Center selected item in media rail.

Fixes #12582

app/src/main/java/org/thoughtcrime/securesms/components/settings/conversation/ConversationSettingsFragment.kt

@@ -513,7 +513,7 @@ class ConversationSettingsFragment : DSLSettingsFragment(
             mediaIds = state.sharedMediaIds,
             onMediaRecordClick = { mediaRecord, isLtr ->
               startActivityForResult(
-                MediaIntentFactory.intentFromMediaRecord(requireContext(), mediaRecord, isLtr),
+                MediaIntentFactory.intentFromMediaRecord(requireContext(), mediaRecord, isLtr, allMediaInRail = true),
                 REQUEST_CODE_RETURN_FROM_MEDIA
               )
             }

app/src/main/java/org/thoughtcrime/securesms/mediapreview/MediaIntentFactory.kt

@@ -52,7 +52,8 @@ object MediaIntentFactory {
   fun intentFromMediaRecord(
     context: Context,
     mediaRecord: MediaRecord,
-    leftIsRecent: Boolean
+    leftIsRecent: Boolean,
+    allMediaInRail: Boolean
   ): Intent {
     val attachment: DatabaseAttachment = mediaRecord.attachment!!
     return create(
@@ -65,7 +66,7 @@ object MediaIntentFactory {
         attachment.size,
         attachment.caption,
         leftIsRecent,
-        allMediaInRail = true,
+        allMediaInRail = allMediaInRail,
         sorting = MediaDatabase.Sorting.Newest,
         isVideoGif = attachment.isVideoGif
       )

app/src/main/java/org/thoughtcrime/securesms/mediapreview/MediaPreviewV2Adapter.kt

@@ -4,6 +4,7 @@ import androidx.core.os.bundleOf
 import androidx.fragment.app.Fragment
 import androidx.viewpager2.adapter.FragmentStateAdapter
 import org.thoughtcrime.securesms.attachments.Attachment
+import org.thoughtcrime.securesms.mediasend.Media
 import org.thoughtcrime.securesms.util.MediaUtil
 
 class MediaPreviewV2Adapter(val fragment: Fragment) : FragmentStateAdapter(fragment) {
@@ -37,6 +38,10 @@ class MediaPreviewV2Adapter(val fragment: Fragment) : FragmentStateAdapter(fragm
     return fragment
   }
 
+  fun findItemPosition(media: Media): Int {
+    return items.indexOfFirst { it.uri == media.uri }
+  }
+
   fun updateBackingItems(newItems: Collection<Attachment>) {
     if (newItems != items) {
       items = newItems.toList()

app/src/main/java/org/thoughtcrime/securesms/mediapreview/MediaPreviewV2Fragment.kt

@@ -24,7 +24,8 @@ import androidx.core.view.WindowInsetsCompat
 import androidx.core.view.isVisible
 import androidx.fragment.app.Fragment
 import androidx.fragment.app.viewModels
-import androidx.recyclerview.widget.PagerSnapHelper
+import androidx.recyclerview.widget.LinearLayoutManager
+import androidx.recyclerview.widget.LinearSmoothScroller
 import androidx.recyclerview.widget.RecyclerView
 import androidx.viewpager2.widget.MarginPageTransformer
 import androidx.viewpager2.widget.ViewPager2.OFFSCREEN_PAGE_LIMIT_DEFAULT
@@ -42,7 +43,9 @@ import org.thoughtcrime.securesms.conversation.mutiselect.forward.MultiselectFor
 import org.thoughtcrime.securesms.conversation.mutiselect.forward.MultiselectForwardFragmentArgs
 import org.thoughtcrime.securesms.database.MediaDatabase
 import org.thoughtcrime.securesms.databinding.FragmentMediaPreviewV2Binding
-import org.thoughtcrime.securesms.mediapreview.MediaRailAdapter.ImageLoadingListener
+import org.thoughtcrime.securesms.mediapreview.mediarail.CenterDecoration
+import org.thoughtcrime.securesms.mediapreview.mediarail.MediaRailAdapter
+import org.thoughtcrime.securesms.mediapreview.mediarail.MediaRailAdapter.ImageLoadingListener
 import org.thoughtcrime.securesms.mediasend.Media
 import org.thoughtcrime.securesms.mediasend.v2.MediaSelectionActivity
 import org.thoughtcrime.securesms.mms.GlideApp
@@ -137,20 +140,11 @@ class MediaPreviewV2Fragment : Fragment(R.layout.fragment_media_preview_v2), Med
 
