Translating and Customizing CUPS

Thanks to its extensive use of templates, images, and message catalogs, CUPS can be easily translated (or customized!) to suit your needs. This help file will guide you through the CUPS localization files so you can get the most out of it.

Getting Started

Start by downloading the CUPS source code from www.cups.org. After you extract the files from the source archive (or clone the Git repository), you will want to copy the following files and directories:

• desktop/cups.desktop - the GNOME/KDE desktop file pointing to the CUPS web interface
• doc/index.html.in - the web interface home page
• locale/cups.pot - the message catalog
• templates/*.tmpl and templates/header.tmpl.in - the web interface template files

With the exception of the message catalogs and desktop file, localization files are placed in subdirectories under the doc and templates using the locale name. Locale names are either ll or ll_CC, where "ll" is the 2-letter language code and "CC" is the 2-letter country code. CUPS does not currently use or support the newer ll-region syntax for locale names.

All non-image files must be encoded using the UTF-8 character set.

Submitting a Translation for CUPS

To submit a translation for inclusion in CUPS, translate the desktop file, all of the template files, the index.html.in file, and the message catalog. Place these files in the correct subdirectories in the CUPS source code archive and run the following command to create an archive with your files:

tar cvf ll_CC.tar.gz desktop/cups.desktop doc/ll_CC locale/cups_ll_CC.po templates/ll_CC

Replace "ll_CC" with the locale name for your translation. Once you have created the archive, go to the CUPS project page and submit a bug report, attaching the translation to the report.

Alternately, you can clone the CUPS project on Github, make your changes, and submit a pull request from the same link.

The Desktop File

The desktop/cups.desktop file provides a link to the CUPS web interface from desktop environments such as GNOME and KDE. To translate this file, add two lines to the bottom with the Name and Comment keys:

Name[ll_CC]=Translation of "Manage Printing"
Comment[ll_CC]=Translation of "CUPS Web Interface"

The Home Page

The index.html.in file is a complete HTML file that is displayed when the user visits "http://localhost:631/". Edit the existing doc/index.html.in and save it in the doc/ll_CC subdirectory so that the configure script can generate it. After configuring, run "make install" in the doc subdirectory to test the new home page.

Message Catalogs

CUPS message catalogs are GNU gettext ".po" text files that provide a list of localized message strings for the CUPS software. Message catalogs are named cups_ll.po or cups_ll_CC.po, where "ll" is the standard 2-letter abbreviation for the language and "CC" is the standard 2-letter abbreviation for the country.

When translating a new message catalog, copy the cups.pot message catalog file in the locale subdirectory of the CUPS source code. For example, to start translating the message catalog to Canadian French, you would type the following commands:

cd locale
cp cups.pot cups_fr_CA.po

Alternatively, you can copy the existing cups_fr.po message catalog and then make any necessary changes.

Once you have make your copy of the file, edit it using your favorite text editor or translation program to translate the text to the desired language.

Then validate your translation using the locale/checkpo utility:

cd locale
./checkpo cups_ll_CC.po

After fixing any errors in your translation, add your locale to the LANGUAGES variable in the Makedefs file and run the "make install" command in the locale subdirectory to test the translation. This variable is automatically updated when you run the configure script.

Template Files

The CUPS scheduler provides a web interface that can be used to do many common printing and administration tasks. The built-in web server supports localization of web pages through the use of subdirectories for each locale, e.g. "fr" for French, "de" for German, "fr_ca" for French in Canada, and so forth.

Template files are HTML files with special formatting characters in them that allow substitution of variables and arrays. The CUPS CGI programs (admin.cgi, classes.cgi, help.cgi, jobs.cgi, and printers.cgi) use these template file to provide dynamic content for the web interface. Template files are installed in the /usr/share/cups/templates directory by default. Table 1 lists the various template files and their purpose.

Translated versions of the template files should be saved in the templates/ll_CC subdirectory. For example, Canadian French template files should be saved in the templates/fr_CA subdirectory. After you have translated all of the templates, add the locale to the LANGUAGES variable in the Makedefs file and run "make install" in the templates subdirectory to test the translation.

Inserting Attributes and Values

Template files consist of HTML with variable substitutions for named inside curly braces "{name}". Variable names are generally the IPP attribute names with the hyphen ("-") replaced by the underscore ("_") character. For example, the job-printer-uri attribute is renamed to job_printer_uri.

