use diffutil to sync articlepager to shared article list on headlines load

3 files changed, 34 insertions, 10 deletions

diff --git a/org.fox.ttrss/src/main/java/org/fox/ttrss/ArticlePager.java b/org.fox.ttrss/src/main/java/org/fox/ttrss/ArticlePager.java
index 6069591f..016bc370 100755
--- a/org.fox.ttrss/src/main/java/org/fox/ttrss/ArticlePager.java
+++ b/org.fox.ttrss/src/main/java/org/fox/ttrss/ArticlePager.java
@@ -10,11 +10,14 @@ import android.view.ViewGroup;
 
 import androidx.annotation.NonNull;
 import androidx.fragment.app.Fragment;
+import androidx.recyclerview.widget.DiffUtil;
 import androidx.viewpager2.adapter.FragmentStateAdapter;
 import androidx.viewpager2.widget.ViewPager2;
 
 import org.fox.ttrss.types.Article;
+import org.fox.ttrss.types.ArticleList;
 import org.fox.ttrss.types.Feed;
+import org.fox.ttrss.util.HeadlinesDiffUtilCallback;
 
 public class ArticlePager extends androidx.fragment.app.Fragment {
 
@@ -27,15 +30,31 @@ public class ArticlePager extends androidx.fragment.app.Fragment {
 	private ViewPager2 m_pager;
 
 	private static class PagerAdapter extends FragmentStateAdapter {
+		private ArticleList m_articles = new ArticleList();
 
-		public PagerAdapter(@NonNull Fragment fragment) {
+		public PagerAdapter(@NonNull Fragment fragment, ArticleList initialArticles) {
 			super(fragment);
+
+			m_articles.clear();
+			m_articles.addAll(initialArticles);
+		}
+
+		private void syncToSharedArticles() {
+			ArticleList tmp = new ArticleList();
+			tmp.addAll(Application.getArticles());
+
+			DiffUtil.DiffResult diffResult = DiffUtil.calculateDiff(new HeadlinesDiffUtilCallback(m_articles, tmp));
+
+			diffResult.dispatchUpdatesTo(this);
+
+			m_articles.clear();
+			m_articles.addAll(tmp);
 		}
 
 		@Override
 		@NonNull
 		public Fragment createFragment(int position) {
-			Article article = Application.getArticles().get(position);
+			Article article = m_articles.get(position);
 
 			ArticleFragment af = new ArticleFragment();
 			af.initialize(article);
@@ -45,7 +64,7 @@ public class ArticlePager extends androidx.fragment.app.Fragment {
 
 		@Override
 		public int getItemCount() {
-			return Application.getArticles().size();
+			return m_articles.size();
 		}
 
 	}
@@ -79,7 +98,7 @@ public class ArticlePager extends androidx.fragment.app.Fragment {
 	public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {    	
 		View view = inflater.inflate(R.layout.fragment_article_pager, container, false);
 
-		m_adapter = new PagerAdapter(this);
+		m_adapter = new PagerAdapter(this, Application.getArticles());
 		
 		m_pager = view.findViewById(R.id.article_pager);
 
@@ -170,4 +189,9 @@ public class ArticlePager extends androidx.fragment.app.Fragment {
 	public void notifyUpdated() {
 		m_adapter.notifyDataSetChanged();
 	}
+
+	public void syncToSharedArticles() {
+		if (m_adapter != null)
+			m_adapter.syncToSharedArticles();
+	}
 }
diff --git a/org.fox.ttrss/src/main/java/org/fox/ttrss/DetailActivity.java b/org.fox.ttrss/src/main/java/org/fox/ttrss/DetailActivity.java
index e97d6cc6..b0f5796d 100755
--- a/org.fox.ttrss/src/main/java/org/fox/ttrss/DetailActivity.java
+++ b/org.fox.ttrss/src/main/java/org/fox/ttrss/DetailActivity.java
@@ -300,7 +300,7 @@ public class DetailActivity extends OnlineActivity implements HeadlinesEventList
 		ArticlePager ap = (ArticlePager) getSupportFragmentManager().findFragmentByTag(FRAG_ARTICLE);
 
         if (ap != null) {
-            ap.notifyUpdated();
+            ap.syncToSharedArticles();
         }
 
 		if (hf != null) {
diff --git a/org.fox.ttrss/src/main/java/org/fox/ttrss/HeadlinesFragment.java b/org.fox.ttrss/src/main/java/org/fox/ttrss/HeadlinesFragment.java
index 6e6cb472..d233e87f 100755
--- a/org.fox.ttrss/src/main/java/org/fox/ttrss/HeadlinesFragment.java
+++ b/org.fox.ttrss/src/main/java/org/fox/ttrss/HeadlinesFragment.java
@@ -793,13 +793,13 @@ public class HeadlinesFragment extends androidx.fragment.app.Fragment implements
 
 			holder.view.setOnClickListener(v -> {
                 m_listener.onArticleSelected(article);
-				setActiveArticleId(article.id);
 
                 // only set active article when it makes sense (in DetailActivity)
-                //if (getActivity() instanceof DetailActivity) {
-                    //m_activeArticleId = article.id;
-                    //m_adapter.notifyDataSetChanged();
-                //}
+                if (getActivity() instanceof DetailActivity) {
+					m_activeArticleId = article.id;
+
+					m_adapter.notifyItemChanged(position);
+				}
             });
 
 			// block footer clicks to make button/selection clicking easier