request_video_bitmap

Triple buffering page flip request.

Description

int request_video_bitmap(BITMAP *bitmap);
This function is used for triple buffering. It requests a page flip to display the specified video bitmap object, but returns immediately rather than waiting for a retrace. The flip 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 on certain hardware: see the comments about request_scroll(). Example: 
      int current_page;
      BITMAP *video_page[3];
      ...
      /* Create pages for page flipping */
      video_page[0] = create_video_bitmap(SCREEN_W, SCREEN_H);
      video_page[1] = create_video_bitmap(SCREEN_W, SCREEN_H);
      video_page[2] = create_video_bitmap(SCREEN_W, SCREEN_H);
      current_page = 0;
      ...
      /* draw the screen and flip pages */
      draw_screen(video_page[current_page]);
      do {
      } while (poll_scroll());
      request_video_bitmap(video_page[current_page]);
      current_page = (current_page+1)%3;
      ...
Returns zero on success and non-zero on failure.
See Also:
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