From c0c03d02b0778216e49d31d92bbdce11da140ac4 Mon Sep 17 00:00:00 2001
From: Tom MacWright <tom@macwright.com>
Date: Mon, 4 Dec 2023 21:46:20 -0500
Subject: [PATCH] Add microtasks to render loop to lessen thread-blocking

---
 lib/backend.ts | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/lib/backend.ts b/lib/backend.ts
index e924ce0..91e3687 100644
--- a/lib/backend.ts
+++ b/lib/backend.ts
@@ -277,6 +277,7 @@ async function render(bbox: BBOX, options: Options = {}) {
     for (const feature of features) {
       drawn++;
       progress(`Drawing (${drawn} / ${features.length} elements)`);
+      await new Promise<void>((resolve) => resolve());
 
       const name = feature.properties?.name;
       switch (feature.geometry.type) {
@@ -438,6 +439,7 @@ async function render(bbox: BBOX, options: Options = {}) {
     const features = grouped.get(group);
     if (!features) continue;
     for (let feature of features) {
+      await new Promise<void>((resolve) => resolve());
       const name = feature.properties?.name;
       if (!(feature.geometry.type === "LineString" && name)) continue;
       if (labeledNames.has(name) || name.length > MAX_NAME_LENGTH) continue;