Adding elevation to appbar on scroll

I'd love to just do this with coordiator but alas...

app/src/main/java/eu/kanade/tachiyomi/ui/catalogue/CatalogueController.kt

@@ -145,6 +145,9 @@ class CatalogueController : NucleusController<CataloguePresenter>(),
         .BottomSheetCallback() {
             override fun onSlide(bottomSheet: View, progress: Float) {
                 shadow2.alpha = (1 - max(0f, progress)) * 0.25f
+                activity?.appbar?.elevation = max(progress * 15f,
+                    if (recycler.canScrollVertically(-1)) 15f else 0f)
+
                 sheet_layout.alpha = 1 - progress
                 activity?.appbar?.y = max(activity!!.appbar.y, -headerHeight * (1 - progress))
                 val oldShow = showingExtenions

app/src/main/java/eu/kanade/tachiyomi/ui/manga/MangaDetailsController.kt

@@ -229,6 +229,7 @@ class MangaDetailsController : BaseController,
         var statusBarHeight = -1
         swipe_refresh.setStyle()
         swipe_refresh.setDistanceToTriggerSync(70.dpToPx)
+        activity!!.appbar.elevation = 0f
 
         recycler.doOnApplyWindowInsets { v, insets, _ ->
             headerHeight = appbarHeight + insets.systemWindowInsetTop

app/src/main/java/eu/kanade/tachiyomi/ui/recents/RecentsController.kt

@@ -136,6 +136,9 @@ class RecentsController(bundle: Bundle? = null) : BaseController(bundle),
             override fun onSlide(bottomSheet: View, progress: Float) {
                 shadow2.alpha = (1 - abs(progress)) * 0.25f
                 shadow.alpha = (1 - abs(progress)) * 0.5f
+                if (progress >= 0) activity?.appbar?.elevation = max(
+                    progress * 15f, if (recycler.canScrollVertically(-1)) 15f else 0f
+                )
                 sheet_layout.alpha = 1 - progress
                 activity?.appbar?.y = max(activity!!.appbar.y, -headerHeight * (1 - progress))
                 val oldShow = showingDownloads

app/src/main/java/eu/kanade/tachiyomi/ui/setting/SettingsController.kt

@@ -15,8 +15,7 @@ import com.bluelinelabs.conductor.ControllerChangeType
 import eu.kanade.tachiyomi.R
 import eu.kanade.tachiyomi.data.preference.PreferencesHelper
 import eu.kanade.tachiyomi.ui.base.controller.BaseController
-import eu.kanade.tachiyomi.util.view.RecyclerWindowInsetsListener
+import eu.kanade.tachiyomi.util.view.scrollViewWith
-import eu.kanade.tachiyomi.util.view.applyWindowInsetsForController
 import rx.Observable
 import rx.Subscription
 import rx.subscriptions.CompositeSubscription
@@ -35,8 +34,7 @@ abstract class SettingsController : PreferenceController() {
             untilDestroySubscriptions = CompositeSubscription()
         }
         val view = super.onCreateView(inflater, container, savedInstanceState)
-        view.applyWindowInsetsForController()
+        scrollViewWith(listView, padBottom = true)
-        listView.setOnApplyWindowInsetsListener(RecyclerWindowInsetsListener)
         return view
     }
 

app/src/main/java/eu/kanade/tachiyomi/util/view/ViewExtensions.kt

@@ -2,6 +2,7 @@
 
 package eu.kanade.tachiyomi.util.view
 
+import android.animation.ValueAnimator
 import android.app.Activity
 import android.content.Context
 import android.content.res.ColorStateList
@@ -30,6 +31,8 @@ import androidx.swiperefreshlayout.widget.SwipeRefreshLayout
 import com.amulyakhare.textdrawable.TextDrawable
 import com.amulyakhare.textdrawable.util.ColorGenerator
 import com.bluelinelabs.conductor.Controller
+import com.bluelinelabs.conductor.ControllerChangeHandler
+import com.bluelinelabs.conductor.ControllerChangeType
 import com.google.android.material.bottomsheet.BottomSheetDialog
 import com.google.android.material.button.MaterialButton
 import com.google.android.material.snackbar.Snackbar
@@ -353,6 +356,31 @@ fun Controller.scrollViewWith(
         statusBarHeight = insets.systemWindowInsetTop
         afterInsets?.invoke(insets)
     }
+    var elevationAnim: ValueAnimator? = null
+    var elevate = false
+    val elevateFunc: (Boolean) -> Unit = { el ->
+        elevate = el
+        elevationAnim?.cancel()
+        elevationAnim = ValueAnimator.ofFloat(
+            activity!!.appbar.elevation, if (el) 15f else 0f
+        )
+        elevationAnim?.addUpdateListener { valueAnimator ->
+            activity!!.appbar.elevation = valueAnimator.animatedValue as Float
+        }
+        elevationAnim?.start()
+    }
+    addLifecycleListener(object : Controller.LifecycleListener() {
+        override fun onChangeStart(
+            controller: Controller,
+            changeHandler: ControllerChangeHandler,
+            changeType: ControllerChangeType
+        ) {
+            super.onChangeStart(controller, changeHandler, changeType)
+            if (changeType.isEnter)
+                elevateFunc(elevate)
+        }
+    })
+    elevateFunc(recycler.canScrollVertically(-1))
     recycler.addOnScrollListener(object : RecyclerView.OnScrollListener() {
         override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
             super.onScrolled(recyclerView, dx, dy)
@@ -365,11 +393,15 @@ fun Controller.scrollViewWith(
                     ) ?: 0
                     activity!!.appbar.animate().y(0f).setDuration(shortAnimationDuration.toLong())
                         .start()
+                    if (elevate) elevateFunc(false)
                 } else {
                     activity!!.appbar.y -= dy
                     activity!!.appbar.y = clamp(
                         activity!!.appbar.y, -activity!!.appbar.height.toFloat(), 0f
                     )
+                    if ((activity!!.appbar.y <= -activity!!.appbar.height.toFloat() ||
+                            dy == 0 && activity!!.appbar.y == 0f) && !elevate)
+                        elevateFunc(true)
                 }
             }
         }
@@ -393,6 +425,10 @@ fun Controller.scrollViewWith(
                             if (closerToTop && !atTop) (-activity!!.appbar.height.toFloat())
                             else 0f
                         ).setDuration(shortAnimationDuration.toLong()).start()
+                    if (recycler.canScrollVertically(-1) && !elevate)
+                        elevateFunc(true)
+                    else if (!recycler.canScrollVertically(-1) && elevate)
+                        elevateFunc(false)
                 }
             }
         }