Add support for swipe-to-change-song on preview sheet

app/src/main/java/org/akanework/gramophone/ui/adapters/TrackInfoAdapter.kt

@@ -0,0 +1,107 @@
+package org.akanework.gramophone.ui.adapters
+
+import android.content.Context
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import android.widget.TextView
+import androidx.media3.common.C
+import androidx.media3.common.MediaItem
+import androidx.media3.common.Player
+import androidx.media3.session.MediaController
+import androidx.recyclerview.widget.DiffUtil
+import androidx.recyclerview.widget.RecyclerView
+import org.akanework.gramophone.R
+
+class TrackInfoAdapter(private val context: Context) :
+    RecyclerView.Adapter<TrackInfoAdapter.TrackViewHolder>() {
+    private var mediaItems = listOf<MediaItem>()
+    private var shuffleIndices: List<Int>? = null
+    private var currentPlayingPosition = 0
+
+    fun updatePlaylist(controller: MediaController?) {
+        val newItems = if (controller != null && controller.mediaItemCount > 0) {
+            val timeline = controller.currentTimeline
+            val shuffleEnabled = controller.shuffleModeEnabled
+            val items = mutableListOf<MediaItem>()
+            val indices = if (shuffleEnabled) mutableListOf<Int>() else null
+
+            var index = timeline.getFirstWindowIndex(shuffleEnabled)
+            var position = 0
+
+            while (index != C.INDEX_UNSET) {
+                items.add(controller.getMediaItemAt(index))
+                indices?.add(index)
+                if (index == controller.currentMediaItemIndex) {
+                    currentPlayingPosition = position
+                }
+                index = timeline.getNextWindowIndex(
+                    index,
+                    Player.REPEAT_MODE_OFF,
+                    shuffleEnabled)
+                position++
+            }
+
+            shuffleIndices = indices
+            items
+        } else {
+            currentPlayingPosition = 0
+            shuffleIndices = null
+            emptyList()
+        }
+
+        val diffCallback = TrackDiffCallback(mediaItems, newItems)
+        val diffResult = DiffUtil.calculateDiff(diffCallback)
+
+        mediaItems = newItems
+        diffResult.dispatchUpdatesTo(this)
+    }
+
+    fun getCurrentPosition(): Int = currentPlayingPosition
+
+    fun getCurrentIndex(pos: Int) = shuffleIndices?.getOrNull(pos) ?: pos
+
+    override fun getItemCount() = mediaItems.size
+
+    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): TrackViewHolder {
+        val view = LayoutInflater.from(parent.context)
+            .inflate(R.layout.item_track_info, parent, false)
+        return TrackViewHolder(view)
+    }
+
+    override fun onBindViewHolder(holder: TrackViewHolder, position: Int) {
+        holder.bind(mediaItems[position])
+    }
+
+    inner class TrackViewHolder(view: View) : RecyclerView.ViewHolder(view) {
+        private val titleView: TextView = view.findViewById(R.id.track_title)
+        private val artistView: TextView = view.findViewById(R.id.track_artist)
+
+        fun bind(mediaItem: MediaItem) {
+            titleView.text = mediaItem.mediaMetadata.title
+            artistView.text = mediaItem.mediaMetadata.artist
+                ?: context.getString(R.string.unknown_artist)
+        }
+    }
+
+    private class TrackDiffCallback(
+        private val oldList: List<MediaItem>,
+        private val newList: List<MediaItem>
+    ) : DiffUtil.Callback() {
+
+        override fun getOldListSize() = oldList.size
+
+        override fun getNewListSize() = newList.size
+
+        override fun areItemsTheSame(oldItemPosition: Int, newItemPosition: Int): Boolean {
+            return oldList[oldItemPosition].mediaId == newList[newItemPosition].mediaId
+        }
+
+        override fun areContentsTheSame(oldItemPosition: Int, newItemPosition: Int): Boolean {
+            val oldItem = oldList[oldItemPosition]
+            val newItem = newList[newItemPosition]
+            return oldItem.mediaMetadata.title == newItem.mediaMetadata.title &&
+                    oldItem.mediaMetadata.artist == newItem.mediaMetadata.artist
+        }
+    }
+}

app/src/main/java/org/akanework/gramophone/ui/components/PlayerBottomSheet.kt

@@ -158,11 +158,13 @@ class PlayerBottomSheet private constructor(
                     previewPlayer.alpha = 1f
                     fullPlayer.alpha = 0f
                     bottomSheetBackCallback!!.isEnabled = false
+                    (previewPlayer as? PreviewBottomSheet)?.setSwipeEnabled(true)
                 }
 
