Xamarin.forms: Feature Request - add key event

[j4587698]

Description

In XF3.0, most support platforms have physical keyboards like mac wpf gtk# and uwp. Android can also be connected to keyboard. So I need keydown keyup or keypress event, not only back button.
I need to monitor the shortcut keys like ctrl+A F1 etc.

[adhamali450]

Why not Android And iOS even if they are not connected to a physical keyboards?

[brettclutch]

I'm trying to do the same thing in a CustomRenderer, I hook up the KeyDown event like so but I recieve no call to the event despite trying tricks with focus to get the CustomRenderer to have focus. I feel like I'm missing something or its broke.

protected override void OnElementChanged(ElementChangedEventArgs e)
{
if (e.OldElement != null)
{
var oldController = (IFlowSKCanvasViewController)e.OldElement;
// unsubscribe from events
oldController.SurfaceInvalidated -= OnSurfaceInvalidated;
oldController.GetCanvasSize -= OnGetCanvasSize;
}

        if (e.NewElement != null)
        {
            var newController = (IFlowSKCanvasViewController)e.NewElement;

            // create the native view
            if (Control == null)
            {
                var view = CreateNativeControl();
                view.PaintSurface += OnPaintSurface;
                SetNativeControl(view);
            }

            Control.KeyDown += Control_KeyDown;

}

Here Control_KeyDown if a breakpoint is inputted will never fire.

[stevehurcombe]

+1 here. I think this would be an important addition to any cross platform dev library!

Personally I want to detect a Ctrl-S (for Save) combination when a Bluetooth keyboard is attached to a mobile device.

[txarito]

+1.
I can't understand how OnKeyDown method isn't accesible from Xamarin.Form ContentPage.

[jwosty]

Yeah, this needs to happen.

[delphian]

+1, Yes please. For the UWP version of my application, or an Android with keyboard, it would be great to detect keystrokes from the ContentPage.

At the moment this is what I have rigged up on a UWP custom renderer :

using BeforeOurTime.MobileApp.Pages.Explore;
using BeforeOurTime.MobileApp.UWP.Pages.Explore;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Windows.UI.Xaml;
using Xamarin.Forms;
using Xamarin.Forms.Platform.UWP;

[assembly: ExportRenderer(typeof(ExplorePage), typeof(CustomExplorePageRenderer))]
namespace BeforeOurTime.MobileApp.UWP.Pages.Explore
{
    public class CustomExplorePageRenderer : PageRenderer
    {
        /// <summary>
        /// Monitor windows core ui keypress when ExplorePage is showing
        /// </summary>
        public CustomExplorePageRenderer() : base()
        {
            // When ExplorePage appears then attach to the ui core keydown event
            Loaded += (object sender, RoutedEventArgs e) =>
            {
                Windows.UI.Core.CoreWindow.GetForCurrentThread().KeyDown += HandleKeyDown;
            };
            // When ExplorePage disappears then detach from the ui core keydown event
            Unloaded += (object sender, RoutedEventArgs e) =>
            {
                Windows.UI.Core.CoreWindow.GetForCurrentThread().KeyDown -= HandleKeyDown;
            };
        }
        /// <summary>
        /// Forward a keypress to an ExplorePage method
        /// </summary>
        /// <param name="window"></param>
        /// <param name="e"></param>
        public void HandleKeyDown(Windows.UI.Core.CoreWindow window, Windows.UI.Core.KeyEventArgs e)
        {
            (Element as ExplorePage).KeyPressed(Element, new KeyEventArgs { Key = e.VirtualKey.ToString() });
        }
    }
}

Note: ExplorePage is checking to see if any child control has focus before processing the key down!

[charlesroddie]

Presumably the right way to do this is to allow a listener to be attached to any View, similarly to touch?

[jwosty]

It would also be nice if gesture event handlers also told you which keyboard buttons were pressed at the time of the gesture. You could use this to cause a click to behave differently from a CTRL+click. However, if key pressed events (or keyup+keydown) were implemented, you could use that to do it yourself.

[volcano619]

I'm stuck at not able to get a event when an entry is empty, and delete is pressed, i hope we can add keyboard events to views

[ArtjomP]

Let me add my 2 cents.
How about to have such a thing as KeyboardGestureRecognizer?

[volcano619]

are we still considering this @samhouts ?

[samhouts]

Yes, we are still considering this. What would the Xamarin.Forms API look like? Can you show examples of how to use it with C# and XAML? Thanks!

[ArtjomP]

OnKeyUp (Down) event for ContentPage would be ok.
I would like more something like this one:
```xaml


Key="X"
AndAlt="True"
AndCtrl="False"
AndShift="True"
Command="{Binding MyCommand}"
Event="..."/>

[kkentt]

@samhouts Anything about this ?