fix(pypipeline): Create a copy of output memoryviews

When pipeline destructors are called, memoryviews can become invalid.

src/python/itkwasm/itkwasm/pipeline.py

@@ -23,25 +23,25 @@
 
 def _memoryview_to_numpy_array(component_type, buf):
     if component_type == IntTypes.UInt8:
-        return np.frombuffer(buf, dtype=np.uint8)
+        return np.frombuffer(buf, dtype=np.uint8).copy()
     elif component_type == IntTypes.Int8:
-        return np.frombuffer(buf, dtype=np.int8)
+        return np.frombuffer(buf, dtype=np.int8).copy()
     elif component_type == IntTypes.UInt16:
-        return np.frombuffer(buf, dtype=np.uint16)
+        return np.frombuffer(buf, dtype=np.uint16).copy()
     elif component_type == IntTypes.Int16:
-        return np.frombuffer(buf, dtype=np.int16)
+        return np.frombuffer(buf, dtype=np.int16).copy()
     elif component_type == IntTypes.UInt32:
-        return np.frombuffer(buf, dtype=np.uint32)
+        return np.frombuffer(buf, dtype=np.uint32).copy()
     elif component_type == IntTypes.Int32:
-        return np.frombuffer(buf, dtype=np.int32)
+        return np.frombuffer(buf, dtype=np.int32).copy()
     elif component_type == IntTypes.UInt64:
-        return np.frombuffer(buf, dtype=np.uint64)
+        return np.frombuffer(buf, dtype=np.uint64).copy()
     elif component_type == IntTypes.Int64:
-        return np.frombuffer(buf, dtype=np.int64)
+        return np.frombuffer(buf, dtype=np.int64).copy()
     elif component_type == FloatTypes.Float32:
-        return np.frombuffer(buf, dtype=np.float32)
+        return np.frombuffer(buf, dtype=np.float32).copy()
     elif component_type == FloatTypes.Float64:
-        return np.frombuffer(buf, dtype=np.float64)
+        return np.frombuffer(buf, dtype=np.float64).copy()
     else:
         raise ValueError('Unsupported component type')
 

src/python/itkwasm/test/test_pipeline.py

@@ -200,9 +200,11 @@ def test_pipeline_write_read_polydata():
     outputs = pipeline.run(args, pipeline_outputs, pipeline_inputs)
 
     out_mesh_dict = asdict(outputs[0].data)
+
     # native itk python binaries require uint64
     out_mesh_dict['cells'] = out_mesh_dict['cells'].astype(np.uint64)
     out_mesh_dict['meshType']['cellComponentType'] = 'uint64'
+    assert np.isclose(out_mesh_dict['points'][0], 3.71636)
     out_mesh = itk.mesh_from_dict(out_mesh_dict)
 
     assert out_mesh.GetNumberOfPoints() == 2903