如何知道导航抽屉是否在Xamarin中打开？

Question

我的Main上有一个NavigationDrawer，当我按下Back按钮（打开NavigationDrawer时）应用程序退出，我希望它只关闭NavigationDrawer。在Java中，Android有这个：

@Override
public void onBackPressed()
{
  if (DrawerLayout.isDrawerOpen(Gravity.START))
    DrawerLayout.closeDrawer(Gravity.START);
  else
    super.onBackPressed();
}

如何在Xamarin.Android中制作？

Answer 1

试试这段代码：

public override void OnBackPressed()
{
    //if (drawerLayout.IsDrawerOpen(YourNavigationView))
    if (drawerLayout.IsDrawerOpen(Android.Support.V4.View.GravityCompat.Start))
    {
        drawerLayout.CloseDrawers();
        // or
        //drawerLayout.CloseDrawer(Android.Support.V4.View.GravityCompat.Start);
        //drawerLayout.CloseDrawer(navigationView);
    }
    else
        base.OnBackPressed();
}

Answer 2

只需委托这样的方法：

drawerLayout = FindViewById<DrawerLayout>(Resource.Id.drawerLayoutID);
drawerLayout.DrawerOpened += delegate
{
   //code when drawer is opened!
};