   private fun initializeAlbumRail() {
     binding.mediaPreviewPlaybackControls.recyclerView.apply {
-      this.itemAnimator = null // Or can crash when set to INVISIBLE while animating by FullscreenHelper https://issuetracker.google.com/issues/148720682
+      layoutManager = LinearLayoutManager(requireContext(), LinearLayoutManager.HORIZONTAL, false)
-      PagerSnapHelper().attachToRecyclerView(this)
+      addItemDecoration(CenterDecoration(0))
       albumRailAdapter = MediaRailAdapter(
         GlideApp.with(this@MediaPreviewV2Fragment),
-        object : MediaRailAdapter.RailItemListener {
+        { media -> jumpViewPagerToMedia(media) },
-          override fun onRailItemClicked(distanceFromActive: Int) {
-            binding.mediaPager.currentItem += distanceFromActive
-          }
-
-          override fun onRailItemDeleteClicked(distanceFromActive: Int) {
-            throw UnsupportedOperationException("Callback unsupported.")
-          }
-        },
-        false,
         object : ImageLoadingListener() {
           override fun onAllRequestsFinished() {
             crossfadeViewIn(this@apply)
@@ -281,14 +275,40 @@ class MediaPreviewV2Fragment : Fragment(R.layout.fragment_media_preview_v2), Med
       if (albumRail.visibility == GONE) {
         albumRail.visibility = View.INVISIBLE
       }
-      albumRailAdapter.setMedia(albumThumbnailMedia, albumPosition)
+
-      albumRail.smoothScrollToPosition(albumPosition)
+      albumRailAdapter.currentItemPosition = albumPosition
+      albumRailAdapter.submitList(albumThumbnailMedia)
+      scrollAlbumRailToCurrentAdapterPosition()
     } else {
       albumRail.visibility = View.GONE
-      albumRailAdapter.setMedia(emptyList())
+      albumRailAdapter.submitList(emptyList())
+      albumRailAdapter.imageLoadingListener.reset()
     }
   }
 
+  private fun scrollAlbumRailToCurrentAdapterPosition() {
+    val currentItemPosition = albumRailAdapter.currentItemPosition
+    val currentList = albumRailAdapter.currentList
+    val albumRail: RecyclerView = binding.mediaPreviewPlaybackControls.recyclerView
+    var selectedItemWidth = -1
+    for (i in currentList.indices) {
+      val isSelected = i == currentItemPosition
+      val stableId = albumRailAdapter.getItemId(i)
+      val viewHolder = albumRail.findViewHolderForItemId(stableId) as? MediaRailAdapter.MediaRailViewHolder
+      if (viewHolder != null) {
+        viewHolder.setSelectedItem(isSelected)
+        if (isSelected) {
+          selectedItemWidth = viewHolder.itemView.width
+        }
+      }
+    }
+    val offsetFromStart = (albumRail.width - selectedItemWidth) / 2
+    val smoothScroller = OffsetSmoothScroller(requireContext(), offsetFromStart)
+    smoothScroller.targetPosition = currentItemPosition
+    val layoutManager = albumRail.layoutManager as LinearLayoutManager
+    layoutManager.startSmoothScroll(smoothScroller)
+  }
+
   private fun crossfadeViewIn(view: View, duration: Long = 200) {
     if (!view.isVisible) {
       val viewPropertyAnimator = view.animate()
@@ -297,6 +317,11 @@ class MediaPreviewV2Fragment : Fragment(R.layout.fragment_media_preview_v2), Med
         .withStartAction {
           view.visibility = VISIBLE
         }
+        .withEndAction {
+          if (view == binding.mediaPreviewPlaybackControls.recyclerView) {
+            scrollAlbumRailToCurrentAdapterPosition()
+          }
+        }
       if (Build.VERSION.SDK_INT >= 21) {
         viewPropertyAnimator.interpolator = PathInterpolator(0.17f, 0.17f, 0f, 1f)
       }
@@ -306,6 +331,12 @@ class MediaPreviewV2Fragment : Fragment(R.layout.fragment_media_preview_v2), Med
 
