Hide toolbar when scrolling up

app/src/main/kotlin/org/koitharu/kotatsu/core/ui/util/FadingAppbarHelper.kt

@@ -0,0 +1,22 @@
+package org.koitharu.kotatsu.core.ui.util
+
+import android.view.View
+import com.google.android.material.appbar.AppBarLayout
+
+class FadingAppbarHelper(
+	private val target: View
+) : AppBarLayout.OnOffsetChangedListener {
+
+	fun setup(appBarLayout: AppBarLayout) {
+		appBarLayout.addOnOffsetChangedListener(this)
+	}
+
+	override fun onOffsetChanged(appBarLayout: AppBarLayout?, verticalOffset: Int) {
+		val scrollRange = appBarLayout?.totalScrollRange
+		if (scrollRange == null || scrollRange == 0) {
+			return
+		}
+
+		target.alpha = 1f + verticalOffset / (scrollRange / 2f)
+	}
+}

app/src/main/kotlin/org/koitharu/kotatsu/main/ui/MainActivity.kt

@@ -42,6 +42,7 @@ import org.koitharu.kotatsu.core.exceptions.resolve.SnackbarErrorObserver
 import org.koitharu.kotatsu.core.prefs.AppSettings
 import org.koitharu.kotatsu.core.prefs.NavItem
 import org.koitharu.kotatsu.core.ui.BaseActivity
+import org.koitharu.kotatsu.core.ui.util.FadingAppbarHelper
 import org.koitharu.kotatsu.core.ui.util.MenuInvalidator
 import org.koitharu.kotatsu.core.ui.util.OptionsMenuBadgeHelper
 import org.koitharu.kotatsu.core.ui.widgets.SlidingBottomNavigationView
@@ -105,6 +106,7 @@ class MainActivity : BaseActivity<ActivityMainBinding>(), AppBarOwner, BottomNav
 
 		viewBinding.fab?.setOnClickListener(this)
 		viewBinding.navRail?.headerView?.setOnClickListener(this)
+		FadingAppbarHelper(viewBinding.toolbarCard).setup(viewBinding.appbar)
 
 		navigationDelegate = MainNavigationDelegate(
 			navBar = checkNotNull(bottomNav ?: viewBinding.navRail),
@@ -376,9 +378,6 @@ class MainActivity : BaseActivity<ActivityMainBinding>(), AppBarOwner, BottomNav
 		viewBinding.toolbarCard.updateLayoutParams<AppBarLayout.LayoutParams> {
 			scrollFlags = appBarScrollFlags
 		}
-		viewBinding.insetsHolder.updateLayoutParams<AppBarLayout.LayoutParams> {
-			scrollFlags = appBarScrollFlags
-		}
 		viewBinding.toolbarCard.background = if (isOpened) {
 			null
 		} else {

app/src/main/kotlin/org/koitharu/kotatsu/settings/sources/catalog/SourcesCatalogActivity.kt

@@ -18,6 +18,7 @@ import org.koitharu.kotatsu.R
 import org.koitharu.kotatsu.core.model.titleResId
 import org.koitharu.kotatsu.core.ui.BaseActivity
 import org.koitharu.kotatsu.core.ui.list.OnListItemClickListener
+import org.koitharu.kotatsu.core.ui.util.FadingAppbarHelper
 import org.koitharu.kotatsu.core.ui.util.ReversibleActionObserver
 import org.koitharu.kotatsu.core.ui.widgets.ChipsView
 import org.koitharu.kotatsu.core.ui.widgets.ChipsView.ChipModel
@@ -57,6 +58,7 @@ class SourcesCatalogActivity : BaseActivity<ActivitySourcesCatalogBinding>(),
 			adapter = sourcesAdapter
 		}
 		viewBinding.chipsFilter.onChipClickListener = this
+		FadingAppbarHelper(viewBinding.toolbar).setup(appBar)
 		viewModel.content.observe(this, sourcesAdapter)
 		viewModel.onActionDone.observeEvent(
 			this,

app/src/main/kotlin/org/koitharu/kotatsu/settings/sources/catalog/SourcesCatalogMenuProvider.kt

@@ -30,7 +30,7 @@ class SourcesCatalogMenuProvider(
 	override fun onMenuItemSelected(menuItem: MenuItem): Boolean = false
 
 	override fun onMenuItemActionExpand(item: MenuItem): Boolean {
-		(activity as? AppBarOwner)?.appBar?.setExpanded(false, true)
+		(activity as? AppBarOwner)?.appBar?.setExpanded(true, true)
 		return expandListener.onMenuItemActionExpand(item)
 	}
 

app/src/main/res/layout-w600dp-land/activity_main.xml

@@ -39,13 +39,6 @@
 			android:stateListAnimator="@null"
 			app:liftOnScroll="false">
 
-			<org.koitharu.kotatsu.core.ui.widgets.WindowInsetHolder
-				android:id="@+id/insetsHolder"
-				android:layout_width="match_parent"
-				android:layout_height="wrap_content"
-				android:layout_gravity="top"
-				app:layout_scrollFlags="scroll|enterAlways|snap" />
-
 			<FrameLayout
 				android:id="@+id/toolbar_card"
 				android:layout_width="match_parent"

app/src/main/res/layout/activity_main.xml

@@ -19,18 +19,11 @@
 		android:layout_width="match_parent"
 		android:layout_height="wrap_content"
 		android:clipToPadding="false"
-		android:fitsSystemWindows="false"
+		android:fitsSystemWindows="true"
 		android:paddingHorizontal="16dp"
 		android:stateListAnimator="@null"
 		app:liftOnScroll="false">
 
-		<org.koitharu.kotatsu.core.ui.widgets.WindowInsetHolder
-			android:id="@+id/insetsHolder"
-			android:layout_width="match_parent"
-			android:layout_height="wrap_content"
-			android:layout_gravity="top"
-			app:layout_scrollFlags="scroll|enterAlways|snap" />
-
 		<FrameLayout
 			android:id="@+id/toolbar_card"
 			android:layout_width="match_parent"