NAME
xdaliclock - melting digital clock
SYNOPSIS
xdaliclock [-toolkitoption ...] [-option ...]
DESCRIPTION
The xdaliclock program displays a digital clock; when a digit changes,
it ‘‘melts’’ into its new shape.
This program was inspired by the Alto and Macintosh programs of the
same name, written by Steve Capps in 1983 or 1984.
OPTIONS
xdaliclock accepts all of the standard toolkit options, and also
accepts the following options:
-help Print a brief summary of the allowed options on the standard
error output.
-12 Use a twelve hour clock.
-24 Use a twenty-four hour clock.
-seconds
Update every second.
-noseconds
Update once per minute; don’t display seconds at all.
-cycle Do color-cycling.
-nocycle
Don’t do color-cycling.
-font fontname
Specifies the X font to use; xdaliclock can correctly animate
any font that contains all the digits plus colon and slash, and
in which the letters aren’t excessively curly.
The xdaliclock program also contains four builtin bitmapped
fonts, which are larger and more attractive than the standard X
fonts. One of these fonts will be used if the -font option is
given one of the fontnames BUILTIN0, BUILTIN1, BUILTIN2, or
BUILTIN3.
-builtin0
This is the same as specifying -font BUILTIN0.
-builtin1
This is the same as specifying -font BUILTIN1.
-builtin2 or -builtin
This is the same as specifying -font BUILTIN2.
-builtin3
This is the same as specifying -font BUILTIN3.
-fullscreen
Make the window take up the whole screen. When -fullscreen is
specified, the displayed time will wander around a little, to
prevent any pixels from being on continuously and causing
phosphor burn-in.
-root Display the clock on the root window instead of in its own
window. This makes the digits wander around too.
-window-id window
Render the clock on a window created by some other program.
-visual visual
Specify which visual to use. Legal values are:
default Use the screen’s default visual (the visual of the root
window.) This is the default.
best Use the visual which supports the most writable color
cells.
class One of StaticGray, StaticColor, TrueColor, GrayScale,
PseudoColor, or DirectColor. Selects the deepest
visual of the given class.
number A number (decimal or hex) is interpreted as a visual id
number, as reported by the xdpyinfo(1) program; in this
way you can select a shallower visual if desired.
If you don’t have a 24-bit system, using a visual other than
the default one may cause colormap flashing.
-transparent
Causes the background of the window to be transparent, if
possible.
If the server supports overlay planes, then they will be used
(this is the case on SGIs, and on certain HP, DEC, and IBM
systems.)
If overlay planes are not available, but the server supports
the Shape extension, then that will be used instead. However,
the Shape extension is very inefficient: it will cause your X
server to use up a lot of cycles.
Also, if the Shape extension is used, you will probably need to
configure your window manager to not put a titlebar on the
XDaliClock window. (This is the case at least with twm, tvtwm,
and mwm.) If you don’t do this, then the window will flicker
constantly, as the window manager tries to add and remove the
titlebar ten times each second.
None of these problems occur if overlay planes are used (or if
the -transparent option is not requested.)
-nontransparent
Don’t make the window’s background be transparent. This is the
default.
-memory low
Use high-bandwidth, low-memory mode. If you have a very fast
connection between the machine this program is running on and
the X server it is displaying on, then xdaliclock can work
correctly by simply making the drawing requests it needs when
it needs them. This is the elegant method. However, the
amount of data necessary to animate the display ends up being a
bit over 10 kilobytes worth of X Protocol per second. On a
fast machine with a local display, or over a fast network,
that’s almost negligible, but (for example) an NCD X Terminal
at 38.4 kbps can’t keep up. That is the reason for:
-memory medium
Use high-memory, low-bandwidth mode. In this mode, xdaliclock
precomputes most of the frames that it will ever need. This is
the sleazy copout method. The bandwidth requirements are
drastically reduced, because instead of telling the server what
bits to draw where, it merely tells it what pixmaps to copy
into the window. Aside from the fact that I consider this to
be cheating, the only downside of this method is that those
pixmaps (about 170 of them, each the size of one character) are
consuming server-memory. This probably isn’t a very big deal,
unless you’re using an exceptionally large font.
-memory high
With memory set to high, the cache is twice as large (the n ->
n+2 transitions are cached as well as the n -> n+1 ones). Even
with memory set to medium, this program can seem sluggish when
using a large font over a very slow connection to the display
server.
-countdown date
Instead of displaying the current time, display a countdown to
the specified date (if the date has already passed, count up
from it.) The date can take two forms: either a time_t (an
integer, the number of seconds past "Jan 1 00:00:00 GMT 1970");
or, a string of the form "Mmm DD HH:MM:SS YYYY", for example,
"Jan 1 00:00:00 2000". This string is interpreted in the local
time zone.
To count up from the current time, do this:
xdaliclock -countdown "‘date ’+%b %d %T %Y’‘"
The following standard X Toolkit command line arguments are commonly
used with xdaliclock:
-display host:dpy
This option specifies the X server to contact.
