blitspin(6) XScreenSaver manual blitspin(6)

NAME

blitspin - rotate a bitmap in an interesting way

SYNOPSIS

blitspin [--display host:display.screen] [--foreground color]
[--background color] [--window] [--root] [--window-id number]
[--mono] [--install] [--visual visual] [--bitmap filename] [--delay
usecs] [--delay2 usecs] [--duration secs]

DESCRIPTION

The blitspin program repeatedly rotates a bitmap by 90 degrees by
using logical operations: the bitmap is divided into quadrants, and
the quadrants are shifted clockwise. Then the same thing is done
again with progressively smaller quadrants, except that all sub-
quadrants of a given size are rotated in parallel. So this takes
O(16*log2(N)) blits of size NxN, with the limitation that the image
must be square, and the size must be a power of 2.

OPTIONS

blitspin accepts the following options:

--window
Draw on a newly-created window. This is the default.

--root Draw on the root window.

--window-id number
Draw on the specified window.

--mono If on a color display, pretend we're on a monochrome display.

--install
Install a private colormap for the window.

--visual visual
Specify which visual to use. Legal values are the name of a
visual class, or the id number (decimal or hex) of a specific
visual.

--bitmap filename
The file name of a bitmap to rotate. It need not be square:
it will be padded with the background color. If unspecified
or the string (default), a builtin bitmap is used.

If support for the XPM library was enabled at compile-time,
the specified file may be in XPM format as well as XBM, and
thus may be a color image.

The *bitmapFilePath resource will be searched if the bitmap
name is not a fully-qualified pathname.

--grab-screen
If this option is specified, then the image which is spun
will be grabbed from the portion of the screen underlying the
blitspin window, or from the system's video input, or from a
random file on disk, as indicated by the grabDesktopImages,
grabVideoFrames, and chooseRandomImages options in the
~/.xscreensaver file; see xscreensaver-settings(1) for more
details.

--delay microseconds
How long to delay between steps of the rotation process, in
microseconds. Default is 500000, one-half second.

--duration seconds
How long to run before loading a new image. Default 120
seconds.

--delay2 microseconds
How long to delay between each 90-degree rotation, in
microseconds. Default is 500000, one-half second. DISPLAY
to get the default host and display number.

--fps Display the current frame rate and CPU load.

ENVIRONMENT

XENVIRONMENT to get the name of a resource file that overrides the
global resources stored in the RESOURCE_MANAGER property.

XSCREENSAVER_WINDOW
The window ID to use with --root.

SEE ALSO

X(1), xscreensaver(1), xscreensaver-settings(1),
xscreensaver-getimage(6)

COPYRIGHT

Copyright (C) 1992, 1993, 1997, 2001 by Jamie Zawinski. Permission
to use, copy, modify, distribute, and sell this software and its
documentation for any purpose is hereby granted without fee, provided
that the above copyright notice appear in all copies and that both
that copyright notice and this permission notice appear in supporting
documentation. No representations are made about the suitability of
this software for any purpose. It is provided "as is" without
express or implied warranty.

AUTHOR

Jamie Zawinski <jwz@jwz.org>, 17-aug-92.

Based on SmallTalk code which appeared in the August 1981 issue of
Byte magazine.

X Version 11 6.09 (07-Jun-2024) blitspin(6)