From 1970db9384c1b832b1446780d2c7427bebadc378 Mon Sep 17 00:00:00 2001
From: Mike Bostock <mbostock@gmail.com>
Date: Tue, 13 Feb 2024 19:07:39 -0800
Subject: [PATCH] chess halo

---
 examples/chess/docs/index.md | 27 +++++++++++++++++++--------
 1 file changed, 19 insertions(+), 8 deletions(-)

diff --git a/examples/chess/docs/index.md b/examples/chess/docs/index.md
index 8e992b114..d1aa4c389 100644
--- a/examples/chess/docs/index.md
+++ b/examples/chess/docs/index.md
@@ -11,12 +11,6 @@ import {revive} from "./components/revive.js";
 const {womens, mens, MONTHS_OF_DATA, TOP_N_COUNT} = await FileAttachment("data/top-ranked-players.json").json().then(revive);
 ```
 
-```js
-function formatTitle(title) {
-  return title === "GM" ? "Grand Master" : title;
-}
-```
-
 ```js
 function bumpChart(data, {x = "month", y = "rating", z = "name", interval = "month", width} = {}) {
   const rank = Plot.stackY2({x, z, order: y, reverse: true});
@@ -43,8 +37,8 @@ function bumpChart(data, {x = "month", y = "rating", z = "name", interval = "mon
         strokeWidth: 24,
         curve: "bump-x",
         sort: {color: "y", reduce: "first"},
-        mixBlendMode: dark ? "lighten" : "darken",
-        interval
+        interval,
+        render: halo({stroke: "var(--theme-background-alt)", strokeWidth: 27})
       })),
       Plot.text(data, {
         ...rank,
@@ -71,6 +65,23 @@ function bumpChart(data, {x = "month", y = "rating", z = "name", interval = "mon
     ]
   })
 }
+
+function halo({stroke = "currentColor", strokeWidth = 3} = {}) {
+  return (index, scales, values, dimensions, context, next) => {
+    const g = next(index, scales, values, dimensions, context);
+    for (const path of [...g.childNodes]) {
+      const clone = path.cloneNode(true);
+      clone.setAttribute("stroke", stroke);
+      clone.setAttribute("stroke-width", strokeWidth);
+      path.parentNode.insertBefore(clone, path);
+    }
+    return g;
+  };
+}
+
+function formatTitle(title) {
+  return title === "GM" ? "Grand Master" : title;
+}
 ```
 
 <div class="grid">