                 BottomSheetBehavior.STATE_DRAGGING, BottomSheetBehavior.STATE_SETTLING -> {
                     fullPlayer.visibility = VISIBLE
                     previewPlayer.visibility = VISIBLE
+                    (previewPlayer as? PreviewBottomSheet)?.setSwipeEnabled(false)
                 }
 
                 BottomSheetBehavior.STATE_EXPANDED, BottomSheetBehavior.STATE_HALF_EXPANDED -> {
@@ -171,6 +173,7 @@ class PlayerBottomSheet private constructor(
                     previewPlayer.alpha = 0f
                     fullPlayer.alpha = 1f
                     bottomSheetBackCallback!!.isEnabled = true
+                    (previewPlayer as? PreviewBottomSheet)?.setSwipeEnabled(false)
                 }
 
                 BottomSheetBehavior.STATE_HIDDEN -> {

app/src/main/java/org/akanework/gramophone/ui/components/PreviewBottomSheet.kt

@@ -3,14 +3,15 @@ package org.akanework.gramophone.ui.components
 import android.content.Context
 import android.util.AttributeSet
 import android.widget.ImageView
-import android.widget.TextView
 import androidx.appcompat.content.res.AppCompatResources
 import androidx.constraintlayout.widget.ConstraintLayout
 import androidx.core.view.HapticFeedbackConstantsCompat
 import androidx.core.view.ViewCompat
 import androidx.media3.common.MediaItem
 import androidx.media3.common.Player
+import androidx.media3.common.Timeline
 import androidx.media3.session.MediaController
+import androidx.viewpager2.widget.ViewPager2
 import coil3.asDrawable
 import coil3.imageLoader
 import coil3.request.Disposable
@@ -23,18 +24,22 @@ import org.akanework.gramophone.R
 import org.akanework.gramophone.logic.playOrPause
 import org.akanework.gramophone.logic.startAnimation
 import org.akanework.gramophone.ui.MainActivity
+import org.akanework.gramophone.ui.adapters.TrackInfoAdapter
 
 class PreviewBottomSheet(context: Context, attrs: AttributeSet?, defStyleAttr: Int, defStyleRes: Int) :
 	ConstraintLayout(context, attrs, defStyleAttr, defStyleRes), Player.Listener {
+
 	private val activity
 		get() = context as MainActivity
 	private val instance: MediaController?
 		get() = activity.getPlayer()
+
 	private val bottomSheetPreviewCover: ImageView
-	private val bottomSheetPreviewTitle: TextView
-	private val bottomSheetPreviewSubtitle: TextView
 	private val bottomSheetPreviewControllerButton: MaterialButton
 	private val bottomSheetPreviewNextButton: MaterialButton
+	private val trackInfoPager: ViewPager2
+	private val trackAdapter: TrackInfoAdapter
+
 	private var lastDisposable: Disposable? = null
 
 	constructor(context: Context, attrs: AttributeSet?, defStyleAttr: Int) :
@@ -44,11 +49,31 @@ class PreviewBottomSheet(context: Context, attrs: AttributeSet?, defStyleAttr: I
 
 	init {
 		inflate(context, R.layout.preview_player, this)
-		bottomSheetPreviewTitle = findViewById(R.id.preview_song_name)
-		bottomSheetPreviewSubtitle = findViewById(R.id.preview_artist_name)
+
 		bottomSheetPreviewCover = findViewById(R.id.preview_album_cover)
 		bottomSheetPreviewControllerButton = findViewById(R.id.preview_control)
 		bottomSheetPreviewNextButton = findViewById(R.id.preview_next)
+		trackInfoPager = findViewById(R.id.track_info_pager)
+
+		trackAdapter = TrackInfoAdapter(context)
+		trackInfoPager.adapter = trackAdapter
+		trackInfoPager.offscreenPageLimit = 1
+
+		trackInfoPager.registerOnPageChangeCallback(object : ViewPager2.OnPageChangeCallback() {
+			override fun onPageSelected(position: Int) {
+				super.onPageSelected(position)
+				instance?.let { controller ->
+					if (position != trackAdapter.getCurrentPosition() &&
+						position < trackAdapter.itemCount) {
+						ViewCompat.performHapticFeedback(
+							trackInfoPager,
+							HapticFeedbackConstantsCompat.CONFIRM
+						)
+						controller.seekTo(trackAdapter.getCurrentIndex(position), 0)
+					}
+				}
+			}
+		})
 
