Add calculation of a dataset's whole bounding box to Dataset (#975)

* add method to Dataset that calculates the whole dataset's bounding box.

* Add test, doc string and changelog entry

* format code

Author: MichaelBuessemeyer

webknossos/Changelog.md

@@ -15,6 +15,7 @@ For upgrade instructions, please check the respective _Breaking Changes_ section
 ### Breaking Changes
 
 ### Added
+- Added a method to the Datasets class that calculates a dataset's bounding box covering all layers. [#975](https://github.com/scalableminds/webknossos-libs/pull/975)
 
 ### Changed
 

webknossos/tests/dataset/test_dataset.py

@@ -1052,6 +1052,25 @@ def test_changing_layer_bounding_box(
     assure_exported_properties(ds)
 
 
+@pytest.mark.parametrize("data_format,output_path", DATA_FORMATS_AND_OUTPUT_PATHS)
+def test_dataset_bounding_box_calculation(
+    data_format: DataFormat, output_path: Path
+) -> None:
+    ds_path = copy_simple_dataset(data_format, output_path, "change_layer_bounding_box")
+    ds = Dataset.open(ds_path)
+    layer = ds.get_layer("color")
+    # BoundingBox(topleft=(0, 0, 0), size=(24, 24, 24))
+    assert layer.bounding_box == ds.calculate_bounding_box(), (
+        "The calculated bounding box of the dataset does not "
+        + "match the color layer's bounding box."
+    )
+    layer.bounding_box = layer.bounding_box.with_size((512, 512, 512))
+    assert layer.bounding_box == ds.calculate_bounding_box(), (
+        "The calculated bounding box of the dataset does not "
+        + "match the color layer's enlarged bounding box."
+    )
+
+
 def test_get_view() -> None:
     ds_path = prepare_dataset_path(DataFormat.WKW, TESTOUTPUT_DIR, "get_view")
     ds = Dataset(ds_path, voxel_size=(1, 1, 1))

webknossos/webknossos/dataset/dataset.py

@@ -1484,6 +1484,19 @@ def add_fs_copy_layer(
         self._export_as_json()
         return self.layers[new_layer_name]
 
+    def calculate_bounding_box(self) -> BoundingBox:
+        """
+        Calculates and returns the enclosing bounding box of all data layers of the dataset.
+        """
+        all_layers = list(self.layers.values())
+        if len(all_layers) <= 0:
+            return BoundingBox.empty()
+        dataset_bbox = all_layers[0].bounding_box
+        for layer in all_layers[1:]:
+            bbox = layer.bounding_box
+            dataset_bbox = dataset_bbox.extended_by(bbox)
+        return dataset_bbox
+
     def copy_dataset(
         self,
         new_dataset_path: Union[str, Path],