Custom Media Route button which hides when there are no Cast devices on the network

CustomMediaRouteButton.kt

@file:Suppress("PackageDirectoryMismatch")
package androidx.mediarouter.app

import android.content.Context
import android.util.AttributeSet
import android.view.View
import androidx.core.content.ContextCompat
import androidx.mediarouter.media.MediaRouter

class CustomMediaRouteButton : MediaRouteButton {

    constructor(context: Context?) : super(context)
    constructor(context: Context?, attrs: AttributeSet?) : super(context, attrs)
    constructor(context: Context?, attrs: AttributeSet?, defStyleAttr: Int) : super(context, attrs, defStyleAttr)

    private var mediaRouter : MediaRouter? = null

    init {
        if (!isInEditMode) {
            mediaRouter = MediaRouter.getInstance(context)
        }
    }
    
    override fun setEnabled(enabled: Boolean) {
        super.setEnabled(enabled)
        // When Cast enables / disables the button, it is because the routes have changed. We also 
        // Want to update the visibility in this case.
        refreshVisibility()
    }

    override fun refreshVisibility() {
        if (mediaRouter?.isRouteAvailable(routeSelector, MediaRouter.AVAILABILITY_FLAG_IGNORE_DEFAULT_ROUTE) == false) {
            // We can't set visibility here, because it would call refreshVisibility again, so we just change alpha to 0 and disable clicks
            alpha = 0f
            isClickable = false
        } else {
            alpha = 1f
            isClickable = true
            super.refreshVisibility()
        }
    }
}