Add BoundingBox.buffer()

related to #406

Author: soxofaan

openeo_driver/util/geometry.py

@@ -585,3 +585,13 @@ def round_to_resolution(self, res_x: float, res_y: float) -> "BoundingBox":
             north=res_y * math.ceil(self.north / res_y) if math.isfinite(self.north) else self.north,
             crs=self.crs,
         )
+
+    def buffer(self, dx: float, dy: Union[float, None] = None) -> "BoundingBox":
+        """Buffer the bounding box by given distance (in units of the bounding box CRS)"""
+        # TODO: what to do with negative buffering that overshoots the bbox width or height? Assert here or in main constructor?
+        # TODO: also support 4-component buffering (left, bottom, right, top)?
+        if dy is None:
+            dy = dx
+        return BoundingBox(
+            west=self.west - dx, south=self.south - dy, east=self.east + dx, north=self.north + dy, crs=self.crs
+        )

tests/util/test_geometry.py

@@ -796,6 +796,19 @@ def test_round_to_resolution_nodata(self):
         rounded = bbox.round_to_resolution(10, 20)
         assert rounded.as_tuple() == (500430, 5649820, 507680, float("inf"), None)
 
+    def test_buffer(self):
+        bbox = BoundingBox(1, 2, 3, 4, crs=4326)
+
+        assert bbox.buffer(1).as_tuple() == (0, 1, 4, 5, "EPSG:4326")
+        assert bbox.buffer(0.1).as_tuple() == (0.9, 1.9, 3.1, 4.1, "EPSG:4326")
+        assert bbox.buffer(-0.1).as_tuple() == (1.1, 2.1, 2.9, 3.9, "EPSG:4326")
+
+        assert bbox.buffer(0.5, 0.1).as_tuple() == (0.5, 1.9, 3.5, 4.1, "EPSG:4326")
+        assert bbox.buffer(0.5, -0.1).as_tuple() == (0.5, 2.1, 3.5, 3.9, "EPSG:4326")
+
+        # TODO: instead of this nonsense result, should this fail, or result in some special empty case?
+        assert bbox.buffer(-10).as_tuple() == (11, 12, -7, -6, "EPSG:4326")
+
 
 class TestValidateGeoJSON:
     @staticmethod