adding overlay traitletto list current overlays, must be updated using get_overlay to keep up to date

Author: cpparts

js/models/event_handler.js

@@ -281,6 +281,7 @@ export default class EventHandler {
       add_MOC_from_dict: this.messageHandler.handleAddMOCFromDict,
       add_overlay: this.messageHandler.handleAddOverlay,
       remove_overlay: this.messageHandler.handleRemoveOverlay,
+      get_overlays: this.messageHandler.handleGetOverlays,
       change_colormap: this.messageHandler.handleChangeColormap,
       get_JPG_thumbnail: this.messageHandler.handleGetJPGThumbnail,
       trigger_selection: this.messageHandler.handleTriggerSelection,

js/models/message_handler.js

@@ -140,13 +140,30 @@ export default class MessageHandler {
     }
   }
 
-  handleRemoveOverlay(msg) {
+  handleRemoveOverlay = (msg) => {
     const overlay_names = msg["name"];
     for (const overlay_name of overlay_names) {
       console.info(`Sending removeOverlay for ${overlay_name}`);
       this.aladin.removeOverlay(overlay_name);
     }
-  }
+    this.handleGetOverlays();
+  };
+
+  handleGetOverlays = () => {
+    const overlay_names = [];
+    const overlays = this.aladin.getOverlays();
+    for (const overlay of overlays) {
+      const overlay_name = overlay["name"];
+      overlay_names.push(overlay_name);
+    }
+    console.info(`Current overlays are ${overlay_names}`);
+    this.model.send({
+      event_type: "current_overlays",
+      content: {
+        overlays: overlay_names,
+      },
+    });
+  };
 
   handleChangeColormap(msg) {
     this.aladin.getBaseImageLayer().setColormap(msg["colormap"]);

src/ipyaladin/widget.py

@@ -177,6 +177,11 @@ class Aladin(anywidget.AnyWidget):
     ).tag(sync=True)
     _wcs = traitlets.Dict().tag(sync=True)
     _fov_xy = traitlets.Dict().tag(sync=True)
+    # Overlays
+    _overlays = traitlets.List(
+        [],
+        help="A list of overlays on the widget.",
+    ).tag(sync=True)
 
     # content of the last click
     clicked_object = traitlets.Dict().tag(sync=True)
@@ -254,6 +259,9 @@ def _handle_custom_message(self, _: any, message: dict, buffers: any) -> None:
             self.listener_callback["select"](message["content"])
         elif event_type == "save_view_as_image":
             self._save_file(message["path"], buffers[0])
+        elif event_type == "current_overlays":
+            self.listener_callback["current_overlays"](message["content"])
+            self._overlays = message["content"]["overlays"]
 
     @property
     def selected_objects(self) -> List[Table]:
@@ -271,6 +279,18 @@ def selected_objects(self) -> List[Table]:
             catalogs.append(Table(objects_data))
         return catalogs
 
+    @property
+    def overlays(self) -> List:
+        """The list of overlays on the widget.
+
+        Returns
+        -------
+        list
+            A list of strings representing the widget overlays.
+
+        """
+        return self._overlays
+
     @property
     def height(self) -> int:
         """The height of the widget.
@@ -957,12 +977,12 @@ def add_graphic_overlay_from_stcs(
 
     @widget_should_be_loaded
     def remove_overlay(self, overlay_name: Union[Iterable[str], str]) -> None:
-        """Remove an overlay layer defined by an STC-S string.
+        """Remove an overlay layer defined by a string.
 
         Parameters
         ----------
         overlay_name : str, Iterable[str]
-            The STC-S string //or an iterable of STC-S strings.
+            The string or an iterable of strings.
 
         """
         overlay_name = [overlay_name] if isinstance(overlay_name, str) else overlay_name
@@ -974,6 +994,15 @@ def remove_overlay(self, overlay_name: Union[Iterable[str], str]) -> None:
             }
         )
 
+    @widget_should_be_loaded
+    def get_overlays(self) -> List:
+        """Update the current overlays defined by their names."""
+        self.send(
+            {
+                "event_name": "get_overlays",
+            }
+        )
+
     @widget_should_be_loaded
     def set_color_map(self, color_map_name: str) -> None:
         """Change the color map of the Aladin Lite widget.
@@ -1039,6 +1068,8 @@ def set_listener(self, listener_type: str, callback: Callable) -> None:
             self.listener_callback["click"] = callback
         elif listener_type == "select":
             self.listener_callback["select"] = callback
+        elif listener_type == "current_overlays":
+            self.listener_callback["current_overlays"] = callback
         else:
             raise ValueError(
                 "listener_type must be 'object_hovered', "