A simple multitouch view for MonoDroid

I needed a multitouch view for MonoDroid (Mono for Android), so I built one :)

I based it on

http://android-er.blogspot.co.uk/2011/05/detect-multi-touch-on-custom-view.html

It seems to work quite well - to see it in action, just include it in your project and then you can use it in your axml or in your C#

The code:

	using Android.Content;
	using Android.Graphics;
	using Android.Util;
	using Android.Views;
	namespace Cirrious.Sphero.WorkBench.UI.Droid.Controls
	{
	// adapted from http://android-er.blogspot.co.uk/2011/05/detect-multi-touch-on-custom-view.html
	public class TouchView : View
	{
	private const int MaximumTouchCount = 2;
	private readonly Paint _paint = new Paint(PaintFlags.AntiAlias);
	private readonly float[] _x = new float[MaximumTouchCount];
	private readonly float[] _y = new float[MaximumTouchCount];
	private readonly bool[] _isTouch = new bool[MaximumTouchCount];
	public TouchView(Context context)
	: base(context)
	{
	}
	public TouchView(Context context, IAttributeSet attrs)
	: base(context, attrs)
	{
	}
	public TouchView(Context context, IAttributeSet attrs, int defStyle)
	: base(context, attrs, defStyle)
	{
	}
	protected override void OnMeasure(int widthMeasureSpec, int heightMeasureSpec)
	{
	SetMeasuredDimension(MeasureSpec.GetSize(widthMeasureSpec), MeasureSpec.GetSize(heightMeasureSpec));
	}
	protected override void OnDraw(Canvas canvas)
	{
	_paint.StrokeWidth = 1;
	_paint.SetStyle(Paint.Style.Fill);
	if (_isTouch[0])
	{
	_paint.Color = Color.Red;
	canvas.DrawCircle(_x[0], _y[0], 75f, _paint);
	}
	if (_isTouch[1])
	{
	_paint.Color = Color.Blue;
	canvas.DrawCircle(_x[1], _y[1], 75f, _paint);
	}
	}
	public override bool OnTouchEvent(MotionEvent motionEvent)
	{
	var pointerIndex = ((int) (motionEvent.Action & MotionEventActions.PointerIdMask) >>
	(int) MotionEventActions.PointerIdShift);
	var pointerId = motionEvent.GetPointerId(pointerIndex);
	var action = (motionEvent.Action & MotionEventActions.Mask);
	var pointCnt = motionEvent.PointerCount;
	if (pointCnt <= MaximumTouchCount)
	{
	if (pointerIndex <= MaximumTouchCount - 1)
	{
	for (var i = 0; i < pointCnt; i++)
	{
	var id = motionEvent.GetPointerId(i);
	_x[id] = (int) motionEvent.GetX(i);
	_y[id] = (int) motionEvent.GetY(i);
	}
	switch (action)
	{
	case MotionEventActions.Down:
	case MotionEventActions.PointerDown:
	case MotionEventActions.Move:
	_isTouch[pointerId] = true;
	break;
	default:
	_isTouch[pointerId] = false;
	break;
	}
	}
	}
	Invalidate();
	return true;
	}
	}
	}

view raw TouchView.cs hosted with ❤ by GitHub

	<?xml version="1.0" encoding="utf-8"?>
	<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
	android:layout_width="fill_parent"
	android:layout_height="fill_parent"
	>
	<cirrious.sphero.workbench.ui.droid.controls.TouchView
	android:layout_width="fill_parent"
	android:layout_height="fill_parent"/>
	</FrameLayout>

view raw View.axml hosted with ❤ by GitHub