   private fun getMediaPreviewFragmentFromChildFragmentManager(currentPosition: Int) = childFragmentManager.findFragmentByTag("f$currentPosition") as? MediaPreviewFragment
 
+  private fun jumpViewPagerToMedia(media: Media) {
+    val viewPagerAdapter = binding.mediaPager.adapter as MediaPreviewV2Adapter
+    val position = viewPagerAdapter.findItemPosition(media)
+    binding.mediaPager.setCurrentItem(position, true)
+  }
+
   private fun getTitleText(mediaRecord: MediaDatabase.MediaRecord, showThread: Boolean): String {
     val recipient: Recipient = Recipient.live(mediaRecord.recipientId).get()
     val defaultFromString: String = if (mediaRecord.isOutgoing) {
@@ -482,6 +513,16 @@ class MediaPreviewV2Fragment : Fragment(R.layout.fragment_media_preview_v2), Med
     viewModel.onDestroyView()
   }
 
+  private class OffsetSmoothScroller(context: Context, val offset: Int) : LinearSmoothScroller(context) {
+    override fun getHorizontalSnapPreference(): Int {
+      return SNAP_TO_START
+    }
+
+    override fun calculateDxToMakeVisible(view: View?, snapPreference: Int): Int {
+      return offset + super.calculateDxToMakeVisible(view, snapPreference)
+    }
+  }
+
   companion object {
     const val ARGS_KEY: String = "args"
 

