Detect device keyboard is on or not in xamarin forms?

Question

Is there any way to detect the device keyboard is on or not in Xamarin Forms?

I tried the solution on this thread, but it is not working, it is breaking with some kind of exception.

Answer 1

Hello,

After testing, I replaced the deprecated API in this solution.

Please refer to the following code snippets for more details about how to detect device keyboard is on or not.

Define interface for the platform service:

public interface IKeyboardService
{
    event EventHandler KeyboardIsShown;
    event EventHandler KeyboardIsHidden;
}

For Android:

Step 1. Add an Instance static variable into MainActivity.cs.

public static MainActivity Instance { get; private set; }
protected override void OnCreate(Bundle savedInstanceState)
{
    base.OnCreate(savedInstanceState);

    Xamarin.Essentials.Platform.Init(this, savedInstanceState);
    global::Xamarin.Forms.Forms.Init(this, savedInstanceState);
    Instance = this;
    LoadApplication(new App());
}

Step 2. Implement IKeyboardService in Android.

[assembly: Xamarin.Forms.Dependency(typeof(KeyboardService))]
namespace App5.Droid
{
    public class KeyboardService : IKeyboardService
    {
        public event EventHandler KeyboardIsShown;
        public event EventHandler KeyboardIsHidden;

        private InputMethodManager inputMethodManager;

        private bool wasShown = false;

        public KeyboardService()
        {
            GetInputMethodManager();
            SubscribeEvents();
        }

        public void OnGlobalLayout(object sender, EventArgs args)
        {
            GetInputMethodManager();
            if (!wasShown && IsCurrentlyShown())
            {
                KeyboardIsShown?.Invoke(this, EventArgs.Empty);
                wasShown = true;
            }
            else if (wasShown && !IsCurrentlyShown())
            {
                KeyboardIsHidden?.Invoke(this, EventArgs.Empty);
                wasShown = false;
            }
        }

        private bool IsCurrentlyShown()
        {
            return inputMethodManager.IsAcceptingText;
        }

        private void GetInputMethodManager()
        {
            if (inputMethodManager == null || inputMethodManager.Handle == IntPtr.Zero)
            {
                inputMethodManager = (InputMethodManager)MainActivity.Instance.GetSystemService(Context.InputMethodService);
            }
        }

        private void SubscribeEvents()
        {
            MainActivity.Instance.Window.DecorView.ViewTreeObserver.GlobalLayout += this.OnGlobalLayout;
        }
    }
}

For iOS, you could implement IKeyboardService as the following code:

[assembly: Xamarin.Forms.Dependency(typeof(KeyboardService))]
namespace App5.iOS
{
    public class KeyboardService : IKeyboardService
    {
        public event EventHandler KeyboardIsShown;
        public event EventHandler KeyboardIsHidden;

        public KeyboardService()
        {
            SubscribeEvents();
        }

        private void SubscribeEvents()
        {
            UIKeyboard.Notifications.ObserveDidShow(OnKeyboardDidShow);
            UIKeyboard.Notifications.ObserveDidHide(OnKeyboardDidHide);
        }

        private void OnKeyboardDidShow(object sender, EventArgs e)
        {
            KeyboardIsShown?.Invoke(this, EventArgs.Empty);
        }

        private void OnKeyboardDidHide(object sender, EventArgs e)
        {
            KeyboardIsHidden?.Invoke(this, EventArgs.Empty);
        }
    }
}

After that, you could invoke this service to detect keybord show/hide event in Xamarin.Forms.

var keyboardService = Xamarin.Forms.DependencyService.Get<IKeyboardService>();
keyboardService.KeyboardIsShown += (s, e) =>
{
    // Add Keyboard show event.
    Console.WriteLine("KeyboardIsShown");
};
keyboardService.KeyboardIsHidden += (s, e) =>
{
    // Add Keyboard hide event.
    Console.WriteLine("KeyboardIsHidden");
};

Update:

You could implement this requirement by following these steps.

Step 1. Modify the IsCurrentlyShown method in Android to determine whether the keyboard pops up based on the overall height change of the page.

private bool IsCurrentlyShown()
{
    Rect r = new Rect();
    var view = MainActivity.Instance.Window.DecorView;
    view.GetWindowVisibleDisplayFrame(r);
    int screenHeight = view.RootView.Height;
    int heightDifference = screenHeight - (r.Bottom);
    if (heightDifference > 200)
    {
        return true;
    }
    else
    {
        return false;

    }
}

Step 2. Set the icon to hide and display in the background code of the page.

protected override void OnAppearing()
{
    base.OnAppearing();
    var keybordservice = DependencyService.Get<IKeyboardService>();
    keybordservice.KeyboardIsShown += (s, e) =>
    {
        test_icon.IsVisible = false;
    };
    keybordservice.KeyboardIsHidden += (s, e) =>
    {
        test_icon.IsVisible = true;
    };
}
// in my testing, I used an image as icon for test.
<Image x:Name="test_icon" Source="icon_about.png"/>

Best Regards,

Alec Liu.

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