ui: add toolbar visual skeleton for selection

Add an overlay toolbar to indicate when selection is occuring.

This has no functionality as of right now.

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

@@ -58,6 +58,7 @@ import org.oxycblt.auxio.music.system.Indexer
 import org.oxycblt.auxio.playback.PlaybackViewModel
 import org.oxycblt.auxio.ui.MainNavigationAction
 import org.oxycblt.auxio.ui.NavigationViewModel
+import org.oxycblt.auxio.ui.SelectionViewModel
 import org.oxycblt.auxio.ui.fragment.ViewBindingFragment
 import org.oxycblt.auxio.util.androidActivityViewModels
 import org.oxycblt.auxio.util.collect
@@ -75,6 +76,7 @@ class HomeFragment : ViewBindingFragment<FragmentHomeBinding>(), Toolbar.OnMenuI
     private val playbackModel: PlaybackViewModel by androidActivityViewModels()
     private val navModel: NavigationViewModel by activityViewModels()
     private val homeModel: HomeViewModel by androidActivityViewModels()
+    private val selectionModel: SelectionViewModel by activityViewModels()
     private val musicModel: MusicViewModel by activityViewModels()
 
     // lifecycleObject builds this in the creation step, so doing this is okay.
@@ -109,7 +111,7 @@ class HomeFragment : ViewBindingFragment<FragmentHomeBinding>(), Toolbar.OnMenuI
             addOnOffsetChangedListener { _, offset ->
                 val range = binding.homeAppbar.totalScrollRange
 
-                binding.homeToolbar.alpha = 1f - (abs(offset.toFloat()) / (range.toFloat() / 2))
+                binding.homeToolbarOverlay.alpha = 1f - (abs(offset.toFloat()) / (range.toFloat() / 2))
 
                 binding.homeContent.updatePadding(
                     bottom = binding.homeAppbar.totalScrollRange + offset)
@@ -158,6 +160,7 @@ class HomeFragment : ViewBindingFragment<FragmentHomeBinding>(), Toolbar.OnMenuI
         collectImmediately(homeModel.currentTab, ::updateCurrentTab)
         collectImmediately(homeModel.songs, homeModel.isFastScrolling, ::updateFab)
         collectImmediately(musicModel.indexerState, ::handleIndexerState)
+        collectImmediately(selectionModel.selected, ::updateSelection)
         collect(navModel.exploreNavigationItem, ::handleNavigation)
     }
 
@@ -276,7 +279,7 @@ class HomeFragment : ViewBindingFragment<FragmentHomeBinding>(), Toolbar.OnMenuI
 
     private fun updateTabConfiguration() {
         val binding = requireBinding()
-        val toolbarParams = binding.homeToolbar.layoutParams as AppBarLayout.LayoutParams
+        val toolbarParams = binding.homeToolbarOverlay.layoutParams as AppBarLayout.LayoutParams
         if (homeModel.tabs.size == 1) {
             // A single tag makes the tab layout redundant, hide it and disable the collapsing
             // behavior.
@@ -382,6 +385,10 @@ class HomeFragment : ViewBindingFragment<FragmentHomeBinding>(), Toolbar.OnMenuI
         }
     }
 
+    private fun updateSelection(selected: List<Music>) {
+        requireBinding().homeToolbarOverlay.updateSelectionAmount(selected.size)
+    }
+
     private fun handleNavigation(item: Music?) {
         val action =
             when (item) {

app/src/main/java/org/oxycblt/auxio/image/ImageGroup.kt

@@ -17,6 +17,7 @@
  
 package org.oxycblt.auxio.image
 
+import android.animation.ValueAnimator
 import android.annotation.SuppressLint
 import android.content.Context
 import android.util.AttributeSet
@@ -61,6 +62,8 @@ constructor(context: Context, attrs: AttributeSet? = null, @AttrRes defStyleAttr
     private val playingIndicator: IndicatorView
     private val selectionIndicator: ImageView
 
+    private var fadeAnimator: ValueAnimator? = null
+
     init {
         // Android wants you to make separate attributes for each view type, but will
         // then throw an error if you do because of duplicate attribute names.
@@ -156,27 +159,40 @@ constructor(context: Context, attrs: AttributeSet? = null, @AttrRes defStyleAttr
     }
 
     private fun invalidateSelectionIndicator() {
-        val targetVis: Int
+        val targetAlpha: Float
         val targetDuration: Long
 
         if (isActivated) {
-            targetVis = VISIBLE
+            targetAlpha = 1f
             targetDuration =
                 context.resources.getInteger(R.integer.anim_fade_enter_duration).toLong()
         } else {
-            targetVis = INVISIBLE
+            targetAlpha = 0f
             targetDuration =
                 context.resources.getInteger(R.integer.anim_fade_exit_duration).toLong()
         }
 
