vue3中，在AMap上编辑已有的多边形。

要在AMap上编辑已有的多边形，可以使用AMap.Polygon类的setPath方法来设置多边形的路径。具体步骤如下：

1. 获取多边形的路径：

const path = polygon.getPath();

2. 在AMap上注册鼠标事件，用于编辑多边形：

AMap.event.addListener(map, 'mousedown', startEdit);
AMap.event.addListener(map, 'mousemove', onEdit);
AMap.event.addListener(map, 'mouseup', endEdit);

其中，startEdit函数用于记录开始编辑时的鼠标位置，onEdit函数用于根据鼠标移动的距离更新多边形的路径，endEdit函数用于结束编辑。

3. 定义编辑函数：

let isEditing = false;
let editIndex = -1;
let startLngLat = null;

function startEdit(e) {
  const point = new AMap.LngLat(e.lnglat.lng, e.lnglat.lat);
  const distance = path.reduce((prev, cur) => {
    const d = point.distance(cur);
    return prev < d ? prev : d;
  }, Infinity);
  if (distance < 10) {
    isEditing = true;
    startLngLat = point;
    editIndex = path.findIndex((p) => p.equals(point));
  }
}

function onEdit(e) {
  if (isEditing && editIndex >= 0) {
    const point = new AMap.LngLat(e.lnglat.lng, e.lnglat.lat);
    const offset = point.distance(startLngLat);
    const newPath = path.slice();
    newPath.splice(editIndex, 1, point);
    polygon.setPath(newPath);
  }
}

function endEdit(e) {
  isEditing = false;
  editIndex = -1;
  startLngLat = null;
}

其中，startEdit函数根据鼠标点击的位置和多边形的路径，确定是否开始编辑；onEdit函数根据鼠标移动的距离和开始编辑时的位置，更新多边形的路径；endEdit函数用于结束编辑。

完整代码如下：

const map = new AMap.Map('map', {
  zoom: 13,
  center: [116.397428, 39.90923],
});

const path = [
  [116.403322, 39.920255],
  [116.410703, 39.897555],
  [116.402292, 39.892353],
  [116.389846, 39.891365],
  [116.39302, 39.90744],
];
const polygon = new AMap.Polygon({
  map: map,
  path: path,
  fillColor: '#00FF00',
  fillOpacity: 0.5,
  strokeColor: '#0099FF',
  strokeWeight: 3,
});
polygon.setMap(map);

let isEditing = false;
let editIndex = -1;
let startLngLat = null;

function startEdit(e) {
  const point = new AMap.LngLat(e.lnglat.lng, e.lnglat.lat);
  const distance = path.reduce((prev, cur) => {
    const d = point.distance(cur);
    return prev < d ? prev : d;
  }, Infinity);
  if (distance < 10) {
    isEditing = true;
    startLngLat = point;
    editIndex = path.findIndex((p) => p.equals(point));
  }
}

function onEdit(e) {
  if (isEditing && editIndex >= 0) {
    const point = new AMap.LngLat(e.lnglat.lng, e.lnglat.lat);
    const offset = point.distance(startLngLat);
    const newPath = path.slice();
    newPath.splice(editIndex, 1, point);
    polygon.setPath(newPath);
  }
}

function endEdit(e) {
  isEditing = false;
  editIndex = -1;
  startLngLat = null;
}

AMap.event.addListener(map, 'mousedown', startEdit);
AMap.event.addListener(map, 'mousemove', onEdit);
AMap.event.addListener(map, 'mouseup', endEdit);