search: improve ui

Improve the search UI by making it edge-to-edge and adding the
liftOnScroll idiom. It does come with the caveat of walking on
eggshells to get the liftOnScroll code working, but its okay. It
may be improved in the future.

app/src/main/java/org/oxycblt/auxio/detail/DetailFragment.kt

@@ -22,6 +22,7 @@ import android.os.Bundle
 import android.view.View
 import androidx.activity.OnBackPressedCallback
 import androidx.annotation.MenuRes
+import androidx.core.view.updatePadding
 import androidx.fragment.app.Fragment
 import androidx.fragment.app.activityViewModels
 import androidx.navigation.fragment.findNavController
@@ -30,6 +31,7 @@ import androidx.recyclerview.widget.RecyclerView
 import org.oxycblt.auxio.databinding.FragmentDetailBinding
 import org.oxycblt.auxio.playback.PlaybackViewModel
 import org.oxycblt.auxio.ui.memberBinding
+import org.oxycblt.auxio.util.applyEdge
 import org.oxycblt.auxio.util.isLandscape
 
 /**
@@ -42,6 +44,10 @@ abstract class DetailFragment : Fragment() {
     protected val binding by memberBinding(FragmentDetailBinding::inflate)
 
     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+        binding.applyEdge { bars ->
+            binding.detailAppbar.updatePadding(top = bars.top)
+        }
+
         requireActivity().onBackPressedDispatcher.addCallback(viewLifecycleOwner, callback)
     }
 

app/src/main/java/org/oxycblt/auxio/home/HomeFragment.kt

@@ -29,7 +29,6 @@ import androidx.navigation.fragment.findNavController
 import androidx.recyclerview.widget.RecyclerView
 import androidx.viewpager2.adapter.FragmentStateAdapter
 import androidx.viewpager2.widget.ViewPager2
-import com.google.android.material.appbar.AppBarLayout
 import com.google.android.material.tabs.TabLayoutMediator
 import org.oxycblt.auxio.MainFragmentDirections
 import org.oxycblt.auxio.R
@@ -44,6 +43,7 @@ import org.oxycblt.auxio.ui.DisplayMode
 import org.oxycblt.auxio.util.applyEdge
 import org.oxycblt.auxio.util.logD
 import org.oxycblt.auxio.util.logE
+import org.oxycblt.auxio.util.makeScrollingViewFade
 
 /**
  * The main "Launching Point" fragment of Auxio, allowing navigation to the detail
@@ -74,16 +74,7 @@ class HomeFragment : Fragment() {
             binding.homeAppbar.updatePadding(top = bars.top)
         }
 
-        // There is basically no way to prevent the toolbar to draw under the status bar when
-        // it collapses, so do the next best thing and fade it out so it doesn't stick out like
-        // a sore thumb. As a side effect, this looks really cool.
-        binding.homeAppbar.addOnOffsetChangedListener(
-            AppBarLayout.OnOffsetChangedListener { _, verticalOffset ->
-                binding.homeToolbar.apply {
-                    alpha = (height + verticalOffset) / height.toFloat()
-                }
-            }
-        )
+        binding.homeAppbar.makeScrollingViewFade(binding.homeToolbar)
 
         binding.homeToolbar.setOnMenuItemClickListener { item ->
             when (item.itemId) {

app/src/main/java/org/oxycblt/auxio/playback/queue/QueueFragment.kt

@@ -27,6 +27,7 @@ import androidx.fragment.app.Fragment
 import androidx.fragment.app.activityViewModels
 import androidx.navigation.fragment.findNavController
 import androidx.recyclerview.widget.ItemTouchHelper
+import kotlinx.coroutines.NonDisposableHandle.parent
 import org.oxycblt.auxio.R
 import org.oxycblt.auxio.databinding.FragmentQueueBinding
 import org.oxycblt.auxio.music.BaseModel
@@ -105,6 +106,7 @@ class QueueFragment : Fragment() {
                 lastShuffle = isShuffling
 
                 binding.queueRecycler.scrollToPosition(0)
+                binding.queueAppbar.isLifted = false // Make sure lifted state changes.
             }
         }
 

app/src/main/java/org/oxycblt/auxio/search/SearchFragment.kt

@@ -24,6 +24,7 @@ import android.view.View
 import android.view.ViewGroup
 import android.view.inputmethod.InputMethodManager
 import androidx.core.view.postDelayed
+import androidx.core.view.updatePadding
 import androidx.core.widget.addTextChangedListener
 import androidx.fragment.app.Fragment
 import androidx.fragment.app.activityViewModels
@@ -42,9 +43,11 @@ import org.oxycblt.auxio.music.Song
 import org.oxycblt.auxio.playback.PlaybackViewModel
 import org.oxycblt.auxio.ui.DisplayMode
 import org.oxycblt.auxio.ui.newMenu
+import org.oxycblt.auxio.util.applyEdge
 import org.oxycblt.auxio.util.applySpans
 import org.oxycblt.auxio.util.getSystemServiceSafe
 import org.oxycblt.auxio.util.logD
+import org.oxycblt.auxio.util.makeScrollingViewFade
 
