Change BottomNavigationView behavior (#5603)

Similar to app bar's scroll behavior

app/src/main/java/eu/kanade/tachiyomi/ui/library/LibraryController.kt

@@ -377,7 +377,7 @@ class LibraryController(
                 actionMode!!,
                 R.menu.library_selection
             ) { onActionItemClicked(it!!) }
-            (activity as? MainActivity)?.showBottomNav(visible = false, collapse = true)
+            (activity as? MainActivity)?.showBottomNav(visible = false, expand = true)
         }
     }
 
@@ -486,7 +486,7 @@ class LibraryController(
         selectionRelay.call(LibrarySelectionEvent.Cleared())
 
         binding.actionToolbar.hide()
-        (activity as? MainActivity)?.showBottomNav(visible = true, collapse = true)
+        (activity as? MainActivity)?.showBottomNav(visible = true, expand = true)
 
         actionMode = null
     }

app/src/main/java/eu/kanade/tachiyomi/ui/main/MainActivity.kt

@@ -28,7 +28,6 @@ import com.bluelinelabs.conductor.Controller
 import com.bluelinelabs.conductor.ControllerChangeHandler
 import com.bluelinelabs.conductor.Router
 import com.google.android.material.appbar.AppBarLayout
-import com.google.android.material.behavior.HideBottomViewOnScrollBehavior
 import com.google.android.material.navigation.NavigationBarView
 import dev.chrisbanes.insetter.applyInsetter
 import eu.kanade.tachiyomi.BuildConfig
@@ -61,6 +60,7 @@ import eu.kanade.tachiyomi.util.lang.launchUI
 import eu.kanade.tachiyomi.util.system.dpToPx
 import eu.kanade.tachiyomi.util.system.toast
 import eu.kanade.tachiyomi.util.view.setNavigationBarTransparentCompat
+import eu.kanade.tachiyomi.widget.HideBottomNavigationOnScrollBehavior
 import kotlinx.coroutines.delay
 import kotlinx.coroutines.flow.drop
 import kotlinx.coroutines.flow.launchIn
@@ -142,15 +142,6 @@ class MainActivity : BaseViewBindingActivity<MainActivityBinding>() {
         if (binding.bottomNav != null) {
             bottomNavAnimator = ViewHeightAnimator(binding.bottomNav!!)
 
-            // If bottom nav is hidden, make it visible again when the app bar is expanded
-            binding.appbar.addOnOffsetChangedListener(
-                AppBarLayout.OnOffsetChangedListener { _, verticalOffset ->
-                    if (verticalOffset == 0) {
-                        showNav(visible = true)
-                    }
-                }
-            )
-
             // Set behavior of bottom nav
             preferences.hideBottomBarOnScroll()
                 .asImmediateFlow { setBottomNavBehaviorOnScroll() }
@@ -502,11 +493,11 @@ class MainActivity : BaseViewBindingActivity<MainActivityBinding>() {
         binding.appbar.setExpanded(true)
 
         if ((from == null || from is RootController) && to !is RootController) {
-            showNav(visible = false, collapse = true)
+            showNav(visible = false, expand = true)
         }
         if (to is RootController) {
             // Always show bottom nav again when returning to a RootController
-            showNav(visible = true, collapse = from !is RootController)
+            showNav(visible = true, expand = from !is RootController)
         }
 
         if (from is TabbedController) {
@@ -542,30 +533,21 @@ class MainActivity : BaseViewBindingActivity<MainActivityBinding>() {
         }
     }
 
-    private fun showNav(visible: Boolean, collapse: Boolean = false) {
+    private fun showNav(visible: Boolean, expand: Boolean = false) {
-        showBottomNav(visible, collapse)
+        showBottomNav(visible, expand)
         showSideNav(visible)
     }
 
     // Also used from some controllers to swap bottom nav with action toolbar
-    fun showBottomNav(visible: Boolean, collapse: Boolean = false) {
+    fun showBottomNav(visible: Boolean, expand: Boolean = false) {
-        binding.bottomNav?.let {
-            val layoutParams = it.layoutParams as CoordinatorLayout.LayoutParams
-            val bottomViewNavigationBehavior =
-                layoutParams.behavior as? HideBottomViewOnScrollBehavior
         if (visible) {
-                if (collapse) {
+            binding.bottomNav?.translationY = 0F
+            if (expand) {
                 bottomNavAnimator?.expand()
             }
-                bottomViewNavigationBehavior?.slideUp(it)
         } else {
-                if (collapse) {
             bottomNavAnimator?.collapse()
         }
-
-                bottomViewNavigationBehavior?.slideDown(it)
-            }
-        }
     }
 
     private fun showSideNav(visible: Boolean) {
@@ -597,10 +579,11 @@ class MainActivity : BaseViewBindingActivity<MainActivityBinding>() {
 
         binding.bottomNav?.updateLayoutParams<CoordinatorLayout.LayoutParams> {
             behavior = when {
-                preferences.hideBottomBarOnScroll().get() -> HideBottomViewOnScrollBehavior<View>()
+                preferences.hideBottomBarOnScroll().get() -> HideBottomNavigationOnScrollBehavior()
                 else -> null
             }
         }
+        binding.bottomNav?.translationY = 0F
     }
 
     private val nav: NavigationBarView

app/src/main/java/eu/kanade/tachiyomi/ui/recent/updates/UpdatesController.kt

@@ -183,7 +183,7 @@ class UpdatesController :
                 actionMode!!,
                 R.menu.updates_chapter_selection
             ) { onActionItemClicked(it!!) }
-            (activity as? MainActivity)?.showBottomNav(visible = false, collapse = true)
+            (activity as? MainActivity)?.showBottomNav(visible = false, expand = true)
         }
 
         toggleSelection(position)
@@ -389,7 +389,7 @@ class UpdatesController :
         adapter?.clearSelection()
 
         binding.actionToolbar.hide()
-        (activity as? MainActivity)?.showBottomNav(visible = true, collapse = true)
+        (activity as? MainActivity)?.showBottomNav(visible = true, expand = true)
 
         actionMode = null
     }

app/src/main/java/eu/kanade/tachiyomi/widget/HideBottomNavigationOnScrollBehavior.kt

@@ -0,0 +1,41 @@
+package eu.kanade.tachiyomi.widget
+
+import android.content.Context
+import android.util.AttributeSet
+import android.view.View
+import androidx.coordinatorlayout.widget.CoordinatorLayout
+import androidx.core.view.ViewCompat
+import com.google.android.material.bottomnavigation.BottomNavigationView
+
+/**
+ * Hide behavior similar to app bar for [BottomNavigationView]
+ */
+class HideBottomNavigationOnScrollBehavior @JvmOverloads constructor(
+    context: Context? = null,
+    attrs: AttributeSet? = null
+) : CoordinatorLayout.Behavior<BottomNavigationView>(context, attrs) {
+
+    override fun onStartNestedScroll(
+        coordinatorLayout: CoordinatorLayout,
+        child: BottomNavigationView,
+        directTargetChild: View,
+        target: View,
+        axes: Int,
+        type: Int
+    ): Boolean {
+        return axes == ViewCompat.SCROLL_AXIS_VERTICAL
+    }
+
+    override fun onNestedPreScroll(
+        coordinatorLayout: CoordinatorLayout,
+        child: BottomNavigationView,
+        target: View,
+        dx: Int,
+        dy: Int,
+        consumed: IntArray,
+        type: Int
+    ) {
+        super.onNestedPreScroll(coordinatorLayout, child, target, dx, dy, consumed, type)
+        child.translationY = (child.translationY + dy).coerceIn(0F, child.height.toFloat())
+    }
+}