Fixes FS#81 - avoid jumps after loading messages

2 files changed, 64 insertions, 32 deletions

diff --git a/src/main/java/de/thedevstack/conversationsplus/services/XmppConnectionService.java b/src/main/java/de/thedevstack/conversationsplus/services/XmppConnectionService.java
index 8ff5f0d2..5e529f3c 100644
--- a/src/main/java/de/thedevstack/conversationsplus/services/XmppConnectionService.java
+++ b/src/main/java/de/thedevstack/conversationsplus/services/XmppConnectionService.java
@@ -1050,32 +1050,38 @@ public class XmppConnectionService extends Service implements OnPhoneContactsLoa
             Log.d("mam", "Query in progress");
 			return;
 		}
+        //TODO Create a separate class for this runnable to store if messages are getting loaded or not. Not really a good idea to do this in the callback.
 		Runnable runnable = new Runnable() {
 			@Override
 			public void run() {
-				final Account account = conversation.getAccount();
-				List<Message> messages = databaseBackend.getMessages(conversation, 50,timestamp);
-                Log.d("mam", "runnable load more messages");
-				if (messages.size() > 0) {
-                    Log.d("mam", "At least one message");
-					conversation.addAll(0, messages);
-					checkDeletedFiles(conversation);
-					callback.onMoreMessagesLoaded(messages.size(), conversation);
-				} else if (conversation.hasMessagesLeftOnServer()
-						&& account.isOnlineAndConnected()
-						&& account.getXmppConnection().getFeatures().mam()) {
-                    Log.d("mam", "mam activate, account online and connected and messages left on server");
-					MessageArchiveService.Query query = getMessageArchiveService().query(conversation,0,timestamp - 1);
-					if (query != null) {
-						query.setCallback(callback);
-					}
-					callback.informUser(R.string.fetching_history_from_server);
-				} else {
-                    Log.d("mam", ((!conversation.hasMessagesLeftOnServer()) ? "no" : "") + " more messages left on server, mam " + ((account.getXmppConnection().getFeatures().mam()) ? "" : "not") + " activated, account is " + ((account.isOnlineAndConnected()) ? "" : "not") + " online or connected)");
-                    callback.onMoreMessagesLoaded(0, conversation);
-                    callback.informUser(R.string.no_more_history_on_server);
+                if (null == callback || !callback.isLoadingInProgress()) { // if a callback is set, ensure that there is no loading in progress
+                    if (null != callback) {
+                        callback.setLoadingInProgress(); // Tell the callback that the loading is in progress
+                    }
+                    final Account account = conversation.getAccount();
+                    List<Message> messages = databaseBackend.getMessages(conversation, 50, timestamp);
+                    Log.d("mam", "runnable load more messages");
+                    if (messages.size() > 0) {
+                        Log.d("mam", "At least one message");
+                        conversation.addAll(0, messages);
+                        checkDeletedFiles(conversation);
+                        callback.onMoreMessagesLoaded(messages.size(), conversation);
+                    } else if (conversation.hasMessagesLeftOnServer()
+                            && account.isOnlineAndConnected()
+                            && account.getXmppConnection().getFeatures().mam()) {
+                        Log.d("mam", "mam activate, account online and connected and messages left on server");
+                        MessageArchiveService.Query query = getMessageArchiveService().query(conversation, 0, timestamp - 1);
+                        if (query != null) {
+                            query.setCallback(callback);
+                        }
+                        callback.informUser(R.string.fetching_history_from_server);
+                    } else {
+                        Log.d("mam", ((!conversation.hasMessagesLeftOnServer()) ? "no" : "") + " more messages left on server, mam " + ((account.getXmppConnection().getFeatures().mam()) ? "" : "not") + " activated, account is " + ((account.isOnlineAndConnected()) ? "" : "not") + " online or connected)");
+                        callback.onMoreMessagesLoaded(0, conversation);
+                        callback.informUser(R.string.no_more_history_on_server);
+                    }
                 }
-			}
+            }
 		};
 		mDatabaseExecutor.execute(runnable);
 	}
@@ -2553,6 +2559,10 @@ public class XmppConnectionService extends Service implements OnPhoneContactsLoa
 		public void onMoreMessagesLoaded(int count, Conversation conversation);
 
 		public void informUser(int r);
+
+        void setLoadingInProgress();
+
+        boolean isLoadingInProgress();
 	}
 
