不使用开始作为顶级导航时，如何配置抽屉式导航按钮？

Question

我正在使用导航图进行导航，并将开始屏幕（启动画面片段）作为显示的第一个片段。问题是，当我转到主 fragment/screen 时，顶部导航按钮显示回来而不是抽屉图标。我们怎样才能控制这个？有哪些选择。如何更改起始目的地？（如果可能的话）

When the user is at a top-level destination, the Navigation button becomes a drawer icon if the destination uses a DrawerLayout. If the destination doesn't use a DrawerLayout, the Navigation button is hidden. When the user is on any other destination, the Navigation button appears as an Up button . To configure the Navigation button using only the start destination as the top-level destination, create an AppBarConfiguration object, and pass in the corresponding navigation graph, as shown below:

示例代码

我的问题是导航到 next_fragment 时后退按钮仍然存在。它应该显示 menu/hamburger 图标。

class MainActivity : AppCompatActivity() {

private lateinit var drawerLayout: DrawerLayout
private lateinit var appBarConfiguration : AppBarConfiguration

override fun onCreate(savedInstanceState: Bundle?) {

    super.onCreate(savedInstanceState)

    val binding = DataBindingUtil.setContentView<ActivityMainBinding>(this, R.layout.activity_main)
    drawerLayout = binding.drawerLayout

    val navController = this.findNavController(R.id.mainNavigationHostFragment)
    NavigationUI.setupActionBarWithNavController(this, navController)

    appBarConfiguration = AppBarConfiguration(setOf(R.id.nextFragment), drawerLayout) 
    NavigationUI.setupWithNavController(binding.mainNavigationDrawerView, navController)

    val navigationHeader = binding.mainNavigationDrawerView.getHeaderView(0)
    val iconButton = navigationHeader.findViewById<ImageButton>(R.id.main_nav_icon_button)
    

}

override fun onSupportNavigateUp(): Boolean {

    val navController = this.findNavController(R.id.mainNavigationHostFragment)
    return NavigationUI.navigateUp(navController, appBarConfiguration)
}

}

Answer 1

不是将 Navigation Graph 传递给 AppbarConfiguration，而是传递应显示 HamBurger icon 的片段的 id，这样当显示了特定的 Fragment，它显示 home/hamburger 图标而不是 back 图标。

也就是

val appBarConfiguration = AppBarConfiguration(setOf(R.id.FAGMENT_THAT_SHOULD_SHOW_HOME_ICON), DRAWER_LAYOUT)

更新

而不是

val navController = this.findNavController(R.id.mainNavigationHostFragment)

NavigationUI.setupActionBarWithNavController(this, navController) 

 appBarConfiguration = AppBarConfiguration(setOf(R.id.nextFragment), drawerLayout) 
    NavigationUI.setupWithNavController(binding.mainNavigationDrawerView, navController)

val navigationHeader = binding.mainNavigationDrawerView.getHeaderView(0)
  val iconButton = navigationHeader.findViewById<ImageButton>(R.id.main_nav_icon_button)

就

val navController = this.findNavController(R.id.mainNavigationHostFragment)

appBarConfiguration = AppBarConfiguration(setOf(R.id.nextFragment), drawerLayout) 
    

NavigationUI.setupActionBarWithNavController(this, navController, appBarConfiguration);

不使用开始作为顶级导航时，如何配置抽屉式导航按钮？

How to configure the Drawer Navigation button when not using the start as the top-level navigation?

android

navigation-drawer

android-navigation