app/src/main/java/org/thoughtcrime/securesms/mediapreview/MediaRailAdapter.java

@@ -1,249 +0,0 @@
-package org.thoughtcrime.securesms.mediapreview;
-
-import android.graphics.drawable.Drawable;
-import android.view.LayoutInflater;
-import android.view.View;
-import android.view.ViewGroup;
-
-import androidx.annotation.NonNull;
-import androidx.annotation.Nullable;
-import androidx.recyclerview.widget.RecyclerView;
-
-import com.bumptech.glide.load.DataSource;
-import com.bumptech.glide.load.engine.GlideException;
-import com.bumptech.glide.request.RequestListener;
-import com.bumptech.glide.request.target.Target;
-
-import org.thoughtcrime.securesms.R;
-import org.thoughtcrime.securesms.components.ThumbnailView;
-import org.thoughtcrime.securesms.mediasend.Media;
-import org.thoughtcrime.securesms.mms.GlideRequests;
-import org.thoughtcrime.securesms.util.adapter.StableIdGenerator;
-
-import java.util.ArrayList;
-import java.util.List;
-import java.util.concurrent.atomic.AtomicInteger;
-
-public class MediaRailAdapter extends RecyclerView.Adapter<MediaRailAdapter.MediaRailViewHolder> {
-
-  private static final int TYPE_MEDIA  = 1;
-  private static final int TYPE_BUTTON = 2;
-
-  private final GlideRequests            glideRequests;
-  private final List<Media>              media;
-  private final RailItemListener         listener;
-  private final StableIdGenerator<Media> stableIdGenerator;
-  private final ImageLoadingListener     imageLoadingListener;
-
-  private RailItemAddListener  addListener;
-  private int                  activePosition;
-  private boolean              editable;
-  private boolean              interactive;
-
-  public MediaRailAdapter(@NonNull GlideRequests glideRequests, @NonNull RailItemListener listener, boolean editable, ImageLoadingListener imageLoadingListener) {
-    this.glideRequests        = glideRequests;
-    this.media                = new ArrayList<>();
-    this.listener             = listener;
-    this.editable             = editable;
-    this.stableIdGenerator    = new StableIdGenerator<>();
-    this.interactive          = true;
-    this.imageLoadingListener = imageLoadingListener;
-
-    setHasStableIds(true);
-  }
-
-  @NonNull
-  @Override
-  public MediaRailViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int type) {
-    switch (type) {
-      case TYPE_MEDIA:
-        return new MediaViewHolder(LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.mediarail_media_item, viewGroup, false));
-      case TYPE_BUTTON:
-        return new ButtonViewHolder(LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.mediarail_button_item, viewGroup, false));
-      default:
-        throw new UnsupportedOperationException("Unsupported view type: " + type);
-    }
-  }
-
-  @Override
-  public void onBindViewHolder(@NonNull MediaRailViewHolder viewHolder, int i) {
-    switch (getItemViewType(i)) {
-      case TYPE_MEDIA:
-        ((MediaViewHolder) viewHolder).bind(media.get(i), i == activePosition, glideRequests, listener, i - activePosition, editable, interactive, imageLoadingListener);
-        break;
-      case TYPE_BUTTON:
-        ((ButtonViewHolder) viewHolder).bind(addListener);
-        break;
-      default:
-        throw new UnsupportedOperationException("Unsupported view type: " + getItemViewType(i));
-    }
-  }
-
-  @Override
-  public int getItemViewType(int position) {
-    if (editable && position == getItemCount() - 1) {
-      return TYPE_BUTTON;
-    } else {
-      return TYPE_MEDIA;
-    }
-  }
-
-  @Override
-  public void onViewRecycled(@NonNull MediaRailViewHolder holder) {
-    holder.recycle();
-  }
-
-  @Override
-  public int getItemCount() {
-    return editable ? media.size() + 1 : media.size();
-  }
-
-  @Override
-  public long getItemId(int position) {
-    switch (getItemViewType(position)) {
-      case TYPE_MEDIA:
-        return stableIdGenerator.getId(media.get(position));
-      case TYPE_BUTTON:
-        return Long.MAX_VALUE;
-      default:
-        throw new UnsupportedOperationException("Unsupported view type: " + getItemViewType(position));
-    }
-  }
-
-  public void setMedia(@NonNull List<Media> media) {
-    setMedia(media, activePosition);
