This can be easily setup within the platform-specific apps and then use a Xamarin.Forms dependency service to subscribe/unsubscribe to the events.
What you capture within those events is up to your needs, in this example I am just capturing and eventing the x/y values.

A generic EventArgs Class and DP Interface:

public class TouchEventArgs<T> : EventArgs
{
    public T EventData { get; private set; }

    public TouchEventArgs(T EventData)
    {
        this.EventData = EventData;
    }
}

public interface IGlobalTouch
{
    void Subscribe(EventHandler handler);
    void Unsubscribe(EventHandler handler);
}

Add the following to the MainActivity of your Xamarin.Android application:

public EventHandler globalTouchHandler;
public override bool DispatchTouchEvent(MotionEvent ev)
{
    globalTouchHandler?.Invoke(null, new TouchEventArgs<Point>(new Point(ev.GetX(), ev.GetY())));
    return base.DispatchTouchEvent(ev);
}

Android Dependency Implementation:

public class GlobalTouch : IGlobalTouch
{
    public GlobalTouch() {}

    public void Subscribe(EventHandler handler)
    {
        (Forms.Context as MainActivity).globalTouchHandler += handler;
    }

    public void Unsubscribe(EventHandler handler)
    {
        (Forms.Context as MainActivity).globalTouchHandler -= handler;
    }
}

Usage in your Xamarin.Forms project:

DependencyService.Get<IGlobalTouch>().Subscribe((sender, e) =>
{
    var point = (e as TouchEventArgs<Point>).EventData;
    System.Diagnostics.Debug.WriteLine($"{point.X}:{point.Y}");
});

Note: You should be assigning a delegate so can unsubscribe...

Output:

307.628997802734:365.563842773438
309.280151367188:365.197265625
311.883605957031:365.390991210938
312.694641113281:380.148590087891
308.030578613281:387.823364257813
291.513244628906:396.339416503906
286.220489501953:396.339416503906
282.100006103516:396.339416503906

The same technique can be used for iOS, there are TouchesBegan , TouchesEnded , TouchesMoved and TouchesCancelled that you can attach to depending upon your needs....

使用SushiHangover分辨率，对于iOS，它将是这样的：

• • 在AppDelegate.cs中实现IUI手势识别器委托**

public partial class AppDelegate : global::Xamarin.Forms.Platform.iOS.FormsApplicationDelegate, IUIGestureRecognizerDelegate
{

• • 在AppDelegate.cs类内的FinishedLaunching方法中添加以下内容：**

Xamarin.Forms.DependencyService.Register<GlobalTouch>();
bool ret = base.FinishedLaunching(app, options);
if (ret)
{
    UITapGestureRecognizer tap = new UITapGestureRecognizer(Self, new ObjCRuntime.Selector("gestureRecognizer:shouldReceiveTouch:"));
    tap.Delegate = (IUIGestureRecognizerDelegate)Self;
    app.KeyWindow.AddGestureRecognizer(tap);
}
return ret;

• • 在AppDelegate.cs中添加此方法：**

[Export("gestureRecognizer:shouldReceiveTouch:")]
public bool ShouldReceiveTouch(UIGestureRecognizer gestureRecognizer, UITouch touch)
{
    Xamarin.Forms.DependencyService.Get<IGlobalTouch>().TapScreen();
    return false;
}

• • 将此添加到GlobalTouch：**

EventHandler globalTouchHandler;

public void TapScreen()
{
    globalTouchHandler?.Invoke(this, null);
}

• • 将此添加到IGlobalTouch：**

void TapScreen();

SushiHangover解决方案的iOS部分：

• • 触摸坐标识别器. cs：**

public class TouchCoordinatesRecognizer : UIGestureRecognizer
{
    public override void TouchesBegan(NSSet touches, UIEvent evt)
    {
        base.TouchesBegan(touches, evt);
        SendCoords(touches);
    }

    public override void TouchesMoved(NSSet touches, UIEvent evt)
    {
        base.TouchesMoved(touches, evt);
        SendCoords(touches);
    }

    public override void TouchesEnded(NSSet touches, UIEvent evt)
    {
        base.TouchesEnded(touches, evt);
        SendCoords(touches);
    }

    public override void TouchesCancelled(NSSet touches, UIEvent evt)
    {
        base.TouchesCancelled(touches, evt);
        SendCoords(touches);
    }

    void SendCoords(NSSet touches)
    {
        foreach (UITouch touch in touches.Cast<UITouch>())
        {
            var window = UIApplication.SharedApplication.KeyWindow;
            var vc = window.RootViewController;

            AppDelegate.Current.globalTouchHandler?.Invoke(null,
                new TouchEventArgs<Point>(
                    new Point(
                        touch.LocationInView(vc.View).X,
                        touch.LocationInView(vc.View).Y)));
            return;
        }
    }
}

• • 应用代理. cs：**

public static AppDelegate Current { get; private set; }

public EventHandler globalTouchHandler;

public override bool FinishedLaunching(UIApplication app, NSDictionary options)
{
    Current = this;

    global::Xamarin.Forms.Forms.Init();
    LoadApplication(new App());
    var res = base.FinishedLaunching(app, options);
    app.KeyWindow.AddGestureRecognizer(new TouchCoordinatesRecognizer()); // <--
    return res;
}

• • 全球触摸. cs：**

public class GlobalTouch : IGlobalTouch
{
    public void Subscribe(EventHandler handler) => AppDelegate.Current.globalTouchHandler += handler;

    public void Unsubscribe(EventHandler handler) => AppDelegate.Current.globalTouchHandler -= handler;
}

不要忘记在android和iOS部件的必要位置将x和y坐标除以DeviceDisplay. MainDisplayInfo. Density。