Fix grouped shapes disappearing after image changes

anylabeling/views/labeling/widgets/canvas.py

@@ -1243,6 +1243,8 @@ def group_selected_shapes(self):
         if len(self.selected_shapes) == 0:
             return
 
+        previous_group_ids = [shape.group_id for shape in self.shapes]
+
         # List all group ids for selected shapes
         group_ids = set()
         has_non_group_shape = False
@@ -1269,13 +1271,18 @@ def group_selected_shapes(self):
                 if shape.group_id is None:
                     shape.group_id = new_group_id
 
+        if previous_group_ids != [shape.group_id for shape in self.shapes]:
+            self.store_shapes()
+            self.shape_moved.emit()
         self.update()
 
     def ungroup_selected_shapes(self):
         """Ungroup selected shapes"""
         if len(self.selected_shapes) == 0:
             return
 
+        previous_group_ids = [shape.group_id for shape in self.shapes]
+
         # List all group ids for selected shapes
         group_ids = set()
         for shape in self.selected_shapes:
@@ -1287,4 +1294,7 @@ def ungroup_selected_shapes(self):
                 if shape.group_id == group_id:
                     shape.group_id = None
 
+        if previous_group_ids != [shape.group_id for shape in self.shapes]:
+            self.store_shapes()
+            self.shape_moved.emit()
         self.update()

tests/test_canvas_grouping.py

@@ -0,0 +1,99 @@
+"""Regression tests for Canvas grouping and persisted group IDs."""
+
+import io
+import os
+import tempfile
+import unittest
+
+os.environ.setdefault("QT_QPA_PLATFORM", "offscreen")
+
+from PIL import Image
+from PyQt6 import QtCore, QtWidgets
+
+from anylabeling.views.labeling.label_file import LabelFile
+from anylabeling.views.labeling.shape import Shape
+from anylabeling.views.labeling.widgets.canvas import Canvas
+
+_APP = QtWidgets.QApplication.instance() or QtWidgets.QApplication([])
+
+
+def make_shape(offset, group_id=None):
+    shape = Shape(label="part", shape_type="rectangle", group_id=group_id)
+    shape.add_point(QtCore.QPointF(offset, offset))
+    shape.add_point(QtCore.QPointF(offset + 5, offset + 5))
+    shape.close()
+    return shape
+
+
+class TestShapeGrouping(unittest.TestCase):
+    def test_grouping_marks_canvas_changed_and_is_undoable(self):
+        canvas = Canvas(parent=None)
+        shapes = [make_shape(1), make_shape(10)]
+        canvas.load_shapes(shapes)
+        canvas.selected_shapes = shapes
+        changes = []
+        canvas.shape_moved.connect(lambda: changes.append(True))
+
+        canvas.group_selected_shapes()
+
+        self.assertEqual([shape.group_id for shape in canvas.shapes], [1, 1])
+        self.assertEqual(len(changes), 1)
+        self.assertTrue(canvas.is_shape_restorable)
+
+        canvas.restore_shape()
+        self.assertEqual([shape.group_id for shape in canvas.shapes], [None, None])
+
+    def test_ungrouping_updates_every_shape_in_the_selected_group(self):
+        canvas = Canvas(parent=None)
+        shapes = [make_shape(1, group_id=7), make_shape(10, group_id=7)]
+        canvas.load_shapes(shapes)
+        canvas.selected_shapes = [shapes[0]]
+        changes = []
+        canvas.shape_moved.connect(lambda: changes.append(True))
+
+        canvas.ungroup_selected_shapes()
+
+        self.assertEqual([shape.group_id for shape in canvas.shapes], [None, None])
+        self.assertEqual(len(changes), 1)
+        self.assertTrue(canvas.is_shape_restorable)
+
+    def test_group_id_survives_label_file_round_trip(self):
+        shapes = [
+            {
+                "label": "part",
+                "text": "",
+                "points": [[1, 1], [6, 6]],
+                "group_id": 3,
+                "shape_type": "rectangle",
+                "flags": {},
+            },
+            {
+                "label": "part",
+                "text": "",
+                "points": [[10, 10], [15, 15]],
+                "group_id": 3,
+                "shape_type": "rectangle",
+                "flags": {},
+            },
+        ]
+        image_buffer = io.BytesIO()
+        Image.new("RGB", (20, 20)).save(image_buffer, format="PNG")
+
+        with tempfile.TemporaryDirectory() as directory:
+            filename = os.path.join(directory, "labels.json")
+            LabelFile().save(
+                filename=filename,
+                shapes=shapes,
+                image_path="image.png",
+                image_height=20,
+                image_width=20,
+                image_data=image_buffer.getvalue(),
+            )
+
+            loaded = LabelFile(filename)
+
+        self.assertEqual([shape["group_id"] for shape in loaded.shapes], [3, 3])
+
+
+if __name__ == "__main__":
+    unittest.main()