 		bottomSheetPreviewControllerButton.setOnClickListener {
 			ViewCompat.performHapticFeedback(it, HapticFeedbackConstantsCompat.CONTEXT_CLICK)
@@ -93,7 +118,8 @@ class PreviewBottomSheet(context: Context, attrs: AttributeSet?, defStyleAttr: I
 		mediaItem: MediaItem?,
 		reason: @Player.MediaItemTransitionReason Int
 	) {
-		if ((instance?.mediaItemCount ?: 0) > 0) {
+		val controller = instance
+		if (controller != null && controller.mediaItemCount > 0) {
 			lastDisposable?.dispose()
 			lastDisposable = context.imageLoader.enqueue(ImageRequest.Builder(context).apply {
 				target(onSuccess = {
@@ -106,12 +132,43 @@ class PreviewBottomSheet(context: Context, attrs: AttributeSet?, defStyleAttr: I
 				allowHardware(bottomSheetPreviewCover.isHardwareAccelerated)
 				error(R.drawable.ic_default_cover)
 			}.build())
-			bottomSheetPreviewTitle.text = mediaItem?.mediaMetadata?.title
-			bottomSheetPreviewSubtitle.text =
-				mediaItem?.mediaMetadata?.artist ?: context.getString(R.string.unknown_artist)
+
+			if (trackAdapter.itemCount == 0) {
+				trackAdapter.updatePlaylist(controller)
+				trackInfoPager.setCurrentItem(trackAdapter.getCurrentPosition(), false)
+			} else {
+				post {
+					trackAdapter.updatePlaylist(controller)
+					if (trackInfoPager.currentItem != trackAdapter.getCurrentPosition()) {
+						trackInfoPager.setCurrentItem(
+							trackAdapter.getCurrentPosition(),
+							true
+						)
+					}
+				}
+			}
 		} else {
 			lastDisposable?.dispose()
 			lastDisposable = null
+			post {
+				trackAdapter.updatePlaylist(null)
+			}
+		}
+	}
+
+	override fun onTimelineChanged(timeline: Timeline, reason: Int) {
+		post {
+			trackAdapter.updatePlaylist(instance)
+			instance?.let { controller ->
+				if (controller.mediaItemCount > 0 &&
+					trackInfoPager.currentItem != trackAdapter.getCurrentPosition()) {
+					trackInfoPager.setCurrentItem(trackAdapter.getCurrentPosition(), false)
+				}
+			}
 		}
 	}
+
+	fun setSwipeEnabled(enabled: Boolean) {
+		trackInfoPager.isUserInputEnabled = enabled
+	}
 }

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

@@ -0,0 +1,24 @@
+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:gravity="center_vertical"
+    android:orientation="vertical">
+
+    <org.akanework.gramophone.ui.components.MarqueeTextView
+        android:id="@+id/track_title"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:textColor="?attr/colorOnSurface"
+        android:textSize="17sp"
+        tools:text="Example title" />
+
+    <org.akanework.gramophone.ui.components.MarqueeTextView
+        android:id="@+id/track_artist"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:textColor="?attr/colorOnSurfaceVariant"
+        tools:text="Example Artist" />
+
+</LinearLayout>

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

@@ -32,32 +32,15 @@
 
 	</com.google.android.material.card.MaterialCardView>
 
-	<!-- TODO remove useless LinearLayout -->
-	<LinearLayout
+	<androidx.viewpager2.widget.ViewPager2
+		android:id="@+id/track_info_pager"
 		android:layout_width="0dp"
 		android:layout_height="wrap_content"
 		android:layout_marginStart="18dp"
-		android:orientation="vertical"
 		app:layout_constraintBottom_toBottomOf="parent"
 		app:layout_constraintEnd_toStartOf="@id/preview_control"
 		app:layout_constraintStart_toEndOf="@id/preview_album_frame"
-		app:layout_constraintTop_toTopOf="parent">
-
-		<org.akanework.gramophone.ui.components.MarqueeTextView
-			android:id="@+id/preview_song_name"
-			android:layout_width="wrap_content"
-			android:layout_height="wrap_content"
-			android:textColor="?attr/colorOnSurface"
-			android:textSize="17sp"
-			tools:text="Example title" />
-
-		<org.akanework.gramophone.ui.components.MarqueeTextView
-			android:id="@+id/preview_artist_name"
-			android:layout_width="wrap_content"
-			android:layout_height="wrap_content"
-			android:textColor="?attr/colorOnSurfaceVariant"
-			tools:text="Example Artist" />
-	</LinearLayout>
+		app:layout_constraintTop_toTopOf="parent" />
 
 	<com.google.android.material.button.MaterialButton
 		android:id="@+id/preview_control"