Flutter 桌面探索 自定义可拖拽导航栏_flutter 导航栏

import 'package:flutter/material.dart';
 
class DraggableNavigationBarItem {
  final Icon icon;
  final String title;
  final double height;
 
  DraggableNavigationBarItem({
    @required this.icon,
    @required this.title,
    this.height = 60.0,
  });
}
 
class DraggableNavigationBar extends StatefulWidget {
  final List<DraggableNavigationBarItem> items;
  final ValueChanged<int> onItemSelected;
  final int initialIndex;
 
  DraggableNavigationBar({
    Key key,
    @required this.items,
    this.onItemSelected,
    this.initialIndex = 0,
  }) : super(key: key);
 
  @override
  _DraggableNavigationBarState createState() => _DraggableNavigationBarState();
}
 
class _DraggableNavigationBarState extends State<DraggableNavigationBar> {
  int _selectedIndex = 0;
 
  @override
  void initState() {
    super.initState();
    _selectedIndex = widget.initialIndex;
  }
 
  // 其他代码略...
}

这个代码实例定义了DraggableNavigationBarItem类来表示导航栏中的每个项，并且定义了DraggableNavigationBar类作为有状态的widget，它管理着选中的项目。initState方法中使用了传入的initialIndex来设置初始选中的项。这个例子为后续的拖拽逻辑和UI设计提供了基本框架。