FocusClearLifecycleObserver.kt

/**
 * example (use in fragment) > 
 *  viewLifecycleOwner.lifecycle.addObserver(
 *      FocusClearLifecycleObserver(binding.root, requireActivity()) {
 *          binding.editText.clearFocus()
 *      })
 *      
 * example (use in activity) >
 *  lifecycle.addObserver(
 *      FocusClearLifecycleObserver(binding.root, this) {
 *          binding.editText.clearFocus()
 *      })
 */
 
class FocusClearLifecycleObserver(
    rootView: View,
    activity: Activity,
    val clearViewFocus: (() -> Unit)
) : LifecycleObserver {

    private var rootView: View? = null
    private var activity: Activity? = null

    init {
        this.rootView = rootView
        this.activity = activity
    }

    @OnLifecycleEvent(Lifecycle.Event.ON_START)
    fun init() {
        if (rootView == null) {
            return
        }

        setLayoutChangeListener()
        setClearFocusClickListener(rootView as ViewGroup)
    }

    @OnLifecycleEvent(Lifecycle.Event.ON_DESTROY)
    fun release() {
        rootView = null
        activity = null
    }

    private fun clearFocus() {
        activity?.hideKeyboard(clearViewFocus)
    }

    private fun setLayoutChangeListener() {
        rootView?.addOnLayoutChangeListener { _, _, _, _, _, _, _, _, _ ->
            if (activity?.isKeyboardVisible() == false) {
                clearFocus()
            }
        }
    }

    @SuppressLint("ClickableViewAccessibility")
    private fun setClearFocusClickListener(viewGroup: ViewGroup) {
        if (viewGroup is ScrollView || viewGroup is ScrollingView) {
            viewGroup.viewTreeObserver.addOnScrollChangedListener {
                clearFocus()
            }
        }

        viewGroup.children.forEach { view ->
            if (view is ViewGroup) {
                setClearFocusClickListener(view)
            }

            if (view !is EditText && !view.hasOnClickListeners()) {
                view.setOnClickListener {
                    clearFocus()
                }
            }
        }
    }
}

fun Activity.isKeyboardVisible(): Boolean {
    val r = Rect()
    val contentView: View = findViewById(android.R.id.content)
    contentView.getWindowVisibleDisplayFrame(r)
    val screenHeight: Int = contentView.rootView.height
    val keypadHeight: Int = screenHeight - r.bottom
    return keypadHeight > screenHeight * 0.15
}