Flutter showSearch 與 AnimatedIcon 的使用

Flutter 搜索頁實現

在通常的 App 頁面，可能都須要搜索功能，常見的就是在主頁上面有一個搜索欄，點擊會跳轉到一個搜索頁面。

在 flutter 中，也有這樣的功能實現，主要是經過 showSearch 就能跳轉到一個搜索頁面。接下來看一下如何實現。

一、自定義 SearchDelegate

使用 flutter 提供的搜索頁面，須要繼承 SearchDelegate 實現本身的 Delegate。 SearchDelegate 提供了一些方法須要咱們本身重寫來實現咱們本身的功能。

• buildActions 顯示在最右邊的圖標列表。
• buildLeading 搜索欄左邊的圖標，通常都是返回。
• buildResults 這個回調裏進行搜索和並返回本身的搜索結果。
• buildSuggestions 返回建議搜索結果。

示例：

class SearchBarViewDelegate extends SearchDelegate<String>{

  String searchHint = "請輸入搜索內容...";
   var sourceList = [
    "dart",
    "dart 入門",
    "flutter",
    "flutter 編程",
    "flutter 編程開發",
  ];

  var  suggestList = [
    "flutter",
    "flutter 編程開發"
  ];


   @override
  String get searchFieldLabel => searchHint;


  @override
  List<Widget> buildActions(BuildContext context) {

    ///顯示在最右邊的控件列表
    return [

    IconButton(
      icon: Icon(Icons.clear),
      onPressed: (){
        query = "";

        ///搜索建議的內容
        showSuggestions(context);
        },
    ),
      IconButton(
          icon: Icon(Icons.search),
          onPressed: ()=>query = "",
      )
    ];
  }


  ///左側帶動畫的控件，通常都是返回
  @override
  Widget buildLeading(BuildContext context) {
    return IconButton(
        icon: AnimatedIcon(icon: AnimatedIcons.menu_arrow, progress: transitionAnimation
        ),
        ///調用 close 關閉 search 界面
        onPressed: ()=>close(context,null),
    );
  }


  ///展現搜索結果
  @override
  Widget buildResults(BuildContext context) {

    List<String> result = List();

    ///模擬搜索過程
    for (var str in sourceList){
      ///query 就是輸入框的 TextEditingController
      if (query.isNotEmpty && str.contains(query)){
          result.add(str);
      }
    }

    ///展現搜索結果
    return ListView.builder(
      itemCount: result.length,
      itemBuilder: (BuildContext context, int index)=>ListTile(
        title: Text(result[index]),
      ),
    );
  }

  @override
  Widget buildSuggestions(BuildContext context) {

    List<String> suggest = query.isEmpty ? suggestList : sourceList.where((input)=>input.startsWith(query)).toList();
    return ListView.builder(
        itemCount: suggest.length,
        itemBuilder: (BuildContext context, int index)=>
    InkWell(
      child:         ListTile(
        title: RichText(
          text: TextSpan(
            text: suggest[index].substring(0, query.length),
            style: TextStyle(color: Colors.blue,fontWeight: FontWeight.bold),
            children: [
              TextSpan(
                text: suggest[index].substring(query.length),
                style: TextStyle(color: Colors.grey),
              ),
            ],
          ),
        ),
      ),
        onTap: (){
       //  query.replaceAll("", suggest[index].toString());
          searchHint = "";
          query =  suggest[index].toString();
         showResults(context);
        },
    ),


    );
  }
}

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二、使用自定義 SearchBarViewDelegate 展示搜索頁面

IconButton(
              icon: Icon(Icons.search),
              onPressed: (){
                showSearch(context: context, delegate: SearchBarViewDelegate());
              }
          )
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效果：

Flutter AnimatedIcon

在 flutter 中也提供一一種 widiget —— AnimatedIcon 來展現帶動畫的 Icon,能夠帶來很好的用戶體驗。在上面的搜索欄中，返回按鈕用的就是這個 widget。

並非全部的 Icon 都能展現這種效果，flutter 中，提供的 AnimatedIcons 一共有以下這些：

abstract class AnimatedIcons {

  /// The material design add to event icon animation.
  static const AnimatedIconData add_event = _$add_event;

  /// The material design arrow to menu icon animation.
  static const AnimatedIconData arrow_menu = _$arrow_menu;

  /// The material design close to menu icon animation.
  static const AnimatedIconData close_menu = _$close_menu;

  /// The material design ellipsis to search icon animation.
  static const AnimatedIconData ellipsis_search = _$ellipsis_search;

  /// The material design event to add icon animation.
  static const AnimatedIconData event_add = _$event_add;

  /// The material design home to menu icon animation.
  static const AnimatedIconData home_menu = _$home_menu;

  /// The material design list to view icon animation.
  static const AnimatedIconData list_view = _$list_view;

  /// The material design menu to arrow icon animation.
  static const AnimatedIconData menu_arrow = _$menu_arrow;

  /// The material design menu to close icon animation.
  static const AnimatedIconData menu_close = _$menu_close;

  /// The material design menu to home icon animation.
  static const AnimatedIconData menu_home = _$menu_home;

  /// The material design pause to play icon animation.
  static const AnimatedIconData pause_play = _$pause_play;

  /// The material design play to pause icon animation.
  static const AnimatedIconData play_pause = _$play_pause;

  /// The material design search to ellipsis icon animation.
  static const AnimatedIconData search_ellipsis = _$search_ellipsis;

  /// The material design view to list icon animation.
  static const AnimatedIconData view_list = _$view_list;
}
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使用步驟

一、定義 AnimationController 控制動畫

controller = AnimationController(vsync: this)
      ..drive(Tween(begin: 0, end: 1))
      ..duration = Duration(milliseconds: 500);
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二、 AnimatedIcon 指定動畫控制器和須要展現的動畫Icon

AnimatedIcon(
        icon: AnimatedIcons.play_pause,
        progress: controller,
        size: 35,
        semanticLabel: "play_pause",
      ),
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三、控制播放

InkWell(
                child:   _icons[index],

           onTap: () {
                  if (controller.status == AnimationStatus.completed) {
                    controller.reverse();
                  } else if (controller.status == AnimationStatus.dismissed) {
                    controller.forward();
                  }
                },
              ),

複製代碼

效果：

github

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