 	public interface OnAccountPasswordChanged {
diff --git a/src/main/java/de/thedevstack/conversationsplus/ui/listeners/ConversationMoreMessagesLoadedListener.java b/src/main/java/de/thedevstack/conversationsplus/ui/listeners/ConversationMoreMessagesLoadedListener.java
index 6e7d5d6a..cdc60187 100644
--- a/src/main/java/de/thedevstack/conversationsplus/ui/listeners/ConversationMoreMessagesLoadedListener.java
+++ b/src/main/java/de/thedevstack/conversationsplus/ui/listeners/ConversationMoreMessagesLoadedListener.java
@@ -24,18 +24,32 @@ public class ConversationMoreMessagesLoadedListener implements XmppConnectionSer
     private ListView messagesView;
     private MessageAdapter messageListAdapter;
     private Toast messageLoaderToast;
+    /*
+    The current loading status
+     */
+    private boolean loadingMessages = false;
 
     public ConversationMoreMessagesLoadedListener(SwipeRefreshLayout swipeLayout, List<Message> messageList, ConversationFragment fragment, ListView messagesView, MessageAdapter messageListAdapter) {
         this.swipeLayout = swipeLayout;
         this.messageList = messageList;
+
         this.fragment = fragment;
         this.messagesView = messagesView;
         this.messageListAdapter = messageListAdapter;
     }
 
+    public void setLoadingInProgress() {
+        this.loadingMessages = true;
+    }
+
+    public boolean isLoadingInProgress() {
+        return this.loadingMessages;
+    }
+
     @Override
     public void onMoreMessagesLoaded(final int c, final Conversation conversation) {
         ConversationActivity activity = (ConversationActivity) fragment.getActivity();
+        // Current selected conversation is not the same the messages are loaded - skip updating message view and hide loading graphic
         if (activity.getSelectedConversation() != conversation) {
             activity.runOnUiThread(new Runnable() {
                 @Override
@@ -45,6 +59,7 @@ public class ConversationMoreMessagesLoadedListener implements XmppConnectionSer
             });
             return;
         }
+        // No new messages are loaded
         if (0 == c) {
             activity.runOnUiThread(new Runnable() {
                 @Override
@@ -56,19 +71,26 @@ public class ConversationMoreMessagesLoadedListener implements XmppConnectionSer
         activity.runOnUiThread(new Runnable() {
             @Override
             public void run() {
-                final int oldPosition = messagesView.getFirstVisiblePosition();
-                int pos = 0;
-                View v = messagesView.getChildAt(0);
-                final int pxOffset = (v == null) ? 0 : v.getTop();
+                final int oldPosition = messagesView.getFirstVisiblePosition(); // Always 0 - because loading starts always when hitting the top
+                String uuid = null;
+                boolean oldMessageListWasEmpty = messageList.isEmpty();
                 if (-1 < oldPosition && messageList.size() > oldPosition) {
                     Message message = messageList.get(oldPosition);
-                    String uuid = message != null ? message.getUuid() : null;
-                    pos = getIndexOf(uuid, messageList);
+                    uuid = message != null ? message.getUuid() : null;
                 }
-                conversation.populateWithMessages(messageList);
-                fragment.updateStatusMessages();
+                View v = messagesView.getChildAt(0);
+                final int pxOffset = (v == null) ? 0 : v.getTop();
+
+                conversation.populateWithMessages(messageList); // This overrides the old message list
+                fragment.updateStatusMessages(); // This adds "messages" to the list for the status
                 messageListAdapter.notifyDataSetChanged();
-                messagesView.setSelectionFromTop(pos, pxOffset);
+                loadingMessages = false; // Loading of messages is finished - next query can be loaded
+
+                int pos = getIndexOf(uuid, messageList);
+
+                if (!oldMessageListWasEmpty) {
+                    messagesView.setSelectionFromTop(pos, pxOffset);
+                }
 
                 if (messageLoaderToast != null) {
                     messageLoaderToast.cancel();
@@ -99,7 +121,7 @@ public class ConversationMoreMessagesLoadedListener implements XmppConnectionSer
         if (uuid == null) {
             return 0;
         }
-        for(int i = 0; i < messages.size(); ++i) {
+        for (int i = 0; i < messages.size(); ++i) {
             if (uuid.equals(messages.get(i).getUuid())) {
                 return i;
             } else {