Common Android Extensions in Kotlin

CommonExtensions.kt

fun View.visible() {
    visibility = View.VISIBLE
}

fun View.invisible() {
    visibility = View.INVISIBLE
}

fun View.gone() {
    visibility = View.GONE
}

fun Context.inflate(res: Int, parent: ViewGroup? = null) : View {
    return LayoutInflater.from(this).inflate(res, parent, false)
}

inline fun Dialog.ifIsShowing(body: Dialog.() -> Unit) {
    if (isShowing) {
        body()
    }
}

inline fun Snackbar.ifIsShowing(body: Snackbar.() -> Unit) {
    if (isShown) {
        body()
    }
}

inline fun ViewGroup.forEach(action: (View) -> Unit) {
    for (index in 0 until childCount) {
        action(getChildAtIndex(index))
    }
}

operator fun ViewGroup.get(position: Int): View? = getChildAt(position)

var View.isVisible: Boolean
    get() = visibility == View.VISIBLE
    set(value) {
        val v = if (value) View.VISIBLE else View.GONE
        if (visibility != v) {
            visibility = v
        }
    }

// dp -> px
val Number.toPx
    get() = TypedValue.applyDimension(
        TypedValue.COMPLEX_UNIT_DIP,
        this.toFloat(),
        Resources.getSystem().displayMetrics
    )

fun Any?.isNull() = this == null