test

Author: timtreis

src/spatialdata_plot/pl/utils.py

@@ -1173,10 +1173,42 @@ def save_fig(
     fig.savefig(path, **kwargs)
 
 
-def _get_linear_colormap(colors: list[str], background: str) -> list[LinearSegmentedColormap]:
+def _get_linear_colormap2(colors: list[str], background: str) -> list[LinearSegmentedColormap]:
     return [LinearSegmentedColormap.from_list(c, [background, c], N=256) for c in colors]
 
 
+def _get_linear_colormap(
+    colors: list[str],
+    background: str = "black",
+) -> list[LinearSegmentedColormap]:
+    """
+    Create one LinearSegmentedColormap per color in `colors` that
+    fades from `background` → the color.
+
+    If background is "transparent" (or "none"), the start point
+    will be the same RGB as the target color but with alpha=0.
+    """
+    cmaps: list[LinearSegmentedColormap] = []
+    for c in colors:
+        # fully opaque target
+        target_rgba = to_rgba(c, alpha=1.0)
+
+        if background.lower() in ("transparent", "none"):
+            # start with same RGB, but zero alpha
+            start_rgba = (target_rgba[0], target_rgba[1], target_rgba[2], 0.0)
+        else:
+            # start from a solid background color
+            start_rgba = to_rgba(background)
+
+        cm = LinearSegmentedColormap.from_list(
+            f"{c}_fade",
+            [start_rgba, target_rgba],
+            N=256,
+        )
+        cmaps.append(cm)
+
+    return cmaps
+
 def _get_listed_colormap(color_dict: dict[str, str]) -> ListedColormap:
     sorted_labels = sorted(color_dict.keys())
     colors = [color_dict[k] for k in sorted_labels]