MultiStateFrameLayout Kotlin Android

attrs_multistate.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
  <declare-styleable name="MultiStateFrameLayout">
    <attr format="reference" name="ms_contentView"/>
    <attr format="reference" name="ms_emptyView"/>
    <attr format="reference" name="ms_loadingView"/>
    <attr format="reference" name="ms_errorView"/>
  </declare-styleable>
</resources>

MultiState.kt

enum class MultiState {
  CONTENT,
  EMPTY,
  LOADING,
  ERROR
}

MultiStateFrameLayout.kt

class MultiStateFrameLayout @JvmOverloads constructor(
  context: Context,
  attrs: AttributeSet? = null,
  defStyleAttr: Int = 0
) : FrameLayout(context, attrs, defStyleAttr) {

  companion object {
    private const val NO_VIEW = -1
  }

  private var contentViewId: Int = NO_VIEW
  private var emptyViewId: Int = NO_VIEW
  private var loadingViewId: Int = NO_VIEW
  private var errorViewId: Int = NO_VIEW

  private var contentView: View? = null
  private var emptyView: View? = null
  private var loadingView: View? = null
  private var errorView: View? = null

  private var currentState = MultiState.CONTENT

  init {
    attrs?.let {
      val typedArray = context.obtainStyledAttributes(it, R.styleable.MultiStateFrameLayout)
      contentViewId = typedArray.getResourceId(R.styleable.MultiStateFrameLayout_ms_contentView, NO_VIEW)
      emptyViewId = typedArray.getResourceId(R.styleable.MultiStateFrameLayout_ms_emptyView, NO_VIEW)
      loadingViewId = typedArray.getResourceId(R.styleable.MultiStateFrameLayout_ms_loadingView, NO_VIEW)
      errorViewId = typedArray.getResourceId(R.styleable.MultiStateFrameLayout_ms_errorView, NO_VIEW)
      typedArray.recycle()
    }
  }

  override fun onAttachedToWindow() {
    super.onAttachedToWindow()
    if (contentViewId != NO_VIEW) contentView = findViewById(contentViewId)
    if (emptyViewId != NO_VIEW) emptyView = findViewById(emptyViewId)
    if (loadingViewId != NO_VIEW) loadingView = findViewById(loadingViewId)
    if (errorViewId != NO_VIEW) errorView = findViewById(errorViewId)

    showState(currentState)
  }

  fun showContent() {
    currentState = CONTENT
    showView(contentView)
  }

  fun showEmpty() {
    currentState = EMPTY
    showView(emptyView)
  }

  fun showLoading() {
    currentState = LOADING
    showView(loadingView)
  }

  fun showError() {
    currentState = ERROR
    showView(errorView)
  }

  fun showState(state: MultiState) {
    when (state) {
      MultiState.CONTENT -> showContent()
      MultiState.EMPTY -> showEmpty()
      MultiState.LOADING -> showLoading()
      MultiState.ERROR -> showError()
    }
  }

  private fun showView(view: View?) {
    view?.run {
      contentView?.visibility = View.GONE
      emptyView?.visibility = View.GONE
      loadingView?.visibility = View.GONE
      errorView?.visibility = View.GONE

      visibility = View.VISIBLE
    }
  }
}