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TdApi.GetChatHistory for Wear OS: Complete Guide

Learn how to properly implement chat history loading in Wear OS using TdApi.GetChatHistory. Pagination optimization, scroll handling, and code examples for performance.

#tdlib-development#wear-os-apps#telegram-client#chat-history#pagination#mobile-optimization#java-android
Question

How to properly use the TdApi.GetChatHistory method to display chat history in a Wear OS Telegram client?

I’m developing a custom Telegram client for Wear OS and have encountered issues when implementing chat history display. I’ve tried several approaches, but none of them work perfectly:

  1. The first approach loads messages unpredictably, following some internal mechanism without clear logic.
  2. The second approach loads messages one by one during scrolling, which creates an unattractive user interface.

I’ve studied the documentation, but it didn’t clarify these issues. The implementation code is available on GitHub for additional context.

Could you please advise on how to properly implement loading and displaying chat history in a Wear OS Telegram client using TdApi.GetChatHistory?

NeuroAgent

TdApi.GetChatHistory returns chat messages in reverse chronological order, and TDLib independently determines the optimal number of messages to return. In a Wear OS client, you should implement pagination using the offset and limit parameters, by initially loading a set of messages and then loading additional portions when scrolling, using the last received message_id as fromId.

Table of Contents

Basic Principles of TdApi.GetChatHistory

TdApi.GetChatHistory is the primary method for retrieving chat history in TDLib. According to the documentation, this method has several key features:

  • Returns messages in reverse chronological order (from newest to oldest)
  • TDLib independently determines the optimal number of messages to return for performance
  • Can work in offline mode if the onlyLocal parameter is set to true
  • Automatically calls openChat for the specified chat

It’s important to understand that the method doesn’t return all messages at once — this would be inefficient for large chats. Instead, TDLib returns a portion of messages that must be loaded gradually.

Method Structure and Parameters

The structure of the TdApi.GetChatHistory method may vary slightly between implementations, but the main parameters remain common:

java
// Main method signature
TdApi.GetChatHistory(long chatId, int fromId, int offset, int limit)

Where:

  • chatId - chat identifier
  • fromId - message identifier from which to load history (used for pagination)
  • offset - offset from fromId (usually 0 for most cases)
  • limit - maximum number of messages to load

Some implementations also have an onlyLocal parameter for working only with the local database.

Optimal Implementation for Wear OS

For a Wear OS client, you need to consider device limitations: small screen, limited resources, and the need for quick response to user actions. Here’s the optimal approach:

1. Initial chat loading

java
// Opening chat before getting history
TdApi.OpenChat openChat = new TdApi.OpenChat(chatId);
client.send(openChat, new Client.ResultHandler() {
    @Override
    public void onResult(TdApi.TLObject object) {
        // After opening the chat, load history
        loadChatHistory();
    }
});

private void loadChatHistory() {
    // Load latest messages
    TdApi.GetChatHistory getHistory = new TdApi.GetChatHistory(
        chatId, 
        0, // fromId = 0 to load latest messages
        0, // offset
        20 // limit - optimal amount for Wear OS
    );
    client.send(getHistory, new Client.ResultHandler() {
        @Override
        public void onResult(TdApi.TLObject object) {
            TdApi.Messages messages = (TdApi.Messages) object;
            // Process received messages
        }
    });
}

2. Optimal message count

For Wear OS, it’s optimal to load 15-30 messages at a time. This allows:

  • Quick content display on a small screen
  • Minimized memory and CPU usage
  • Smooth scrolling without delays

Pagination and Scroll Handling

Proper pagination is key to solving unpredictable loading issues. Here’s how to implement it:

1. Loading more when scrolling to the top

java
private void loadMoreMessages() {
    if (isLoadingMore || !canLoadMore()) return;
    
    isLoadingMore = true;
    
    // Get ID of first visible message
    int firstVisibleMessageId = getFirstVisibleMessageId();
    
    TdApi.GetChatHistory getHistory = new TdApi.GetChatHistory(
        chatId,
        firstVisibleMessageId, // fromId - first visible message
        0, // offset
        15 // limit
    );
    
    client.send(getHistory, new Client.ResultHandler() {
        @Override
        public void onResult(TdApi.TLObject object) {
            TdApi.Messages messages = (TdApi.Messages) object;
            if (messages.messages.length > 0) {
                // Add new messages to the beginning of the list
                prependMessages(messages.messages);
            }
            isLoadingMore = false;
        }
    });
}

private boolean canLoadMore() {
    // Check if there are more messages to load
    return totalMessageCount > displayedMessagesCount;
}

