PolyUtil

• clipPolygon applies Sutherland-Hodgman clipping and expects an L.Bounds in pixel space.
• polygonCenter weights by projected area and requires a CRS argument.
• centroid averages vertices arithmetically and shifts toward dense vertex clusters.

var size = map.getSize();
var box = new L.Bounds(L.point(0, 0), L.point(size.x, size.y));

var ring = polygon.getLatLngs()[0].map(function (latlng) {
  return map.latLngToLayerPoint(latlng);
});

var clipped = L.PolyUtil.clipPolygon(ring, box, true);

ctx.beginPath();
clipped.forEach(function (p, i) {
  if (i === 0) { ctx.moveTo(p.x, p.y); }
  else { ctx.lineTo(p.x, p.y); }
});
ctx.closePath();
ctx.fill();

var ring = polygon.getLatLngs()[0];

var center = L.PolyUtil.polygonCenter(ring, map.options.crs);
var average = L.PolyUtil.centroid(ring);

L.marker(center).bindTooltip('面积重心').addTo(map);
L.circleMarker(average, { radius: 4 }).bindTooltip('顶点平均').addTo(map);

• Both center functions accept a single ring only, so holes must be handled separately.
• Concave polygons can place the area centroid outside the shape itself.