feat: Background colors (#53)

* feat: Set background colors

* Remove unused methods in view adaptors

Author: gselzer

src/scenex/adaptors/_pygfx/_view.py

@@ -34,8 +34,17 @@ def __init__(self, view: model.View, **backend_kwargs: Any) -> None:
 
         self._snx_set_scene(view.scene)
         self._snx_set_camera(view.camera)
-        # TODO: this is needed... but breaks tests until we deal with Layout better.
-        # self._snx_set_background_color(view.layout.background_color)
+
+        # -- Layout components -- #
+        self._background_mat = pygfx.BackgroundMaterial()
+        self._background = pygfx.Background(None, material=self._background_mat)
+        self._pygfx_scene.add(self._background)
+
+        # -- Layout connections -- #
+        self._model.layout.events.background_color.connect(self._set_background_color)
+
+        # -- Layout initialization -- #
+        self._set_background_color(view.layout.background_color)
 
     def _snx_set_visible(self, arg: bool) -> None:
         pass
@@ -67,28 +76,9 @@ def _draw(self, renderer: pygfx.renderers.WgpuRenderer) -> None:
 
         renderer.render(self._pygfx_scene, self._pygfx_cam, rect=rect, flush=False)
 
-    def _snx_set_position(self, arg: tuple[float, float]) -> None:
-        logger.warning("View.set_position not implemented for pygfx")
-
-    def _snx_set_size(self, arg: tuple[float, float] | None) -> None:
-        logger.warning("Ignoring View.set_size(None): Don't know how to handle this...")
-
-    def _snx_set_background_color(self, color: Color | None) -> None:
-        colors = (color.rgba,) if color is not None else ()
-        background = pygfx.Background(None, material=pygfx.BackgroundMaterial(*colors))
-        self._pygfx_scene.add(background)
-
-    def _snx_set_border_width(self, arg: float) -> None:
-        logger.warning("View.set_border_width not implemented for pygfx")
-
-    def _snx_set_border_color(self, arg: Color | None) -> None:
-        logger.warning("View.set_border_color not implemented for pygfx")
-
-    def _snx_set_padding(self, arg: int) -> None:
-        logger.warning("View.set_padding not implemented for pygfx")
-
-    def _snx_set_margin(self, arg: int) -> None:
-        logger.warning("View.set_margin not implemented for pygfx")
+    def _set_background_color(self, color: Color | None) -> None:
+        rgba = color.rgba if color is not None else (0, 0, 0, 0)
+        self._background_mat.set_colors(rgba)
 
     def _snx_render(self) -> np.ndarray:
         """Render to offscreen buffer."""

src/scenex/adaptors/_vispy/_view.py

@@ -1,6 +1,5 @@
 from __future__ import annotations
 
-import warnings
 from typing import TYPE_CHECKING, Any, cast
 
 import numpy as np
@@ -40,7 +39,12 @@ def __init__(self, view: model.View, **backend_kwargs: Any) -> None:
         self._snx_set_camera(view.camera)
         self._snx_set_scene(view.scene)
 
+        # -- Layout connections -- #
+        self._model.layout.events.background_color.connect(self._set_background_color)
         view.layout.events.all.connect(self._on_layout_changed)
+
+        # -- Layout initialization -- #
+        self._set_background_color(view.layout.background_color)
         self._on_layout_changed()
 
     def _on_vispy_viewbox_resized(self, event: Any) -> None:
@@ -54,9 +58,6 @@ def _on_layout_changed(self, event: Any | None = None) -> None:
         self._vispy_viewbox.update()
         self._cam_adaptor._set_view(rect.width, rect.height)
 
-    def _snx_get_native(self) -> Any:
-        return self._vispy_viewbox
-
     def _snx_set_visible(self, arg: bool) -> None:
         pass
 
@@ -96,31 +97,9 @@ def _snx_set_camera(self, cam: model.Camera) -> None:
     def _draw(self) -> None:
         self._vispy_viewbox.update()
 
-    def _snx_set_position(self, arg: tuple[float, float]) -> None:
-        raise NotImplementedError()
-
-    def _snx_set_size(self, arg: tuple[float, float] | None) -> None:
-        raise NotImplementedError()
-
-    def _snx_set_border_width(self, arg: float) -> None:
-        warnings.warn(
-            "set_border_width not implemented for vispy", RuntimeWarning, stacklevel=2
-        )
-
-    def _snx_set_border_color(self, arg: Color | None) -> None:
-        warnings.warn(
-            "set_border_color not implemented for vispy", RuntimeWarning, stacklevel=2
-        )
-
-    def _snx_set_padding(self, arg: int) -> None:
-        warnings.warn(
-            "set_padding not implemented for vispy", RuntimeWarning, stacklevel=2
-        )
-
-    def _snx_set_margin(self, arg: int) -> None:
-        warnings.warn(
-            "set_margin not implemented for vispy", RuntimeWarning, stacklevel=2
-        )
+    def _set_background_color(self, color: Color | None) -> None:
+        color_data = None if color is None else color.rgba
+        self._vispy_viewbox.bgcolor = color_data
 
     def _snx_render(self) -> np.ndarray:
         """Render to screenshot."""

