public KeyButton(Context context, AttributeSet attrs) : base(context, attrs)
{
TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.KeyButton);
mNote = a.getInteger(R.styleable.KeyButton_note, 69);
mVelocity = a.getInteger(R.styleable.KeyButton_velocity, 80);
a.recycle();
}