ExampleImageFileThread.kt

val mainHandler = Handler(Looper.getMainLooper()) { msg ->
    // do something with msg
    // Main Thread here!!
    true
}

val imageThread = ImageFileThread(mainHandler) {
    val message = Message().apply {
        data = bundleOf(
            "image_url" to "https://example.com/img.png"
        )
    }
    sendMessage(message)
}

// start the thread
imageThread.start()