🐛 fix(label_widget): prevent PyQt6 attribute panel crash

anylabeling/views/labeling/label_widget.py

@@ -97,6 +97,12 @@
 LABEL_OPACITY = 128
 
 
+def _measure_text_width(font_metrics, text):
+    if hasattr(font_metrics, "horizontalAdvance"):
+        return font_metrics.horizontalAdvance(text)
+    return font_metrics.width(text)
+
+
 class LabelingWidget(LabelDialog):
     """The main widget for labeling images"""
 
@@ -3720,12 +3726,12 @@ def update_attributes(self, shape_index):
             if hasattr(self, "grid_layout_container"):
                 font_metrics = QFontMetrics(self.grid_layout_container.font())
             else:
-                font_metrics = QLabel().font()
+                font_metrics = QFontMetrics(QLabel().font())
             available_width = self.scroll_area.width() - 30
             property_display = property
-            if font_metrics.width(property) > available_width:
+            if _measure_text_width(font_metrics, property) > available_width:
                 while (
-                    font_metrics.width(property_display + "...")
+                    _measure_text_width(font_metrics, property_display + "...")
                     > available_width
                     and len(property_display) > 1
                 ):
@@ -3747,18 +3753,19 @@ def update_attributes(self, shape_index):
                 main_layout.setSpacing(2)
 
                 def get_truncated_text(text, max_width):
-                    if font_metrics.width(text) <= max_width:
+                    if _measure_text_width(font_metrics, text) <= max_width:
                         return text, text
                     truncated = text
                     while (
-                        font_metrics.width(truncated + "...") > max_width
+                        _measure_text_width(font_metrics, truncated + "...")
+                        > max_width
                         and len(truncated) > 1
                     ):
                         truncated = truncated[:-1]
                     return truncated + "...", text
 
                 def get_button_width(text):
-                    return font_metrics.width(text) + 30
+                    return _measure_text_width(font_metrics, text) + 30
 
                 def create_radio_button_with_handler(
                     display_text, original_text, prop, shape_idx

tests/test_label_widget_metrics.py

@@ -0,0 +1,43 @@
+import os
+import unittest
+
+os.environ.setdefault("QT_QPA_PLATFORM", "offscreen")
+
+try:
+    from PyQt6 import QtGui, QtWidgets
+
+    PYQT_AVAILABLE = True
+except Exception:
+    PYQT_AVAILABLE = False
+
+
+@unittest.skipUnless(
+    PYQT_AVAILABLE, "PyQt6 is required for label widget metrics tests"
+)
+class TestLabelWidgetMetrics(unittest.TestCase):
+
+    def setUp(self):
+        self.app = QtWidgets.QApplication.instance()
+        if self.app is None:
+            self.app = QtWidgets.QApplication([])
+
+    def test_measure_text_width_matches_horizontal_advance(self):
+        from anylabeling.views.labeling.label_widget import _measure_text_width
+
+        font = self.app.font()
+        metrics = QtGui.QFontMetrics(font)
+
+        self.assertEqual(
+            _measure_text_width(metrics, "bodyColor"),
+            metrics.horizontalAdvance("bodyColor"),
+        )
+
+    def test_measure_text_width_falls_back_to_width(self):
+        from anylabeling.views.labeling.label_widget import _measure_text_width
+
+        class LegacyFontMetrics:
+            def width(self, text):
+                return len(text) * 7
+
+        metrics = LegacyFontMetrics()
+        self.assertEqual(_measure_text_width(metrics, "vehicle"), 49)