request_scroll (3) - Linux Manuals
request_scroll: Queues a hardware scroll request with triple buffering. Allegro game programming library.
request_scroll - Queues a hardware scroll request with triple buffering. Allegro game programming library.
int request_scroll(int x, int y);
This function is used for triple buffering. It requests a hardware scroll
to the specified position, but returns immediately rather than waiting
for a retrace. The scroll will then take place during the next vertical
retrace, but you can carry on running other code in the meantime and use
the poll_scroll() routine to detect when the flip has actually taken
Triple buffering is only possible with certain drivers: you can look at the
GFX_CAN_TRIPLE_BUFFER bit in the gfx_capabilities flag to see if it will
work with the current driver.
This function returns zero on success, non-zero otherwise.