-        if (selectionIndicator.visibility == targetVis) {
+        if (selectionIndicator.alpha == targetAlpha) {
             return
         }
 
-        TransitionManager.beginDelayedTransition(
+        if (!isLaidOut) {
-            this, MaterialFade().apply { duration = targetDuration })
+            selectionIndicator.alpha = targetAlpha
+            return
+        }
 
-        selectionIndicator.visibility = targetVis
+        if (fadeAnimator != null) {
+            fadeAnimator?.cancel()
+            fadeAnimator = null
+        }
+
+        fadeAnimator = ValueAnimator.ofFloat(selectionIndicator.alpha, targetAlpha).apply {
+            duration = targetDuration
+            addUpdateListener {
+                selectionIndicator.alpha = it.animatedValue as Float
+            }
+            start()
+        }
     }
 
     fun bind(song: Song) {

app/src/main/java/org/oxycblt/auxio/ui/SelectionToolbarOverlay.kt

@@ -0,0 +1,118 @@
+package org.oxycblt.auxio.ui
+
+import android.animation.ValueAnimator
+import android.content.Context
+import android.util.AttributeSet
+import android.widget.FrameLayout
+import androidx.annotation.AttrRes
+import androidx.appcompat.widget.Toolbar
+import androidx.core.view.isInvisible
+import androidx.transition.TransitionManager
+import com.google.android.material.appbar.MaterialToolbar
+import com.google.android.material.transition.MaterialFadeThrough
+import org.oxycblt.auxio.R
+import org.oxycblt.auxio.util.logD
+import kotlin.math.max
+import kotlin.math.min
+
+/**
+ * A wrapper around a Toolbar that enables an overlaid toolbar showing information about
+ * an item selection.
+ * @author OxygenCobalt
+ */
+class SelectionToolbarOverlay
+@JvmOverloads
+constructor(context: Context, attrs: AttributeSet? = null, @AttrRes defStyleAttr: Int = 0) :
+    FrameLayout(context, attrs, defStyleAttr){
+    private lateinit var innerToolbar: MaterialToolbar
+    private val selectionToolbar = MaterialToolbar(context).apply { 
+        inflateMenu(R.menu.menu_selection_actions)
+        setNavigationIcon(R.drawable.ic_close_24)
+    }
+
+    private var fadeThroughAnimator: ValueAnimator? = null
+
+    override fun onFinishInflate() {
+        super.onFinishInflate()
+        check(childCount == 1 && getChildAt(0) is MaterialToolbar) {
+            "SelectionToolbarOverlay Must have only one MaterialToolbar child"
+        }
+
+        innerToolbar = getChildAt(0) as MaterialToolbar
+        addView(selectionToolbar)
+    }
+
+    /**
+     * Add listeners for the selection toolbar.
+     */
+    fun setListeners(onExit: Toolbar.OnMenuItemClickListener,
+                     onMenuItemClick: Toolbar.OnMenuItemClickListener) {
+        // TODO: Sub
+    }
+
+    /**
+     * Update the selection amount in the selection Toolbar. This will animate the selection
+     * Toolbar into focus if there is now a selection to show.
+     */
+    fun updateSelectionAmount(amount: Int): Boolean {
+        logD("Updating selection amount to $amount")
+        return if (amount > 0) {
+            selectionToolbar.title = context.getString(R.string.fmt_selected, amount)
+            animateToolbarVisibility(true)
+        } else {
+            animateToolbarVisibility(false)
+        }
+    }
+
+    private fun animateToolbarVisibility(selectionVisible: Boolean): Boolean {
+        // TODO: Animate nicer Material Fade transitions using animators (Normal transitions
+        //  don't work due to translation)
+        val targetInnerAlpha: Float
+        val targetSelectionAlpha: Float
+
+        if (selectionVisible) {
+            targetInnerAlpha = 0f
+            targetSelectionAlpha = 1f
+        } else {
+            targetInnerAlpha = 1f
+            targetSelectionAlpha = 0f
+        }
+
+        if (innerToolbar.alpha == targetInnerAlpha &&
+            selectionToolbar.alpha == targetSelectionAlpha) {
+            return false
+        }
+
+        if (!isLaidOut) {
+            changeToolbarAlpha(targetInnerAlpha)
+            return true
+        }
+
+        if (fadeThroughAnimator != null) {
+            fadeThroughAnimator?.cancel()
+            fadeThroughAnimator = null
+        }
+
+        fadeThroughAnimator = ValueAnimator.ofFloat(innerToolbar.alpha, targetInnerAlpha).apply {
+            duration = context.resources.getInteger(R.integer.anim_fade_enter_duration).toLong()
+            addUpdateListener {
+                changeToolbarAlpha(it.animatedValue as Float)
+            }
+            start()
+        }
+
+        return true
+    }
+
+    private fun changeToolbarAlpha(innerAlpha: Float ) {
+        innerToolbar.apply {
+            alpha = innerAlpha
+            isInvisible = innerAlpha == 0f
+        }
+
+        selectionToolbar.apply {
+            alpha = 1 - innerAlpha
+            isInvisible = innerAlpha == 1f
+        }
+    }
+}

