bw-fb — display a black and white bw image on a framebuffer
bw-fb [-ahiczRGB ] [-F framebuffer] [-s squarefilesize] [-w file_width] [-n file_height] [-S squarescrsize] [-W scr_width] [-N scr_height] [-x file_xoff] [-y file_yoff] [-X scr_xoff] [-Y src_yoff] [infile.bw]
bw-fb
reads a
bw(5)
format file
from standard input if an input file is not given, and displays the
image on the currently selected framebuffer.
The environment variable
FB_FILE
specifies
the current framebuffer; see
brlcad(1).
Alternatively, the framebuffer may be explicitly specified
by using the
-F
flag.
By default, the
bw
file (and, automatically, the requested framebuffer size) is assumed to be 512x512 pixels.
Specifying the
-a
flag causes the program to attempt to autosize.
A table of common image sizes is consulted, and if any match
the size of the input file, then the width and height values
associated with that size will be used.
If the
-i
flag is specified, the image is output from top to bottom.
Customarily,
bw
files are stored bottom to top, so this
inverts the image.
The
-c
flag causes the screen to be cleared before the image is displayed.
The default behavior is to overwrite the current image
with the new image without clearing the screen.
The
-z
flag will zoom and center on the image being displayed
to make it fill the display area.
The flags
-R, -G, and -B
select individual color planes into which the image will be loaded.
One or more can be given. By default all three colors are written
with the
bw
pixel value.
The
-w file_width
flag specifies the width of each scanline in the input file, in pixels.
The
-n file_height
flag specifies the height in scanlines of the input file.
Both are set to to the same value via
-s squarefilesize.
(-W scr_width,
-N scr_height, and
-S squarescrsize
perform these roles for the display device; if none of these
three options are used, the display device uses the dimensions
of the input file.)
-x file_xoff,
-y file_yoff,
-X scr_xoff,
and
-y scr_yoff
will offset into the file or onto the screen by the given amounts.
The coordinate system for these offsets is first quadrant, with
the origin at the lower left corner of the image.
A bw(5) file contains sequences of pixels. Each pixel is stored as one unsigned char. The first pixel in a bw file is the lower left corner of the image. The pixels proceed from left-to-right across each scanline, with scanlines being written from the bottom to the top of the image.