Merge branch '1077-save-threaded-discussion-position' into 'master'

Save list position in threaded conversations and main blog feed

Closes #1077

See merge request briar/briar!1054

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogFragment.java

@@ -3,12 +3,14 @@ package org.briarproject.briar.android.blog;
 import android.content.DialogInterface;
 import android.content.Intent;
 import android.os.Bundle;
+import android.os.Parcelable;
 import android.support.annotation.UiThread;
 import android.support.design.widget.Snackbar;
 import android.support.v4.content.ContextCompat;
 import android.support.v7.app.ActionBar;
 import android.support.v7.app.AlertDialog;
 import android.support.v7.widget.LinearLayoutManager;
+import android.support.v7.widget.RecyclerView.LayoutManager;
 import android.view.LayoutInflater;
 import android.view.Menu;
 import android.view.MenuInflater;
@@ -62,9 +64,12 @@ public class BlogFragment extends BaseFragment
 	BlogController blogController;
 	@Inject
 	SharingController sharingController;
+	@Nullable
+	private Parcelable layoutManagerState;
 
 	private GroupId groupId;
 	private BlogPostAdapter adapter;
+	private LayoutManager layoutManager;
 	private BriarRecyclerView list;
 	private MenuItem writeButton, deleteButton;
 	private boolean isMyBlog = false, canDeleteBlog = false;
@@ -101,11 +106,17 @@ public class BlogFragment extends BaseFragment
 		adapter = new BlogPostAdapter(requireNonNull(getActivity()), this,
 				getFragmentManager());
 		list = v.findViewById(R.id.postList);
-		list.setLayoutManager(new LinearLayoutManager(getActivity()));
+		layoutManager = new LinearLayoutManager(getActivity());
+		list.setLayoutManager(layoutManager);
 		list.setAdapter(adapter);
 		list.showProgressBar();
 		list.setEmptyText(getString(R.string.blogs_other_blog_empty_state));
 
+		if (savedInstanceState != null) {
+			layoutManagerState =
+					savedInstanceState.getParcelable("layoutManager");
+		}
+
 		return v;
 	}
 
@@ -126,6 +137,15 @@ public class BlogFragment extends BaseFragment
 		list.stopPeriodicUpdate();
 	}
 
+	@Override
+	public void onSaveInstanceState(Bundle outState) {
+		super.onSaveInstanceState(outState);
+		if (layoutManager != null) {
+			layoutManagerState = layoutManager.onSaveInstanceState();
+			outState.putParcelable("layoutManager", layoutManagerState);
+		}
+	}
+
 	@Override
 	public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
 		inflater.inflate(R.menu.blogs_blog_actions, menu);
@@ -238,7 +258,12 @@ public class BlogFragment extends BaseFragment
 							list.showData();
 						} else {
 							adapter.addAll(posts);
-							if (reload) list.scrollToPosition(0);
+							if (reload || layoutManagerState == null) {
+								list.scrollToPosition(0);
+							} else {
+								layoutManager.onRestoreInstanceState(
+										layoutManagerState);
+							}
 						}
 					}
 

briar-android/src/main/java/org/briarproject/briar/android/blog/FeedFragment.java

@@ -2,6 +2,7 @@ package org.briarproject.briar.android.blog;
 
 import android.content.Intent;
 import android.os.Bundle;
+import android.os.Parcelable;
 import android.support.annotation.UiThread;
 import android.support.design.widget.Snackbar;
 import android.support.v4.content.ContextCompat;
@@ -54,7 +55,10 @@ public class FeedFragment extends BaseFragment implements
 	private BlogPostAdapter adapter;
 	private LinearLayoutManager layoutManager;
 	private BriarRecyclerView list;
-	private Blog personalBlog = null;
+	@Nullable
+	private Blog personalBlog;
+	@Nullable
+	private Parcelable layoutManagerState;
 
 	public static FeedFragment newInstance() {
 		FeedFragment f = new FeedFragment();
@@ -91,6 +95,11 @@ public class FeedFragment extends BaseFragment implements
 		list.setEmptyText(R.string.blogs_feed_empty_state);
 		list.setEmptyAction(R.string.blogs_feed_empty_state_action);
 
+		if (savedInstanceState != null) {
+			layoutManagerState =
+					savedInstanceState.getParcelable("layoutManager");
+		}
+
 		return v;
 	}
 
@@ -123,6 +132,15 @@ public class FeedFragment extends BaseFragment implements
 		// TODO save list position in database/preferences?
 	}
 
+	@Override
+	public void onSaveInstanceState(Bundle outState) {
+		super.onSaveInstanceState(outState);
+		if (layoutManager != null) {
+			layoutManagerState = layoutManager.onSaveInstanceState();
+			outState.putParcelable("layoutManager", layoutManagerState);
+		}
+	}
+
 	private void loadPersonalBlog() {
 		feedController.loadPersonalBlog(
 				new UiResultExceptionHandler<Blog, DbException>(this) {
@@ -150,6 +168,12 @@ public class FeedFragment extends BaseFragment implements
 							if (clear) adapter.setItems(posts);
 							else adapter.addAll(posts);
 							if (posts.isEmpty()) list.showData();
+							if (layoutManagerState == null) {
+								list.scrollToPosition(0);  // Scroll to the top
+							} else {
+								layoutManager.onRestoreInstanceState(
+										layoutManagerState);
+							}
 						} else {
 							LOG.info("Concurrent update, reloading");
 							loadBlogPosts(clear);

briar-android/src/main/java/org/briarproject/briar/android/threaded/ThreadListActivity.java

@@ -3,6 +3,7 @@ package org.briarproject.briar.android.threaded;
 import android.content.Intent;
 import android.net.Uri;
 import android.os.Bundle;
+import android.os.Parcelable;
 import android.support.annotation.CallSuper;
 import android.support.annotation.StringRes;
 import android.support.annotation.UiThread;
@@ -63,6 +64,8 @@ public abstract class ThreadListActivity<G extends NamedGroup, I extends ThreadI
 	protected TextInputView textInput;
 	protected GroupId groupId;
 	@Nullable
+	private Parcelable layoutManagerState;
+	@Nullable
 	private MessageId replyId;
 
 	protected abstract ThreadListController<G, I> getController();
@@ -188,6 +191,11 @@ public abstract class ThreadListActivity<G extends NamedGroup, I extends ThreadI
 		if (messageId != null)
 			adapter.setItemWithIdVisible(messageId);
 		list.showData();
+		if (layoutManagerState == null) {
+			list.scrollToPosition(0);  // Scroll to the top
+		} else {
+			layoutManager.onRestoreInstanceState(layoutManagerState);
+		}
 	}
 
 	protected void loadSharingContacts() {
@@ -228,11 +236,21 @@ public abstract class ThreadListActivity<G extends NamedGroup, I extends ThreadI
 	@Override
 	protected void onSaveInstanceState(Bundle outState) {
 		super.onSaveInstanceState(outState);
+		if (layoutManager != null) {
+			layoutManagerState = layoutManager.onSaveInstanceState();
+			outState.putParcelable("layoutManager", layoutManagerState);
+		}
 		if (replyId != null) {
 			outState.putByteArray(KEY_REPLY_ID, replyId.getBytes());
 		}
 	}
 
+	@Override
+	protected void onRestoreInstanceState(Bundle savedInstanceState) {
+		super.onRestoreInstanceState(savedInstanceState);
+		layoutManagerState = savedInstanceState.getParcelable("layoutManager");
+	}
+
 	@Override
 	public boolean onOptionsItemSelected(MenuItem item) {
 		switch (item.getItemId()) {