app/src/main/res/drawable/ic_play_next_24.xml

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="utf-8"?>
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="24"
+    android:viewportHeight="24"
+    android:tint="?attr/colorControlNormal">
+  <path
+      android:fillColor="@android:color/white"
+      android:pathData="M13,14H15V11H18V9H15V6H13V9H10V11H13ZM8,18Q7.175,18 6.588,17.413Q6,16.825 6,16V4Q6,3.175 6.588,2.587Q7.175,2 8,2H20Q20.825,2 21.413,2.587Q22,3.175 22,4V16Q22,16.825 21.413,17.413Q20.825,18 20,18ZM8,16H20Q20,16 20,16Q20,16 20,16V4Q20,4 20,4Q20,4 20,4H8Q8,4 8,4Q8,4 8,4V16Q8,16 8,16Q8,16 8,16ZM4,22Q3.175,22 2.588,21.413Q2,20.825 2,20V6H4V20Q4,20 4,20Q4,20 4,20H18V22ZM8,4Q8,4 8,4Q8,4 8,4V16Q8,16 8,16Q8,16 8,16Q8,16 8,16Q8,16 8,16V4Q8,4 8,4Q8,4 8,4Z"/>
+</vector>

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

@@ -13,13 +13,20 @@
         style="@style/Widget.Auxio.AppBarLayout"
         android:fitsSystemWindows="true">
 
-        <com.google.android.material.appbar.MaterialToolbar
+        <org.oxycblt.auxio.ui.SelectionToolbarOverlay
-            android:id="@+id/home_toolbar"
+            android:id="@+id/home_toolbar_overlay"
             android:layout_width="match_parent"
-            android:layout_height="wrap_content"
+            android:layout_height="wrap_content">
-            app:layout_scrollFlags="scroll|enterAlways"
+
-            app:menu="@menu/menu_home"
+            <com.google.android.material.appbar.MaterialToolbar
-            app:title="@string/info_app_name" />
+                android:id="@+id/home_toolbar"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                app:layout_scrollFlags="scroll|enterAlways"
+                app:menu="@menu/menu_home"
+                app:title="@string/info_app_name" />
+
+        </org.oxycblt.auxio.ui.SelectionToolbarOverlay>
 
         <com.google.android.material.tabs.TabLayout
             android:id="@+id/home_tabs"

app/src/main/res/menu/menu_selection_actions.xml

@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="utf-8"?>
+<menu xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto">
+    <item
+        android:id="@+id/action_play_next"
+        android:title="@string/lbl_play_next"
+        android:icon="@drawable/ic_play_next_24"
+        app:showAsAction="ifRoom"/>
+    <item
+        android:id="@+id/action_queue_add"
+        android:title="@string/lbl_queue_add"
+        app:showAsAction="never" />
+    <item
+        android:id="@+id/action_play"
+        android:title="@string/lbl_play_selected"
+        app:showAsAction="never"/>
+    <item
+        android:id="@+id/action_shuffle"
+        android:title="@string/lbl_shuffle_selected"
+        app:showAsAction="never"/>
+</menu>

app/src/main/res/values/strings.xml

@@ -96,7 +96,9 @@
     <string name="lbl_playback">Now playing</string>
     <string name="lbl_equalizer">Equalizer</string>
     <string name="lbl_play">Play</string>
+    <string name="lbl_play_selected">Play selected</string>
     <string name="lbl_shuffle">Shuffle</string>
+    <string name="lbl_shuffle_selected">Shuffle selected</string>
 
     <string name="lbl_queue">Queue</string>
     <string name="lbl_play_next">Play next</string>
@@ -338,6 +340,9 @@
     <!-- Format Namespace | Value formatting/plurals -->
     <eat-comment />
 
+    <!-- As in an amount of items that are selected -->
+    <string name="fmt_selected">%d Selected</string>
+
     <!-- As in "Disc 1", "Disc 2", etc. in a set -->
     <string name="fmt_disc_no">Disc %d</string>