Touch

Touch is the most common input system on mobile devices. Pointers are points on the device screen corresponding to finger touches. Devices with multi-touch functionality support multiple simultaneous pointers.

PointerDispatcher

The PointerDispatcher is a class used to track pointer events.

public abstract class PointerDispatcher
{
    public IList<PointerPoint> Points { get; }

    public event EventHandler<PointerEventArgs> PointerDown;
    public event EventHandler<PointerEventArgs> PointerUp;
    public event EventHandler<PointerEventArgs> PointerMove;
}

The Points property gets a list of points detected on the surface in the current frame.

The PointerDown, PointerUp, and PointerMove events are available to track touch and pointer points.

PointerPoint

The PointerPoint class provides the following information:

Property	Description
Id	A number that is uniquely associated with this touch. It is usually provided by the underlying platform.
Position	The pointer position in screen coordinates.
State	Gets the current pointer state. See Button States for more information.

Using PointerDispatcher

The PointerDispatcher can be found within the Display or Surface objects. The following sample code shows how to access the pointer dispatcher from a Component or Service.

[BindService]
protected GraphicsPresenter graphicsPresenter;

protected override void Update(TimeSpan time)
{
    PointerDispatcher pointerDispatcher = this.graphicsPresenter.FocusedDisplay?.PointerDispatcher;

    if (pointerDispatcher == null)
    {
        return;
    }

    foreach (PointerPoint p in pointerDispatcher.Points)
    {
        if (p.State == ButtonState.Pressing)
        {
            // Do something
        }
    }
}