Utilize ItemCallback for ReactWithAnyAdapter.

Fixes #9918

app/src/main/java/org/thoughtcrime/securesms/reactions/any/ReactWithAnyEmojiAdapter.java

@@ -9,6 +9,7 @@ import android.widget.TextView;
 
 import androidx.annotation.NonNull;
 import androidx.core.widget.NestedScrollView;
+import androidx.recyclerview.widget.DiffUtil;
 import androidx.recyclerview.widget.ListAdapter;
 import androidx.recyclerview.widget.RecyclerView;
 
@@ -35,7 +36,7 @@ final class ReactWithAnyEmojiAdapter extends ListAdapter<ReactWithAnyEmojiPage,
                            @NonNull EmojiPageViewGridAdapter.VariationSelectorListener variationSelectorListener,
                            @NonNull Callbacks callbacks)
   {
-    super(new AlwaysChangedDiffUtil<>());
+    super(new PageChangedCallback());
 
     this.emojiEventListener        = emojiEventListener;
     this.variationSelectorListener = variationSelectorListener;
@@ -169,4 +170,17 @@ final class ReactWithAnyEmojiAdapter extends ListAdapter<ReactWithAnyEmojiPage,
   interface ScrollableChild {
     void setNestedScrollingEnabled(boolean isEnabled);
   }
+
+  private static class PageChangedCallback extends DiffUtil.ItemCallback<ReactWithAnyEmojiPage> {
+
+    @Override
+    public boolean areItemsTheSame(@NonNull ReactWithAnyEmojiPage oldItem, @NonNull ReactWithAnyEmojiPage newItem) {
+      return oldItem.getLabel() == newItem.getLabel();
+    }
+
+    @Override
+    public boolean areContentsTheSame(@NonNull ReactWithAnyEmojiPage oldItem, @NonNull ReactWithAnyEmojiPage newItem) {
+      return oldItem.equals(newItem);
+    }
+  }
 }

app/src/main/java/org/thoughtcrime/securesms/reactions/any/ReactWithAnyEmojiPage.java

@@ -7,6 +7,7 @@ import androidx.annotation.StringRes;
 import org.whispersystems.libsignal.util.guava.Preconditions;
 
 import java.util.List;
+import java.util.Objects;
 
 /**
  * Represents a swipeable page in the ReactWithAnyEmoji dialog fragment, encapsulating any
@@ -41,4 +42,17 @@ class ReactWithAnyEmojiPage {
   public @AttrRes int getIconAttr() {
     return pageBlocks.get(0).getPageModel().getIconAttr();
   }
+
+  @Override
+  public boolean equals(Object o) {
+    if (this == o) return true;
+    if (o == null || getClass() != o.getClass()) return false;
+    ReactWithAnyEmojiPage that = (ReactWithAnyEmojiPage) o;
+    return pageBlocks.equals(that.pageBlocks);
+  }
+
+  @Override
+  public int hashCode() {
+    return Objects.hash(pageBlocks);
+  }
 }

app/src/main/java/org/thoughtcrime/securesms/reactions/any/ReactWithAnyEmojiPageBlock.java

@@ -5,6 +5,8 @@ import androidx.annotation.StringRes;
 
 import org.thoughtcrime.securesms.components.emoji.EmojiPageModel;
 
+import java.util.Objects;
+
 /**
  * Wraps a single "class" of Emojis, be it a predefined category, recents, etc. and provides
  * a label for that "class".
@@ -26,4 +28,19 @@ class ReactWithAnyEmojiPageBlock {
   public EmojiPageModel getPageModel() {
     return pageModel;
   }
+
+  @Override
+  public boolean equals(Object o) {
+    if (this == o) return true;
+    if (o == null || getClass() != o.getClass()) return false;
+    ReactWithAnyEmojiPageBlock that = (ReactWithAnyEmojiPageBlock) o;
+    return label == that.label                                     &&
+           pageModel.getIconAttr() == that.pageModel.getIconAttr() &&
+           Objects.equals(pageModel.getEmoji(), that.pageModel.getEmoji());
+  }
+
+  @Override
+  public int hashCode() {
+    return Objects.hash(label, pageModel.getEmoji());
+  }
 }