#RequestBeforeAnimationFrame

The RequestBeforeAnimationFrame method, part of the VSyncObserver class, schedules a function to be executed just before the next screen repaint, synchronized with the VSync signal. Unlike RequestAnimationFrame, callbacks registered with this method are guaranteed to be executed before any standard animation frame callbacks. This is useful for tasks that need to update state or perform calculations before other visual updates occur in the same frame.

This method also provides two overloads for C++ std::function and C-style function pointers.

#Method Signature

#With std::function callback

void RequestBeforeAnimationFrame(uintptr_t id, lynx::pub::VSyncObserverCallback callback);

#With C-function callback

void RequestBeforeAnimationFrame(uintptr_t id,
                                 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);

#Example

This example demonstrates how to schedule a high-priority task before other animations.

// Assuming 'vsync_observer' is a valid std::unique_ptr<VSyncObserver>.

uintptr_t high_priority_id = 2;

vsync_observer->RequestBeforeAnimationFrame(high_priority_id, [](int64_t start_time, int64_t end_time) {
    // This logic runs before other RequestAnimationFrame callbacks.
    // Ideal for pre-calculation or state updates.
    printf("High-priority task executed for frame: %lld\\n", start_time);
});

#Compatibility