-  }
-
-  public void setMedia(@NonNull List<Media> records, int activePosition) {
-    this.activePosition = activePosition;
-
-    this.media.clear();
-    this.media.addAll(records);
-
-    notifyDataSetChanged();
-  }
-
-  public void setActivePosition(int activePosition) {
-    this.activePosition = activePosition;
-    notifyDataSetChanged();
-  }
-
-  public void setAddButtonListener(@Nullable RailItemAddListener addListener) {
-    this.addListener = addListener;
-    notifyDataSetChanged();
-  }
-
-  public void setEditable(boolean editable) {
-    this.editable = editable;
-    notifyDataSetChanged();
-  }
-
-  public void setInteractive(boolean interactive) {
-    this.interactive = interactive;
-    notifyDataSetChanged();
-  }
-
-  static abstract class MediaRailViewHolder extends RecyclerView.ViewHolder {
-    public MediaRailViewHolder(@NonNull View itemView) {
-      super(itemView);
-    }
-
-    abstract void recycle();
-  }
-
-  static class MediaViewHolder extends MediaRailViewHolder {
-
-    private final ThumbnailView image;
-    private final View          outline;
-    private final View          deleteButton;
-    private final View          captionIndicator;
-
-    MediaViewHolder(@NonNull View itemView) {
-      super(itemView);
-      image            = itemView.findViewById(R.id.rail_item_image);
-      outline          = itemView.findViewById(R.id.rail_item_outline);
-      deleteButton     = itemView.findViewById(R.id.rail_item_delete);
-      captionIndicator = itemView.findViewById(R.id.rail_item_caption);
-    }
-
-    void bind(@NonNull Media media, boolean isActive, @NonNull GlideRequests glideRequests,
-              @NonNull RailItemListener railItemListener, int distanceFromActive, boolean editable,
-              boolean interactive, @NonNull ImageLoadingListener listener)
-    {
-      listener.onRequest();
-      image.setImageResource(glideRequests, media.getUri(), 0, 0, false, listener);
-      image.setOnClickListener(v -> railItemListener.onRailItemClicked(distanceFromActive));
-
-      outline.setVisibility(isActive && interactive ? View.VISIBLE : View.GONE);
-
-      captionIndicator.setVisibility(media.getCaption().isPresent() ? View.VISIBLE : View.GONE);
-
-      if (editable && isActive && interactive) {
-        deleteButton.setVisibility(View.VISIBLE);
-        deleteButton.setOnClickListener(v -> railItemListener.onRailItemDeleteClicked(distanceFromActive));
-      } else {
-        deleteButton.setVisibility(View.GONE);
-      }
-    }
-
-    void recycle() {
-      image.setOnClickListener(null);
-      deleteButton.setOnClickListener(null);
-    }
-  }
-
-  static class ButtonViewHolder extends MediaRailViewHolder {
-
-    public ButtonViewHolder(@NonNull View itemView) {
-      super(itemView);
-    }
-
-    void bind(@Nullable RailItemAddListener addListener) {
-      if (addListener != null) {
-        itemView.setOnClickListener(v -> addListener.onRailItemAddClicked());
-      }
-    }
-
-    @Override
-    void recycle() {
-      itemView.setOnClickListener(null);
-    }
-  }
-
-  public interface RailItemListener {
-    void onRailItemClicked(int distanceFromActive);
-    void onRailItemDeleteClicked(int distanceFromActive);
-  }
-
-  public interface RailItemAddListener {
-    void onRailItemAddClicked();
-  }
-
-  abstract static class ImageLoadingListener implements RequestListener<Drawable> {
-    final private AtomicInteger activeJobs = new AtomicInteger();
-
-    void onRequest() {
-      activeJobs.incrementAndGet();
-    }
-
-    @Override
-    public boolean onLoadFailed(@Nullable GlideException e, Object model, Target<Drawable> target, boolean isFirstResource) {
-      int count = activeJobs.decrementAndGet();
-      if (count == 0) {
-        onAllRequestsFinished();
-      }
-      return false;
-    }
-
-    @Override
-    public boolean onResourceReady(Drawable resource, Object model, Target<Drawable> target, DataSource dataSource, boolean isFirstResource) {
-      int count = activeJobs.decrementAndGet();
-      if (count == 0) {
-        onAllRequestsFinished();
-      }
-      return false;
-    }
-
-    abstract void onAllRequestsFinished();
-  }
-}

