NAME

       nsdejavu - DjVu browser plugin

SYNOPSIS

       /usr/lib/x86_64-linux-gnu/mozilla/plugins/nsdejavu.so

DESCRIPTION

       The shared library nsdejavu.so uses the Netscape browser plugin API to display DjVu images
       in in a number of popular web browsers.  Different web browsers provide various  level  of
       support   for   Netscape  plugins.   Please  check  section  "Browser  Compatibility"  for
       instructions on how to enable the DjVu browser plugin.

       The DjVuLibre browser plugin works by  invoking  a  standalone  viewer  with  the  special
       command line option -netscape.  The plugin first searches a program named djview.  If this
       program cannot be found, it searches for  djview4  and  finally  djview3.   It  is  always
       possible  to  override this search strategy by setting the environment variable NPX_DJVIEW
       to the full path of the desired executable.

MIME TYPES AND EXTENSIONS

       Typing the URL of a recognized DjVu document in  your  web  browser  should  automatically
       invoke  the  DjVu browser plugin.  Each browser uses different methods to determine that a
       particular URL is in fact a DjVu document.  Web server normally provide a MIME type to web
       browsers.  The official MIME type for DjVu documents is image/vnd.djvu.  For compatibility
       with ancient versions of the DjVu viewer, it is common to  use  instead  the  experimental
       MIME  type  image/x-djvu  or  image/x.djvu.   Web servers should be configured to send the
       proper MIME type for DjVu documents.  Most web browsers also recognize files  ending  with
       .djvu or .djv as DjVu files.

       An  easy way to check if an http server is giving an appropriate content-type is to invoke
       the following command with a URL corresponding to an actual DjVu file on the server.

         curl -u URL | grep Content-Type

       The result should be one of the following, preferably the first.

         Content-Type: image/vnd.djvu
         Content-Type: image/x.djvu
         Content-Type: image/x-djvu

       Any other MIME type indicates a server misconfiguration.

CGI-STYLE FLAGS

       The behavior of the DjVu browser plugin can be specified by augmenting  the  URL  using  a
       syntax  similar  to  that  used  by  the  CGI  programs.   This syntax is described by the
       following template:

          http://.../file.djvu?djvuopts&keyword=value&keyword=value&...

       The DjVu browser plugin only recognizes keywords that appear after the word djvuopts.  The
       keywords recognized by each viewer are listed in the corresponding man page.  Unrecognized
       keywords are ignored.  The most common keywords are:

       page=pagename
              Specify which page is displayed by name or by ordinal number.

       zoom=zoomfactor
              Set the zoom factor.  Legal values for zoomfactor are:

                           ┌───────────────────────────────────────────────────────┐
                           │number    Magnification factor in range 10% to 999%.   │
                           │one2one   Select the "one-to-one" mode.                │
                           │width     Select the "fit width" mode.                 │
                           │page      Select the "fit page" mode.                  │
                           │stretch   Stretch the image to the plugin window size. │
                           └───────────────────────────────────────────────────────┘

BROWSER COMPATIBILITY

       The DjVu browser plugin has been tested with several popular web browsers: Netscape 4  and
       6;  Gecko based browsers such as Mozilla, Galeon and Firefox; KHTML based browsers such as
       Konqueror; and Opera.  Please read the browser documentation to find out where the  plugin
       library should be installed.

EMBEDDING DJVU IMAGES IN HTML PAGES

       You can integrate DjVu content on an HTML web page with either the <embed> or the <object>
       tag.  This method will work even if your web server does not support the DjVu  MIME  type.
       The  CGI  style  flags  can  be  directly  used  as  attributes of the embedding tag.  The
       following example shows the W3C standard syntax with the OBJECT tag:

          <object data="myfile.djvu" type="image/vnd.djvu"
                    width="100%" height="100%" >
              <param name="page" value="iii">
              <param name="zoom" value="stretch">
              This browser cannot render djvu data.
          </object>

       And this is the customary syntax with the EMBED tag:

          <embed src="myfile.djvu" type="image/vnd.djvu"
                    width="100%" height="100%"
                    page="iii" zoom="stretch"></embed>

INTERFACING THE DJVIEW PLUGIN WITH JAVASCRIPT

       Recent versions of the djview4 plugin can be controlled from the JavaScript interpreter of
       browsers implementing the Mozilla NPRuntime API.  To access the plugin object, include the
       attribute id="pluginname" into the <object> or <embed> tag and use the JavaScript function
       getElementById("pluginname").

       The  plugin  object  implements  two  methods to retrieve and set the value of the options
       usually recognized as CGI-style flags.   It  also  can  evaluate  a  specified  JavaScript
       expression whenever something changes in the status of the djview interface.

       pluginobject.setdjvuopt("key",value)
              Set  the value of the djvu option key to the character string value.  This achieves
              the same effect as specifying option key=value  among  the  CGI-style  flags.   For
              instance,  values  of  the  key page can be page IDs, page titles, page numbers, or
              page names.

       pluginobject.getdjvuopt("key")
              Return the value of the djvu option key as a string.  The returned value is  always
              a character string, even when the return is logically a number.  Boolean values are
              returned as strings yes or no.  Besides the usual CGI-style  flags,  this  function
              recognizes  the  additional  key pages and returns the total number of pages in the
              DjVu document.  An empty string is returned when the key is not recognized.

       pluginobject.onchange="code";
              Ensure that string code is evaluated in the context of the plugin  object  whenever
              something  changes  in  the  djview  graphical  user interface.  For instance, this
              evaluation happens when progressive refinements are  painted,  and  when  the  user
              manipulates the image interactively.

       pluginobject.version
              Return  a  string describing the plugin version.  This property can be used to test
              whether the djview plugin is scriptable in this browser.

       Note that the scriptability feature may not be accessible until the djview plugin is fully
       loaded.   Therefore  it  is  advisable  to  check pluginobject.version from the JavaScript
       onload before calling any other method.

CREDITS

       This program was  written  by  Andrei  Erofeev  <andrew_erofeev@yahoo.com>  and  was  then
       improved     by     Bill     Riemers    <docbill@sourceforge.net>    and    Léon    Bottou
       <leonb@users.sourceforge.net>.

SEE ALSO

       djvu(1), ddjvu(1), djview4(1)