feat(crosshair): restore frozen ROI profiles when a pin is re-adopted

bec_widgets/utils/crosshair.py

@@ -137,6 +137,9 @@ class Crosshair(QObject):
         self.pinned_v_line = None
         self.pinned_h_line = None
         self.pinned_pos = None
+        # Last emitted pin payload, kept so the pin can be re-announced to consumers
+        # after it is re-adopted: ("2d", payload) | ("1d", payload) | None.
+        self._pinned_emit = None
         self._pin_hit_radius_px = 12  # how close (scene px) a click counts as "on the pin"
         self.update_markers()
         self.check_log()
@@ -648,8 +651,10 @@ class Crosshair(QObject):
         self._draw_pin(draw_pt[0], draw_pt[1])
         self.pinned_pos = draw_pt
         if pinned_2d is not None:
+            self._pinned_emit = ("2d", pinned_2d)
             self.coordinatesPinned2D.emit(pinned_2d)
-        if pinned_1d is not None:
+        elif pinned_1d is not None:
+            self._pinned_emit = ("1d", pinned_1d)
             self.coordinatesPinned1D.emit(pinned_1d)
 
     def _draw_pin(self, x: float, y: float):
@@ -715,6 +720,7 @@ class Crosshair(QObject):
             self.plot_item.removeItem(self.pinned_label)
             self.pinned_label = None
         self.pinned_pos = None
+        self._pinned_emit = None
         if had_pin:
             self.pinCleared.emit()
 
@@ -733,6 +739,7 @@ class Crosshair(QObject):
             "h_line": self.pinned_h_line,
             "label": self.pinned_label,
             "pos": self.pinned_pos,
+            "emit": self._pinned_emit,
         }
         # Detach the removal callback: this crosshair is about to be deleted and a
         # detached pin has no owner to clear it through.
@@ -744,6 +751,7 @@ class Crosshair(QObject):
         self.pinned_h_line = None
         self.pinned_label = None
         self.pinned_pos = None
+        self._pinned_emit = None
         return state
 
     def adopt_pin(self, state):
@@ -759,10 +767,25 @@ class Crosshair(QObject):
         self.pinned_h_line = state.get("h_line")
         self.pinned_label = state.get("label")
         self.pinned_pos = state.get("pos")
+        self._pinned_emit = state.get("emit")
         # Rebind the removal callback to this crosshair (the previous owner is gone).
         if self.pinned_point is not None:
             self.pinned_point._on_remove = self.clear_pin
 
+    def reemit_pin(self):
+        """Re-announce the current pin's coordinates to consumers.
+
+        Used after :meth:`adopt_pin` so dependent state (e.g. the image ROI panels'
+        frozen reference profiles) can be rebuilt for a pin that survived a toggle.
+        """
+        if self._pinned_emit is None:
+            return
+        kind, payload = self._pinned_emit
+        if kind == "2d":
+            self.coordinatesPinned2D.emit(payload)
+        elif kind == "1d":
+            self.coordinatesPinned1D.emit(payload)
+
     def _pin_hit(self, scene_pos) -> bool:
         """Return True if a click at ``scene_pos`` (scene pixels) lands on the pinned marker."""
         if self.pinned_pos is None:

bec_widgets/widgets/plots/image/image_base.py

@@ -658,6 +658,10 @@ class ImageBase(PlotBase):
             self.crosshair.coordinatesPinned2D.connect(self.pin_image_slices)
             self.crosshair.pinCleared.connect(self.clear_pinned_slices)
             self.image_updated.connect(self.update_image_slices)
+            # If a pin survived a previous toggle, rebuild its frozen profiles now that
+            # the consumer slots are connected again.
+            if self.crosshair.pinned_pos is not None:
+                self.crosshair.reemit_pin()
         else:
             self.unhook_crosshair()
             # Hide the ROI panels (the crosshair is destroyed, so its pin signals

tests/unit_tests/test_image_view_next_gen.py

@@ -1095,6 +1095,39 @@ def test_pin_survives_scan_reset(qtbot, mocked_client):
     assert bec_image_view.y_roi_pinned is not None
 
 
+def test_pin_and_profiles_restored_after_roi_toggle(qtbot, mocked_client):
+    """Toggling crosshair-ROI off then on restores both the marker and its frozen profiles."""
+    import numpy as np
+
+    bec_image_view = create_widget(qtbot, Image, client=mocked_client)
+    test_data = np.arange(25).reshape(5, 5)
+    bec_image_view.on_image_update_2d({"data": test_data}, {})
+    switch = bec_image_view.toolbar.components.get_action("image_switch_crosshair")
+    switch.actions["crosshair_roi"].action.trigger()
+    qtbot.wait(50)
+
+    bec_image_view.crosshair.set_pin(2.0, 3.0)
+    assert bec_image_view.x_roi_pinned is not None
+    pin_point = bec_image_view.crosshair.pinned_point
+
+    # Toggle the ROI crosshair off: marker persists, frozen curves are cleared.
+    switch.actions["crosshair_roi"].action.trigger()
+    qtbot.wait(20)
+    assert bec_image_view.crosshair is None
+    assert bec_image_view._detached_pin is not None
+    assert bec_image_view.x_roi_pinned is None
+
+    # Toggle back on: marker is re-adopted AND the frozen profiles are rebuilt.
+    switch.actions["crosshair_roi"].action.trigger()
+    qtbot.wait(20)
+    assert bec_image_view.crosshair is not None
+    assert bec_image_view.crosshair.pinned_point is pin_point
+    assert bec_image_view.x_roi_pinned is not None
+    assert bec_image_view.y_roi_pinned is not None
+    _, x_pinned = bec_image_view.x_roi_pinned.getData()
+    np.testing.assert_array_equal(x_pinned, test_data[:, 3])
+
+
 def test_detached_pin_can_be_removed_with_right_click(qtbot, mocked_client, monkeypatch):
     """A pin left on the plot after disabling crosshair remains removable."""
     from qtpy.QtWidgets import QMenu