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blitspin(6)		      XScreenSaver manual		   blitspin(6)

       blitspin	- rotate a bitmap in an	interesting way

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

       The blitspin program repeatedly rotates a bitmap	by 90 degrees by using
       logical operations: the bitmap is divided into quadrants, and the quad-
       rants  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.

       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 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

       -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.

	       If this option is specified, then the image which is spun  will
	       be  grabbed from	the portion of the screen underlying the blit-
	       spin window, or from the	system's video input, or from a	random
	       file  on	disk, as indicated by the grabDesktopImages, grabVide-
	       oFrames,	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 mi-
	       croseconds.  Default is 500000, one-half	second.

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

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

       -fps    Display the current frame rate and CPU load.

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

       X(1), xscreensaver(1), xscreensaver-demo(1), xscreensaver-getimage(1)

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

       Jamie Zawinski <>, 17-aug-92.

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

X Version 11		      5.44 (20-Mar-2020)		   blitspin(6)


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