Flutter实现底部导航栏样式

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本文链接:https://blog.csdn.net/dongxingxxx/article/details/103271038

一、Flutter实现底部导航栏

在手机端App主界面中,我们经常看到下面有多个按钮Tab,点击下面的Tab,切换上面的页面。类似与如下效果

                                      

在实现Flutter实现底部导航栏的时候,我们先学习连个widget. 

1、BottomNavigationBar


   BottomNavigationBar({
    Key key,
    @required this.items, //子选项
    this.onTap,           //点击事件
    this.currentIndex = 0,//选中第几个
    BottomNavigationBarType type, //底部导航栏样式
    this.fixedColor,//文字颜色
    this.iconSize = 24.0,//icon图片大小
    Color selectedItemColor, //选中item的颜色
    this.unselectedItemColor,//未选中的item颜色
    this.selectedIconTheme = const IconThemeData(), //选中图标样式
    this.unselectedIconTheme = const IconThemeData(),//未选中图标样式
    this.selectedFontSize = 14.0, //选中字体大小
    this.unselectedFontSize = 12.0,//为选中字体大小
    this.selectedLabelStyle,//选中标签的样式
    this.unselectedLabelStyle,//未选中标签样式
    this.showSelectedLabels = true,//是否显示选中对象的标签
    bool showUnselectedLabels,//是否显示未选中对象的标签
    })

    const BottomNavigationBarItem({
    @required this.icon,//未选中图标
    this.title,//文字
    Widget activeIcon,//选中图标
    this.backgroundColor,// 测试发现type设置为shifting时,backgroundColor才有效
    })

BottomNavigationBar的使用用方法如下:

bottomNavigationBar: new BottomNavigationBar(
        currentIndex: _currentIndex,
        selectedLabelStyle: TextStyle(color: selectColor,fontSize: 14),
        unselectedLabelStyle: TextStyle(color: unSelectColor,fontSize: 12),
        unselectedIconTheme: IconThemeData(color: unSelectColor),
        selectedIconTheme: IconThemeData(color: selectColor),
        onTap: (index) {
          mPageController.jumpToPage(index);
          setState(() {
            _currentIndex = index;
          });
        },
        items: [
          createBottomTab(Icons.home, mTabs[0]),
          createBottomTab(Icons.local_hospital,mTabs[1]),
          createBottomTab(Icons.account_balance, mTabs[2]),
        ],
      ),

因为item中标签除图标和文本之外基本不一致,所以我们创建一个方法,嗲用即可:

createBottomTab1(IconData icon, String title) {
    return new BottomNavigationBarItem(
        icon: Icon(
          icon,
        ),
        title: new Text(
          title,
        ));
  }

2、PageView

PageView({
    Key key,
    this.scrollDirection = Axis.horizontal, //滑动在轴上的方向
    this.reverse = false,         //在轴方向上方向是否颠倒
    PageController controller,    //Page控制器
    this.physics,  //页面响应用户交互方式
    this.pageSnapping = true,//设置为false可禁用页面捕捉,这对于自定义滚动行为很有用。
    this.onPageChanged,//页面发生改变时出发
    List<Widget> children = const <Widget>[],//页面widget
    this.dragStartBehavior = DragStartBehavior.start,//设置拖拽方式
  })


PageController({
    this.initialPage = 0,   //初始显示页面
    this.keepPage = true,   //页面加载后是否保留页面
    this.viewportFraction = 1.0,//页面占据空间的大小
  })
PageView使用如下
PageView(
        controller: mPageController,
        children: widget.mViews,
        onPageChanged: (index){
          mTabController.animateTo(index);
          setState(() {
            _currentIndex = index;
          });
        },
      ),

完整代码如下:

class MainApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    // TODO: implement build
    return new MaterialApp(
      home: new Scaffold(
        body: new MainWidget(),
      ),
    );
  }
}

class MainWidget extends StatelessWidget {

  @override
  Widget build(BuildContext context) {
    // TODO: implement build
    List<Widget> mViews = [
      new Home(),
      new Work(),
      new Mine(),
    ];
    List<String> mTabs = ["首页", "办事", "我的"];

    return new WillPopScope(child: new TabNavigator('鸽子飞飞飞', mTabs, mViews,Colors.red,Colors.grey), onWillPop: null);
  }
}

class TabNavigator extends StatefulWidget {
  /*定义标题*/
  final String title;

  /*底部标题文本*/
  final List<String> mTabs;

  /*根视图,相当于Fragment视图*/
  final List<Widget> mViews;

  /*设置选中空间的颜色值*/
  final Color selectColor;
  final Color unSelectColor;

  TabNavigator(this.title, this.mTabs, this.mViews, this.selectColor,
      this.unSelectColor);

  @override
  State<StatefulWidget> createState() {
    // TODO: implement createState
    return new _TabNavigatorState(title, mTabs,selectColor, unSelectColor);
  }
}

class _TabNavigatorState extends State<TabNavigator>
    with SingleTickerProviderStateMixin {
  final String title;
  final List<String> mTabs;
  final Color selectColor;
  final Color unSelectColor;

  _TabNavigatorState(this.title, this.mTabs,this.selectColor, this.unSelectColor);

  int _currentIndex = 0;

  PageController mPageController;
  TabController mTabController;

  @override
  void initState() {
    // TODO: implement initState
    super.initState();
    mPageController = new PageController(initialPage: 0, keepPage: true);
    mTabController =
        new TabController(length: widget.mViews.length, vsync: this);
  }

  @override
  void dispose() {
    // TODO: implement dispose
    super.dispose();
    mPageController.dispose();
    mTabController.dispose();
  }

  @override
  Widget build(BuildContext context) {
    // TODO: implement build
    return new Scaffold(
      appBar: new AppBar(
        title: new Text('$title'),
      ),
      bottomNavigationBar: new BottomNavigationBar(
        currentIndex: _currentIndex,
        selectedLabelStyle: TextStyle(color: selectColor,fontSize: 14),
        unselectedLabelStyle: TextStyle(color: unSelectColor,fontSize: 12),
        unselectedIconTheme: IconThemeData(color: unSelectColor),
        selectedIconTheme: IconThemeData(color: selectColor),
        onTap: (index) {
          mPageController.jumpToPage(index);
          setState(() {
            _currentIndex = index;
          });
        },
        items: [
         // createBottomTab(Icons.home, mTabs[0],0),
          createBottomTab1(Icons.home, mTabs[0]),
          //createBottomTab(Icons.local_hospital,mTabs[1],1),
          createBottomTab1(Icons.local_hospital,mTabs[1]),
          //createBottomTab(Icons.account_balance, mTabs[2],2),
          createBottomTab1(Icons.account_balance, mTabs[2]),
        ],
      ),
      body: PageView(
        controller: mPageController,
        children: widget.mViews,
        onPageChanged: (index){
          mTabController.animateTo(index);
          setState(() {
            _currentIndex = index;
          });
        },
      ),
    );
  }

  createBottomTab1(IconData icon, String title) {
    return new BottomNavigationBarItem(
        icon: Icon(
          icon,
        ),
        title: new Text(
          title,
        ));
  }
}

运行的时候,只需要在main方法中执行runApp即可

void main() {
  runApp(MainApp());
}

 

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