Emit event from points data setter (#6117)

Closes #6116

# Description

Adds back an event emission from the Points layer data setter. Commits
summary:

- Add failing test for layer data setter event
- Emit event on points data setter

## Type of change
<!-- Please delete options that are not relevant. -->
- [x] Bug-fix (non-breaking change which fixes an issue)

---------

Co-authored-by: Grzegorz Bokota <bokota+github@gmail.com>

napari/layers/points/_tests/test_points.py

@@ -2486,3 +2486,24 @@ def test_point_selection_remains_evented_after_update():
     assert isinstance(layer.selected_data, Selection)
     layer.selected_data = {0, 1}
     assert isinstance(layer.selected_data, Selection)
+
+
+def test_points_data_setter_emits_event():
+    data = np.random.random((5, 2))
+    emitted_events = Mock()
+    layer = Points(data)
+    layer.events.data.connect(emitted_events)
+    layer.data = np.random.random((5, 2))
+    emitted_events.assert_called_once()
+
+
+def test_points_add_delete_only_emit_one_event():
+    data = np.random.random((5, 2))
+    emitted_events = Mock()
+    layer = Points(data)
+    layer.events.data.connect(emitted_events)
+    layer.add(np.random.random(2))
+    assert emitted_events.call_count == 1
+    layer.selected_data = {3}
+    layer.remove_selected()
+    assert emitted_events.call_count == 2

napari/layers/points/points.py

@@ -535,6 +535,17 @@ def data(self) -> np.ndarray:
 
     @data.setter
     def data(self, data: Optional[np.ndarray]):
+        """Set the data array and emit a corresponding event."""
+        self._set_data(data)
+        self.events.data(
+            value=self.data,
+            action=ActionType.CHANGE.value,
+            data_indices=slice(None),
+            vertex_indices=((),),
+        )
+
+    def _set_data(self, data: Optional[np.ndarray]):
+        """Set the .data array attribute, without emitting an event."""
         data, _ = fix_data_points(data, self.ndim)
         cur_npoints = len(self._data)
         self._data = data
@@ -1924,7 +1935,7 @@ def add(self, coords):
             Point or points to add to the layer data.
         """
         cur_points = len(self.data)
-        self.data = np.append(self.data, np.atleast_2d(coords), axis=0)
+        self._set_data(np.append(self.data, np.atleast_2d(coords), axis=0))
         self.events.data(
             value=self.data,
             action=ActionType.ADD.value,
@@ -1959,7 +1970,7 @@ def remove_selected(self):
                     self._value -= offset
                     self._value_stored -= offset
 
-            self.data = np.delete(self.data, index, axis=0)
+            self._set_data(np.delete(self.data, index, axis=0))
             self.events.data(
                 value=self.data,
                 action=ActionType.REMOVE.value,