ui-leanback

name	ui-leanback
description	Trigger: TV UI & Media Clients. Implementing Leanback-compliant interfaces, handling D-pad focus, View Binding, and Glide image loading.

UI Leanback & Media Client Standards

View Binding Implementation

Mandatory for all new UI and refactors. Replaces findViewById.

In Activities

private lateinit var binding: ActivityExampleBinding

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    binding = ActivityExampleBinding.inflate(layoutInflater)
    setContentView(binding.root)
}

In Fragments

private var _binding: FragmentExampleBinding? = null
private val binding get() = _binding!!

override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View {
    _binding = FragmentExampleBinding.inflate(inflater, container, false)
    return binding.root
}

override fun onDestroyView() {
    super.onDestroyView()
    _binding = null
}

Handling Includes

val progressBinding = IncludeLoadingProgressBinding.bind(binding.root)

Image Loading with Glide

Standard for all image loading and caching.

Glide.with(context)
    .load(url)
    .placeholder(R.drawable.default_video_still)
    .error(R.drawable.default_error)
    .into(binding.imageView)

Animations (XML Only)

MotionLayout is prohibited. Use XML animations in res/anim.

Example Fade In (res/anim/fade_in.xml)

<alpha xmlns:android="http://schemas.android.com/apk/res/android"
    android:interpolator="@android:anim/accelerate_interpolator"
    android:fromAlpha="0.0" android:toAlpha="1.0"
    android:duration="300" />

Focus Effects (D-pad Navigation)

Non-negotiable for TV UI. Provide clear visual feedback.

Scale-up on Focus

view.setOnFocusChangeListener { v, hasFocus ->
    if (hasFocus) {
        v.animate().scaleX(1.1f).scaleY(1.1f).setDuration(200).start()
    } else {
        v.animate().scaleX(1.0f).scaleY(1.0f).setDuration(200).start()
    }
}

Alternatively, use a drawable selector with a border or background change.