XScreenSaver(1)XScreenSaver(1)NAMEblitspin - rotate a bitmap in an interesting way
SYNOPSISblitspin [-display host:display.screen] [-foreground
color] [-background color] [-window] [-root] [-mono]
[-install] [-visual visual] [-bitmap filename] [-delay
usecs] [-delay2 usecs]
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.
OPTIONSblitspin 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 com
pile-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, grab_
VideoFrames, and chooseRandomImages options in the
~/.xscreensaver file; see xscreensaver-demo(1) for
more details.
-delay microseconds
How long to delay between steps of the rotation
process, in microseconds. Default is 500000, one-
half second.
-delay2 microseconds
How long to delay between each 90-degree rotation,
in microseconds. Default is 500000, one-half sec
ond. DISPLAY to get the default host and display
number.
ENVIRONMENT
XENVIRONMENT to get the name of a resource file that over
rides the global resources stored in the RESOURCE_MANAGER
property.
SEE ALSOX(1), xscreensaver(1), xscreensaver-demo(1), xscreensaver-
getimage(1)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 pro
vided "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 24-Nov-97 XScreenSaver(1)
