InvertedScrollContentView.java

package chat.rocket.reactnative.scroll;

import android.view.View;
import com.facebook.react.views.view.ReactViewGroup;
import java.util.ArrayList;
import java.util.Collections;

/**
 * Content view for inverted FlatLists. Reports its children to accessibility in reversed order so
 * TalkBack traversal matches the visual order (newest-first) when used inside InvertedScrollView.
 */
public class InvertedScrollContentView extends ReactViewGroup {

  private boolean mIsInvertedContent = false;

  public InvertedScrollContentView(android.content.Context context) {
    super(context);
  }

  public void setIsInvertedContent(boolean isInverted) {
    mIsInvertedContent = isInverted;
  }

  @Override
  public void addChildrenForAccessibility(ArrayList<View> outChildren) {
    super.addChildrenForAccessibility(outChildren);
    if (mIsInvertedContent) {
      Collections.reverse(outChildren);
    }
  }

  @Override
  public void addFocusables(ArrayList<View> views, int direction, int focusableMode) {
    super.addFocusables(views, direction, focusableMode);
    if (mIsInvertedContent) {
      // Find indices of focusables that are children of this view
      ArrayList<Integer> childIndices = new ArrayList<>();
      for (int i = 0; i < views.size(); i++) {
        View v = views.get(i);
        if (v.getParent() == this) {
          childIndices.add(i);
        }
      }
      // Reverse only the sublist of children focusables
      int n = childIndices.size();
      for (int i = 0; i < n / 2; i++) {
        int idx1 = childIndices.get(i);
        int idx2 = childIndices.get(n - 1 - i);
        View temp = views.get(idx1);
        views.set(idx1, views.get(idx2));
        views.set(idx2, temp);
      }
    }
  }
}