mapboxGL中popup遮挡的优化

// 调整popup位置
that.popup.on('open', function(){
  var ele = $(that.popup.getElement());
  var offset = ele.offset();
  var top = offset.top;
  var left = offset.left;
  var right = ele.width() + left;
  var mapEle = $(map.getContainer());
  var mapOffset = mapEle.offset();
  var mapTop = mapOffset.top;
  var mapLeft = mapOffset.left;
  var mapRight = mapEle.width() + mapLeft;
  var center = map.getCenter();
  var centerPx = map.project(center);
  var h = 0, v = 0, size = 20;
  if(top < mapTop) {
    v = mapTop - top + size;
  }
  if(left < mapLeft) {
    h = mapLeft - left + size;
  }
  if(right > mapRight) {
    h = mapRight - right - size;
  }
  centerPx = [centerPx.x - h, centerPx.y - v];
  map.panTo(map.unproject(centerPx));
});