observer method

src/compas_viewer/commands.py

@@ -236,9 +236,6 @@ def select_all(viewer: "Viewer"):
         if obj.show and not obj.is_locked:
             obj.is_selected = True
 
-    viewer.ui.sidebar.update()
-    viewer.renderer.update()
-
 
 select_all_cmd = Command(title="Select All", callback=select_all)
 
@@ -247,9 +244,6 @@ def deselect_all(viewer: "Viewer"):
     for obj in viewer.scene.objects:
         obj.is_selected = False
 
-    viewer.ui.sidebar.update()
-    viewer.renderer.update()
-
 
 deselect_all_cmd = Command(title="DeSelect All", callback=deselect_all)
 
@@ -275,8 +269,6 @@ def select_object(viewer: "Viewer", event: QMouseEvent):
         if selected_obj:
             selected_obj.is_selected = True
 
-        viewer.ui.sidebar.update()
-
     viewer.renderer.update()
 
 
@@ -295,7 +287,6 @@ def select_multiple(viewer: "Viewer", event: QMouseEvent):
         selected_obj = viewer.scene.instance_colors.get(tuple(unique_color[0]))  # type: ignore
         if selected_obj:
             selected_obj.is_selected = True
-            viewer.ui.sidebar.update()
 
     viewer.renderer.update()
 
@@ -343,8 +334,6 @@ def select_window(viewer: "Viewer", event: QMouseEvent):
                 obj.is_selected = True
                 continue
 
-        viewer.ui.sidebar.update()
-
     viewer.renderer.update()
 
 
@@ -364,8 +353,6 @@ def deselect_object(viewer: "Viewer", event: QMouseEvent):
         if selected_obj:
             selected_obj.is_selected = False
 
-        viewer.ui.sidebar.update()
-
     viewer.renderer.update()
 
 
@@ -394,7 +381,6 @@ def delete_selected():
         if obj.is_selected:
             viewer.scene.remove(obj)
             del obj
-    viewer.renderer.update()
 
 
 # =============================================================================
@@ -411,9 +397,6 @@ def clear_scene(viewer: "Viewer"):
         viewer.scene.remove(obj)
         del obj
 
-    viewer.ui.sidebar.update()
-    viewer.renderer.update()
-
 
 clear_scene_cmd = Command(title="Clear Scene", callback=clear_scene)
 

src/compas_viewer/components/sceneform.py

@@ -114,8 +114,6 @@ def on_item_clicked(self, item, column):
                 if self.callback and node.is_selected:
                     self.callback(node)
 
-        self.viewer.renderer.update()
-
     def on_item_selection_changed(self):
         for item in self.selectedItems():
             if self.callback:

src/compas_viewer/observer.py

@@ -0,0 +1,34 @@
+from PySide6.QtCore import QTimer
+
+from compas_viewer.base import Base
+
+
+class Observer(Base):
+    def __init__(self):
+        self._observers = set(
+            (
+                self.viewer.renderer,
+                self.viewer.ui.sidebar,
+            )
+        )
+
+        self.update_timer = QTimer()
+        self.update_timer.setSingleShot(True)
+        self.update_timer.timeout.connect(self.update_observers)
+        self.debounce_interval = 200
+
+    def add_observer(self, observer):
+        if observer not in self._observers:
+            self._observers.add(observer)
+
+    def remove_observer(self, observer):
+        if observer in self._observers:
+            self._observers.remove(observer)
+
+    def request_update(self):
+        if not self.update_timer.isActive():
+            self.update_timer.start(self.debounce_interval)
+
+    def update_observers(self):
+        for observer in self._observers:
+            observer.update()

src/compas_viewer/scene/scene.py

@@ -9,6 +9,7 @@
 from compas.datastructures import Datastructure
 from compas.geometry import Geometry
 from compas.scene import Scene
+from compas_viewer.observer import Observer
 
 from .sceneobject import ViewerSceneObject
 
@@ -68,17 +69,21 @@ class ViewerScene(Scene):
     def __init__(self, name: str = "ViewerScene", context: str = "Viewer"):
         super().__init__(name=name, context=context)
 
+        #  Observer
+        self._observer = None
+
         #  Primitive
         self.objects: list[ViewerSceneObject]
         #  Selection
         self.instance_colors: dict[tuple[int, int, int], ViewerSceneObject] = {}
         self._instance_colors_generator = instance_colors_generator()
 
     @property
-    def viewer(self):
-        from compas_viewer import Viewer
-
-        return Viewer()
+    def observer(self):
+        """Observer: The observer object for the scene."""
+        if self._observer is None:
+            self._observer = Observer()
+        return self._observer
 
     # TODO: These fixed kwargs could be moved to COMPAS core.
     def add(
@@ -183,4 +188,17 @@ def add(
             u=u,
             **kwargs,
         )
+        self.observer.request_update()
         return sceneobject
+
+    def remove(self, obj: ViewerSceneObject) -> None:
+        """
+        Remove an object from the scene.
+
+        Parameters
+        ----------
+        obj : :class:`compas_viewer.scene.ViewerSceneObject`
+            The object to remove.
+        """
+        super().remove(obj)
+        self.observer.request_update()

src/compas_viewer/scene/sceneobject.py

@@ -16,6 +16,7 @@
 from compas_viewer.gl import make_vertex_buffer
 from compas_viewer.gl import update_index_buffer
 from compas_viewer.gl import update_vertex_buffer
+from compas_viewer.observer import Observer
 from compas_viewer.renderer.shaders import Shader
 
 # Type template of point/line/face data for generating the buffers.
@@ -101,6 +102,9 @@ def __init__(
     ):
         #  Basic
         super().__init__(**kwargs)
+
+        self._observer = None
+
         self.show = show
         self.show_points = show_points if show_points is not None else False
         self.show_lines = show_lines if show_lines is not None else True
@@ -111,7 +115,7 @@ def __init__(
 
         #  Selection
         self._is_locked = is_locked
-        self.is_selected = not is_locked and is_selected
+        self._is_selected = False
 
         #  Visual
         self.background: bool = False
@@ -135,6 +139,23 @@ def __init__(
 
         self._inited = False
 
+    @property
+    def observer(self) -> bool:
+        """bool : Whether the scene is requested to be updated."""
+        if self._observer is None:
+            self._observer = Observer()
+        return self._observer
+
+    @property
+    def is_selected(self):
+        return self._is_selected
+
+    @is_selected.setter
+    def is_selected(self, value):
+        if self._is_selected != value:
+            self._is_selected = value
+            self.observer.request_update()
+
     @property
     def is_locked(self):
         return self._is_locked