Loading [MaterialButton]. Support showing loading spinner on the button

LoadingMaterialButton.kt

import android.content.Context
import android.graphics.Color
import android.graphics.drawable.Drawable
import android.util.AttributeSet
import androidx.swiperefreshlayout.widget.CircularProgressDrawable
import com.google.android.material.button.MaterialButton

/**
 * Loading [MaterialButton]. Showing loading spinner on the button
 *
 * @author Ivan V on 24.02.2022
 */
class LoadingMaterialButton @JvmOverloads constructor(
    context: Context,
    attrs: AttributeSet? = null,
    defStyleAttr: Int = 0,
) : MaterialButton(context, attrs, defStyleAttr) {

    companion object {
        private const val EMPTY_TEXT = ""
    }

    private var btnText = EMPTY_TEXT

    private val progressDrawable by lazy {
        CircularProgressDrawable(context).apply {
            setStyle(CircularProgressDrawable.DEFAULT)
            setColorSchemeColors(Color.WHITE)
        }
    }

    private val callback = object : Drawable.Callback {
        override fun unscheduleDrawable(who: Drawable, what: Runnable) {
            // Do nothing
        }

        override fun invalidateDrawable(who: Drawable) {
            invalidate()
        }

        override fun scheduleDrawable(who: Drawable, what: Runnable, `when`: Long) {
            // Do nothing
        }
    }

    fun startLoading() {
        btnText = text.toString()
        text = EMPTY_TEXT
        enableButton(false)
        progressDrawable.callback = callback
        foreground = progressDrawable
        progressDrawable.start()
    }

    fun stopLoading() {
        text = btnText
        enableButton(true)
        if (progressDrawable.isRunning) {
            progressDrawable.stop()
        }
    }

    private fun enableButton(enabled: Boolean) {
        isClickable = enabled
        isFocusable = enabled
    }

    override fun onDetachedFromWindow() {
        super.onDetachedFromWindow()
        stopLoading()
    }
}