request_scroll - Man Page

#include <allegro.h>

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  place.

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.

poll_scroll(3), request_video_bitmap(3), gfx_capabilities(3), scroll_screen(3)

enable_triple_buffer(3), gfx_capabilities(3), poll_scroll(3), request_video_bitmap(3), scroll_screen(3).