-geometry geometry
This option specifies the preferred size and position of the
clock window.
-bg color
This option specifies the color to use for the background of
the window. The default is ‘‘white.’’
-fg color
This option specifies the color to use for the foreground of
the window. The default is ‘‘black.’’
-bd color
This option specifies the color to use for the border of the
window. The default is the same as the foreground color.
-rv This option indicates that reverse video should be simulated by
swapping the foreground and background colors.
-bw number
This option specifies the width in pixels of the border
surrounding the window.
-xrm resourcestring
This option specifies a resource string to be used.
COMMANDS
Clicking and holding any mouse button in the xdaliclock window will
cause it to display the date while the button is held.
Typing ‘‘space’’ at the xdaliclock window will toggle between a twelve
hour and twenty-four hour display.
Typing ‘‘q’’ or ‘‘^C’’ at the window quits.
If the xdaliclock window is iconified or otherwise unmapped, it will go
to sleep until it is mapped again.
X RESOURCES
xdaliclock understands all of the core resource names and classes as
well as:
mode (class Mode)
Whether to display 12-hour or 24-hour time. If 12, this is the
same as the -12 command line argument; if 24, this is the same
as -24.
datemode (class DateMode)
Specifies how the date should be printed when a mouse button is
held down. This may be one of the strings mm/dd/yy, dd/mm/yy,
yy/mm/dd, yy/dd/mm, mm/yy/dd, or dd/yy/mm. The default is
mm/dd/yy. If seconds are not being displayed, then only the
first four digits will ever be displayed (mm/dd instead of
mm/dd/yy, for example.)
seconds (class Seconds)
Whether to display seconds. If true, this is the same as the
-seconds command line argument; if false, this is the same as
-noseconds.
cycle (class Cycle)
Whether to do color cycling. If true, this is the same as the
-cycle command line argument; if false, this is the same as
-nocycle.
font (class Font)
The same as the -font command line option: the font to melt.
If this is one of the strings BUILTIN0, BUILTIN1, BUILTIN2, or
BUILTIN3, then one of the large builtin fonts will be used.
Otherwise, this must be the name of a valid X font.
fullScreen (class FullScreen)
The same as the -fullscreen command-line option.
root (class Root)
The same as the -root command-line option.
visualID (class VisualID)
The same as the -visual command-line option.
transparent (class Transparent)
Whether to make the window’s background be transparent, if
possible. If true, this is the same as the -transparent
command line argument; if false, this is the same as
-nontransparent.
memory (class Memory)
This must be high, medium, or low, the same as the -memory
command-line option.
countdown (class Countdown)
Same as the -countdown command-line option.
ENVIRONMENT
DISPLAY
to get the default host and display number.
XENVIRONMENT
to get the name of a resource file that overrides the global
resources stored in the RESOURCE_MANAGER property.
TZ to get the current time zone. If you want to force the clock to
display some other time zone, set this variable before starting it.
For example:
sh: TZ=GMT0 xdaliclock
csh: ( setenv TZ PST8PDT ; xdaliclock )
You may notice that the format of the TZ variable (which is used by
the C library ctime(3) and localtime(3) routines) is not actually
documented anywhere. The fourth character (the digit) is the only
thing that really matters: it is the offset in hours from GMT. The
first three characters are ignored. The last three characters are
used to flag daylight savings time: their presence effectively adds
1 to the zone offset. (I am not making this up...)
BUGS
Other system load will sometimes cause the second-display to increment
by more than one second at a time, in order to remain synchronized to
the current time.
The -memory option is disgusting and shouldn’t be necessary, but I’m
not clever enough to eliminate it. It has been said that hacking
graphics in X is like finding sqrt(pi) with roman numerals.
When using a small font (less than 48x56 or so) it’s possible that
shipping a bitmap to the server would be more efficient than sending a
DrawSegments request (since the endpoints are specified using 16 bits
each, when all that we really need is 6 or 7 bits.)
Support for the Shared Memory Extension would be a good thing.
It should display the day of the week somewhere.
The color cycling should be less predictable; it should vary saturation
and intensity as well, and should be more careful that foreground and
background contrast well.
The correct default datemode should be extracted from the current
locale.
Should have a -analog mode (maybe someday...)
UPGRADES
The latest version can always be found at
http://www.jwz.org/xdaliclock/
There is a version of this program for PalmOS available there as well.
SEE ALSO
X(1), xrdb(1), xlsfonts(1), xclock(1), dclock(1), oclock(1), tclock(1),
xscreensaver(1)
COPYRIGHT
Copyright © 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2002
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.
AUTHOR
Jamie Zawinski <jwz@jwz.org>, 18-sep-91.
Please let me know if you find any bugs or make any improvements.
Thanks to Ephraim Vishniac <ephraim@think.com> for explaining the
format of the bitmap resources in the Macintosh version of this, so
that I could snarf them for the -builtin3 font.
And thanks to Steve Capps for the really great idea.