1 .TH XScreenSaver 1 "24-Nov-97" "X Version 11"
3 blitspin - rotate a bitmap in an interesting way
6 [\-display \fIhost:display.screen\fP] [\-foreground \fIcolor\fP] [\-background \fIcolor\fP] [\-window] [\-root] [\-mono] [\-install] [\-visual \fIvisual\fP] [\-bitmap \fIfilename\fP] [\-delay \fIusecs\fP] [\-delay2 \fIusecs\fP]
8 The \fIblitspin\fP program repeatedly rotates a bitmap by 90 degrees by
9 using logical operations: the bitmap is divided into quadrants, and the
10 quadrants are shifted clockwise. Then the same thing is done again with
11 progressively smaller quadrants, except that all sub-quadrants of a
12 given size are rotated in parallel. So this takes \fBO(16*log2(N))\fP
13 blits of size NxN, with the limitation that the image must be square,
14 and the size must be a power of 2.
17 accepts the following options:
20 Draw on a newly-created window. This is the default.
23 Draw on the root window.
26 If on a color display, pretend we're on a monochrome display.
29 Install a private colormap for the window.
31 .B \-visual \fIvisual\fP
32 Specify which visual to use. Legal values are the name of a visual class,
33 or the id number (decimal or hex) of a specific visual.
35 .B \-bitmap \fIfilename\fP
36 The file name of a bitmap to rotate. It need not be square: it
37 will be padded with the background color. If unspecified or the
38 string \fI(default)\fP, a builtin bitmap is used.
40 If support for the \fIXPM\fP library was enabled at compile-time,
41 the specified file may be in \fIXPM\fP format as well as \fIXBM\fP, and
42 thus may be a color image.
44 The \fB*bitmapFilePath\fP resource will be searched if the bitmap
45 name is not a fully-qualified pathname.
48 If this option is specified, then the image which is spun will be grabbed
49 from the portion of the screen underlying the blitspin window. (Or, it
50 may come from an external video source: see below.)
53 .B \-delay \fImicroseconds\fP
54 How long to delay between steps of the rotation process, in microseconds.
55 Default is 500000, one-half second.
58 .B \-delay2 \fImicroseconds\fP
59 How long to delay between each 90-degree rotation, in microseconds.
60 Default is 500000, one-half second.
62 to get the default host and display number.
64 On some systems (currently, only SGIs), this program can, instead of grabbing
65 a desktop image, grab a frame of video from an external camera and manipulate
66 that instead. The following resources control that.
69 .B grabVideoProbability \fR(Float)\fP
70 What portion of the time to grab video rather than a screen image,
71 between 0.0 and 1.0. Defaults to 0.5, or half the time.
73 .B videoDevice \fR(Integer)\fP
74 The number of the default video input device to check first. If unspecified,
75 the default camera (from videopanel(1)) will be checked first. After that, all
76 other available video input devices will be checked in order.
78 The first one which produces a non-black image will be used. If all images
79 are black, the others will be re-checked a few times before giving up and
80 falling back to simply grabbing a desktop image (but note that this takes a
81 few seconds, so if you don't actually have any video sources hooked up, you
82 should consider turning off video grabbing by setting
83 \fBgrabVideoProbability\fP to 0.0.)
85 .B videoGain \fR(Float)\fP
86 The amount by which to brighten the grabbed image. This defaults to 2.2.
89 to get the name of a resource file that overrides the global resources
90 stored in the RESOURCE_MANAGER property.
95 Copyright \(co 1992, 1993, 1997 by Jamie Zawinski.
96 Permission to use, copy, modify, distribute, and sell this software and its
97 documentation for any purpose is hereby granted without fee, provided that
98 the above copyright notice appear in all copies and that both that copyright
99 notice and this permission notice appear in supporting documentation. No
100 representations are made about the suitability of this software for any
101 purpose. It is provided "as is" without express or implied warranty.
103 Jamie Zawinski <jwz@jwz.org>, 17-aug-92.
105 Based on SmallTalk code which appeared in the August 1981 issue of Byte