app/src/main/java/org/thoughtcrime/securesms/mediapreview/mediarail/CenterDecoration.kt

@@ -0,0 +1,45 @@
+package org.thoughtcrime.securesms.mediapreview.mediarail
+
+import android.graphics.Rect
+import android.view.View
+import androidx.annotation.Px
+import androidx.core.view.doOnPreDraw
+import androidx.recyclerview.widget.LinearLayoutManager
+import androidx.recyclerview.widget.RecyclerView
+
+/**
+ * From: <a href="https://stackoverflow.com/a/53510142">https://stackoverflow.com/a/53510142</a>
+ */
+class CenterDecoration(@Px private val spacing: Int) : RecyclerView.ItemDecoration() {
+
+  private var firstViewWidth = -1
+  private var lastViewWidth = -1
+
+  override fun getItemOffsets(outRect: Rect, view: View, parent: RecyclerView, state: RecyclerView.State) {
+    super.getItemOffsets(outRect, view, parent, state)
+    val adapterPosition = (view.layoutParams as RecyclerView.LayoutParams).absoluteAdapterPosition
+    val layoutManager = parent.layoutManager as LinearLayoutManager
+    if (adapterPosition == 0) {
+      if (view.width != firstViewWidth) {
+        view.doOnPreDraw { parent.invalidateItemDecorations() }
+      }
+      firstViewWidth = view.width
+      outRect.left = parent.width / 2 - view.width / 2
+      if (layoutManager.itemCount > 1) {
+        outRect.right = spacing / 2
+      } else {
+        outRect.right = outRect.left
+      }
+    } else if (adapterPosition == layoutManager.itemCount - 1) {
+      if (view.width != lastViewWidth) {
+        view.doOnPreDraw { parent.invalidateItemDecorations() }
+      }
+      lastViewWidth = view.width
+      outRect.right = parent.width / 2 - view.width / 2
+      outRect.left = spacing / 2
+    } else {
+      outRect.left = spacing / 2
+      outRect.right = spacing / 2
+    }
+  }
+}

app/src/main/java/org/thoughtcrime/securesms/mediapreview/mediarail/MediaRailAdapter.kt

