#RegisterAfterAnimationFrameListener

The RegisterAfterAnimationFrameListener method, part of the VSyncObserver class, registers a persistent listener that is called after every VSync signal occurs. Unlike RequestAnimationFrame, which is a one-shot request, no API is exposed to unregister this listener, making it suitable for continuous monitoring or tasks that need to run on every frame.

This method must be called on the BTS (Background Thread Script) thread. It also supports both C++ std::function and C-style function pointer callbacks.

#Method Signature

#With std::function callback

void RegisterAfterAnimationFrameListener(lynx::pub::VSyncObserverCallback callback);

#With C-function callback

void RegisterAfterAnimationFrameListener(vsync_observer_callback callback, void* user_data);

#Parameters

#Callback Functions

The C++ lynx::pub::VSyncObserverCallback signature is:

void(int64_t frame_start_time, int64_t frame_end_time);

The C vsync_observer_callback signature is:

void(void* user_data, int64_t frame_start_time, int64_t frame_end_time);

#Important Notes

• Execution Thread: This method and its callbacks are intended to be used on the BTS thread.
• Persistent Listener: The registered callback will be invoked for every subsequent VSync signal, not just once.
• Lifecycle: Keep the VSyncObserver instance alive while the runtime may invoke the callback. The API does not provide an explicit unregister operation.

#Example

This example shows how to register a listener to log information for every frame.

// Assuming this code is running on the BTS thread and 'vsync_observer' is available.

vsync_observer->RegisterAfterAnimationFrameListener([](int64_t start_time, int64_t end_time) {
    // This will be logged on every single frame.
    // Useful for performance monitoring or continuous updates.
    printf("Frame processed. Start: %lld, End: %lld\\n", start_time, end_time);
});

#Compatibility