screen(3alleg4) [debian man page]

screen(3alleg4) 						  Allegro manual						   screen(3alleg4)

NAME

       screen - Global pointer to the screen hardware video memory. Allegro game programming library.

SYNOPSIS

       #include <allegro.h>

       extern BITMAP *screen;

DESCRIPTION

       Global  pointer to a bitmap, sized VIRTUAL_W x VIRTUAL_H. This is created by set_gfx_mode(), and represents the hardware video memory. Only
       a part of this bitmap will actually be visible, sized SCREEN_W x SCREEN_H.  Normally this is the top left  corner  of  the  larger  virtual
       screen,	so  you can ignore the extra invisible virtual size of the bitmap if you aren't interested in hardware scrolling or page flipping.
       To move the visible window to other parts of the screen bitmap, call scroll_screen().  Initially the clipping rectangle will be limited	to
       the  physical  screen  size,  so if you want to draw onto a larger virtual screen space outside this rectangle, you will need to adjust the
       clipping.

       For example, to draw a pixel onto the screen you would write:

	  putpixel(screen, x, y, color);

       Or to implement a double-buffered system:

	  /* Make a bitmap in RAM. */
	  BITMAP *bmp = create_bitmap(320, 200);
	  /* Clean the memory bitmap. */
	  clear_bitmap(bmp);
	  /* Draw onto the memory bitmap. */
	  putpixel(bmp, x, y, color);
	  /* Copy it to the screen. */
	  blit(bmp, screen, 0, 0, 0, 0, 320, 200);

       Warning: be very careful when using this pointer at the same time as any bitmaps created by the	create_video_bitmap()  function  (see  the
       description of this function for more detailed information). And never try to destroy it with destroy_bitmap().

SEE ALSO

       set_gfx_mode(3alleg4), is_screen_bitmap(3alleg4), create_video_bitmap(3alleg4), scroll_screen(3alleg4)

Allegro 							   version 4.4.2						   screen(3alleg4)

Check Out this Related Man Page

create_video_bitmap(3alleg4)					  Allegro manual				      create_video_bitmap(3alleg4)

NAME

       create_video_bitmap - Creates a video memory bitmap. Allegro game programming library.

SYNOPSIS

       #include <allegro.h>

       BITMAP *create_video_bitmap(int width, int height);

DESCRIPTION

       Allocates  a  video  memory  bitmap  of the specified size. This can be used to allocate offscreen video memory for storing source graphics
       ready for a hardware accelerated blitting operation, or to create multiple video memory pages  which  can  then	be  displayed  by  calling
       show_video_bitmap().  Read the introduction of this chapter for a comparison with other types of bitmaps and other specific details.

       Warning:  video memory bitmaps are usually allocated from the same space as the screen bitmap, so they may overlap with it; it is therefore
       not a good idea to use the global screen at the same time as any surfaces returned by this function.

RETURN VALUE

       Returns a pointer to the bitmap on success, or NULL if you have run out of video ram. Remember to destroy this bitmap before any subsequent
       call to set_gfx_mode().

SEE ALSO

       create_bitmap(3alleg4),	 create_bitmap_ex(3alleg4),  create_system_bitmap(3alleg4),  create_sub_bitmap(3alleg4),  destroy_bitmap(3alleg4),
       screen(3alleg4),     show_video_bitmap(3alleg4),      gfx_capabilities(3alleg4),      is_video_bitmap(3alleg4),	    clear_bitmap(3alleg4),
       clear_to_color(3alleg4), ex3buf(3alleg4), exaccel(3alleg4), exflip(3alleg4), exupdate(3alleg4)

Allegro 							   version 4.4.2				      create_video_bitmap(3alleg4)

Linux and UNIX Man Pages

screen(3alleg4) [debian man page]

Check Out this Related Man Page