worldwide todo list: global map (List/Map toggle, clustered category pins, Global strip, pick on map, location_precision, tasks.geojson)

src/lib/worldtodo/cluster.ts

@@ -0,0 +1,45 @@
+// Tiny screen-space clustering for the task map (a few hundred pins at most, so O(n²) is fine
+// and avoids a plugin). Points are in projected pixels at the current zoom.
+
+export type ScreenPoint = { x: number; y: number; weight: number };
+
+/**
+ * Greedy clustering: the heaviest unassigned point (largest scale) takes every unassigned
+ * point within `radius` px. Returns groups in that order; radius 0 keeps every point alone.
+ */
+export function clusterPoints<T extends ScreenPoint>(points: T[], radius: number): T[][] {
+	const order = [...points].sort((a, b) => b.weight - a.weight);
+	const used = new Set<T>();
+	const groups: T[][] = [];
+	const r2 = radius * radius;
+	for (const p of order) {
+		if (used.has(p)) continue;
+		used.add(p);
+		const group = [p];
+		if (radius > 0)
+			for (const q of order) {
+				if (used.has(q)) continue;
+				const dx = q.x - p.x;
+				const dy = q.y - p.y;
+				if (dx * dx + dy * dy <= r2) {
+					used.add(q);
+					group.push(q);
+				}
+			}
+		groups.push(group);
+	}
+	return groups;
+}
+
+/** Offsets (px) that fan out `n` pins sharing one coordinate in a small ring. */
+export function ringOffsets(n: number): { dx: number; dy: number }[] {
+	if (n <= 1) return [{ dx: 0, dy: 0 }];
+	const r = 16 + n * 3;
+	return Array.from({ length: n }, (_, i) => {
+		const a = (2 * Math.PI * i) / n - Math.PI / 2;
+		return { dx: Math.round(Math.cos(a) * r), dy: Math.round(Math.sin(a) * r) };
+	});
+}
+
+/** Rounded lat/lon key, so tasks on the same centroid can be fanned out. */
+export const coordKey = (lat: number, lon: number) => `${lat.toFixed(4)},${lon.toFixed(4)}`;