LED Sign 3.1
Updated: August 11, 1996
Self-test and demonstration Page
If you don't read anything else, read the section
This is a packaged applet.
About LED Sign V3.1
In Spring 1996, Darrick Browne, the original author of LED Sign,
announced that he would no longer support the applet. I had given
Darrick some code snippets and suggestions, for which he credited me
in the sources (thanks, Darrick!). Since I make active use of LED Sign
at my site, I decided to take the code and run with it. This is my first
release of LED Sign. If you are interested in what I have done since
version 2.7, see Changes since V2.7.
My time is devoted primarily to the
O'Reilly WebSite Web Server. I get an enormous amount of
email, and I read a dozen or so usenet newsgroups and mailing lists.
Bottom line is that I cannot provide technical support for this
package. I hope you can understand. Darrick has provided a reasonably
complete set of documentation files, to which I have added to make them
represent V3.1. Like Darrick, I will delete any email I receive asking
for technical support. If you have questions about how to set up an
applet, check the java site at http://www.javasoft.com/. If you have
other problems, I would suggest checking the usenet newsgroups
I will continue to improve LED Sign so if you have any bug
reports or suggestions, please let me know.
- Script controlled, multiple scripts may be chained together
- Colored text (red, orange, yellow, green, cyan, blue, purple, and white)
- Variable fonts, transitions, and LED size
- Displays the current time/date
- Scripts may be fed through server-side include processor for
- URL links - takes you to another page if you click on the sign
while a certain message is being displayed
- Separate border color when current message has a URL link
- Frame/Window targets on URL links - Use LED Sign with your
frames and windows
This applet was designed to be "user friendly". Everything you see
the sign displaying is run entirely by a script. LED Sign will
provide errors and warnings in the Java console of your browser to
help make the setup easier and quicker.
More on the
Here is the Demo script that the sign
above is running.
The LED applet also has a large amount of flexibility. The size, size
of border, color of border, size of the LED's, and even the font that
the sign uses are all configurable. The size and border parameters
can be easily set in the applet "command line" in the HTML. The font
is specified by a data file that contains the shape for each letter.
The font data file can have as many or few characters as needed. If a
character is used in the message but is not in the font data file,
then it will be substituted by a space.
Examples of LED Sign
Here are some sites that use LED Sign on their pages.
Download LED Sign V3.1
Read the insallation document
INSTALL.txt. This is a packaged applet, something you probably haven't yet
seen. Installing it requires you to make some decisions about where you
are going to store globally named classes and packages.
Download the ZIP file LEDSign31.zip, or the
Unix tar/gz file LEDSign31.tar.gz
If you are running Win95/NT you might need
to unzip and untar the archive. WinZip will retain the long filenames
which are needed for the applet to work.
The LED Sign V3.1 distribution comes with all source code,
pre-compiled binaries, Symantec Cafe' project files,
example scripts, fonts, and the HTML
documentation you see here.
This is a packaged applet
This is probably the first applet you have seen that is packaged using a
globally unique package name (per the Sun recommendations). The name of
the package is com.dc3.applet.LEDSign. This may drive you crazy
at first. Get used to it. If Java keeps growing in use and the vision is
realized, it will be important that applet and utility class names don't
When you unarchived/unzipped this, it created a directory hierarchy
of com/dc3/applet/ledsign/. This correponds to the package name
of this applet, com.dc3.applet.LEDSign. The CODEBASE parameter
in your APPLET tags must specify the URL of the root directory
that contains the com directory! This is analogous to the
CLASSPATH used when developing (it should also contain this root).
I know this is going to be a pain, but don't shoot the messenger
(me). This is the way things are going to be soon anyway. If others
follow the Sun recommendations for class packaging, you'll end up with a
unified directory hierarchy for classes from anywhere.
If you want some more details, see the INSTALL.TXT document that comes with this kit.
Using the ZIP container
This package contains an uncompressed ZIP file whch contains
all of the LED Sign classes, in their proper directory path hierarchy
for the package name. As of Netscape 3.0b7, you can specify the
archive="<URL path>" parameter in the <APPLET> tag. This causes the
browser to read the ZIP file and get its classes from there. This
permits the applet classes to be loaded much faster.
Check out this cool program by W. Scott Dillman. LED Font will turn any
of your windows TrueType fonts into new LED Sign fonts. So now you can
use Arial, Times, Courier, etc., on LED Sign! It's super easy! If you
use LED Font and like it. Please drop
Scott Dillman a line and thank him
for the great job he did. He deserves it! Also, stop over and check out
YES! I have Windows 3.1/95/NT and I want to
download LED Font V1.1!
Check the LEDSign FAQ.
Self-Test and Demonstration
I have included a fairly thorough
self-test and demonstration page. Try it out!
- Changing the delay parameter does not take effect immediately.
This is clearly a multi-thread synchronization problem. I just
discovered it and will fix it as soon as I get a chance.
Changes since V2.7
- Added separate border color(s) which are used when the current
message has a URL link associated with it. The default colors produce a
3-D blue border (the well-known color for hyperlinked text).
- Added new parameter smooth_leds to draw the LEDs in sizes 3
and 4 as real circles. This is a bit slower, but much prettier. It's quite
usable with the newer JIT engines that come with Netscape 3.0b6 and
later, and Internet Explorer 2.0B3 and later.
- Added Chain directive to the script language, allowing
one script to chain to another.
- Brightened up the default red LED color somewhat. It was too dim on
"accurate" color displays.
- Darkened the "off" LED color somewhat. It was too light on
"accurate" color displays.
- Corrected the suggested value of the 'ht' parameter warning (written
to Java console) when not set to the pixel height of the selected font.
- Turned applet into a Java "package" called
com.dc3.applet.LEDSign. This follows the Java standard for
package names, and will prevent name clashes in the future.
- Additional cleanup of error handling, replacing lots of tested ifs
with structured exceptions. Some of this was required to get the
chain directive to work and to prevent nullPointerException
from being thrown when the script finished. There is more work to do on
this, but the applet is substantially more robust in this regard now.
- Trim trailing whitespace from numbers when reading font files. The
LEDFont utility was leaving trailing blanks on dimensions, which caused
The original LED Sign Java applet is written and Copyright 1995 by
Changes to this applet are written by and Copyright 1996 by
Robert B. Denny