Registration: Propagate the result of the atlas loading dialog

This allows calling code to handle cases where the user cancelled the
(down)load.

Author: olivierdelree

src/histalign/frontend/__init__.py

@@ -335,7 +335,7 @@ def prepare_gui_for_new_project(self) -> None:
         tab.alignment_widget.reset_volume()
         tab.alignment_widget.reset_histology()
 
-    def switch_workspace(self) -> None:
+    def switch_workspace(self) -> bool:
         """Handles a change in the current workspace.
 
         Note that when this function is called, the workspace should already have been
@@ -353,7 +353,7 @@ def switch_workspace(self) -> None:
         # Update the registration tab
         tab = self.registration_tab
 
-        tab.load_atlas()
+        return tab.load_atlas()
 
     def propagate_workspace(self) -> None:
         """Ensures workspace models are properly shared with all that rely on it."""
@@ -412,7 +412,9 @@ def _create_project(self, settings: ProjectSettings) -> None:
 
         # Initialise a new workspace
         self.workspace = Workspace(settings)
-        self.switch_workspace()
+        if not self.switch_workspace():
+            # The user cancelled the download/load of the atlas
+            return
 
         # Update workspace state
         self.workspace_is_dirty = True
@@ -455,7 +457,9 @@ def _open_project(self, path: str | Path) -> None:
         except ValueError as e:
             _module_logger.error(f"Failed to load project from '{path}': {e}")
             return InvalidProjectFileDialog(self).open()
-        self.switch_workspace()
+        if not self.switch_workspace():
+            # The user cancelled the download/load of the atlas
+            return
 
         # Restore registration saved state
         tab = self.registration_tab

src/histalign/frontend/registration/__init__.py

@@ -341,7 +341,7 @@ def clear_volume_state(self) -> None:
         """Clears any atlas on the GUI."""
         self.alignment_widget.reset_volume()
 
-    def load_atlas(self) -> int:
+    def load_atlas(self) -> bool:
         """Loads the atlas and annotations volumes."""
         _module_logger.debug("Loading atlas and annotations.")
 
@@ -355,14 +355,19 @@ def load_atlas(self) -> int:
         annotation_volume.loaded.connect(
             lambda: _module_logger.debug("Annotations loaded.")
         )
-        self.annotation_volume = annotation_volume
         atlas_volume = unwrap(self.alignment_widget.volume_slicer).volume
 
         # Set up the dialog and loader threads
         dialog = AtlasProgressDialog(self)
         annotation_loader_thread = VolumeLoaderThread(annotation_volume)
         atlas_loader_thread = VolumeLoaderThread(atlas_volume)
 
+        dialog.canceled.connect(annotation_loader_thread.requestInterruption)
+        dialog.canceled.connect(atlas_loader_thread.requestInterruption)
+        dialog.canceled.connect(
+            lambda: _module_logger.debug("Volume (down)loading cancelled by user.")
+        )
+
         atlas_volume.downloaded.connect(
             lambda: dialog.setLabelText("Loading atlas"),
             type=QtCore.Qt.ConnectionType.QueuedConnection,
@@ -379,13 +384,17 @@ def load_atlas(self) -> int:
         annotation_loader_thread.start()
         atlas_loader_thread.start()
 
-        result = dialog.exec()  # Blocking
+        result = QtWidgets.QDialog.DialogCode(dialog.exec())  # Blocking
 
         # Ensure we wait for the threads to be destroyed
         annotation_loader_thread.wait()
         atlas_loader_thread.wait()
 
-        return result
+        successful = result == QtWidgets.QDialog.DialogCode.Accepted
+        if successful:
+            self.annotation_volume = annotation_volume
+
+        return successful
 
     def locate_mouse(self) -> None:
         if self.annotation_volume is None: