如何在ngMaterial md-autocomplete中过滤查询？

$scope.items = [
  { name: 'Apple' },
  { name: 'Banana' },
  { name: 'Orange' },
  { name: 'Pineapple' }
];

$scope.getItems = function(query) {
  // 根据查询过滤选项列表
  // 返回过滤后的选项数组
};

<md-autocomplete ng-model="selectedItem" md-items="item in items" md-item-text="item.name">
  <md-item-template>
    <span md-highlight-text="searchText">{{item.name}}</span>
  </md-item-template>
</md-autocomplete>

<md-autocomplete ng-model="selectedItem" md-items="item in getItems(searchText)" md-item-text="item.name">
  <md-item-template>
    <span md-highlight-text="searchText">{{item.name}}</span>
  </md-item-template>
</md-autocomplete>