Give you fab a movable experience

MovableFabButton.kt

class MovableFabButton : FloatingActionButton, View.OnTouchListener {

    private var downRawX: Float = 0.toFloat()
    private var downRawY: Float = 0.toFloat()
    private var dX: Float = 0.toFloat()
    private var dY: Float = 0.toFloat()

    constructor(context: Context) : super(context) {
        init()
    }

    constructor(context: Context, attrs: AttributeSet) : super(context, attrs) {
        init()
    }

    constructor(context: Context, attrs: AttributeSet, defStyleAttr: Int) : super(context, attrs, defStyleAttr) {
        init()
    }

    private fun init() {
        setOnTouchListener(this)
    }

    override fun onTouch(view: View, motionEvent: MotionEvent): Boolean {
        val layoutParams = view.layoutParams as ViewGroup.MarginLayoutParams
        when (motionEvent.action) {
            MotionEvent.ACTION_DOWN -> {
                downRawX = motionEvent.rawX
                downRawY = motionEvent.rawY
                dX = view.x - downRawX
                dY = view.y - downRawY
                return true
            }
            MotionEvent.ACTION_MOVE -> {
                val viewWidth = view.width
                val viewHeight = view.height
                val viewParent = view.parent as View
                val parentWidth = viewParent.width
                val parentHeight = viewParent.height
                var newX = motionEvent.rawX + dX
                newX = layoutParams.leftMargin.toFloat().coerceAtLeast(newX)
                newX = (parentWidth - viewWidth - layoutParams.rightMargin).toFloat().coerceAtMost(newX)
                var newY = motionEvent.rawY + dY
                newY = layoutParams.topMargin.toFloat().coerceAtLeast(newY)
                newY = (parentHeight - viewHeight - layoutParams.bottomMargin).toFloat().coerceAtMost(newY)
                view.animate().x(newX).y(newY).setDuration(0).start()
                return true

            }
            MotionEvent.ACTION_UP -> {
                val upRawX = motionEvent.rawX
                val upRawY = motionEvent.rawY
                val upDX = upRawX - downRawX
                val upDY = upRawY - downRawY
                return if (abs(upDX) < CLICK_DRAG_TOLERANCE && Math.abs(upDY) < CLICK_DRAG_TOLERANCE) {
                    performClick()
                } else {
                    true
                }
            }
            else -> return super.onTouchEvent(motionEvent)
        }

    }

    companion object {
        private const val CLICK_DRAG_TOLERANCE = 10f
    }

}

view.xml

<MovableFabButton
        android:id="@+id/fab_home"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentEnd="true"
        android:layout_alignParentBottom="true"
        android:layout_margin="@dimen/fab_margin"
        android:src="@drawable/ic_home"
        android:tint="@android:color/white" />