2. Scroll handling in Wear OS

For Wear OS, it’s important to implement smooth scrolling without intermittent loading:

java
// In Wear OS Activity or Fragment
@Override
public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
    if (newState == RecyclerView.SCROLL_STATE_IDLE) {
        // Scrolling finished, check if more loading is needed
        checkAndLoadMore();
    }
}

@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
    if (dy > 0) { // Scrolling down
        checkIfLoadMoreNeeded();
    }
}

private void checkIfLoadMoreNeeded() {
    if (isNearTop()) {
        loadMoreMessages();
    }
}

private boolean isNearTop() {
    // Check if scrolling is near the top of the list
    return layoutManager.findFirstVisibleItemPosition() < 5;
}

Solutions to Common Problems

Problem 1: Unpredictable message loading

Cause: Incorrect use of fromId and limit parameters.

Solution: Always use the last loaded position for fromId:

java
// Correct - use the last loaded message_id
private int lastLoadedMessageId = 0;

private void loadInitialMessages() {
    lastLoadedMessageId = 0;
    loadMessagesFromId(lastLoadedMessageId);
}

private void loadMessagesFromId(int fromId) {
    TdApi.GetChatHistory getHistory = new TdApi.GetChatHistory(
        chatId,
        fromId,
        0,
        20
    );
    // Send request...
}

Problem 2: Loading messages one by one when scrolling

Cause: Too small limit value or incorrect pagination logic.

Solution: Increase the limit and implement caching:

java
// Optimal parameters for Wear OS
private static final int MESSAGES_PER_PAGE = 20;
private static final int PREFETCH_THRESHOLD = 10; // Load in advance 10 messages

private void optimizeLoading() {
    if (shouldPrefetch()) {
        prefetchMessages();
    }
}

private boolean shouldPrefetch() {
    return layoutManager.findFirstVisibleItemPosition() < PREFETCH_THRESHOLD;
}

private void prefetchMessages() {
    int firstVisibleId = getFirstVisibleMessageId();
    loadMessagesFromId(firstVisibleId);
}

Code Examples

Complete implementation for Wear OS

java
public class WearChatActivity extends Activity {
    private long chatId;
    private TdClient client;
    private ChatAdapter adapter;
    private int lastLoadedMessageId = 0;
    private boolean isLoading = false;
    private RecyclerView recyclerView;
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_wear_chat);
        
        chatId = getIntent().getLongExtra("chat_id", 0);
        setupRecyclerView();
        openChatAndLoadHistory();
    }
    
    private void setupRecyclerView() {
        recyclerView = findViewById(R.id.recycler_view);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));
        adapter = new ChatAdapter();
        recyclerView.setAdapter(adapter);
        
        recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
            @Override
            public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
                if (dy > 0 && isNearTop()) {
                    loadMoreMessages();
                }
            }
        });
    }
    
    private void openChatAndLoadHistory() {
        // First open the chat
        client.send(new TdApi.OpenChat(chatId), result -> {
            if (result.getConstructor() == TdApi.Ok.CONSTRUCTOR) {
                loadInitialMessages();
            }
        });
    }
    
    private void loadInitialMessages() {
        if (isLoading) return;
        isLoading = true;
        
        lastLoadedMessageId = 0;
        loadMessagesFromId(lastLoadedMessageId);
    }
    
    private void loadMoreMessages() {
        if (isLoading || !canLoadMore()) return;
        isLoading = true;
        
        loadMessagesFromId(lastLoadedMessageId);
    }
    
    private void loadMessagesFromId(int fromId) {
        TdApi.GetChatHistory request = new TdApi.GetChatHistory(
            chatId,
            fromId,
            0,
            MESSAGES_PER_PAGE
        );
        
        client.send(request, result -> {
            if (result.getConstructor() == TdApi.Messages.CONSTRUCTOR) {
                TdApi.Messages messages = (TdApi.Messages) result;
                processLoadedMessages(messages);
            }
            isLoading = false;
        });
    }
    
    private void processLoadedMessages(TdApi.Messages messages) {
        if (messages.messages.length == 0) return;
        
        // Update the last loaded ID
        lastLoadedMessageId = messages.messages[messages.messages.length - 1].id;
        
        // Add messages to adapter
        if (lastLoadedMessageId == 0) {
            // Initial load
            adapter.setMessages(messages.messages);
        } else {
            // Additional load
            adapter.addMessagesAtTop(messages.messages);
        }
    }
    
    private boolean isNearTop() {
        return ((LinearLayoutManager) recyclerView.getLayoutManager())
            .findFirstVisibleItemPosition() < 3;
    }
    
    private boolean canLoadMore() {
        return adapter.getItemCount() < getTotalMessageCount();
    }
}

