NAME palette - recurrently or randomly displays or selects one file from a
collection of files from within an HTML document. SYNOPSIS
<IMG SRC='/cgi-bin/palette?<file-collection>[+[options]]'>
or
<A HREF='/cgi-bin/palette?<file-collection>[+[options]]'>...</a>;>
where the <file-collection> specifies an address.number.type of
files in the collection and where 'options' includes any order of the
characters [+dhmruw]. Brackets [] are used in this document to denote
optional values and are not used in the actual syntax. AVAILABILITY
http://www.eiu.edu • http://www.ux1.eiu.edu • http://www.pen.eiu.edu
• http://www.research.eiu.edu
DESCRIPTION The script allows web developers to periodically or randomly display
an image from a collection of images in any HTML document. The script
requires all of the images to be located in a common directory, to be
of the same type (e.g. gif or jpeg), and to be named by a format that
includes a common collection name and a unique ID value. OPTIONS Any combination of options is prefixed by a single '+' and includes any
order of the following case-sensitive letters.
++ |
Display the current documentation and disable
all other actions of the script. |
+d |
Daily changes a target file every day of the month
from a sequential selection list. |
+h |
Hourly changes a target file every hour of the 24-hour
day from a sequential selection list. |
+m |
Monthly changes a target file every month of the
year from a sequential selection list. |
+r |
Randomly changes a target file from a sequential
selection list. |
+u |
Minutely (default) changes a target file every minute
of the hour from a sequential selection list. |
+w |
Weekly changes a target file every day of the week
from a sequential selection list. |
USAGE To sequentially display every minute of the hour (the default, same as
the +u option) one of the following four gif-type images, rename each
of the files to have both a common collection name (e.g., palette.ID.gif)
and a unique identification (ID) number placed between the collection
name and file type.
 palette.00.gif
 palette.01.gif
 palette.02.gif
 palette.03.gif
The ID numbers in any collection must begin with a value of zero (0).
Additionally, all ID numbers must be 'padded' with zeros if the total
number of digits in the ID is less than 2. This is why there are extra
zeros in the above filenames. Next, move all of the images into a common
location (directory). Finally, create one of the following image tags
in an HTML document.
<IMG SRC='/cgi-bin/palette?/private/palette.4.gif'>
or
<IMG SRC='/cgi-bin/palette?private/palette.4.gif'>
or
<IMG SRC='/cgi-bin/palette?palette.4.gif'>
Note the differences in the string of characters after the question mark.
The '/private/' string in the first example indicates the collection is
located in a sub-directory at the server's root, whereas the 'private/'
string in the second shows the collection is now located in a sub-directory
at the current location of the HTML document. The absence of a path in
the last example indicates that the collection is located in the same
directory as the current HTML document. In all three cases, the image
collection will begin with 'palette' name and end with a 'gif' type extension.
The number in-between the name and type specifies that there are a total
of four images in the collection for random selection. The first image
must have the name palette.00.gif and the last one will have the name
palette.03.gif. Change the ID number to 2 in the above examples to limit
the selection to just two images (i.e., palette.00.gif and palette.01.gif).
|
recurrently-selected (every minute) image
|
The image above was randomly selected from the collection of four images
that were specified by the first of the three <IMG SRC='...'> tag
examples. Hold down the Shift key and press the Reload (Refresh) button
to see a different random image. This will force the client's browser
to get a new copy of the image from the server instead of using a locally-cached
copy. The process may have to be repeated for the image to change to a
different figure. Creating a random link to one of the following four html-type documents,
rename each of the files to have both a common collection name (e.g.,
palette.ID.html) and a unique identification (ID) number placed between
the collection name and file type.
palette.00.html
palette.01.html
palette.02.html
palette.03.html
The ID numbers in any collection must begin with a value of zero (0).
Additionally, all ID numbers must be 'padded' with zeros if the total
number of digits in the ID is less than 2. This is why there are extra
zeros in the above filenames. Next, move all of the documents into a common
location (directory). Finally, create one of the following anchor tags
in an HTML document.
<A HREF='/cgi-bin/palette?/private/palette.4.html+r'>...</a>
or
<A HREF='/cgi-bin/palette?private/palette.4.html+r'>...</a>
or
<A HREF='/cgi-bin/palette?palette.4.html+r'>...</a>
Note the differences in the string of characters after the question mark.
The '/private/' string in the first example indicates the collection is
located in a sub-directory at the server's root, whereas the 'private/'
string in the second shows the collection is now located in a sub-directory
at the current location of the HTML document. The absence of a path in
the last example indicates that the collection is located in the same
directory as the current HTML document. In all three cases, the document
collection will begin with 'palette' name and end with a 'html' type extension.
The number in-between the name and type specifies that there are a total
of four documents in the collection for random selection. The first document
must have the name palette.00.html and the last one will have the name
palette.03.html. Change the ID number to 2 in the above examples to limit
the selection to just two documents (i.e., palette.00.html and palette.01.html).
randomly-selected
document link
The link above was randomly selected from the collection of four documents
that were specified by the first of the three <A HREF='...'> tag
examples. While at the the 'linked' document, hold down the Shift key
and press the Reload (Refresh) button to see a different random document.
Holding down the Shift key will force the client's browser to get a new
copy of the document from the server instead of using a locally-cached
copy. The process may have to be repeated for the document to change to
a different file. FILES There are no files directly associated with the operation of the script
other than those in the image collection referenced by the developer in
the <IMG SRC='...'> tag. SEE ALSO
CGI Suite (Collection of General Purpose Scripts)
DIAGNOSTICS palette was developed to handle all types of user-, owner-, and server-related
errors. However, the script will send back to the client a 'broken' image
for all errors that are related to nonexistent image files. WARNINGS Using an <IMG SRC='...'> tag that references a non-image collection
will produce a 'broken' image on the client's browser. File selection
is only pseudo-random because the seeding of the random number generator
(srand (time ^ $$)) was chosen for speed. NOTES palette has been tested without problem on Windows NT Workstations with
Netscape Communicator 4.x and Microsoft Internet Explorer 3.x web browsers.
Older versions of these and other browsers that do not support JavaScript
and Cascading Style Sheets will not display the response messages and
documentation as fully designed. This browser limitation, however, has
no effect on the function of the script. BUGS There are no known bugs in the current version. AUTHOR Gerald Charles Wagner. Version 2.0 (Release June 1999). |