@@ -0,0 +1,132 @@
+package org.thoughtcrime.securesms.mediapreview.mediarail
+
+import android.graphics.drawable.Drawable
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import androidx.recyclerview.widget.DiffUtil
+import androidx.recyclerview.widget.ListAdapter
+import androidx.recyclerview.widget.RecyclerView
+import com.bumptech.glide.load.DataSource
+import com.bumptech.glide.load.engine.GlideException
+import com.bumptech.glide.request.RequestListener
+import com.bumptech.glide.request.target.Target
+import org.thoughtcrime.securesms.R
+import org.thoughtcrime.securesms.components.ThumbnailView
+import org.thoughtcrime.securesms.mediasend.Media
+import org.thoughtcrime.securesms.mms.GlideRequests
+import org.thoughtcrime.securesms.util.adapter.StableIdGenerator
+import org.thoughtcrime.securesms.util.visible
+import java.util.concurrent.atomic.AtomicInteger
+
+/**
+ * This is the RecyclerView.Adapter for the row of thumbnails present in the media viewer screen.
+ */
+class MediaRailAdapter(private val glideRequests: GlideRequests, listener: RailItemListener, imageLoadingListener: ImageLoadingListener) : ListAdapter<Media, MediaRailAdapter.MediaRailViewHolder>(MediaDiffer()) {
+  val imageLoadingListener: ImageLoadingListener
+
+  var currentItemPosition: Int = -1
+
+  private val listener: RailItemListener
+  private val stableIdGenerator: StableIdGenerator<Media>
+
+  init {
+    this.listener = listener
+    stableIdGenerator = StableIdGenerator()
+    this.imageLoadingListener = imageLoadingListener
+    setHasStableIds(true)
+  }
+
+  override fun onCreateViewHolder(viewGroup: ViewGroup, type: Int): MediaRailViewHolder {
+    return MediaRailViewHolder(LayoutInflater.from(viewGroup.context).inflate(R.layout.mediarail_media_item, viewGroup, false))
+  }
+
+  override fun onBindViewHolder(viewHolder: MediaRailViewHolder, i: Int) {
+    viewHolder.bind(getItem(i), i == currentItemPosition, glideRequests, listener, imageLoadingListener)
+  }
+
+  override fun onViewRecycled(holder: MediaRailViewHolder) {
+    holder.recycle()
+  }
+
+  override fun getItemId(position: Int): Long {
+    return stableIdGenerator.getId(getItem(position))
+  }
+
+  class MediaRailViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
+    private val image: ThumbnailView
+    private val outline: View
+    private val captionIndicator: View
+
+    init {
+      image = itemView.findViewById(R.id.rail_item_image)
+      outline = itemView.findViewById(R.id.rail_item_outline)
+      captionIndicator = itemView.findViewById(R.id.rail_item_caption)
+    }
+
+    fun bind(
+      media: Media,
+      isCurrentlySelected: Boolean,
+      glideRequests: GlideRequests,
+      railItemListener: RailItemListener,
+      listener: ImageLoadingListener
+    ) {
+      listener.onRequest()
+      image.setImageResource(glideRequests, media.uri, 0, 0, false, listener)
+      image.setOnClickListener { railItemListener.onRailItemClicked(media) }
+      captionIndicator.visibility = if (media.caption.isPresent) View.VISIBLE else View.GONE
+      setSelectedItem(isCurrentlySelected)
+    }
+
+    fun recycle() {
+      image.setOnClickListener(null)
+    }
+
+    fun setSelectedItem(isActive: Boolean) {
+      outline.visible = isActive
+    }
+  }
+
+  fun interface RailItemListener {
+    fun onRailItemClicked(media: Media)
+  }
+
+  abstract class ImageLoadingListener : RequestListener<Drawable?> {
+    private val activeJobs = AtomicInteger()
+    fun onRequest() {
+      activeJobs.incrementAndGet()
+    }
+
+    final override fun onLoadFailed(e: GlideException?, model: Any, target: Target<Drawable?>, isFirstResource: Boolean): Boolean {
+      val count = activeJobs.decrementAndGet()
+      if (count == 0) {
+        onAllRequestsFinished()
+      }
+      return false
+    }
+
+    final override fun onResourceReady(resource: Drawable?, model: Any, target: Target<Drawable?>, dataSource: DataSource, isFirstResource: Boolean): Boolean {
+      val count = activeJobs.decrementAndGet()
+      if (count == 0) {
+        onAllRequestsFinished()
+      }
+      return false
+    }
+
+    fun reset() {
+      activeJobs.set(0)
+    }
+
+    abstract fun onAllRequestsFinished()
+  }
+
+  class MediaDiffer : DiffUtil.ItemCallback<Media>() {
+    override fun areItemsTheSame(oldItem: Media, newItem: Media): Boolean {
+      return oldItem.uri == newItem.uri
+    }
+
+    override fun areContentsTheSame(oldItem: Media, newItem: Media): Boolean {
+      return oldItem == newItem
+    }
+  }
+}

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

@@ -50,7 +50,7 @@
 
     <androidx.recyclerview.widget.RecyclerView
         android:id="@+id/media_preview_album_rail"
-        android:layout_width="wrap_content"
+        android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:layout_gravity="center"
         android:layout_marginBottom="11dp"
@@ -58,7 +58,6 @@
         android:layout_marginEnd="12dp"
         android:orientation="horizontal"
         android:visibility="gone"
-        app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager"
         tools:layout_height="64dp" />
 
