Ok i solved my problem. I post the example code:
Path p;
Region r;
@Override
public void onDraw(Canvas canvas) {
p = new Path();
p.moveTo(50, 50);
p.lineTo(100, 50);
p.lineTo(100, 100);
p.lineTo(80, 100);
p.close();
canvas.drawPath(p, paint);
RectF rectF = new RectF();
p.computeBounds(rectF, true);
r = new Region();
r.setPath(p, new Region((int) rectF.left, (int) rectF.top, (int) rectF.right, (int) rectF.bottom));
}
public boolean onTouch(View view, MotionEvent event) {
Point point = new Point();
point.x = event.getX();
point.y = event.getY();
points.add(point);
invalidate();
Log.d(TAG, "point: " + point);
if(r.contains((int)point.x,(int) point.y))
Log.d(TAG, "Touch IN");
else
Log.d(TAG, "Touch OUT");
return true;
}