blitspin
Section: XScreenSaver manual (6x)
Updated: 6.00-1.fc34 (02-Apr-2021)
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NAME
blitspin - rotate a bitmap in an interesting way
SYNOPSIS
blitspin
[-display
host:display.screen]
[-foreground
color] [-background
color] [-window] [-root]
[-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.
- -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.
SEE ALSO
X(1),
xscreensaver(1),
xscreensaver-settings(1),
xscreensaver-getimage(6x)
COPYRIGHT
Copyright © 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.