.TH blitspin "" "" "X Application"
.PC "Rotate a bitmap in an interesting way"
.fi
\fBblitspin
[\-background \fIcolor\fB]
[\-bitmap \fIfilename\fB]
[\-delay \fImicroseconds\fB]
[\-delay2 \fImicroseconds\fB]
[\-display \fIhost:display.screen\fB]
[\-foreground \fIcolor\fB]
[\-mono]
[\-root]
[\-window]\fR
.PP
.B blitspin
repeatedly rotates a bitmap by 90\(de by using logical operations.
It divides the bitmap into quadrants, and shifts the quadrants clockwise.
It then does the same thing again with progressively smaller quadrants,
except that it rotates all sub-quadrants of a given size in parallel.
So this takes \fBO(16\(mulog2(\fIN\fB))\fR blits of size \fIN\(mu\fIN\fR,
with the limitation that the image must be square
and the size must be a power of two.
.SH Options
.B blitspin
recognizes the following options:
.IP "\fB\-bitmap \fIname\fR"
Rotate
.IR name .
It need not be square:
it will be padded with the background color.
Default is
.BR xlogo64 ,
but
.B escherknot
is also nice.
You really need to run this on a bigger bitmap than
those shipped with the X distribution to do it justice.
.IP
If
.I name
is not a full path name,
.B blitspin
searches the directories named in resourcd
.BR *bitmapFilePath .
.IP "\fB\-delay \fImicroseconds\fR"
Delay
.I microseconds
between steps of the rotation process.
The default is 500,000.
.IP "\fB\-delay2 \fImicroseconds\fR"
Delay
.I microseconds
between each 90\(de rotation.
The default is 500,000.
.IP "\fB\-display \fIhost\^\fB[:\fIserver\^\fB][.\fIscreen\^\fB]\fR"
Display the client's window on screen number
.I screen
of
.I server
on host system
.IR host .
.IP "\fB\-foreground \fIcolor\fR"
Set the color of the foreground to
.IR color .
.IP \fB\-mono\fR
Map the application to black and white, even if run on a color server.
.IP "\fB\-root\fR"
Draw the application on the root window.
.IP "\fB\-window\fR"
Draw the application in its own window.
This is the default.
.SH "Environmental Variables"
.B blitspin
reads the following environmental variables:
.IP \fBDISPLAY\fR
The default host and display number.
.IP \fBXENVIRONMENT\fR
The name of the resource file that overrides the global resources
stored in the property
.BR RESOURCE_MANAGER .
.SH "See Also"
.B
X,
xscreensaver
.R
.SH Notes
.B blitspin
was written by
Jamie Zawinski (jwz@lucid.com).
It is based on SmallTalk code that appeared in the August 1981 issue of
.I Byte
magazine.
.PP
Copyright \(co 1992 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.
