How to change the image on a FloatingActionButton?

Question

In Kotlin I'm trying to change the image on a floating action button when it's clicked so that it rotates on it's Y axis and shows a different image and background color.

My code is this:

private fun rotateFabOnYAxis(fab: View, context: Context) {

        fab.animate().rotationY(180f).setListener(object: Animator.AnimatorListener {

            override fun onAnimationStart(animation: Animator?) {
                fab.background = ContextCompat.getDrawable(context, R.drawable.helmet)
            }

            override fun onAnimationEnd(animation: Animator?) {
            }

            override fun onAnimationCancel(animation: Animator?) {

            }

            override fun onAnimationRepeat(animation: Animator?) {
                // This method is called when the animation repeats
            }

        })

My fab is initialized and rotated like this:

val fab: View = findViewById(R.id.fab)

fab.setOnClickListener { view ->
            rotateFabOnYAxis(fab, this)
}

and the.xml where the fab id is:

    <com.google.android.material.floatingactionbutton.FloatingActionButton
        android:id="@+id/fab"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="end|bottom"
        android:src="@drawable/bike_helmet_plus_1"
        android:layout_margin="30dp" />

I've read tons of different answers saying to use getImageDrawable() , setImageResource() , or setImageBitmap() but my fab has none of those functions available so I'm a little stumped. In my code I'm trying to access the fab.background property directly but it's not working either.

Also the fab is indeed rotating 180 degrees in the Y axis, but it maintains the original image

Am I missing something?

Thanks.

Answer 1

I managed to figure it out.
My fab was being explicitly cast into View, rather than ImageView.

After changing View to ImageView I was then able to access the setImageDrawbable() function