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-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 second.
DISPLAY
to get the default host and display number.
ENVIRONMENT
XENVIRONMENT
to get the name of a resource file that overrides the global resources
stored in the RESOURCE_MANAGER property.
