set_gfx_mode(3alleg4)                                             Allegro manual                                             set_gfx_mode(3alleg4)

NAME

       set_gfx_mode - Sets a graphic video mode. Allegro game programming library.

SYNOPSIS

       #include <allegro.h>

       int set_gfx_mode(int card, int w, int h, int v_w, int v_h);

DESCRIPTION

       Switches  into graphics mode. The card parameter should usually be one of the Allegro magic drivers (read introduction of chapter "Graphics
       modes") or see the platform specific documentation for a list of the available drivers. The w and h parameters specify what screen  resolu-
       tion you want.  The color depth of the graphic mode has to be specified before calling this function with set_color_depth().

       The  v_w and v_h parameters specify the minimum virtual screen size, in case you need a large virtual screen for hardware scrolling or page
       flipping. You should set them to zero if you don't care about the virtual screen size.

       When you call set_gfx_mode(), the v_w and v_h parameters represent the minimum size of virtual screen that is acceptable for your  program.
       The  range  of  possible  sizes  is  usually very restricted, and Allegro may end up creating a virtual screen much larger than the one you
       request.  Allowed sizes are driver dependent and some drivers do not allow virtual screens that are larger than the visible screen at  all:
       don't assume that whatever you pass will always work.

       In mode-X the virtual width can be any multiple of eight greater than or equal to the physical screen width, and the virtual height will be
       set accordingly (the VGA has 256k of vram, so the virtual height will be 256*1024/virtual_width).

       Currently, using a big virtual screen for page flipping is considered bad practice.   There  are  platforms  which  don't  support  virtual
       screens  bigger  than  the  physical  screen but can create different video pages to flip back and forth. This means that, if you want page
       flipping and aren't going to use hardware scrolling, you should call set_gfx_mode() with (0,0) as the virtual screen size and later  create
       the  different  video  pages  with  create_video_bitmap().  Otherwise  your  program  will  be limited to the platforms supporting hardware
       scrolling.

       After you select a graphics mode, the physical and virtual screen sizes can be checked with the macros SCREEN_W, SCREEN_H,  VIRTUAL_W,  and
       VIRTUAL_H.

RETURN VALUE

       Returns zero on success. On failure returns a negative number and stores a description of the problem in allegro_error.

SEE ALSO

       set_color_depth(3alleg4),   request_refresh_rate(3alleg4),   screen(3alleg4),   gfx_capabilities(3alleg4),   allegro_error(3alleg4),   cre-
       ate_video_bitmap(3alleg4), get_desktop_resolution(3alleg4), SCREEN_W(3alleg4), SCREEN_H(3alleg4), VIRTUAL_W(3alleg4), VIRTUAL_H(3alleg4)

Allegro                                                            version 4.4.2                                             set_gfx_mode(3alleg4)