Fixes FS#81 - avoid jumps after loading messages

1 files changed, 32 insertions, 10 deletions

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 {