BITMAP(6)							   Games Manual 							 BITMAP(6)

NAME

       bitmap - external format for bitmaps

SYNOPSIS

       #include <libg.h>

DESCRIPTION

       Bitmaps are described in graphics(2).  Fonts and bitmaps are stored in external files in machine-independent formats.

       Bitmap  files  are  read  and  written  using  rdbitmapfile and wrbitmapfile (see balloc(2)).  A bitmap file starts with 5 decimal strings:
       ldepth, r.min.x, r.min.y, r.max.x, and r.max.y.	Each number is right-justified and blank padded in 11 characters,  followed  by  a  blank.
       The  rest  of  the  file contains the r.max.y-r.min.y rows of bitmap data.  A row consists of the byte containing pixel r.min.x and all the
       bytes up to and including the byte containing pixel r.max.x-1.  A pixel with x-coordinate = x in a bitmap with ldepth = ld will appear as w
       =  2^ld	contiguous  bits in a byte, with the pixel's high order bit starting at the byte's bit number w*(x mod (8/w)), where bits within a
       byte are numbered 0 to 7 from the high order to the low order bit.  If w is greater than 8, it is a multiple of 8, so pixel values take	up
       an integral number of bytes.  Rows contain integral number of bytes, so there may be some unused pixels at either end of a row.

       The rdbitmap and wrbitmap functions described in balloc(2) also deal with rows in this format, stored in user memory.

       Some small images, in particular 48x48 face files as used by seemail (see mail(1)) and 16x16 cursors, can be stored textually, suitable for
       inclusion in C source.  Each line of text represents one scan line as a comma-separated sequence of hexadecimal bytes, shorts, or words	in
       C  format.   For cursors, each line defines a pair of bytes.  (It takes two images to define a cursor; each must be stored separately to be
       processed by programs such as tweak(1).)  Face files of one bit per pixel are stored as a sequence of shorts, those of larger  pixel  sizes
       as  a  sequence	of  longs.   Software that reads these files must deduce the image size from the input; there is no header.  These formats
       reflect history rather than design.

SEE ALSO

       tweak(1), graphics(2), bitblt(2), balloc(2), face(6), font(6)

																	 BITMAP(6)