Keyboard visibility events

keyboard.md

/**
 * Fires events when keyboard visibility changes
 */
fun Activity.onKeyboardVisibilityChange(action: (visible: Boolean) -> Unit) {
    findViewById<View>(Window.ID_ANDROID_CONTENT)?.apply {
        viewTreeObserver.addOnGlobalLayoutListener(object : ViewTreeObserver.OnGlobalLayoutListener {
            val rectangle = Rect(0, 0, 0, 0)
            val heightThreshold = resources.displayMetrics.density * KEYBOARD_VISIBILITY_THRESHOLD_DP
            var wasOpen = false
            override fun onGlobalLayout() {
                val activityRoot = findViewById<ViewGroup>(Window.ID_ANDROID_CONTENT).getChildAt(0)
                activityRoot.getWindowVisibleDisplayFrame(rectangle)
                val heightDiff = activityRoot.rootView.height - rectangle.height()
                val isOpen = heightDiff > heightThreshold
                if (isOpen == wasOpen) return
                wasOpen = isOpen
                action.invoke(isOpen)
            }
        })
    }
}