1NSDEJAVU(1)                        DjView-4                        NSDEJAVU(1)
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NAME

6       nsdejavu - DjVu browser plugin
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SYNOPSIS

10       /usr/lib64/mozilla/plugins/nsdejavu.so
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WARNING

14       Using  nsdejavu  as  a plugin in 2020 is very difficult because popular
15       browsers either do not support netscape plugins  (chrome),  or  removed
16       support  for  netscape  plugins  other than flash (firefox).  We regret
17       this decision because djview/nsdejavu is a perfect example of very well
18       behaved plugin that would have been easy to support.
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DESCRIPTION

22       The  shared library nsdejavu.so uses the Netscape browser plugin API to
23       display DjVu images in in a number of popular web browsers.   It  works
24       by invoking a standalone viewer out-of-process with the special command
25       line option -netscape.  The  plugin  first  searches  a  program  named
26       djview.   If  this program cannot be found, it searches for djview4 and
27       finally djview3.  It is always possible to override this search  strat‐
28       egy  by setting the environment variable NPX_DJVIEW to the full path of
29       the desired executable.
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MIME TYPES AND EXTENSIONS

34       Typing the URL of a recognized DjVu document in your web browser should
35       automatically  invoke  the DjVu browser plugin.  Each browser uses dif‐
36       ferent methods to determine that a particular URL is  in  fact  a  DjVu
37       document.   Web  server  normally  provide a MIME type to web browsers.
38       The official MIME type for DjVu documents is image/vnd.djvu.  For  com‐
39       patibility  with  ancient  versions of the DjVu viewer, it is common to
40       use instead the experimental MIME type  image/x-djvu  or  image/x.djvu.
41       Web  servers should be configured to send the proper MIME type for DjVu
42       documents.  Most web browsers also recognize files ending with .djvu or
43       .djv as DjVu files.
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45       An  easy  way  to check if an http server is giving an appropriate con‐
46       tent-type is to invoke the following command with a  URL  corresponding
47       to an actual DjVu file on the server.
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49         curl -u URL | grep Content-Type
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51       The result should be one of the following, preferably the first.
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53         Content-Type: image/vnd.djvu
54         Content-Type: image/x.djvu
55         Content-Type: image/x-djvu
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57       Any other MIME type indicates a server misconfiguration.
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CGI-STYLE FLAGS

62       The  behavior of the DjVu browser plugin can be specified by augmenting
63       the URL using a syntax similar to that used by the CGI programs.   This
64       syntax is described by the following template:
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66          http://.../file.djvu?djvuopts&keyword=value&keyword=value&...
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68       The  DjVu browser plugin only recognizes keywords that appear after the
69       word djvuopts.  The keywords recognized by each viewer  are  listed  in
70       the  corresponding  man  page.  Unrecognized keywords are ignored.  The
71       most common keywords are:
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73       page=pagename
74              Specify which page is displayed by name or by ordinal number.
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76       zoom=zoomfactor
77              Set the zoom factor.  Legal values for zoomfactor are:
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79                  ┌───────────────────────────────────────────────────────┐
80number    Magnification factor in range 10% to 999%.   │
81one2one   Select the "one-to-one" mode.                │
82width     Select the "fit width" mode.                 │
83page      Select the "fit page" mode.                  │
84stretch   Stretch the image to the plugin window size. │
85                  └───────────────────────────────────────────────────────┘
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BROWSER COMPATIBILITY

89       The DjVu browser plugin  has  been  tested  with  several  popular  web
90       browsers:  Netscape  4  and  6;  Gecko  based browsers such as Mozilla,
91       Galeon and Firefox; KHTML based browsers such as Konqueror; and  Opera.
92       Please  read  the  browser  documentation  to find out where the plugin
93       library should be installed.
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EMBEDDING DJVU IMAGES IN HTML PAGES

98       You can integrate DjVu content on an HTML  web  page  with  either  the
99       <embed>  or  the  <object> tag.  This method will work even if your web
100       server does not support the DjVu MIME type.  The CGI style flags can be
101       directly  used as attributes of the embedding tag.  The following exam‐
102       ple shows the W3C standard syntax with the OBJECT tag:
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104          <object data="myfile.djvu" type="image/vnd.djvu"
105                    width="100%" height="100%" >
106              <param name="page" value="iii">
107              <param name="zoom" value="stretch">
108              This browser cannot render djvu data.
109          </object>
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111       And this is the customary syntax with the EMBED tag:
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113          <embed src="myfile.djvu" type="image/vnd.djvu"
114                    width="100%" height="100%"
115                    page="iii" zoom="stretch"></embed>
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INTERFACING THE DJVIEW PLUGIN WITH JAVASCRIPT

118       Recent versions of the  djview4  plugin  can  be  controlled  from  the
119       JavaScript  interpreter  of browsers implementing the Mozilla NPRuntime
120       API.  To access the plugin object, include  the  attribute  id="plugin‐
121       name"  into the <object> or <embed> tag and use the JavaScript function
122       getElementById("pluginname").
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124       The plugin object implements two methods to retrieve and set the  value
125       of  the  options  usually  recognized  as CGI-style flags.  It also can
126       evaluate a specified JavaScript expression whenever  something  changes
127       in the status of the djview interface.
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129       pluginobject.setdjvuopt("key",value)
130              Set  the  value  of  the djvu option key to the character string
131              value.  This achieves  the  same  effect  as  specifying  option
132              key=value  among  the  CGI-style flags.  For instance, values of
133              the key page can be page IDs, page titles, page numbers, or page
134              names.
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136       pluginobject.getdjvuopt("key")
137              Return  the  value  of  the  djvu  option  key as a string.  The
138              returned value is always  a  character  string,  even  when  the
139              return  is  logically  a number.  Boolean values are returned as
140              strings yes or no.  Besides  the  usual  CGI-style  flags,  this
141              function  recognizes  the  additional  key pages and returns the
142              total number of pages in the DjVu document.  An empty string  is
143              returned when the key is not recognized.
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145       pluginobject.onchange="code";
146              Ensure that string code is evaluated in the context of the plug‐
147              in object whenever something changes  in  the  djview  graphical
148              user interface.  For instance, this evaluation happens when pro‐
149              gressive refinements are painted, and when the user  manipulates
150              the image interactively.
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152       pluginobject.version
153              Return  a  string  describing the plugin version.  This property
154              can be used to test whether the djview plugin is  scriptable  in
155              this browser.
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157       Note  that  the  scriptability  feature may not be accessible until the
158       djview plugin is fully loaded.  Therefore  it  is  advisable  to  check
159       pluginobject.version  from  the  JavaScript  onload  before calling any
160       other method.
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CREDITS

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

170       djvu(1), ddjvu(1), djview4(1)
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174DjView-4                           1/4/2007                        NSDEJAVU(1)
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