     <LinearLayout

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

@@ -1,91 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-
-<FrameLayout
-    xmlns:android="http://schemas.android.com/apk/res/android"
-    tools:viewBindingIgnore="true"
-    xmlns:tools="http://schemas.android.com/tools"
-    xmlns:app="http://schemas.android.com/apk/res-auto"
-    android:layout_width="match_parent"
-    android:layout_height="match_parent"
-    android:background="@color/core_grey_95">
-
-    <org.thoughtcrime.securesms.components.viewpager.HackyViewPager
-        android:id="@+id/media_pager"
-        android:layout_width="match_parent"
-        android:layout_height="match_parent"
-        android:clickable="true"/>
-
-    <LinearLayout
-        android:id="@+id/media_preview_details_container"
-        android:layout_width="match_parent"
-        android:layout_height="wrap_content"
-        android:layout_gravity="bottom"
-        android:animateLayoutChanges="true"
-        android:background="@drawable/image_preview_shade"
-        android:gravity="bottom"
-        android:orientation="vertical"
-        android:visibility="gone"
-        tools:visibility="visible">
-
-        <org.thoughtcrime.securesms.components.MaxHeightScrollView
-            android:id="@+id/media_preview_caption_container"
-            android:layout_width="match_parent"
-            android:layout_height="wrap_content"
-            android:paddingTop="32dp"
-            android:animateLayoutChanges="true"
-            app:scrollView_maxHeight="120dp">
-
-            <org.thoughtcrime.securesms.components.emoji.EmojiTextView
-                android:id="@+id/media_preview_caption"
-                android:layout_width="match_parent"
-                android:layout_height="wrap_content"
-                android:paddingStart="16dp"
-                android:paddingEnd="16dp"
-                android:paddingBottom="8dp"
-                style="@style/Signal.Text.Body"
-                android:textColor="@color/core_white"
-                android:gravity="bottom"
-                tools:text="With great power comes great responsibility." />
-
-        </org.thoughtcrime.securesms.components.MaxHeightScrollView>
-
-        <androidx.recyclerview.widget.RecyclerView
-            android:id="@+id/media_preview_album_rail"
-            android:layout_width="match_parent"
-            android:layout_height="wrap_content"
-            android:layout_marginTop="8dp"
-            android:layout_marginStart="12dp"
-            android:layout_marginEnd="12dp"
-            tools:layout_height="64dp"/>
-
-        <FrameLayout
-            android:id="@+id/media_preview_playback_controls_container"
-            android:layout_width="match_parent"
-            android:layout_height="wrap_content"
-            android:animateLayoutChanges="true"/>
-
-    </LinearLayout>
-
-    <com.google.android.material.appbar.AppBarLayout
-        android:id="@+id/toolbar_layout"
-        android:layout_width="match_parent"
-        android:layout_height="wrap_content"
-        android:background="@color/media_preview_bar_background"
-        app:elevation="0dp">
-
-        <View
-            android:id="@+id/toolbar_cutout_spacer"
-            android:layout_width="match_parent"
-            android:layout_height="0dp"
-            android:visibility="gone" />
-
-        <androidx.appcompat.widget.Toolbar
-            android:id="@+id/toolbar"
-            android:theme="?actionBarStyle"
-            android:layout_width="match_parent"
-            android:layout_height="?attr/actionBarSize"
-            android:background="@android:color/transparent" />
-
-    </com.google.android.material.appbar.AppBarLayout>
-
-</FrameLayout>

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

@@ -4,8 +4,8 @@
     tools:viewBindingIgnore="true"
     xmlns:app="http://schemas.android.com/apk/res-auto"
     xmlns:tools="http://schemas.android.com/tools"
-    android:layout_width="46dp"
+    android:layout_width="@dimen/media_rail_item_size"
-    android:layout_height="46dp"
+    android:layout_height="@dimen/media_rail_item_size"
     android:layout_margin="4dp"
     android:animateLayoutChanges="true">
 
@@ -42,14 +42,4 @@
         android:visibility="gone"
         tools:visibility="visible"/>
 
-    <ImageView
-        android:id="@+id/rail_item_delete"
-        android:layout_width="wrap_content"
-        android:layout_height="wrap_content"
-        android:layout_gravity="end|top"
-        android:layout_margin="1dp"
-        android:src="@drawable/ic_x_28"
-        android:visibility="gone"
-        tools:visibility="visible"/>
-
 </FrameLayout>

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

@@ -243,4 +243,5 @@
     <dimen name="exo_media_preview_button_height">48dp</dimen>
     <dimen name="media_preview_button_horizontal_margin">8dp</dimen>
     <dimen name="media_preview_lottie_button_dimen">36dp</dimen>
+    <dimen name="media_rail_item_size">46dp</dimen>
 </resources>