request_scroll(3)

NAME
request_scroll

SYNOPSIS
#include <allegro.h>

int request_scroll(int x, int y);

DESCRIPTION
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 (see examples/ex3buf.c). Triple buffering is only possible on certain hardware: it will work in any mode-X resolution if the timer retrace simulator is active (but this doesn't work correctly under win95), plus it is supported by the VBE 3.0 and VBE/AF drivers for a limited number of high-end graphics cards. 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.

SEE ALSO
poll_scroll(3), request_video_bitmap(3), gfx_capabilities(3), timer_simulate_retrace(3), scroll_screen(3)