Fix type annotation, docstring, and add tests for literal color support

- Change `color: str | None` to `color: ColorLike | None` in
  render_labels signature and _validate_label_render_params to match
  render_shapes/render_points
- Update docstring to document that color-like values (named colors,
  hex strings, RGB(A) tuples) are accepted as literal colors
- Add tests for hex string and RGBA tuple color inputs

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: timtreis

src/spatialdata_plot/pl/basic.py

@@ -631,7 +631,7 @@ def render_images(
     def render_labels(
         self,
         element: str | None = None,
-        color: str | None = None,
+        color: ColorLike | None = None,
         *,
         groups: list[str] | str | None = None,
         contour_px: int | None = 3,
@@ -662,11 +662,13 @@ def render_labels(
         element : str | None
             The name of the labels element to render. If `None`, all label
             elements in the `SpatialData` object will be used and all parameters will be broadcasted if possible.
-        color : str | None
-            Can either be string representing a color-like or key in :attr:`sdata.table.obs` or in the index of
-            :attr:`sdata.table.var`. The latter can be used to color by categorical or continuous variables. If the
-            color column is found in multiple locations, please provide the table_name to be used for the element if you
-            would like a specific table to be used. By default one table will automatically be choosen.
+        color : ColorLike | None
+            Can either be color-like (name of a color as string, e.g. "red", hex representation, e.g. "#000000" or
+            "#000000ff", or an RGB(A) array as a tuple or list containing 3-4 floats within [0, 1]. If an alpha value
+            is indicated, the value of `fill_alpha` takes precedence if given) or a string representing a key in
+            :attr:`sdata.table.obs` or in the index of :attr:`sdata.table.var`. The latter can be used to color by
+            categorical or continuous variables. If the color column is found in multiple locations, please provide the
+            table_name to be used for the element if you would like a specific table to be used.
         groups : list[str] | str | None
             When using `color` and the key represents discrete labels, `groups` can be used to show only a subset of
             them. Other values are set to NA. The list can contain multiple discrete labels to be visualized.

src/spatialdata_plot/pl/utils.py

@@ -2414,7 +2414,7 @@ def _validate_label_render_params(
     sdata: sd.SpatialData,
     element: str | None,
     cmap: list[Colormap | str] | Colormap | str | None,
-    color: str | None,
+    color: ColorLike | None,
     fill_alpha: float | int,
     contour_px: int | None,
     groups: list[str] | str | None,

tests/_images/Labels_can_color_by_hex.png

@@ -87,6 +87,12 @@ def test_plot_can_stack_render_labels(self, sdata_blobs: SpatialData):
     def test_plot_can_color_by_color_name(self, sdata_blobs: SpatialData):
         sdata_blobs.pl.render_labels("blobs_labels", color="red").pl.show()
 
+    def test_plot_can_color_by_hex(self, sdata_blobs: SpatialData):
+        sdata_blobs.pl.render_labels("blobs_labels", color="#ff0000").pl.show()
+
+    def test_plot_can_color_by_rgba_tuple(self, sdata_blobs: SpatialData):
+        sdata_blobs.pl.render_labels("blobs_labels", color=(1.0, 0.0, 0.0, 0.5)).pl.show()
+
     def test_plot_can_color_labels_by_continuous_variable(self, sdata_blobs: SpatialData):
         sdata_blobs.pl.render_labels("blobs_labels", color="channel_0_sum").pl.show()