[io] Resolve the geometry of a block that only has artefacts

doctr/io/elements.py

@@ -409,7 +409,8 @@ def __init__(
             line_boxes = [word.geometry for line in lines for word in line.words]
             artefact_boxes = [artefact.geometry for artefact in artefacts]
             # Check whether this is a rotated or straight box (geometries read back from an export are lists)
-            box_resolution_fn = resolve_enclosing_rbbox if len(lines[0].geometry) == 4 else resolve_enclosing_bbox
+            first_geometry = lines[0].geometry if lines else artefacts[0].geometry
+            box_resolution_fn = resolve_enclosing_rbbox if len(first_geometry) == 4 else resolve_enclosing_bbox
             geometry = box_resolution_fn(line_boxes + artefact_boxes)  # type: ignore
 
         super().__init__(lines=lines, artefacts=artefacts)

tests/common/test_io_elements.py

@@ -442,6 +442,14 @@ def test_block():
     }
 
 
+def test_block_artefacts_only():
+    artefacts = _mock_artefacts()
+    block = elements.Block(artefacts=artefacts)
+    assert block.lines == []
+    assert block.geometry == ((0, 0), (1, 1))
+    assert block.render() == ""
+
+
 def test_block_rotated_lines_from_dict():
     # Rotated geometries read back from an export are nested lists, not numpy arrays
     polygon = [[0.1, 0.1], [0.4, 0.2], [0.35, 0.4], [0.05, 0.3]]