Fix error thrown when last video is deleted

sleap/gui/app.py

@@ -1102,7 +1102,7 @@ def _update_gui_state(self):
         self._buttons["delete node"].setEnabled(has_selected_node)
         self._buttons["toggle grayscale"].setEnabled(has_video)
         self._buttons["show video"].setEnabled(has_selected_video)
-        self._buttons["remove video"].setEnabled(has_selected_video)
+        self._buttons["remove video"].setEnabled(has_video)
         self._buttons["delete instance"].setEnabled(has_selected_instance)
         self.suggestions_dock.suggestions_form_widget.buttons[
             "generate_button"
@@ -1207,18 +1207,23 @@ def _after_plot_update(self, frame_idx):
     def _after_plot_change(self, player, frame_idx, selected_inst):
         """Called each time a new frame is drawn."""
 
-        # Store the current LabeledFrame (or make new, empty object)
-        self.state["labeled_frame"] = self.labels.find(
-            self.state["video"], frame_idx, return_new=True
-        )[0]
+        # Store the current frame_idx and LabeledFrame (or make new, empty object)
+        self.state["frame_idx"] = frame_idx
+        self.state["labeled_frame"] = (
+            self.labels.find(self.state["video"], frame_idx, return_new=True)[0]
+            if frame_idx is not None
+            else None
+        )
 
         # Show instances, etc, for this frame
         for overlay in self.overlays.values():
-            overlay.add_to_scene(self.state["video"], frame_idx)
+            overlay.redraw(self.state["video"], frame_idx)
 
         # Select instance if there was already selection
         if selected_inst is not None:
             player.view.selectInstance(selected_inst)
+        else:
+            self.state["instance"] = None
 
         if self.state["fit"]:
             player.zoomToFit()

sleap/gui/overlays/base.py

@@ -61,6 +61,8 @@ def remove_from_scene(self):
 
         This method does not need to be called when changing the plot to a new frame.
         """
+        if self.items is None:
+            return
         for item in self.items:
             self.player.scene.removeItem(item)
 

sleap/gui/widgets/slider.py

@@ -248,8 +248,10 @@ def value(self) -> float:
         """Returns value of slider."""
         return self._val_main
 
-    def setValue(self, val: float) -> float:
+    def setValue(self, val: Optional[float]):
         """Sets value of slider."""
+        if val is None:
+            return
         self._val_main = val
         x = self._toPos(val)
         self.handle.setPos(x, 0)

sleap/gui/widgets/video.py

@@ -410,22 +410,35 @@ def load_video(self, video: Video, plot=True):
 
         self.video = video
 
-        # Is this necessary?
-        self.view.scene.setSceneRect(0, 0, video.width, video.height)
+        if self.video is None:
+            self.reset()
+        else:
+            # Is this necessary?
+            self.view.scene.setSceneRect(0, 0, video.width, video.height)
 
-        self.seekbar.setMinimum(0)
-        self.seekbar.setMaximum(self.video.last_frame_idx)
-        self.seekbar.setEnabled(True)
-        self.seekbar.resizeEvent()
+            self.seekbar.setMinimum(0)
+            self.seekbar.setMaximum(self.video.last_frame_idx)
+            self.seekbar.setEnabled(True)
+            self.seekbar.resizeEvent()
 
         if plot:
             self.plot()
 
     def reset(self):
         """Reset viewer by removing all video data."""
+        # Reset view and video
         self.video = None
-        self.state["frame_idx"] = None
         self.view.clear()
+        self.view.setImage(
+            QImage(sleap.util.get_package_file("sleap/gui/background.png"))
+        )
+
+        # Handle overlays and gui state in callback
+        frame_idx = None
+        selected_instance = None
+        self.changedPlot.emit(self, frame_idx, selected_instance)
+
+        # Reset seekbar
         self.seekbar.setMaximum(0)
         self.seekbar.setEnabled(False)