 /**
  * A [Fragment] that allows for the searching of the entire music library.
@@ -79,6 +82,12 @@ class SearchFragment : Fragment() {
 
         binding.lifecycleOwner = viewLifecycleOwner
 
+        binding.applyEdge { bars ->
+            binding.searchAppbar.updatePadding(top = bars.top)
+        }
+
+        binding.searchAppbar.makeScrollingViewFade(binding.searchToolbar)
+
         binding.searchToolbar.apply {
             val itemId = when (searchModel.filterMode) {
                 DisplayMode.SHOW_SONGS -> R.id.option_filter_songs
@@ -131,18 +140,18 @@ class SearchFragment : Fragment() {
 
         searchModel.searchResults.observe(viewLifecycleOwner) { results ->
             searchAdapter.submitList(results) {
+                // We've just scrolled back to the top, reset the lifted state
+                // TODO: Maybe find a better way to keep scroll state when the search
+                //  results didn't actually change.
                 binding.searchRecycler.scrollToPosition(0)
+                binding.searchAppbar.isLifted = false
             }
 
             if (results.isEmpty()) {
-                // If the data is empty, then the ability for the toolbar to collapse
-                // on scroll should be disabled.
                 binding.searchAppbar.setExpanded(true)
                 binding.searchRecycler.visibility = View.GONE
-                toolbarParams.scrollFlags = AppBarLayout.LayoutParams.SCROLL_FLAG_NO_SCROLL
             } else {
                 binding.searchRecycler.visibility = View.VISIBLE
-                toolbarParams.scrollFlags = defaultParams
             }
         }
 

app/src/main/java/org/oxycblt/auxio/util/ViewUtil.kt

@@ -32,11 +32,13 @@ import androidx.annotation.AttrRes
 import androidx.annotation.ColorInt
 import androidx.annotation.ColorRes
 import androidx.annotation.DrawableRes
+import androidx.coordinatorlayout.widget.CoordinatorLayout
 import androidx.core.content.ContextCompat
 import androidx.core.view.updatePadding
 import androidx.recyclerview.widget.GridLayoutManager
 import androidx.recyclerview.widget.RecyclerView
 import androidx.viewbinding.ViewBinding
+import com.google.android.material.appbar.AppBarLayout
 import org.oxycblt.auxio.R
 
 /**
@@ -140,6 +142,33 @@ fun @receiver:AttrRes Int.resolveAttr(context: Context): Int {
     return color.resolveColor(context)
 }
 
+/**
+ * Make this [AppBarLayout] fade a scrolling [view] out when it collapses.
+ * This is mostly because I am unable to figure out how to get a collapsing view not
+ * to draw under the status bar in edge-to-edge mode.
+ */
+fun AppBarLayout.makeScrollingViewFade(view: View) {
+    addOnOffsetChangedListener(
+        AppBarLayout.OnOffsetChangedListener { _, verticalOffset ->
+            view.alpha = (view.height + verticalOffset) / view.height.toFloat()
+        }
+    )
+}
+
+/**
+ * Force-update this [AppBarLayout]'s lifted state. This is useful when the dataset changes
+ * and the lifted state must be updated.
+ */
+fun AppBarLayout.updateLiftedState(recycler: RecyclerView) {
+    post {
+        val coordinator = (parent as CoordinatorLayout)
+
+        (layoutParams as CoordinatorLayout.LayoutParams).behavior?.onNestedPreScroll(
+            coordinator, this, recycler, 0, 0, IntArray(2), 0
+        )
+    }
+}
+
 /**
  * Apply edge-to-edge tweaks to the root of a [ViewBinding].
  * @param onApply What to do when the system bar insets are provided

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

@@ -12,7 +12,7 @@
             android:layout_width="match_parent"
             android:layout_height="wrap_content"
             android:background="?attr/colorSurface"
-            android:elevation="@dimen/elevation_normal">
+            app:liftOnScroll="true">
 
             <androidx.appcompat.widget.Toolbar
                 android:id="@+id/search_toolbar"