Curley braces ("{" and "}") to indicate substitutions, and the backslash ("\") character for quoting. To insert any of these special characters as-is you need to use the HTML &name; mechanism or prefix each special character with the backslash ("\".)

You substitute the value of a variable using {NAME} in your template file. If the variable is undefined then the {NAME} string is output as-is.

To substitute an empty string if the variable is undefined, use {?NAME} instead.

Array Substitutions

The number of array elements can be inserted using {#NAME}. If the array is undefined then 0 is output. The current array element (starting at 1) is inserted with {#}.

Arrays are handled using {[NAME] at the beginning of a section and } at the end. The information between the closing bracket ("]") and closing brace ("}") is repeated for as many elements as are in the named array. For example, the following template will display a list of each job in the job_id array:

<TABLE>
<TR>
	<TH>Job ID</TH>
	<TH>Destination</TH>
	<TH>Title</TH>
</TR>

{[job_id]
<TR>
	<TD>{?job_id}</TD>
	<TD>{?job_printer_name}</TD>
	<TD>{?job_name}</TD>
</TR>
}
</TABLE>

Arrays can be nested, however all elements within the curly braces ("{" and "}") are indexed using the innermost array.

Conditional Tests

Templates can also test variables against specific values and conditionally include text in the template. The format is:

{variable?true:false}
{variable=value?true:false}
{variable!value?true:false}
{variable<value?true:false}
{variable>value?true:false}

where true is the text that is included if the condition is true and false is the text that is included if the condition is false. A value of # is replaced with the current element number (starting at 1.) The character after the variable name specifies the condition to test. Table 2 shows the available test conditions.

What to Localize in a Template File

Because HTML contains both markup (that generally is not localized) and text (which is localized), you should carefully avoid changing the markup unless it contains human-readable text. The following HTML examples show how to correctly localize template files:

<!-- English table heading -->
<table class="list" summary="Printer List">

<!-- Correctly localized to French; the class attribute is unchanged but summary is localized -->
<table class="list" summary="Liste des imprimantes">


<!-- English hyperlink -->
<li><a {SECTION=help?class="active" :}href="/help/">Help</a></li>

<!-- Correctly localized to Danish; the href attribute is unchanged while the link text is localized -->
<li><a {SECTION=help?class="active" :}href="/help/">Hjælp</a></li>

CGI Programs

CUPS uses five CGI programs to manage the dynamic web interfaces:

• admin.cgi
• classes.cgi
• help.cgi
• jobs.cgi
• printers.cgi

Each CGI program accepts standard form variables such as OP for the operation to perform, PRINTER_NAME for the printer or class name to operate on, QUERY for any search words,FIRST for the first class, job, or printer to display, and ORDER to control the order that classes, jobs, or printers are displayed.

In addition, the classes.cgi, jobs.cgi, and printers.cgi programs support a WHICH_JOBS variable to control which jobs are displayed. Table 3 lists the supported values.

admin.cgi

The admin.cgi program handles all of the printer and class administration functions and is run for all direct accesses to the /admin resource. For most operations it uses the PRINTER_NAME and OP form variables to specify the action requested. Table 4 shows the supported OP values.

classes.cgi

The classes.cgi program is responsible for listing class information, including jobs destined for that class. It is for all direct accesses to the /classes resource and supports the optional form variables OP and WHICH_JOBS. If no form variables are supplied then the CGI lists all or a specific class and the active jobs on each class. Table 5 shows the supported OP values.

help.cgi

The help.cgi program handles all of the on-line help functions and is run for all direct accesses to the /help resource.

jobs.cgi

The jobs.cgi program handles all of the job functions and is run for all direct accesses to the /jobs resource. For most operations it uses the JOB_ID, OP, and WHICH_JOBS form variables to specify the action requested. Table 6 shows the supported OP values.

printers.cgi

The printers.cgi program is responsible for listing printer information, including jobs destined for that printer. It is for all direct accesses to the /printers resource and supports the optional form variables OP and WHICH_JOBS. If no form variables are supplied then the CGI lists all printers or a specific printer and the active jobs on that printer. Table 7 shows the supported OP values.