Adapter for Wear OS

java
public class ChatAdapter extends RecyclerView.Adapter<ChatViewHolder> {
    private List<TdApi.Message> messages = new ArrayList<>();
    
    @Override
    public ChatViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext())
            .inflate(R.layout.item_wear_message, parent, false);
        return new ChatViewHolder(view);
    }
    
    @Override
    public void onBindViewHolder(ChatViewHolder holder, int position) {
        TdApi.Message message = messages.get(position);
        holder.bind(message);
    }
    
    @Override
    public int getItemCount() {
        return messages.size();
    }
    
    public void setMessages(TdApi.Message[] newMessages) {
        messages.clear();
        messages.addAll(Arrays.asList(newMessages));
        notifyDataSetChanged();
    }
    
    public void addMessagesAtTop(TdApi.Message[] newMessages) {
        messages.addAll(0, Arrays.asList(newMessages));
        notifyItemRangeInserted(0, newMessages.length);
    }
    
    public int getTotalMessageCount() {
        return messages.get(messages.size() - 1).totalCount;
    }
}

Performance Optimization Recommendations

1. Message caching

Implement two-level caching:

java
public class MessageCache {
    private LruCache<Long, List<TdApi.Message>> chatCache;
    private Map<Long, Integer> lastLoadedIds;
    
    public MessageCache() {
        int maxMemory = (int) (Runtime.getRuntime().maxMemory() / 1024);
        int cacheSize = maxMemory / 8; // 1/8 of available memory
        
        chatCache = new LruCache<Long, List<TdApi.Message>>(cacheSize) {
            @Override
            protected int sizeOf(Long key, List<TdApi.Message> messages) {
                return messages.size() * 64; // Approximate message size
            }
        };
    }
    
    public void cacheMessages(long chatId, List<TdApi.Message> messages) {
        chatCache.put(chatId, messages);
    }
    
    public List<TdApi.Message> getCachedMessages(long chatId) {
        return chatCache.get(chatId);
    }
}

2. Optimization for Wear OS

java
// Settings for Wear OS
private void setupWearOptimizations() {
    // Reduce the number of items in RecyclerView
    recyclerView.setItemViewCacheSize(10);
    recyclerView.setDrawingCacheEnabled(true);
    recyclerView.setDrawingCacheQuality(View.DRAWING_CACHE_QUALITY_LOW);
    
    // Use simplified ViewHolder
    adapter.setItemViewTypeCount(2); // Only text and media messages
    
    // Disable animations for performance
    recyclerView.setItemAnimator(null);
}

3. Loading state management

java
public class ChatStateManager {
    private enum LoadingState { IDLE, LOADING_INITIAL, LOADING_MORE }
    private LoadingState currentState = LoadingState.IDLE;
    
    public boolean canLoadMore() {
        return currentState == LoadingState.IDLE;
    }
    
    public void setLoadingInitial() {
        currentState = LoadingState.LOADING_INITIAL;
    }
    
    public void setLoadingMore() {
        currentState = LoadingState.LOADING_MORE;
    }
    
    public void setIdle() {
        currentState = LoadingState.IDLE;
    }
}

Sources

  1. TDLib: getChatHistory Class Reference - Official TDLib documentation
  2. TdApi.GetChatHistory API Documentation - Detailed method description
  3. Getting started with TDLib - TDLib getting started guide
  4. getChatHistory issues on GitHub - Discussion of problems and solutions
  5. Implementation example on Stack Overflow - Practical code examples

Conclusion

Key points for successful implementation:

  1. Understand how TDLib works: The method independently determines the optimal number of messages, so don’t try to bypass this limitation forcibly.

  2. Implement correct pagination: Use the last loaded message_id as fromId for the next load.

  3. Optimize for Wear OS: Load 15-30 messages at a time, use caching, and minimize the number of requests.

  4. Handle scrolling smoothly: Implement message prefetching in advance to avoid delays when scrolling.

  5. Manage state: Track loading state to avoid duplicate requests.

Practical recommendations:

  • Start by loading 20 messages when opening a chat
  • Implement additional loading when reaching the first 5 visible messages
  • Use two-level caching to improve performance
  • Add a loading indicator for better UX
  • Handle network errors and retry requests as needed

By following these principles, you can create a smooth and performant Telegram client for Wear OS with proper chat history functionality.

How to optimize message loading performance in a resource-constrained Wear OS application?How to implement two-level message caching in a Telegram client for Wear OS?How to handle network errors when loading chat history in TDLib for Wear OS?How to create a RecyclerView adapter for efficient message display on small Wear OS screens?How to manage loading state in a Telegram client for Wear OS to avoid duplicate requests?How to integrate TDLib into an existing Android application for Wear OS with minimal changes?
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