "Apply pixel_to_mm filter to convert to real-world units.")
+
+    @property
+    def author(self) -> str: return "LabDAQ"
+
+    # ── Lifecycle ─────────────────────────────────────────────────────────
+
+    def on_load(self, context: PluginContext) -> None:
+        self._ctx = context
+        self._win: Optional[object] = None
+        self._toolbar_btn = None
+
+        from tracker import CameraTracker
+        from device  import MotionCaptureDevice
+
+        self._tracker = CameraTracker()
+        self._device  = MotionCaptureDevice(self._tracker)
+
+    def on_unload(self) -> None:
+        self._tracker.stop()
+        if self._win is not None:
+            self._win.close()
+            self._win = None
+
+    # ── Integration hooks ─────────────────────────────────────────────────
+
+    def get_devices(self) -> list:
+        return [self._device]
+
+    def get_filter_classes(self) -> dict:
+        from filter import PixelToMMFilter
+        return {"pixel_to_mm": PixelToMMFilter}
+
+    def get_toolbar_actions(self) -> List[PluginAction]:
+        return [
+            PluginAction(
+                label    = "Motion Capture",
+                icon     = "🎥",
+                tooltip  = "Open motion capture window",
+                checkable = True,
+                callback = self._toggle_window,
+                button_ref_callback = self._store_btn,
+            )
+        ]
+
+    def get_settings_widget(self) -> Optional[QWidget]:
+        w = QWidget()
+        lay = QFormLayout(w)
+        lay.setContentsMargins(0, 4, 0, 4)
+
+        self._s_cam = QSpinBox()
+        self._s_cam.setRange(0, 9)
+        self._s_cam.setValue(
+            self._win.get_camera_index() if self._win else 0)
+        self._s_cam.setObjectName("traceWidthSpin")
+        self._s_cam.valueChanged.connect(self._sync_cam_to_window)
+        lay.addRow("Camera index:", self._s_cam)
+
+        self._s_pxmm = QDoubleSpinBox()
+        self._s_pxmm.setRange(0.01, 100_000)
+        self._s_pxmm.setDecimals(2)
+        self._s_pxmm.setSuffix("  px/mm")
+        self._s_pxmm.setValue(
+            self._win.get_px_per_mm() if self._win else 10.0)
+        self._s_pxmm.setObjectName("cfgGlobalSpin")
+        self._s_pxmm.valueChanged.connect(self._sync_pxmm_to_window)
+        lay.addRow("Calibration:", self._s_pxmm)
+
+        hint = QLabel(
+            "Calibration: count how many pixels span a known real distance\n"
+            "in the camera frame, then divide pixels ÷ mm."
+        )
+        hint.setObjectName("traceSource")
+        hint.setWordWrap(True)
+        lay.addRow(hint)
+
+        return w
+
+    # ── Profile state ─────────────────────────────────────────────────────
+
+    def get_save_state(self) -> Dict[str, Any]:
+        return {
+            "camera_index": self._win.get_camera_index() if self._win else 0,
+            "px_per_mm":    self._win.get_px_per_mm()    if self._win else 10.0,
+        }
+
+    def apply_save_state(self, state: Dict[str, Any]) -> None:
+        if self._win is not None:
+            self._win.set_camera_index(state.get("camera_index", 0))
+            self._win.set_px_per_mm(state.get("px_per_mm", 10.0))
+        # Store for when window is opened later
+        self._pending_state = state
+
+    # ── Internal ──────────────────────────────────────────────────────────
+
+    def _store_btn(self, btn) -> None:
+        self._toolbar_btn = btn
+
+    def _toggle_window(self, checked: bool) -> None:
+        if self._win is None:
+            from window import MotionCaptureWindow
+            self._win = MotionCaptureWindow(
+                self._tracker, self._ctx.main_window)
+            self._win.closed.connect(self._on_win_closed)
+
+            # Apply any state that arrived before window was created
+            state = getattr(self, "_pending_state", None)
+            if state:
+                self._win.set_camera_index(state.get("camera_index", 0))
+                self._win.set_px_per_mm(state.get("px_per_mm", 10.0))
+
+        if checked:
+            geo = self._ctx.main_window.geometry()
+            if not self._win.isVisible():
+                self._win.move(geo.right() + 8, geo.top() + 40)
+            self._win.show()
+            self._win.raise_()
+        else:
+            self._win.hide()
+
+    def _on_win_closed(self) -> None:
+        if self._toolbar_btn is not None:
+            self._toolbar_btn.setChecked(False)
+
+    def _sync_cam_to_window(self, v: int) -> None:
+        if self._win:
+            self._win.set_camera_index(v)
+
+    def _sync_pxmm_to_window(self, v: float) -> None:
+        if self._win:
+            self._win.set_px_per_mm(v)