tests/adaptors/_pygfx/test_layout.py

@@ -0,0 +1,43 @@
+from __future__ import annotations
+
+import numpy as np
+import pytest
+from cmap import Color
+
+import scenex as snx
+import scenex.adaptors._pygfx as adaptors
+from scenex.adaptors import get_adaptor_registry
+
+
+@pytest.fixture
+def view() -> snx.View:
+    return snx.View()
+
+
+@pytest.fixture
+def adaptor(view: snx.View) -> adaptors.View:
+    adaptor = get_adaptor_registry().get_adaptor(view, create=True)
+    assert isinstance(adaptor, adaptors.View)
+    return adaptor
+
+
+def test_background_color(view: snx.View, adaptor: adaptors.View) -> None:
+    # Default background color from Layout defaults (black)
+    np.testing.assert_array_almost_equal(
+        adaptor._background_mat.color_bottom_left.rgba,
+        Color("black").rgba,
+    )
+
+    # Changing the model color propagates to the native background material
+    view.layout.background_color = Color("red")
+    np.testing.assert_array_almost_equal(
+        adaptor._background_mat.color_bottom_left.rgba,
+        Color("red").rgba,
+    )
+
+    # Setting to None makes the background transparent
+    view.layout.background_color = None
+    np.testing.assert_array_almost_equal(
+        adaptor._background_mat.color_bottom_left.rgba,
+        np.zeros(4),
+    )

tests/adaptors/_vispy/test_layout.py

@@ -0,0 +1,43 @@
+from __future__ import annotations
+
+import numpy as np
+import pytest
+from cmap import Color
+
+import scenex as snx
+import scenex.adaptors._vispy as adaptors
+from scenex.adaptors import get_adaptor_registry
+
+
+@pytest.fixture
+def view() -> snx.View:
+    return snx.View()
+
+
+@pytest.fixture
+def adaptor(view: snx.View) -> adaptors.View:
+    adaptor = get_adaptor_registry().get_adaptor(view, create=True)
+    assert isinstance(adaptor, adaptors.View)
+    return adaptor
+
+
+def test_background_color(view: snx.View, adaptor: adaptors.View) -> None:
+    # Default background color from Layout defaults (black)
+    np.testing.assert_array_almost_equal(
+        adaptor._vispy_viewbox.bgcolor.rgba.ravel(),
+        Color("black").rgba,
+    )
+
+    # Changing the model color propagates to the native viewbox bgcolor
+    view.layout.background_color = Color("red")
+    np.testing.assert_array_almost_equal(
+        adaptor._vispy_viewbox.bgcolor.rgba.ravel(),
+        Color("red").rgba,
+    )
+
+    # Setting to None sets the viewbox background to all zeros
+    view.layout.background_color = None
+    np.testing.assert_array_almost_equal(
+        adaptor._vispy_viewbox.bgcolor.rgba.ravel(),
+        np.zeros(4),
+    )

tests/test_basic_scene.py

@@ -21,6 +21,9 @@
 """.strip()
 
 
+_BACKEND_INTERNAL = frozenset({"Background"})
+
+
 def _obj_name(obj: Any) -> str:
     """Return the name of a backend node object.
     Replace backend names with the corresponding model name.
@@ -32,9 +35,26 @@ def _obj_name(obj: Any) -> str:
         return "Points"
     if name == "SubScene":
         return "Scene"
+    if name in _BACKEND_INTERNAL:
+        return "<BackendInternal>"
     return name
 
 
+def _filter_backend_nodes(tree: Any) -> Any:
+    """Recursively remove backend-internal nodes from a tree_dict result.
+
+    Some backends (e.g. pygfx) automatically add nodes like Background to
+    represent layout properties (background color). These have no counterpart
+    in the scenex model tree, so we filter them out for structural comparisons.
+    """
+    if isinstance(tree, str):
+        return tree
+    return {
+        k: [_filter_backend_nodes(c) for c in v if not (c == "<BackendInternal>")]
+        for k, v in tree.items()
+    }
+
+
 def _child_names(obj: Any) -> list[str]:
     """Get the names of the children of a obj."""
     return [_obj_name(child) for child in obj.children]
@@ -72,7 +92,7 @@ def test_view_tree_matches_native(basic_view: snx.View) -> None:
     native_scene = _native_scene(basic_view.scene)
     view_tree = snx.util.tree_dict(native_scene, obj_name=_obj_name)
     assert isinstance(view_tree, dict)
-    assert model_tree == view_tree
+    assert model_tree == _filter_backend_nodes(view_tree)
 
 
 def test_changing_parent_updates_adaptor() -> None: