SIMPLE SOLUTIONS

BLITSPIN - reference manual online

Rotate a bitmap in an interesting way.

Chapter
5.34 (24-Oct-2015)
blitspin(6x)                           XScreenSaver manual                           blitspin(6x)

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 opera‐ tions: 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 bit‐ map 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, 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. -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-demo(1), xscreensaver-getimage(1)
AUTHOR Jamie Zawinski <@jwz.org>, 17-aug-92. Based on SmallTalk code which appeared in the August 1981 issue of Byte magazine.
X Version 11 5.34 (24-Oct-2015) blitspin(6x)
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blitspin(6x) referred by
refer to xscreensaver-getimage(1)