如何在 xamarin android 中隐藏导航栏？

Question

This question seems to be asked quite often, but looking through the various answers (non Xamarin) non of them work with Xamarin ...

In my activity I have tried various forms of doing:

public override void OnWindowFocusChanged( bool hasFocus ) {
  base.OnWindowFocusChanged( hasFocus );

  if ( hasFocus ) {
    var uiOptions =
      SystemUiFlags.HideNavigation |
      SystemUiFlags.LayoutHideNavigation |
      SystemUiFlags.LayoutFullscreen |
      SystemUiFlags.Fullscreen |
      SystemUiFlags.LayoutStable |
      SystemUiFlags.ImmersiveSticky;

    Window.DecorView.SystemUiVisibility = (StatusBarVisibility) uiOptions;
  }
}

I have also tried this in the activity OnCreate() . Nothing seems to work.

I have read:https://developer.android.com/training/system-ui/immersive.html https://cmsdk.com/android/hide-navigation-bar-android-xamarin.html http://codegur.com/28394281/in-xamarin-android-how-can-i-hide-the-navigation-bar

Activity.cs:

using Android.App;
using Android.Graphics;
using Android.OS;
using Android.Support.V4.Content;
using Android.Views;
using Android.Widget;
using Calligraphy;
using Dictionary.Fragments;
using Dictionary.Logic.Translation;
using Newtonsoft.Json;

namespace Dictionary.Activities {

  [Activity( MainLauncher = true )]
  public class MainActivity: Activity {

    protected override void OnCreate( Bundle bundle ) {
      base.OnCreate( bundle );
      SetContentView( Resource.Layout.Main );
      SetToolbar();
      SetStatusBarColor();
      ShowSearchFragment();
    }

    public override void OnWindowFocusChanged( bool hasFocus ) {
      base.OnWindowFocusChanged( hasFocus );

      if ( hasFocus ) {
        var uiOptions =
          SystemUiFlags.HideNavigation |
          SystemUiFlags.LayoutHideNavigation |
          SystemUiFlags.LayoutFullscreen |
          SystemUiFlags.Fullscreen |
          SystemUiFlags.LayoutStable |
          SystemUiFlags.ImmersiveSticky;

        Window.DecorView.SystemUiVisibility = (StatusBarVisibility) uiOptions;
      }
    }

    public override bool OnCreateOptionsMenu( IMenu menu ) {
      MenuInflater.Inflate( Resource.Menu.Toolbar, menu );
      return base.OnCreateOptionsMenu( menu );
    }

    protected override void AttachBaseContext( Android.Content.Context @base ) {
      base.AttachBaseContext( CalligraphyContextWrapper.Wrap( @base ) );
    }

    private void SetStatusBarColor() {
      Window.AddFlags( WindowManagerFlags.DrawsSystemBarBackgrounds );
      Window.SetStatusBarColor( new Color( ContextCompat.GetColor( this, Resource.Color.PrimaryColorDark ) ) );
    }

    private void SetToolbar() {
      var toolbar = FindViewById<Toolbar>( Resource.Id.toolbar );
      SetActionBar( toolbar );
      ActionBar.Title = GetString( Resource.String.AppName );
    }

    private void ShowSearchFragment() {
      var searchFragment = new SearchFragment();
      searchFragment.TranslationSelected += OnTranslationSelected;
      var fragTrans = FragmentManager.BeginTransaction();
      fragTrans.Add( Resource.Id.fragHolder, searchFragment );
      fragTrans.Commit();
    }
  }
}

Issue found:

This edit box in my Search Fragment is causing the keyboard to show, breaking the fullscreen mode, even when the keyboard is gone, full screen does not return.

<EditText android:id="@+id/txtSearch"
                    android:layout_width="match_parent"
                    android:layout_height="48dp"
                    android:background="#FFF"
                    android:gravity="center"
                    android:hint="@string/SearchHint"
                    android:imeOptions="flagNoExtractUi|actionDone"
                    android:inputType="textNoSuggestions"
                    android:singleLine="true"
                    android:textColorHint="#ABABAB"
                    android:textSize="18sp"
                    fontPath="Fonts/amiri-regular.ttf"
                    android:textCursorDrawable="@drawable/cursor"/>

Answer 1

I propose a little improvement to @Grace Feng answer. If we add a constructor to the class of the listener

public class OnGlobalLayoutListener : Java.Lang.Object, IOnGlobalLayoutListener
{

    private int mScreenheight;

    private View mDecorView;

    public OnGlobalLayoutListener(int mioScreenheight, View mioDecorView)
    {
        mScreenheight = mioScreenheight;
        mDecorView = mioDecorView;
    }

    public void OnGlobalLayout()
    {
        Rect r = new Rect();

        var keypadHeight = mScreenheight - r.Bottom;
        if (keypadHeight <= mScreenheight * 0.15)
        {
            var uiOptions =
                SystemUiFlags.HideNavigation |
                SystemUiFlags.LayoutFullscreen |
                SystemUiFlags.Fullscreen |
                SystemUiFlags.ImmersiveSticky;

            mDecorView.SystemUiVisibility = (StatusBarVisibility)uiOptions;
        }

    }
}

we can use it in any activity:

        RelativeLayout vista = FindViewById<RelativeLayout>(Resource.Id.main);

        int altezza_schermo = vista.Height;

        View decorView = Window.DecorView;

        vista.ViewTreeObserver.AddOnGlobalLayoutListener(new OnGlobalLayoutListener(altezza_schermo, decorView));

Answer 2

I found the cause to be a EditText in my SearchFragment, which takes the focus and brings up the keyboard, which makes this not work, even after the keyboard is gone.

I think a workaround for this issue is to detect whether the keyboard is open or not, and if the keyboard is closed, set the view to full screen again.

You can create a listener to detect if the keyboard is closed. For example:

protected override void OnCreate(Bundle bundle)
{
    base.OnCreate(bundle);

    // Set our view from the "main" layout resource
    SetContentView(Resource.Layout.Main);

    decorview = Window.DecorView;
    LinearLayout root = FindViewById<LinearLayout>(Resource.Id.rootView);
    screenheight = root.Height;
    root.ViewTreeObserver.AddOnGlobalLayoutListener(new mOnGlobalLayoutListener());
}

public static int screenheight;
public static View decorview;

And the mOnGlobalLayoutListener can be something like this:

public class mOnGlobalLayoutListener : Java.Lang.Object, IOnGlobalLayoutListener
{
    public void OnGlobalLayout()
    {
        Rect r = new Rect();
        var keypadHeight = MainActivity.screenheight - r.Bottom;
        if (keypadHeight <= MainActivity.screenheight * 0.15)
        {
            var uiOptions =
                SystemUiFlags.HideNavigation |
                SystemUiFlags.LayoutHideNavigation |
                SystemUiFlags.LayoutFullscreen |
                SystemUiFlags.Fullscreen |
                SystemUiFlags.LayoutStable |
                SystemUiFlags.ImmersiveSticky;

            MainActivity.decorview.SystemUiVisibility = (StatusBarVisibility)uiOptions;
        }
    }
}

Tested and it works fine when the keyboard is closed.

Answer 3

The whole thing in Oncreate can be replaced with:

decorview = Window.DecorView;
decorview.ViewTreeObserver.AddOnGlobalLayoutListener(new mOnGlobalLayoutListener());

Most of the stuff in unknown with this release of Xamarin forms