Add highlight_color (#666)

Closes #661

lonboard/_layer.py

@@ -238,6 +238,18 @@ def _add_extension_traits(self, extensions: Sequence[BaseExtension]):
     - Default: `False`
     """
 
+    highlight_color = VariableLengthTuple(
+        t.Int(), default_value=None, minlen=3, maxlen=4
+    )
+    """
+    RGBA color to blend with the highlighted object (the hovered over object if
+    `auto_highlight=true`). When the value is a 3 component (RGB) array, a default alpha
+    of 255 is applied.
+
+    - Type: List or Tuple of integers
+    - Default: `[0, 0, 128, 128]`
+    """
+
     selected_bounds = t.Tuple(
         t.Float(), t.Float(), t.Float(), t.Float(), allow_none=True, default_value=None
     ).tag(sync=True)

src/model/base-layer.ts

@@ -17,6 +17,7 @@ export abstract class BaseLayerModel extends BaseModel {
   protected visible: LayerProps["visible"];
   protected opacity: LayerProps["opacity"];
   protected autoHighlight: LayerProps["autoHighlight"];
+  protected highlightColor: LayerProps["highlightColor"];
 
   protected extensions: BaseExtensionModel[];
 
@@ -32,6 +33,7 @@ export abstract class BaseLayerModel extends BaseModel {
     this.initRegularAttribute("visible", "visible");
     this.initRegularAttribute("opacity", "opacity");
     this.initRegularAttribute("auto_highlight", "autoHighlight");
+    this.initRegularAttribute("highlight_color", "highlightColor");
     this.initRegularAttribute("selected_bounds", "selectedBounds");
 
     this.extensions = [];
@@ -74,6 +76,9 @@ export abstract class BaseLayerModel extends BaseModel {
       visible: this.visible,
       opacity: this.opacity,
       autoHighlight: this.autoHighlight,
+      ...(isDefined(this.highlightColor) && {
+        highlightColor: this.highlightColor,
+      }),
       onClick: this.onClick.bind(this),
     };
   }