Adding feature to remove annotations

src/gui/tabs/annotation_tab.py

@@ -39,6 +39,8 @@ class AnnotationTab(QWidget):
         self.current_image_path = None
         self.current_image_id = None
         self.current_annotations = []
+        # IDs of annotations currently selected on the canvas (multi-select)
+        self.selected_annotation_ids = []
 
         self._setup_ui()
 
@@ -62,6 +64,8 @@ class AnnotationTab(QWidget):
         self.annotation_canvas = AnnotationCanvasWidget()
         self.annotation_canvas.zoom_changed.connect(self._on_zoom_changed)
         self.annotation_canvas.annotation_drawn.connect(self._on_annotation_drawn)
+        # Selection of existing polylines (when tool is not in drawing mode)
+        self.annotation_canvas.annotation_selected.connect(self._on_annotation_selected)
         canvas_layout.addWidget(self.annotation_canvas)
 
         canvas_group.setLayout(canvas_layout)
@@ -107,6 +111,10 @@ class AnnotationTab(QWidget):
         self.annotation_tools.clear_annotations_requested.connect(
             self._on_clear_annotations
         )
+        # Delete selected annotation on canvas
+        self.annotation_tools.delete_selected_annotation_requested.connect(
+            self._on_delete_selected_annotation
+        )
         self.right_splitter.addWidget(self.annotation_tools)
 
         # Image loading section
@@ -292,6 +300,25 @@ class AnnotationTab(QWidget):
             logger.error(f"Failed to save annotation: {e}")
             QMessageBox.critical(self, "Error", f"Failed to save annotation:\n{str(e)}")
 
+    def _on_annotation_selected(self, annotation_ids):
+        """
+        Handle selection of existing annotations on the canvas.
+
+        Args:
+            annotation_ids: List of selected annotation IDs, or None/empty if cleared.
+        """
+        if not annotation_ids:
+            self.selected_annotation_ids = []
+            self.annotation_tools.set_has_selected_annotation(False)
+            logger.debug("Annotation selection cleared on canvas")
+            return
+
+        # Normalize to a unique, sorted list of integer IDs
+        ids = sorted({int(aid) for aid in annotation_ids if isinstance(aid, int)})
+        self.selected_annotation_ids = ids
+        self.annotation_tools.set_has_selected_annotation(bool(ids))
+        logger.debug(f"Annotations selected on canvas: IDs={ids}")
+
     def _on_simplify_on_finish_changed(self, enabled: bool):
         """Update canvas simplify-on-finish flag from tools widget."""
         self.annotation_canvas.simplify_on_finish = enabled
@@ -323,7 +350,7 @@ class AnnotationTab(QWidget):
         Handle when an object class is selected or cleared.
 
         When a specific class is selected, only annotations of that class are drawn.
-        When the selection is cleared (\"-- Select Class --\"), all annotations are shown.
+        When the selection is cleared ("-- Select Class --"), all annotations are shown.
         """
         if class_data:
             logger.debug(f"Object class selected: {class_data['class_name']}")
@@ -332,14 +359,89 @@ class AnnotationTab(QWidget):
                 'No class selected ("-- Select Class --"), showing all annotations'
             )
 
+        # Changing the class filter invalidates any previous selection
+        self.selected_annotation_ids = []
+        self.annotation_tools.set_has_selected_annotation(False)
+
         # Whenever the selection changes, update which annotations are visible
         self._redraw_annotations_for_current_filter()
 
     def _on_clear_annotations(self):
         """Handle clearing all annotations."""
         self.annotation_canvas.clear_annotations()
+        # Clear in-memory state and selection, but keep DB entries unchanged
+        self.current_annotations = []
+        self.selected_annotation_ids = []
+        self.annotation_tools.set_has_selected_annotation(False)
         logger.info("Cleared all annotations")
 
+    def _on_delete_selected_annotation(self):
+        """Handle deleting the currently selected annotation(s) (if any)."""
+        if not self.selected_annotation_ids:
+            QMessageBox.information(
+                self,
+                "No Selection",
+                "No annotation is currently selected.",
+            )
+            return
+
+        count = len(self.selected_annotation_ids)
+        if count == 1:
+            question = "Are you sure you want to delete the selected annotation?"
+            title = "Delete Annotation"
+        else:
+            question = (
+                f"Are you sure you want to delete the {count} selected annotations?"
+            )
+            title = "Delete Annotations"
+
+        reply = QMessageBox.question(
+            self,
+            title,
+            question,
+            QMessageBox.Yes | QMessageBox.No,
+            QMessageBox.No,
+        )
+        if reply != QMessageBox.Yes:
+            return
+
+        failed_ids = []
+        try:
+            for ann_id in self.selected_annotation_ids:
+                try:
+                    deleted = self.db_manager.delete_annotation(ann_id)
+                    if not deleted:
+                        failed_ids.append(ann_id)
+                except Exception as e:
+                    logger.error(f"Failed to delete annotation ID {ann_id}: {e}")
+                    failed_ids.append(ann_id)
+
+            if failed_ids:
+                QMessageBox.warning(
+                    self,
+                    "Partial Failure",
+                    "Some annotations could not be deleted:\n"
+                    + ", ".join(str(a) for a in failed_ids),
+                )
+            else:
+                logger.info(
+                    f"Deleted {count} annotation(s): "
+                    + ", ".join(str(a) for a in self.selected_annotation_ids)
+                )
+
+            # Clear selection and reload annotations for the current image from DB
+            self.selected_annotation_ids = []
+            self.annotation_tools.set_has_selected_annotation(False)
+            self._load_annotations_for_current_image()
+
+        except Exception as e:
+            logger.error(f"Failed to delete annotations: {e}")
+            QMessageBox.critical(
+                self,
+                "Error",
+                f"Failed to delete annotations:\n{str(e)}",
+            )
+
     def _load_annotations_for_current_image(self):
         """
         Load all annotations for the current image from the database and
@@ -349,12 +451,17 @@ class AnnotationTab(QWidget):
         if not self.current_image_id:
             self.current_annotations = []
             self.annotation_canvas.clear_annotations()
+            self.selected_annotation_ids = []
+            self.annotation_tools.set_has_selected_annotation(False)
             return
 
         try:
             self.current_annotations = self.db_manager.get_annotations_for_image(
                 self.current_image_id
             )
+            # New annotations loaded; reset any selection
+            self.selected_annotation_ids = []
+            self.annotation_tools.set_has_selected_annotation(False)
             self._redraw_annotations_for_current_filter()
         except Exception as e:
             logger.error(
@@ -393,7 +500,12 @@ class AnnotationTab(QWidget):
                 polyline = ann["segmentation_mask"]
                 color = ann.get("class_color", "#FF0000")
 
-                self.annotation_canvas.draw_saved_polyline(polyline, color, width=3)
+                self.annotation_canvas.draw_saved_polyline(
+                    polyline,
+                    color,
+                    width=3,
+                    annotation_id=ann["id"],
+                )
                 self.annotation_canvas.draw_saved_bbox(
                     [ann["x_min"], ann["y_min"], ann["x_max"], ann["y_max"]],
                     color,