xdaliclock - Man Page

melting digital clock


xdaliclock [-toolkitoption ...] [-option ...]


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.


xdaliclock accepts all of the standard toolkit options, and also accepts the following options:


Print a brief summary of the allowed options on the standard error output.


Use a twelve hour clock.


Use a twenty-four hour clock.


Update every second.


Update once per minute; don't display seconds at all.


Do color-cycling.


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.


This is the same as specifying -font BUILTIN0.


This is the same as specifying -font BUILTIN1.

-builtin2 or -builtin

This is the same as specifying -font BUILTIN2.


This is the same as specifying -font BUILTIN3.


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.


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:


Use the screen's default visual (the visual of the root window.)   This is the default.


Use the visual which supports the most writable color cells.


One of StaticGray, StaticColor, TrueColor, GrayScale, PseudoColor, or DirectColor.  Selects the deepest visual of the given class.


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.


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.)


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.


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.


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.



to get the default host and display number.


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


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...)


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...)


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)


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.


11-Sep-2002 X Version 11