Intercept global event Xamarin Forms - xamarin.forms

Question

In MainActivity.cs I have this method
public override bool OnKeyUp(Keycode keyCode, KeyEvent e)
{
if (keyCode.ToString().Equals("F1"))
{
App.Left = true;
App.Right = false;
}
else if (keyCode.ToString().Equals("F2"))
{
App.Left = false;
App.Right = true;
}
else
{
App.Left = false;
App.Right = false;
}
return base.OnKeyUp(keyCode, e);
}
In my Page class, how can I constantly check whether left or right are true and in case trigger an event?

Answer 1

Create a plugin using Dependency Service and your shared interface should look like this:
public interface IKeyEvent
{
event Action<KeyResult> OnKeyEvent;
}
public enum KeyResult {None, Left, Right};
Implement this for different platforms (Android/iOS/UWP) accordingly and bind it to PCL project. (Check dependency service implementation for help)
Link it to platform-specific KeyUp event.
for android it would be like this:
Droid.KeyEventHandler
[assembly: Dependency(typeof(KeyEventHandler))]
namespace YourNameSpace.Droid
{
public class KeyEventHandler : IKeyEvent
{
public static KeyEventHandler Current;
public KeyEventHandler()
{
Current = this;
}
public event Action<KeyResult> OnKeyResult;
public void RaiseKeyEvent(KeyResult key)
{
OnKeyResult?.Invoke(key);
}
}
}
MainActivity
public override bool OnKeyUp(Keycode keyCode, KeyEvent e)
{
KeyResult keyResult = KeyResult.None; // need to reference YourNameSpace.Shared project to use this enum
if (keyCode == KeyCode.A)
{
keyResult = KeyResult.Left;
}
else if (keyCode == KeyCode.D))
{
keyResult = KeyResult.Right;
}
else
{
keyResult = KeyResult.None;
}
if (KeyEventHandler.Current != null)
{
KeyEventHandler.Current.RaiseKeyEvent(keyResult);
}
return base.OnKeyUp(keyCode, e);
}
NOTE: Left and right keys are mapped to A and D of physical keyboard respectively, for some reason my Macbook's F1/F2 keys were not registering to simulator so I used A/D.
Hope this helps :)